JP7328003B2 - Manifold for gas supply - Google Patents

Description

The present invention relates to a gas supply manifold having a plurality of nozzles projecting toward a plurality of burners of a combustion device and distributing fuel gas to the plurality of nozzles.

It is known that a combustion device installed in a hot water supply system or a heating system has a plurality of burners and can switch the number of burners for supplying and burning fuel gas according to the required amount of heat. It is Such combustion devices include a gas supply manifold that distributes fuel gas to a plurality of nozzles projecting toward a plurality of burners. A nozzle hole is formed at the tip of each nozzle of the gas supply manifold, and fuel gas is jetted out from the nozzle hole toward the burner.

In a combustion apparatus equipped with such a gas supply manifold, water droplets that condense on the tip of the nozzle after the burner extinguishes may clog the nozzle hole, causing a water seal. Fuel gas does not blow out at the time of ignition, resulting in poor ignition. Therefore, it has been proposed to increase the pressure of the fuel gas applied to the nozzle at the time of ignition (increase the amount of fuel gas supplied) to blow away the water droplets blocking the nozzle hole with the pressure of the fuel gas to eliminate the water seal. (For example, Patent Document 1).

JP 2014-159907 A

However, if the pressure of the fuel gas at the time of ignition is limited and cannot be increased, there is a problem that it is difficult to eliminate the water seal by blowing off the water droplets blocking the nozzle hole with the pressure of the fuel gas.

SUMMARY OF THE INVENTION The present invention has been made in response to the above-mentioned problems in the prior art, and provides a gas supply manifold that can eliminate the water seal of the nozzle even when the fuel gas is at a low pressure at the time of ignition. aim.

In order to solve the above problems, the gas supply manifold of the present invention employs the following configuration. i.e.
A gas supply manifold comprising a plurality of nozzles projecting toward a plurality of burners of a combustion device and distributing fuel gas to the plurality of nozzles,
The nozzle has a tapered shape with a reduced diameter toward the burner, and is formed in a shape having a convex portion that protrudes further toward the tip side,
a nozzle hole through which the fuel gas is ejected toward the burner is open to the convex portion;
In the external shape of the cross section of the nozzle cut along a plane including the central axis of the nozzle, the tapered slope of the convex portion is gentler than the tapered slope of the portion immediately adjacent to the convex portion. In addition, the taper-shaped gradient is bent from the nearest portion to the convex portion without a gradual change.
It is characterized by

When water droplets adhere to the tip of the nozzle, the water droplets become hemispherical due to surface tension and block the nozzle hole. Since the film thickness of the water droplets blocking the nozzle hole becomes thin, it is possible to eliminate the water seal by blowing off the water droplets even with low-pressure fuel gas at the time of ignition.

If the slope of the tapered shape of the convex portion is gentler than the slope of the tapered shape of the portion of the nozzle that is immediately connected to the convex portion, the convex portion protrudes further on the tip side of the tapered nozzle. It is possible to reduce the film thickness of the water droplets blocking the nozzle hole by the amount of protrusion of the convex portion in a state where the water droplets are attached to cover the portion near the tip of the nozzle. Moreover, since the taper-shaped gradient is bent from the nearest portion to the convex portion without a gradual change, a circumferential groove is provided at the base of the convex portion, and water droplets are drawn into this groove from the tip side of the convex portion. can be accumulated in

2 is an explanatory diagram showing an example of a combustion device 2 mounted on the water heater 1; FIG. It is an explanatory view showing the structure of the manifold 20 and the burner 10 of the present embodiment. It is explanatory drawing which expanded and showed the nozzle 21 of a present Example. FIG. 4 is an explanatory diagram showing a state in which a water seal has occurred in the nozzle 21; FIG. 7 is an explanatory diagram showing an example in which the amount of projection of the convex portion 21b of the nozzle 21 is changed; FIG. 4 is an explanatory view showing an example in which a convex portion 21b of a nozzle 21 is formed in a reverse tapered shape that expands in diameter toward the tip; FIG. 4 is an explanatory diagram showing an example in which the outer shape of a nozzle 21 is cylindrical;

FIG. 1 is an explanatory diagram showing an example of a combustion device 2 mounted on a water heater 1. FIG. The combustion device 2 has a plurality of (15 in the illustrated example) burners 10 housed in a combustion chamber 3 . In the combustion chamber 3, a plurality of nozzles 21 for injecting fuel gas toward the burner 10 protrude. A combustion fan 5 for sending the fuel, a spark plug 6 for sending a spark to the burner 10 by high voltage discharge, a flame rod 7 for detecting the flame (ignition) of the burner 10, and the like are provided. Details of the burner 10 and the manifold 20 will be described later using separate drawings. Further, the manifold 20 of this embodiment corresponds to the "gas supply manifold" of the present invention.

