JPH054564B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a forced-air combustion device that supplies combustion air to a burner using a blower, and particularly relates to a forced-air combustion device that supplies combustion air to a burner using a blower. and on mixing improvements.

[Prior Art] In forced-air combustion devices, especially in all-primary air combustion combustion equipment, stable combustion cannot be obtained unless the fuel gas and air are mixed sufficiently, and if the mixing is insufficient. may cause ignition failure or misfire.

For this reason, in order to inject the fuel as far upstream as possible in the air supply path, the fuel is injected within the case of the blower upstream of the mixing chamber, and in order to further achieve sufficient mixing and distribution, a baffle plate is installed in the mixing chamber. It is provided.

[Problems to be Solved by the Invention] However, in recent years, there has been an increasing demand for downsizing, for example in gas water heaters, etc., and as combustion equipment is downsized, the volume of mixing chambers etc. is reduced. Furthermore, since the fuel is supplied to the burner in a short time after it is injected, it is not possible to secure a sufficient mixing space and mixing time after the fuel is injected, unlike in the conventional method, resulting in insufficient mixing.

The present invention aims to further improve the mixing of fuel and air in forced air combustion devices.

[Means for Solving the Problems] The present invention provides a forced air combustion device that supplies combustion air to a burner by a blower including a blower case having an inlet in the direction of the rotational axis of an impeller. A cover member is provided that covers the opening and forms an air supply passage between the blower case and a plurality of downstream sides for distributing and spouting fuel gas supplied from the fuel supply section into the air supply passage. A fuel distribution plate having a fuel jet port and changing the air flow in the air supply passage to the intake port is disposed at a downstream end in the covering member, and a fuel distribution plate in the air supply passage upstream of the fuel distribution plate The technical means is that a plurality of upstream fuel injection ports and a throttle member are arranged on the blower case side to eject fuel gas.

[Operation and Effects of the Invention] In the present invention, an air supply passage is formed between the air supply passage and the blower case by a cover member that covers the intake port, and a plurality of downstream side passages of the fuel distribution plate arranged at the downstream end inside the air supply passage are formed between the air supply passage and the blower case. Fuel gas is ejected from the fuel injection port. In addition, a throttle member and a plurality of upstream fuel jet ports are arranged on the upstream side of the fuel distribution plate in the air supply passage, so that the air passing through the air supply passage is expanded after being throttled by the throttle member. At times, the fuel gas ejected from the upstream fuel nozzle is mixed with the fuel gas, and the fuel distribution plate changes the airflow in the air supply passage to the intake port, and at that time, the fuel gas is mixed with the fuel gas ejected from the upstream fuel nozzle. Fuel gushes out.
Therefore, the fuel gas ejected from the downstream fuel injection port further mixes with the mixture of fuel gas and air, and at the same time, the direction of the mixture passing through the air supply passage changes to It is changed by the dispersion plate and is smoothly guided to the suction port.

As a result, the mixing performance within the limited space of the blower and its upstream portion is improved, and the air-fuel mixture is smoothly guided into the blower case.
Therefore, the air supply passage can be set short, and the equipment can be easily downsized, with less adverse effects on combustibility.

[Example] Next, the present invention will be explained based on examples.

The gas water heater 1 shown in Fig. 2 is equipped with a high-efficiency combustor 2 that is compact and achieves low noise through all primary air combustion.
0, and a supply section 20 that supplies a mixture of fuel gas and air to the combustion section 10.The supply section 20 is equipped with an air supply case 31 that guides air and fuel gas. A heat exchanger 50 is provided, and the entire heat exchanger 50 is housed in a water heater casing (not shown).

In the combustion section 10, a burner plate 12 in the shape of a flat plate made of ceramic and having a large number of flame ports is disposed at the opening at the lower end of a cylindrical combustion case 11, and an exhaust pan 13 is arranged at the opening at the upper end of the combustion case 11. A combustion chamber 14 is formed by the combustion case 11, and an exhaust passage 15 is formed by the exhaust pan 13.

An exhaust port 16 is formed in the exhaust pan 13 to exhaust combustion gas generated in the combustion chamber 14 to the outside. In addition, glass wool 13a is provided on the opposing surfaces inside the exhaust pan 13 to prevent repeated reflections of air vibrations.
is formed and changes its reflection direction.

Here, the inclined surface 13b is formed by fixing several layers of glass wool 13a with an inorganic binder.

A water tube type heat exchanger 50 connected to a water supply source such as a water supply is provided above the combustion case 11, and heats water passing through the interior.

