JPH02169920A - Forced air blasting type combustion equipment - Google Patents

Abstract

PURPOSE:To enable reliable ignition and prevent the generation of abnormal noise on ignition by connecting an air supply duct accommodated to a combustion chamber, providing in an air supply duct a damper that swings according to the air flow generated accompanying the operation of an air blower and changes the opening of the air supply port of the air supply duct, and suppressing the swinging of the damper upon ignition. CONSTITUTION:A damper 38 swingably supported by a shaft 37 near an air supply port 31a inside an air supply case 31, and the damper 38 changes the corresponding sectional area of a supply part 20 by its swinging and swings according to the wind pressure of air sucked from the air supply port 31a accompanying the operation of an air blower 25, and changes the corresponding sectional area. A control device 70 actuates a damper locking device 40 and controls the minimum opening of the damper 38 according to the slow ignition combustion rate at the ignition time. And only an ignition power is supplied to an excitation coil 42a of a solenoid 42 and maintains the opening of the damper 38. Namely, the end of a damper locking bar 43b protrudes in the air supply case 31, and abuts the damper 38 during the operating time of the solenoid 42, and maintains the opening accommodated to the slow ignition combustion rate.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a forced air combustion device equipped with an air blower.
In particular, it relates to improvements to reduce noise during steady combustion and to prevent noise from occurring during ignition.

[Prior Art] In forced-air combustion devices, such as small gas water heaters, in which combustion air is supplied by a blower and combustion occurs within a narrow combustion chamber, noise may be generated due to resonance within the combustor casing. is likely to occur.

The inventors of the present application have discovered that such noise is caused by a mismatch between the natural frequencies f1 and f2 of the combustion section, which consists of a combustion chamber and exhaust passage, and the supply section, which consists of a mixing chamber, a blower casing, etc. Basic measures for prevention and solutions to noise caused by changes in the combustion layer are presented in Japanese Patent Application No. 138030/1982 and Japanese Patent Application No. 138030/1983.
It was already introduced in issue 031.

One way to do this is to connect an air supply duct to the casing of a blower for supplying combustion air in order to increase the volume of the supply section, which was previously small compared to the volume of the combustion section. The natural frequencies f1 and f2 of the supply section are made to match, and the combustion layer is changed to increase the natural frequency f of the combustion section.
1 changes, as a means to make the natural frequency f2 of the supply section correspond to it, a damper is provided in the supply air duct to change the opening degree of the intake port of the supply air duct according to the combustion amount,
The natural frequency f2 of the supply section is changed in accordance with changes in the amount of combustion, thereby preventing noise caused by changes in the amount of combustion.

[Problem to be solved by the invention] However, in general, when igniting combustion equipment, each combustor uses a relatively large amount of gas within the range in which the combustion amount can be changed, in order to ignite reliably and safely. Ignition is performed with a slow ignition combustion amount in the middle of a variable range, for example, and with a large proportion of fuel to the supplied combustion air.

Therefore, in the forced air combustion device equipped with the damper described above, when ignition pressure is generated due to ignition, the damper is biased in the closing direction, and the natural frequency f of the supply section is
2 is lower than the natural frequency f1 of the combustion section.

In addition, in combustion equipment, the initial stage of ignition (cold
Even if combustion is performed with the same amount of combustion during steady combustion (hot) and steady combustion (hot), the flame stability and natural frequency of the combustion equipment will vary.
are different.

Therefore, each natural frequency f1 of the combustion part and the supply part is
Even if the damper opening characteristics are set so that , f2 are the same, in the early stage of ignition, when the damper is biased toward closing by the ignition pressure, the opening of the air supply port changes, causing the supply section to change. The natural frequency f2 and the natural frequency f1 of the combustion part may deviate greatly, causing abnormal noise, especially when
There is a problem in that this is likely to occur during LD.

The present invention provides a forced-air combustion device that does not generate noise even when the combustion amount is changed during steady combustion (hot), ignites reliably at the time of ignition, and does not generate abnormal noises even when ignited. The purpose is to provide.

[Means for Solving the Problems] The present invention connects an air supply duct corresponding to the combustion chamber to a blower casing that accommodates a blower for supplying combustion air to a combustion chamber equipped with a burner. A damper is arranged in the air supply duct to change the opening degree of the air supply port of the air supply duct by swinging according to the airflow generated by the operation of the blower, and the damper is arranged at least when the burner is ignited. The technical means is to provide a damper suppressing means for suppressing the swinging of the damper.