A gas passage 15 for supplying fuel gas to the manifold 20 includes a main valve 16 that opens and closes the gas passage 15, and a proportional valve 17 that adjusts the flow rate of the fuel gas supplied to the manifold 20 downstream of the main valve 16. is provided. Further, in the illustrated example, the gas passage 15 is branched into three on the downstream side of the proportional valve 17 in correspondence with the fact that the plurality of (15) burners 10 are divided into three burner groups, A first switching valve 18a for opening and closing a branch passage corresponding to a first burner group composed of three burners 10, and a second switching valve 18a for opening and closing a branch passage corresponding to a second burner group composed of five burners 10. 2 switching valve 18b and a third switching valve 18c for opening and closing a branch passage corresponding to a third burner group composed of seven burners 10 are provided.

In the combustion device 2, the amount of generated heat (hot water supply capacity) can be switched by controlling the opening and closing of the three switching valves 18a, 18b, and 18c to select the burner group that supplies the fuel gas. For example, when the amount of heat required is minimal, only the first switching valve 18a is opened. On the other hand, when the amount of heat required is the maximum, all three switching valves 18a, 18b, 18c are opened. If the amount of heat in between is required, one or two of the three switching valves 18a, 18b, and 18c are appropriately selected and opened.

A heat exchanger 30 is provided above the combustion chamber 3 . A water supply passage 31 is connected to one end of the heat exchanger 30 , and a hot water supply passage 32 is connected to the other end of the heat exchanger 30 . The clean water supplied through the water supply passage 31 is heated in the heat exchanger 30 by heat exchange with combustion exhaust gas from the burner 10 , and then becomes hot water and flows out to the hot water supply passage 32 . The water supply passage 31 is provided with a flow rate sensor 33 for detecting the flow rate of water flowing through the water supply passage 31, and the user of the hot water supply device 1 opens a callan 34 provided in the hot water supply passage 32 to detect the heat exchanger. When water is supplied to the burner 30, the flow rate sensor 33 detects a flow of water equal to or greater than a predetermined flow rate, whereby combustion in the burner 10 is started.

An exhaust port 35 is provided above the heat exchanger 30 . Combustion exhaust from the burner 10 is sent upward by the air blown by the combustion fan 5 , passes through the heat exchanger 30 , and is discharged to the outside of the water heater 1 through an exhaust port 35 .

FIG. 2 is an explanatory diagram showing the structures of the manifold 20 and the burner 10 of this embodiment. First, FIG. 2A shows a perspective view of the manifold 20 viewed from the burner 10 side. The manifold 20 of this embodiment is configured by combining a plate-like main body 22 formed by die casting using an aluminum alloy and a cover plate 23 formed by sheet metal. The main body 22 is provided with a pair of upper and lower nozzles 21 protruding toward the burner 10 from the surface opposite to the surface covered with the cover plate 23, the same number as the burner 10 (15 in this embodiment). . Nozzle holes 21 a are opened at the tips of these nozzles 21 . The detailed shape of the nozzle 21 will be described later using another drawing. Further, below the nozzle 21, the three switching valves 18a, 18b, 18c for opening and closing the three branched passages of the gas passage 15 are provided.

Moreover, the burner 10 of this embodiment is configured by combining a pair of plate-like members formed of sheet metal, and has a flat shape. The burner 10 has a plurality of flame ports 11 at its upper end and a pair of upper and lower gas inlets 12 at its end on the manifold 20 side. A mixing passage 13 connects the gas inlet 12 and the flame port 11 . When the manifold 20 and the burner 10 are installed in the combustion device 2, the pair of upper and lower nozzles 21 of the manifold 20 and the pair of upper and lower gas inlets 12 of the burner 10 are arranged to face each other. Although only one burner 10 is illustrated in FIG. 2(a), the burner 10 is provided corresponding to each pair of the upper and lower nozzles 21. As shown in FIG.

FIG. 2(b) shows a cross-sectional view of the manifold 20 taken along a plane parallel to the burner 10. As shown in FIG. As shown in the figure, a distribution passage 24 is formed between the main body 22 and the cover plate 23 of the manifold 20. In the manifold 20 of this embodiment, three distribution passages are provided corresponding to the three burner groups described above. A passage 24 is formed. Each distribution passage 24 communicates with the gas passage 15 via a gas circulation hole 25, and the three switching valves 18a, 18b, 18c described above open and close the corresponding gas circulation holes 25. As shown in FIG. Therefore, by controlling the opening and closing of the three switching valves 18a, 18b, 18c, it is possible to switch the distribution passage 24 for supplying the fuel gas.