In addition, two sparker electrodes 1 for ignition are provided near the burner plate 12 in the combustion case 11.
7. Frame rod 18 for detecting ignition;
Each is provided with a thermocouple 19 for detecting combustion temperature to correct the air-fuel ratio.

The supply unit 20 includes a mixing case 21 provided below the combustion case 11 and covering the burner plate 12.
and a blower case 22 provided in communication with an inlet 21a at the lower end of the mixing case 21.

The mixing case 21 disperses the air-fuel mixture supplied from the inlet 21a and guides it to the combustion section 10.
A rectifying plate 24 is provided inside the mixing case 21, and the plurality of holes 24a of the rectifying plate 24 disperse and rectify the air-fuel mixture.

As shown in FIGS. 1 and 3, the blower case 22 includes a scroll casing 22a having an approximately short cylindrical shape with one bottom open, and a flat plate portion 23 provided to close the opening of the scroll casing 22a. The blower case 22 is equipped with a blower 25.

An air outlet 22b is provided on the outer periphery of the scroll casing 22a, communicating with the inlet 21a of the mixing case 21 and forming a constant angle with respect to the center of the scroll casing 22a.

The flat plate part 23 is provided with a bullmouth-shaped suction port 23a that protrudes toward the scroll casing 22a at its center, and according to the rotational state of the blower 25, air and fuel gas are sucked in from the suction port 23a, and the air and fuel gas are sucked into the air outlet 22b. It blows out.

A fuel ejection pipe 23b for ejecting fuel gas supplied from the fuel pipe 60 is formed integrally with the flat plate part 23 on the surface of the flat plate part 23, which is the outside of the blower case 22. The spout ports 23c are provided in one row.

Here, among the jet ports 23c arranged in one row, the jet port 2 that is the most upstream side with respect to the blow port 22b of the blower case 22 when the blower 25 is operated is shown.
The diameter of 3c1 is made larger than the diameter of other nozzles 23c, and fuel gas is supplied into the fuel nozzle pipe 23b at the same pressure, so the amount of fuel gas ejected from nozzle 23c1 is greater than that of other nozzles. It will be more than 23c.

The blower 25 includes an impeller 25a inside the blower case 22, and rotates the impeller 25a by a motor 25b provided outside the blower case 22, sucks air and fuel gas through the intake port 23a, and blows the air and fuel gas. The air-fuel mixture is blown out from the outlet 22b and is supplied to the combustion section 10 via the mixing case 21.

Here, the motor 25b is controlled according to the required combustion amount, and the impeller 25b is rotated at a rotation speed according to the control state.
Rotate a to the left as shown in FIG.

An air supply case 31 is installed in the blower case 22 so as to cover the intake port 23a and the fuel injection pipe 23b.
is provided.

The air supply case 31 has an equivalent volume V ₂ , a passage equivalent length l 2 , and an equivalent passage length l _{2 in order to match the natural frequency f 2 of} the supply section 20 with the natural frequency f 1 based on the acoustic characteristics of the combustion section ₁₀ . This is provided to ensure a cross-sectional area _S2 .

The air supply case 31 has a substantially rectangular parallelepiped shape that is open in two directions, with one open part facing the flat plate part 23 of the blower case 22 and the other open part facing the air supply port 31a.
An air supply path 32 that opens downward in the figure and is hermetically joined to the blower case 22 and guides combustion air sucked in from the air supply port 31a and fuel gas ejected into the air supply case 31 to the suction port 23a. It is a covering member of the present invention to be formed.

A fuel supply port 31c is provided through one side wall 31b of the air supply case 31 to be connected to the fuel pipe 60a.

Inside the air supply case 31, as shown in FIG.
The fuel dispersion plate 33 is arranged to be inclined so as to cover the fuel supply port 31c and a part of the inside of the air supply case 31.

The fuel distribution plate 33 has a step in the middle, is airtightly fixed to the inside of the air supply case 31 by packing 34, and forms an inclined surface for smoothly guiding the air-fuel mixture to the intake port 23a. air case 31
and the fuel distribution plate 33 form a fuel distribution chamber 35.

The fuel distribution plate 33 is provided with a plurality of fuel injection ports 33a distributed in a row, and the blower case 2
On the most upstream side of the second outlet 22b, there are several fuel outlets 33b separated from the fuel outlet 33a.
is additionally provided.

Thereby, more fuel gas supplied into the fuel distribution chamber 35 is ejected from the fuel supply port 33b toward the upstream side of the air supply path 32, so that efficient mixing is performed.

This fuel dispersion plate 33 has fuel jet ports 33a, 33b that have different sizes and numbers depending on the type of gas used, and can easily handle different gas types, and can control the fuel supply amount and the fuel gas. and air are mixed properly.