[Operation and Effects of the Invention] In the present invention, since the blower casing is provided with an air supply duct corresponding to the combustion chamber, the natural frequency of the supply section consisting of the blower casing, the air supply duct, etc. Basically, the natural frequency f1 can be made close to the natural frequency f1 of the combustion section consisting of a chamber, an exhaust stack, etc.

In addition, a damper is installed inside the air supply duct, and the opening degree of the air supply port of the air supply duct is changed by the airflow generated by the operation of the blower, so even if the combustion amount is changed, the supply The natural frequency f2 of the combustion section can be changed to correspond to the natural frequency f1 of the combustion section.

Therefore, no noise is generated during normal steady combustion.

Further, when ignition is performed, for example, at an intermediate slow ignition combustion amount within the range in which the combustion amount can be changed, the damper exhibits an opening degree corresponding to the combustion amount in accordance with the operation of the blower. When the internal pressure in the combustion chamber increases due to the ignition pressure as the burner ignites, a force is generated that urges the damper in the C closing direction.

However, the air supply duct is equipped with a damper suppressing means, and in order to suppress the swinging of the damper when the burner is ignited,
Even if the internal pressure in the combustion chamber increases during ignition, the opening degree of the air supply port does not decrease. Therefore, since a considerable cross-sectional area of the opening of the supply section is secured, no noise is generated during ignition.

[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 total air combustion. The supply section 20 is equipped with an air supply case 31 that guides the air and the fuel gas, and a heat exchanger 50 is provided in the combustion section 10. The whole is housed in a water heater casing (not shown).

In the combustion section 10, a burner plate 12 in the shape of a flat ceramic plate 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. The combustion chamber 14 is covered by the combustion case 11 and the exhaust passage 15 is covered by the exhaust pan 13.
are formed respectively.

The exhaust pan 13 contains combustion gas generated in the combustion chamber 14.
An exhaust port 16 is formed to discharge the gas to the outside. Also,
Glass wool 13a is placed on the opposing inner surfaces of the exhaust pan 13 to prevent repeated reflections of air vibrations.
An inclined surface 13b is formed by changing the direction of reflection. 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.

Also, near the burner plate 12 in the combustion case 11, there are two sparker electrodes 17 for ignition, a flame rod 18 for detecting ignition, and a thermocouple 19 for detecting combustion temperature for correcting the air-fuel ratio. are provided for each.

The supply section 20 includes a mixing case 21 provided below the combustion case 11 to cover 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, and a plurality of holes 2 of the rectifying plate 24
4a performs dispersion and rectification of 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.

The scroll casing 22 is connected to the inlet 21a of the mixing case 21 on the outer circumference of the scroll casing 22a.
An air outlet 22b is provided which forms a certain angle with the center direction of the air outlet 22b.

The flat plate part 23 has a scroll casing 22 at its center.
A bellmouth-shaped suction port 23a is provided that protrudes toward the a side, and air and fuel gas are sucked in from the suction port 23a and blown out from the blowout port 22b according to the rotational state of the blower 25.

On the surface of the flat plate part 23 which is the outside of the blower case 22,
A fuel ejection pipe 23b for ejecting fuel gas supplied from the fuel pipe 60 is formed integrally with the flat plate part 23, and a plurality of ejection ports 23c are provided in one row in the fuel ejection pipe 23b.
There is. Here, in order to improve the mixing, among the jet ports 23C arranged in a row, the diameter of the jet port 23c1, which is closest to the air outlet 22b of the blower case 22 when the blower 25 is operated, is set as follows. The diameter is larger than that of the other jet ports 23c.

The blower 25 has an impeller 25a inside the blower case 22.
A motor 2 provided on the outside of the blower case 22
5b rotates the impeller 25a, sucks air and fuel gas through the suction port 23a, blows them out from the blowout port 22b, and supplies the air-fuel mixture 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 5a.

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

In order to match the natural frequency f2 of the supply section 20 with the natural frequency f1 based on the acoustic characteristics of the combustion section 10, the air supply case 31 has an equivalent volume ■2 of the supply section 20 and an equivalent passage length A2. and is provided to ensure an equivalent 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 opening downward in the figure as an air supply port 31a. It is hermetically joined to the blower case 22 and has an air supply port 31a.
An air supply path 32 is formed that guides the combustion air sucked in from the air supply case 31 and the fuel gas ejected into the air supply case 31 to the suction port 23a.

A fuel supply port 31c, which is connected to a fuel pipe 60a, is provided through one side wall 31b of the air supply gas 31, as shown in FIG.

A fuel distribution plate 33 is provided inside the air supply case 31 so as to cover the fuel supply port 31c and a part of the inside of the air supply case 31.
are arranged at an angle.