A plurality of nozzles 21 communicate with distribution passages 24 , and when switching valve 18 is opened, fuel gas flowing from gas flow holes 25 is supplied to nozzles 21 through distribution passages 24 . When the fuel gas is ejected from the nozzle 21, it flows into the gas inlet 12 of the burner 10 while sucking combustion air from the surroundings due to the ejector effect, and the fuel gas and the combustion air passing through the mixing passage 13 are mixed. , the mixture gas is combusted at the flame port 11 at the upper end of the burner 10 .

In the combustion apparatus 2 having such a manifold 20, after the burner 10 is extinguished, warm and moist combustion exhaust gas flows back from the heat exchanger 30 side to the manifold 20 side, which may cause dew condensation. If the nozzle hole 21a is clogged with water droplets adhering to the tip of the nozzle 21 and a water seal occurs, the fuel gas will not be ejected at the next ignition, and the corresponding burner 10 will fail to ignite. Therefore, in the manifold 20 of this embodiment, the following configuration is adopted in order to easily solve the problem even when the nozzles 21 are water-sealed.

FIG. 3 is an explanatory diagram showing an enlarged nozzle 21 of this embodiment. First, FIG. 3A shows a perspective view of the nozzle 21 viewed from the burner 10 side. The nozzle 21 of this embodiment projects substantially horizontally toward the gas inlet 12 of the burner 10 in a state where the manifold 20 is installed in the combustion device 2, and the outer diameter decreases toward the tip. It is tapered. A convex portion 21b is integrally formed on the tip side of the nozzle 21, and the nozzle hole 21a is opened in the tip surface 21c of the convex portion 21b.

FIG. 3(b) shows a cross-sectional view of the nozzle 21 cut along a plane including the central axis of the nozzle 21. As shown in FIG. As shown in the drawing, the nozzle 21 has a cross-sectional outline such that an angle θ1 formed by a tangent line (a dashed line in the drawing) on the root side of the projection 21b and a central axis (a dashed line in the drawing) connects with the projection 21b. It is smaller than the angle .theta.2 formed by the tangential line (two-dot chain line in the figure) in the immediate vicinity and the central axis. By doing so, the protrusion 21b protrudes further at the tip of the nozzle 21 . Further, the tip surface 21c of the convex portion 21b is a flat surface substantially perpendicular to the projecting direction (central axis) of the nozzle 21. As shown in FIG.

FIG. 4 is an explanatory diagram showing a state in which the nozzle 21 is water-sealed. The drawing shows a cross section obtained by cutting the nozzle 21 along a plane including the central axis of the nozzle 21 . As a comparison with this embodiment, FIG. 4(a) shows a conventional nozzle 21 that does not have a convex portion 21b on the tip side. A nozzle hole 21a opens in a flat tip surface 21c.

In the illustrated example, water droplets are attached not only to the tip surface 21c of the nozzle 21 but also to the tip side of the tapered outer surface. there is If it is attempted to blow away such water droplets with the pressure of the fuel gas when the burner 10 is ignited to break the water seal, the amount of fuel gas supplied (increasing the opening of the proportional valve 17) will increase the amount of fuel that will be applied to the nozzle 21. It is necessary to increase the gas pressure. However, when the pressure of the fuel gas at the time of ignition increases, a large amount of fuel gas is supplied to the burner 10, which may increase the ignition noise. Therefore, if the pressure of the fuel gas at the time of ignition is limited and cannot be increased, it will be difficult to eliminate the water seal.

On the other hand, as shown in FIG. 4(b), the nozzle 21 of this embodiment has a convex portion 21b protruding further on the tip side. If the amount (radius) of water droplets adhering to the tip of the nozzle 21 is the same, the film thickness of the water droplets blocking the nozzle hole 21a is reduced by the amount of protrusion 21b. Therefore, even if the pressure of the fuel gas is lower, the water droplets can be blown away to eliminate the water seal.

FIG. 5 is an explanatory diagram showing an example in which the projection amount of the convex portion 21b of the nozzle 21 is changed. 5 also shows a cross section obtained by cutting the nozzle 21 along a plane including the central axis of the nozzle 21, as in FIG. In the example shown in FIG. 5(a), the protrusion amount of the convex portion 21b is larger than in the example shown in FIG. 4(b). In this case, assuming that the amount (radius) of the water droplets adhering to the tip of the nozzle 21 is the same, the film thickness of the water droplets blocking the nozzle hole 21a is reduced by the amount of projection of the convex portion 21b. Therefore, it is possible to further reduce the pressure of the fuel gas required for blowing off the water droplets when the burner 10 is ignited.

In addition, in the example shown in FIG. 5(b), the amount of protrusion of the convex portion 21b is larger than that in the example of FIG. Under the condition, the tip surface 21c of the projection 21b protrudes from the hemispherical water droplet, so the nozzle 21 is not water-sealed. In such a situation, a circumferential groove 21d surrounding the distal end surface 21c is provided on the distal end side of the outer surface of the nozzle 21 (connecting portion of the convex portion 21b), and water droplets can be collected in this groove 21d. It can be understood that there is Water droplets are drawn into the grooves 21d from the tip surface 21c, so that the effect of suppressing the occurrence of water sealing of the nozzle 21 can be obtained.

Further, from the viewpoint of providing the nozzle 21 with the circumferential groove 21d for collecting water droplets as described above, the external shape of the convex portion 21b is not tapered with a diameter decreasing toward the tip as shown in FIG. As shown in FIG. 6, it may be inversely tapered so that the diameter increases toward the tip. As a result, the depth of the groove 21d can be ensured, so that the capacity for storing water droplets can be increased.

As described above, in the manifold 20 of this embodiment, the nozzles 21 protruding toward the burner 10 are formed in a shape having a protruding portion 21b which further protrudes toward the tip side. A nozzle hole 21a opens at 21b. As a result, even when water droplets adhere to the tip side of the nozzle 21, the film thickness of the water droplet that becomes hemispherical due to surface tension and closes the nozzle hole 21a is as large as the projected portion 21b. Thinner than without. Therefore, when the burner 10 is ignited, the water droplets can be blown off with fuel gas at a lower pressure to eliminate the water seal.

Although the manifold 20 of this embodiment has been described above, the present invention is not limited to the above embodiment, and can be implemented in various forms without departing from the gist of the invention.

For example, in the above-described embodiment, the outer shape of the nozzle 21 projecting from the manifold 20 toward the burner 10 is tapered toward the tip. However, the outer shape of the nozzle 21 is not limited to a tapered shape, and may be a columnar shape with a constant outer diameter as shown in FIG. A portion 21b may be provided. In such a nozzle 21, even if water droplets adhering to the end face 21e become hemispherical due to surface tension and block the nozzle hole 21a, the protrusion 21b does not have the protrusion 21b (nozzle hole on the end face 21e). 21a is open), the film thickness of the water droplets blocking the nozzle hole 21a is thinner, so that the water droplets can be blown off with fuel gas at a lower pressure to eliminate the water seal.

Further, in the above-described embodiment, the outer shape of the cross section obtained by cutting the nozzle 21 along a plane perpendicular to the projecting direction is circular. However, the external shape of the cross section of the nozzle 21 is not limited to a circular shape, and may be polygonal such as a pentagon or a hexagon.

Further, in the nozzle 21 of the above-described embodiment, the tip surface 21c of the convex portion 21b is a flat surface substantially perpendicular to the direction in which the nozzle 21 protrudes. However, the tip surface 21c of the convex portion 21b is not limited to a flat surface, and may be a spherical surface or a conical surface. However, while the shape of the outer surface and inner surface of the nozzle 21 is formed integrally with the main body 22 of the manifold 20 by die casting, the nozzle hole 21a is often formed later by perforating with a drill, press, or the like. By making the tip surface 21c of the nozzle 21 a flat surface, it becomes easier to drill holes than in the case of a spherical surface or a conical surface, and displacement of the nozzle hole 21a can be suppressed.

DESCRIPTION OF SYMBOLS 1... Water heater, 2... Combustion device, 3... Combustion chamber,
5 Combustion fan 6 Ignition plug 7 Flame rod
DESCRIPTION OF SYMBOLS 10... Burner, 11... Flame port, 12... Gas inlet,
13... Mixing passage, 15... Gas passage, 16... Main valve,
17... Proportional valve, 18... Switching valve, 20... Manifold,
21... Nozzle, 21a... Nozzle hole, 21b... Convex part,
21c... tip face, 21d... groove, 21e... end face,
22...main body, 23...cover plate, 24...distribution passage,
25... Gas circulation hole, 30... Heat exchanger, 31... Water supply passage,
32... Hot water supply passage, 33... Flow rate sensor, 34... Callan,
35... Exhaust port.

Claims (1)

A gas supply manifold comprising a plurality of nozzles projecting toward a plurality of burners of a combustion device and distributing fuel gas to the plurality of nozzles,
The nozzle has a tapered shape with a reduced diameter toward the burner, and is formed in a shape having a convex portion that protrudes further toward the tip side,
a nozzle hole through which the fuel gas is ejected toward the burner is open to the convex portion;
In the external shape of the cross section of the nozzle cut along a plane including the central axis of the nozzle, the tapered slope of the convex portion is gentler than the tapered slope of the portion immediately adjacent to the convex portion. In addition, the taper-shaped gradient is bent from the nearest portion to the convex portion without a gradual change.
A gas supply manifold characterized by:

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