In addition, depending on the type of gas used, the fuel distribution plate 3
3 is replaced, the flat plate portion 23 provided with the fuel jet pipe 23b is also replaced with one having a jet port 23c according to the type of gas.

In the air supply passage 32 on the upstream side of the air supply case 31, the width of the air supply passage 32 is gradually reduced toward the fuel injection pipe 23b so that the air passing therethrough is not disturbed. A diaphragm plate 36 is provided as the diaphragm member of the present invention.

Therefore, the throttle plate 36 forms a ventilate that reduces the cross-sectional area of the air supply passage 32 and once restricts the air passing through the air supply passage 32, so that each injection port 23c of the fuel injection pipe 23b and the fuel Dispersion plate 3
The fuel gas ejected from the three fuel ejection ports 33a, 33b can be mixed well with air.

A damper 38 swingably supported by a shaft 37 is provided in the air supply case 31 near the air supply port 31a. The damper 38 is provided to change the equivalent cross-sectional area S ₂ of the supply section 20 by its swinging motion. , and changes the equivalent cross-sectional area S ₂ .
As a result, when the combustion amount of the combustor 2 is large and the amount of air blown is large, the damper 38 is opened and the equivalent cross-sectional area _S2 becomes large, and when the amount of combustion is small and the amount of air blown is small, the damper 38 is opened. The opening degree of is reduced, reducing the equivalent cross-sectional area _S2 .

The tip 38 on the outer circumferential side when the damper 38 swings
In a part of a, when the equivalent cross-sectional area S ₂ of the supply section 20 becomes the minimum and exhibits the minimum opening degree, the air supply case 3
A protrusion 38b is formed which abuts on the wall portion 31d of 1. As a result, the equivalent cross-sectional area S ₂ of the supply section 20
Even when the tip 3 of the damper 38
An appropriate gap is formed between the air supply case 8a and the wall portion 31d of the air supply case 31, and the necessary amount of air can be supplied.

When the equivalent cross-sectional area S ₂ of the supply section 20 is the minimum, the damper 38 has a protrusion 38b that comes into contact with the wall 31d of the air supply case 31, as shown in FIG. When the equivalent cross-sectional area S ₂ becomes maximum and exhibits the maximum opening, the damper 38
As shown by the two-dot chain line, it is stabilized with an appropriate distance from the diaphragm plate 36.

Further, curved portions 38c and 38d are formed at both ends of the damper 38 in the axial direction to guide the air sucked in and pushing up the damper 38 inward.
These curved portions 38c and 38d prevent the air hitting the damper 38 from escaping to the outside of the curved portions 38c and 38d, making it difficult for dust and the like to adhere to the inner wall surface of the air supply case 31.

Further, bearing portions 38e and 38f of the damper 38
is provided on the flat plate portion 23 side of the blower case 22 with respect to the damper 38 that receives wind pressure, so that a horizontal distance between the center of gravity of the damper 38 and the shaft 37 can be secured;
The rotational moment due to the weight of the damper 38 can always bias the damper 38 in the closed state, and even when the damper 38 is at its maximum opening, airflow can pass between the damper 38 and the throttle plate 36. Therefore, the damper 38 can be stabilized in each case.

Upstream of the wall 31d of the air supply case 31 against which the protrusion 38b of the damper 38 comes into contact, a protrusion 39 that protrudes inward of the air supply case 31 is provided in order to change the direction of the sucked air flow. Due to this protrusion 39, when the damper 38 is in the closed state, air from the air supply port 31a is difficult to hit the 1/3 part from the tip 38a of the damper 38, and when it is fully open, the entire damper 38 is Because air hits the
The opening degree of the damper 38 can be made proportional to the combustion amount.

The shaft 37 is loosely supported at both ends by a cylindrical bearing member 40 made of fluororesin.
0 is fitted and supported within a fitting groove formed in the flat plate portion 23 and the air supply case 31.

A filter 41 made of a metal mesh is provided in the air supply port 31a.

Fuel pipe 60a that guides fuel to fuel supply port 31c
is connected to the fuel injection pipe 23b, and is connected to the fuel injection pipe 23b.
3b is connected to a fuel pipe 60.

A proportional control valve (not shown) that is controlled together with the blower 25 according to the required combustion amount is provided upstream of the fuel pipe 60, and the supply amount is controlled by the proportional control valve in the fuel injection pipe 23b and the fuel supply port 31c. A regulated fuel gas is provided.

The heat exchanger 50 is connected to a water pipe (not shown) that leads water from the water supply, and the water pipe upstream of the heat exchanger 50 is equipped with a water flow control valve, a water flow sensor, and an inlet water temperature thermistor from the upstream side. Further, a hot water outlet temperature thermistor is provided downstream of the heat exchanger 50, and a water faucet (not shown) that is operated by the user is provided at the downstream end.