The fuel distribution plate 33 has a stepped portion in the middle, and the backing 3
4 is airtightly fixed to the inside of the air supply case 31 to form an inclined surface for smoothly guiding the air-fuel mixture to the intake port 23a, and a fuel distribution chamber 35 is formed by the air supply case 31 and the fuel distribution plate 33. do. The fuel distribution plate 33 is provided with a plurality of fuel injection ports 33a distributed in a row, and furthermore, a plurality of fuel injection ports 33a are provided on the most downstream side with respect to the air outlet 22b of the blower case 22, and are separated from the fuel injection ports 33a. Several fuel jets 33
b is provided. As a result, the fuel gas supplied into the fuel distribution chamber 35 is transferred from the fuel injection port 33b to the air supply path 3.
Since a large amount is ejected on the upstream side of No. 2, efficient mixing is performed.

This fuel dispersion plate 33 has fuel injection 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 fuel gas. and air are mixed properly. Note that when the fuel distribution plate 33 is replaced depending on the type of gas, the flat plate portion 23 integrated with the fuel injection pipe 23b is also replaced at the same time.

A fuel injection port 3 is provided on the fuel distribution chamber 35 side of the fuel distribution plate 33.
Along the edge of the fuel gas outlet 33,
A fuel guiding plate 33c for guiding the fuel to a is fixed by spot welding. As a result, even if the amount of fuel gas supplied into the fuel distribution chamber 35 or the gas pressure changes, the fuel gas is smoothly ejected from the fuel jet port 33a, and abnormal sounds such as resonance are not generated when passing through the fuel jet port 33a. do not have.

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.

Therefore, since the throttle plate 36 forms a venturi that reduces the cross-sectional area of the air supply passage 32 and once restricts the air passing through the air supply passage 32, the throttle plate 36 reduces the cross-sectional area of the air supply passage 32 and once restricts the air passing through the air supply passage 32. Each fuel jet port 33a, 3 of the plate 33
The fuel gas ejected from 3b 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 S2 of the supply section 20 by its swinging.
8 operates in accordance with the wind pressure of air sucked in from the air supply port 31a with the operation of the blower 25, and changes the equivalent cross-sectional area S2. 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. becomes smaller, and the equivalent cross-sectional area S2
Make smaller.

When the damper 38 swings, a portion of the tip 38a on the outer circumferential side comes into contact with the inner wall 31g of the air supply case 31 when the equivalent cross-sectional area S2 of the supply section 20 becomes the minimum and exhibits the minimum opening degree. A protrusion 38b is formed. As a result, even when the equivalent cross-sectional area S2 of the supply section 20 is minimized, an appropriate gap is formed between the tip 38a of the damper 38 and the inner wall 31g of the air intake gauge 31, and the necessary amount of air can be removed. can be supplied.

In the damper 38, when the equivalent cross-sectional area S2 of the supply section 20 is minimized, as shown in FIG. When the area S2 becomes maximum and exhibits the maximum opening degree, the damper 38 moves toward the diaphragm plate 3 as shown by the two-dot chain line A.
It stabilizes after a moderate interval of 6.

Further, at both ends of the damper 38 in the axial direction, there are curved portions 3 for guiding the air sucked in and pushing up the damper 38 inward.
8c and 38d are formed.

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, and dust and the like are prevented from escaping from the side walls 31b and 38d of the air supply case 31.
It becomes difficult to adhere to the inner surface of 31d.

Furthermore, since the bearing parts 38e and 38f of the damper 38 are provided on the flat plate part 23 side of the blower case 22 with respect to the damper 38 which receives wind pressure, the horizontal distance between the center of gravity of the damper 38 and the shaft 37 can be ensured. The rotational moment due to the weight of the damper 38 can always bias the damper 38 to the closed state, and even when the damper 38 is at its maximum opening,
Since the air flow can pass between the damper 38 and the diaphragm plate 36, the damper 38 can be stabilized in each case.

The inner wall 31g of the air supply case 31 that the protrusion 38b of the damper 38 comes into contact with is provided with a protrusion 39 that protrudes toward the inside of the air supply case 31 in order to change the direction of the sucked air flow. There is. 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 Since the damper 38 is exposed to air, the opening degree of the damper 38 can be made proportional to the amount of combustion.

Both ends of the shaft 37 are loosely supported by cylindrical bearing members 37a made of fluororesin, and the bearing members 37a are fitted and supported in fitting grooves formed in the flat plate portion 23 and the air supply case 31.

A damper locking device 40 is provided on the outside of the air supply case 31 to limit the minimum opening degree of the damper 38.

The damper locking device 40 includes a solenoid 42 and a solenoid 42 in a casing 41 fixed to the air supply case 31.
A link mechanism 43 driven by a link mechanism 43 is provided.

The solenoid 42 includes an excitation coil 42a and an excitation coil 42.
It consists of a plunger 42b that is driven when power is applied to a.
The plunger 42b is connected to the link mechanism 4 by the driving pin 44.
It is connected to 3.

The link mechanism 43 includes a connecting rod 43a rotatably supported by a support shaft 45, a damper locking rod 43b connected to the connecting rod 43a by a connecting pin 46, and loosely supported in the opening 41a of the casing 41. Consisting of

The tip of the damper locking rod 43b protrudes into the air supply case 31, and is located as shown by the solid line in FIG. In addition, the position of the damper 38 is maintained at an opening corresponding to the slow ignition combustion amount.

This damper locking device 40 is controlled by a control device 70 so that the excitation coil 42 of the solenoid 42 is operated only when the ignition is activated.
a is energized to maintain the opening degree of the damper 38.

A filter 47 made of a metal mesh is provided in the air supply port 31a.

A fuel pipe 60a that guides fuel to the fuel supply port 31c is connected to a fuel jet pipe 23b, and the fuel jet pipe 23b is connected to the fuel pipe 60.
is connected to.

Upstream of the fuel pipe 60, a blower 25 is installed depending on the required combustion amount.
A proportional control valve 61 is provided in the fuel injection pipe 23b and the fuel supply port 31C.
1, the fuel gas whose supply amount is adjusted is supplied.

The heat exchanger 50 is connected to a water pipe (not shown) that leads water from the water supply, and the water pipe of the heat exchanger 50 is equipped with a water flow control valve, a flow 1 sensor, and a large water temperature thermistor from the upstream side. Further, a hot water 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 control device 70 controls the combustion amount of the combustor 2 by controlling the blower 25, the proportional control valve 61, etc., based on detection signals from a flow rate sensor, an inlet water temperature thermistor, etc. (not shown), and a temperature set by the controller 71. do.

Further, the control device 70 controls the sparker electrode 1 at the time of ignition.
7. Solenoid valve (not shown), blower 25 and proportional control valve 6
1, the damper locking device 40 is operated to lock the damper 3.
The minimum opening degree of No. 8 is limited according to the slow ignition combustion amount.

The gas water heater 1 having the above configuration operates as follows.

When the user sets the hot water temperature using the controller 71 and operates the faucet to start hot water supply, the combustor 2 starts combustion in a predetermined sequence, and the water flow into the heat exchanger 50 is controlled by the water flow control valve. The amount of water inflow is adjusted.

When the blower 25 is controlled to a slow ignition speed and air is sucked in from the air supply port 31a by its operation, the damper 3
8 changes the opening degree according to the amount of air supply.

At this time, the excitation coil 42a of the solenoid 42 is energized to drive the plunger 42b.

Accordingly, in the damper locking device 40, the plunger 4
Link mechanism 43 connected by drive pin 44 at the tip of 2b
operates, and the damper locking rod 43b is activated via the connecting rod 43a.
enters the air supply case 31 and comes into contact with the damper 38, and the damper locking rod 43b and the damper 38 are positioned as indicated by two-dot chain lines C and B in FIG.

Therefore, the damper 38 exhibits an opening degree corresponding to the slow ignition combustion amount as the minimum opening degree, regardless of the air flow caused by the operation of the blower 25.

On the other hand, the proportional control valve 6
1, fuel gas whose supply amount is adjusted for slow ignition is ejected, the fuel gas is ejected over a wide range, and mixes well with air.

When a spark discharge is performed as an ignition operation at the sparker electrode 17, the air-fuel mixture supplied into the combustion chamber 14 is ignited, and at this time, ignition pressure is generated.

This ignition pressure tends to bias the damper 38 in the closing direction, but since the minimum opening degree of the damper 38 is limited by the damper locking rod 43b of the damper locking device 40, the damper 38 has a slow ignition combustion amount. It is possible to maintain an opening corresponding to .

Therefore, the natural frequency f2 of the supply section 20 matches the natural frequency f1 of the combustion section 10, so that no abnormal noise is generated during ignition.

When ignition is detected by the flame rod 18, the energization to the excitation coil 42a is stopped, the damper locking device 40 finishes locking the damper 38, and the damper locking rod 43b and the damper 38 are moved as shown in FIG. Return as shown by the solid line.

Thereafter, the damper 38 swings to each position as follows according to the sucked air 1.

The combustion amount of the combustor 2 is small, and the rotation speed of the blower 25 is the fifth.
In the figure, between N1 and N2, the damper 38 comes into contact with the inner part 9131g and exhibits an opening state where the opening area is the minimum, as shown by the broken line A.

When the combustion amount is increased and the rotation speed of the air blower 8125 is between N2 and N3, the damper 38 exhibits an opening degree that corresponds to the air blow amount.

The combustion amount is further increased, and the rotation speed of the air blower 125 is increased to N.
Between 3 and N4, the damper 38 is fully open.

Therefore, between the minimum opening degree and the maximum opening degree, the equivalent cross-sectional area S2 of the supply section 20 changes depending on the combustion amount, so the fuel j
P, as the natural frequency f1 of the combustion section 10 changes depending on the amount, the natural frequency f2 of the supply section 20 changes in the same way, reducing noise even if the amount of combustion changes. can be done. 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, no abnormal sound or noise is generated during ignition or steady combustion, and a low-noise combustion device can be achieved.

FIG. 6 shows a second embodiment of the present invention.

Here, a viscous damper 80 having a damping force that does not impede the swinging of the damper 38 is connected to the damper 38.

The viscous damper 80 has a piston 82 arranged inside a cylinder 81, a silicone oil 83 filled in the cylinder 81, and a connecting pin for connecting with the damper 38 at the tip of a drive shaft 84 that moves together with the piston 82. 85 are provided.

Correspondingly, in the damper 38, a sliding portion 38g is provided integrally with the damper 38, a sliding groove 38h is formed in the sliding portion 38g, and a connecting pin at the tip of the drive shaft 84 is formed in the sliding groove 38h. 85 is loosely fitted. The piston 82 has a flow hole 82a.
is formed, and movement within the cylinder 81 is suppressed by the viscosity of the silicone oil 83.

In the viscous damper 80, the damping force is proportional to the movement speed of the piston 82, so when a sudden pressure is applied, a large damping force is generated.

Therefore, a large braking force is generated only when a sudden kinetic force is applied to the damper 38 and acts on the piston 82 via the drive shaft 84, such as when the combustion section 10 is ignited. When the damper 38 exhibits a gentle change such as during normal rocking, the damper 38 is displaced in accordance with the airflow passing through the air supply case 31 because the damping force is small.

Therefore, the damper 38 is braked only at the time of ignition, and its movement can be stopped, and the opening degree corresponding to the slow ignition combustion amount can be maintained in the supply section 20 at the time of ignition.

Therefore, the natural frequency f2 of the supply section 20 matches the natural frequency f1 of the combustion section 10, so that no abnormal noise is generated during ignition.

In the second embodiment, a piston-type viscous damper 80 is used, but the shaft 37 is made to rotate together with the damper 38,
The shaft 37 is connected to a rotating disc type viscous damper, and the damper 3
8 may be provided with a damping force.

Furthermore, a windmill is provided on the shaft 37, and the shaft is connected to the damper 38 with a claw.
A ratchet mechanism consisting of a windmill and a pawl is installed so that the ratchet can freely rotate in the opening direction, but cannot be closed in the closing direction, and when ignition is detected, the pawl is removed from the windmill to eliminate the lock. You can also do this.

In the embodiments described above, the damper 38 is actively provided with a device that suppresses the swinging of the damper 38, but depending on the combustion characteristics of the combustion section 10, the ignition operation is performed at the combustion amount at which the damper 38 exhibits the minimum opening degree. If this is done, the opening degree of the damper 38 will not change.

Therefore, even if the amount of combustion at the time of ignition is changed and the air supply case 31 is used as a damper suppressing means to ignite with the damper 38 in contact with the inner IT 31g, no abnormal noise will be generated at the time of ignition.

[Brief explanation of the drawing]

1 to 4 show a gas water heater according to a first embodiment of the present invention, in which FIG. 1 is a side sectional view of the supply section, FIG. 2 is a front view showing a schematic configuration of the gas water heater, and FIG. The figure is an exploded perspective view showing the configuration 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 relationship between the rotation speed of the blower, the combustion amount, and the opening degree of the damper in the supply section of the present invention, and FIG. 6 is a side sectional view of the supply section showing the second embodiment of the present invention. be. In the figure, 22...Blower case (blower casing),
25...Blower, 31...Air supply case (air supply duct I
-), 38... damper, 40... damper locking device (
damper suppression means>. Figure 4

Claims (1)

[Claims] 1) An air supply duct corresponding to the combustion chamber is connected to a blower casing that houses a blower for supplying combustion air to a combustion chamber equipped with a burner. a damper that swings according to the airflow generated by the air supply duct to change the opening degree of the air supply port of the air supply duct, and damper suppressing means for suppressing swinging of the damper at least when the burner is ignited. A forced air combustion device characterized by being equipped with.