The gas water heater having the above configuration is controlled by a control device and operates as follows.

When the user sets the hot water temperature using the controller and operates the faucet to start hot water supply, the combustor 2 starts combustion in a predetermined sequence, and the water flows into the heat exchanger 50 using the water flow control valve. The inflow amount of water is adjusted.

Due to the operation of the blower 25, air is supplied to the air supply port 31.
It is sucked in from a.

On the other hand, fuel gas whose supply amount is adjusted by the proportional control valve is ejected from the ejection port 23c of the fuel injection pipe 23b and the fuel injection ports 33a and 33b to the fuel distribution plate 33.

Therefore, since the fuel gas is ejected over a wide area, it mixes well with air.

Here, among the jet ports 23c arranged in a row, the diameter of the jet port 23c1, which is the most upstream side with respect to the blow port 22b of the blower case 22, is larger than the diameter of the other jet ports 23c. spout 2
More fuel gas is ejected from 3c1 than from the other ejection ports 23c.

Similarly, from the fuel supply port 31c to the fuel distribution chamber 35
The fuel gas flowing into the fuel outlet 33a, 3
3b into the air supply passage 32, and the fuel is ejected from the fuel injection port 33.
Since the outlet b is additionally provided on the upstream side of the outlet 22b, the more upstream the outlet, the greater the amount of fuel ejected.

Therefore, it is ejected uniformly from each ejection port 23c,
Furthermore, compared to the case where the fuel is ejected only from the fuel injection port 33a, more mixing time and mixing space can be ensured, so that the mixture with air is better.

On the other hand, the damper 38 swings to each position as follows depending on the amount of air sucked in.

When the combustion amount of the combustor 2 is small and the rotation speed of the blower 25 is between N1 and N2 in FIG.
The damper 38 comes into contact with the wall 31d and exhibits an opening state with the minimum opening area as shown by the broken line A.

The combustion amount is increased and the rotation speed of the blower 25 is increased to N.
Between 2 and N3, the damper 38 exhibits an opening degree that corresponds to the amount of air blown.

When the combustion amount is further increased and the rotational speed of the blower 25 is between N3 and N4, the damper 38 is fully opened.

Therefore, between the minimum opening degree and the maximum opening degree, the equivalent cross-sectional area S ₂ of the supply section 20 changes depending on the combustion amount, so the natural frequency f of the combustion section 10 changes depending on the combustion amount. ₁ , the natural frequency f ₂ of the supply section 20 changes in the same way, so that even if the combustion amount changes, noise can be reduced. Note that at this time, the combustion amount of the combustor 2 changes as shown by the solid line B.

As described above, according to the present invention, fuel gas is ejected from the plurality of ejection ports upstream of the blower, so that it is ejected over a wide range and can be mixed well with air. Further, at this time, since more fuel gas is ejected toward the upstream side, more space and time can be secured for mixing, so that mixing can be further improved.

[Brief explanation of the drawing]

1 to 4 show a gas water heater according to an embodiment of the present invention, FIG. 1 is an exploded perspective view showing the configuration of the supply section, FIG. 2 is a front view showing the schematic structure of the gas water heater, 3 is a side sectional view of the supply section, and FIG. 4 is an exploded perspective view showing the inside of the air supply case. FIG. 5 is a characteristic diagram showing the amount of combustion air supplied by the supply section of the present invention and the opening degree of the damper. In the figure, 2... combustor (forced air combustion device),
12...burner plate (burner), 22... blower case, 23a... suction port, 23c... jet port (multiple upstream fuel jet ports), 25... blower,
25a... Impeller, 31... Air supply case (covering member), 32... Air supply path (air supply passage), 33a... Fuel jetting port (plurality of downstream fuel jetting ports), 36...
Aperture plate (aperture member).

Claims (1)

[Scope of Claims] 1. In a forced-air combustion device that supplies combustion air to a burner by a blower provided with a blower case having an inlet in the direction of the rotational axis of an impeller, the blower covers the inlet. In addition to providing a cover member that forms an air supply passage between the case and the case,
A fuel dispersion device that includes a plurality of downstream fuel jet ports for distributing and ejecting fuel gas supplied from a fuel supply section into the air supply passage, and changing the air flow in the air supply passage to the intake port. A plate is disposed at a downstream end within the cover member, and a plurality of upstream fuel jet ports and a throttle member are disposed for spouting fuel gas to the blower case side in the air supply passage upstream of the fuel distribution plate. A forced air combustion device characterized by: