JPH02161211A - Combustion control device - Google Patents

Abstract

PURPOSE:To prevent the generation of abnormal noise directly after ignition, especially during cold time ignition by changing a burner combustion volume into a combustion volume to be decided by a combustion volume decision making means after the lapse of a specified time since an ignition detection means detects the ignition of said burner. CONSTITUTION:When ignition is detected by a flame rod 18 at time 't', a combustion volume Qi during a specified ignition time called for until the temperature of a burner 2 is stabilized, is maintained as illustrated in a solid line A. Therefore, this construction makes it possible to conform the characteristic frequency f2 of a supply section to the characteristic frequency of a combustion section 10 even right after the ignition when the temperature of a burner 2 for a burner plate 12 or the like fails to rise to a satisfactory extent, thereby preventing the generation of noise. Then, at time t3, the combustion volume is changed into a combustion volume to be decided based on a controller 71 or the like. A blower 25 and a proportional control valve 61 are controlled from the above data.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a control device for controlling the amount of combustion in a combustion device equipped with a blower, and in particular aims to reduce noise during steady combustion, and also at the initial stage of ignition. Concerning improvements to prevent noise generation.

[Prior Art] In combustion devices, such as small gas water heaters, in which combustion air is supplied by a blower and combustion is carried out in a narrow combustion chamber, noise is generated by the combustion air inside the combustor casing. Likely to happen.

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 for noise caused when the combustion amount changes are described in Japanese Patent Application No. 63-138030 and Japanese Patent Application No. 63-138.
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 conventionally had a small volume compared to the combustion section. As a means to match the natural frequencies f1 and f2 of the supply section, and also to make the natural frequency f2 of the supply section correspond to the natural frequency f1 of the combustion section even if the combustion amount is changed and the natural frequency f1 of the combustion section changes. , a damper is installed in the supply air duct to change the opening degree of the intake port of the supply air duct according to the combustion amount, and the natural frequency f2 of the supply section is changed according to the change in the combustion amount, thereby reducing the combustion amount. This is to prevent noise caused by changes.

In addition, in general, when igniting combustion equipment, in order to ignite reliably and safely, in a combustor that can change the combustion amount, it is necessary to ignite the fire regardless of the set temperature such as hot water temperature or heating temperature. For example, when ignition is performed with a slow ignition combustion amount in the middle of the range in which the combustion amount can be changed, or with a large ratio of fuel to the supplied combustion air, and ignition is detected, the respective settings are set. The amount of combustion is changed based on the temperature, etc., and combustion is performed.

[Problem to be solved by the invention] However, immediately after ignition, as shown by the broken line C in FIG.
Between ignition time t1 and time t3, the temperature of combustion equipment such as burners is low (approximately 100°C or less), and the temperature of combustion equipment such as burners is low (approximately 100°C or less), and the Because the flame stability of the combustion air is different, even if the combustion is performed with the same amount of combustion, the pressure at the combustion air supply section will be different. Especially when an exhaust extension pipe is connected for exhaust, the exhaust extension pipe, etc. This tendency is strong because the temperature is also low and harsh.

For this reason, in a combustion device equipped with the above-mentioned damper, the fixed vibration frequencies fl and f2 of the combustion section and the supply section are made to match, in order to prevent the generation of noise mainly during steady combustion, which is used for a long time. Even if the damper opening characteristic is given to , the amount of combustion air supplied at the initial stage of ignition, especially at the cold time, will be larger than the supply amount during steady combustion because the temperature of the combustor etc. is low.

Also, the time t1 at the time of ignition and the time t3 when the temperature of the combustor etc. has increased.
If the combustion amount is changed based on the set temperature, etc. at time t2 immediately after ignition (for example, 0.5 seconds after tl) when the temperature of the combustor etc. is not sufficiently high between A large amount of combustion is required for this (excluding re-ignition), and as shown by the broken line in FIG. 5, the amount of combustion becomes large.

Therefore, the natural frequency f1 in the combustion part is determined during the period from time t1 to t3 (for example, 5 seconds or more) until the temperature of the combustor such as a plate rises to a certain degree, for example 100 degrees Celsius. Since there is a large difference between the combustion Jt (combustion temperature), which is a condition, and the combustor temperature, which determines the pressure in the supply section, which is a condition for determining the natural frequency f2 in the supply section, the natural frequency f1 of the combustion section and There is a problem in that the natural frequency f2 of the supply section does not match, and noise such as resonance may occur.

The present invention does not generate noise even when the combustion amount is changed during steady combustion (hot), and ignites reliably at the time of ignition, and generates abnormal noise immediately after ignition, especially when igniting in cold conditions. The purpose of the present invention is to provide a combustion control device that prevents combustion from occurring.

[Means for Solving the Problems] The present invention includes a blower for supplying combustion air to a burner, and a combustion amount determining means for determining the combustion amount of the burner, and when igniting, the combustion amount determining means A combustion control device that performs an ignition operation with a combustion amount that is different from the combustion amount determined by , comprising ignition detection means for detecting ignition of the burner, the ignition detection means detecting ignition of the burner for a predetermined period of time. Later, the technical means is to change the combustion amount of the burner to the combustion amount determined by the combustion amount determining means.

[Operation and Effects of the Invention] In the present invention, the combustion amount of the burner is determined by the combustion amount determining means, but at the time of ignition, a combustion amount different from this combustion amount, for example, an intermediate slow combustion amount within the changeable combustion amount range is determined. This is done with the amount of ignition combustion.

Therefore, by setting the slow ignition combustion amount to a combustion amount that does not generate noise such as resonance even immediately after ignition in a cold state, it is possible to eliminate noise immediately after ignition.

Furthermore, for a predetermined period of time after ignition is detected, combustion continues at the combustion rate at the time of ignition, and the combustion rate does not change during that time, so the air flow does not become unstable. No noise is generated even when the combustor is cold immediately after ignition, when the temperature of the combustor is low.

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

The gas water heater 1 shown in FIG. 1 is equipped with a high-efficiency combustor 2 that is compact and achieves low noise through all-over 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 inside of the exhaust pan 13 facing each other 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 wood-tube heat exchanger 50 connected to a water supply source such as a water supply is provided above the combustion case 11 to heat 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 unit 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 coos 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. 2 and 3, the blower coos 22 includes a scroll casing 22a having a generally 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 portion 23, and a plurality of ejection ports 23c are provided in one row in the fuel ejection pipe 23b.

Here, in order to improve the mixing, when the blower 25 is operated, the blower case 2 is
The outlet 2 which is the most upstream side with respect to the outlet 22b of the outlet 2
The diameter of the spout 3c1 is larger than the diameter 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 rotates the impeller 25a at a rotation speed according to the control state.

The blower coos 22 is provided with an air supply case 31 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 J2. 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 is provided through one side wall 31b of the air supply case 31 to be connected to the fuel pipe 60a.

Further, on each side wall 31b, 31d of the air supply case 31, a fourth
As shown in the figure, a plurality of through holes 31e and 31f are provided in a distributed manner through the inside and outside of the air supply case 31, respectively.

These through holes 31e and 31f are provided to acoustically release the ignition pressure in the combustion chamber 14 that is applied to the supply unit 20 when ignition occurs in the combustion unit 10, and are provided in the blower case 22. It is provided in such a way that it has less influence on the throttling performance of the air supply path 32 through which the air sucked from the suction port 23a passes.

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 dispersion plate 33 is provided with a plurality of fuel injection ports 33a distributed in a row, and the fuel injection ports 22 of the blower case 22 are provided with a plurality of fuel injection ports 33a.
Several fuel injection ports 33b are provided on the most upstream side with respect to b, separated from one fuel injection port 33a.

As a result, more of the fuel gas supplied into the fuel distribution chamber 35 is ejected from the fuel injection port 33b on the upstream side of the air supply path 32, so that 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 remains in the fuel injection port 33a.
is ejected smoothly and does not generate abnormal sounds such as resonance when passing through.

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. An arranged aperture 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
It is possible to improve the mixing of the fuel gas ejected from 3b and 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 S becomes large, and when the amount of combustion is small and the amount of air blown is small, the damper 38 is opened. degree becomes smaller, equivalent cross-sectional area 82
Make smaller.

When the damper 38 swings, a portion of the tip 38a on the outer circumferential side has a part that 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 the opening degree is the minimum. A contacting protrusion 38b is formed. As a result, even when the equivalent cross-sectional area S2 of the supply section 20 becomes the minimum, the tip 38a of the damper 38 and the inner wall 31g of the air supply case 31
A suitable gap is formed between the two and the necessary amount of air can be supplied.

When the equivalent cross-sectional area S2 of the supply section 20 is the minimum, the damper 38 has this protrusion 38b in contact with the inner wall 31g of the air supply case 31, as shown in FIG. When the area S2 becomes the maximum and exhibits the maximum opening degree, the damper 38 moves toward the diaphragm plate 36 as shown by the two-dot chain line.
It stabilizes after a moderate interval.

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 secured, and the damper 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,
Since the air flow can pass between the damper 38 and the diaphragm plate 36, the damper 38 can be stabilized in each case.

Upstream of the inner wall 31g of the air supply case 31 with which the protrusion 38b of the damper 38 comes into contact, there is a protrusion 3 that protrudes toward the inside of the air supply case 31 in order to change the direction of the sucked air flow.
is provided. This protrusion 39 allows the damper 3
8 is in the closed state, air from the air supply port 31a hits the tip 38a to 173 of the damper 38.
When the damper 38 is fully opened, air hits the entire damper 38, so the opening degree of the damper 38 can be made proportional to the combustion amount.

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 filter 41 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.

A blower 2 is installed in the 1st stream of the fuel pipe 60 depending on the required combustion amount.
A proportional control valve 61 controlled together with the proportional control valve 61 is provided, and fuel gas whose supply amount is adjusted by the proportional control valve 61 is supplied to the fuel injection pipe 23b and the fuel supply port 31C.

The heat exchanger 50 is connected to a wooden 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 rate sensor, and an inlet water temperature thermistor from the upstream side. Further, a hot water temperature thermistor is provided downstream of the heat exchanger 50, and a faucet (not shown) is provided at the downstream end, which can be damaged by the user.

The control device 70 determines the combustion amount based on a detection signal from a flow rate sensor, an inlet water temperature thermistor, etc. (not shown) and a set temperature by the controller 71, and controls the blower 25 and the proportional control valve 61v based on the combustion amount. The amount of combustion in the combustor 2 is controlled.

In addition, in order to safely and reliably ignite the ignition, the control device 70 controls the combustion amount of the combustor 2 to a slow ignition combustion amount Qi, and also controls the temperature of the combustor 2 to a slow ignition combustion amount Qi, as shown in Fig. 5. so as not to generate noise even when the
The slow ignition combustion amount Qi of the combustion amount at the time of ignition is maintained until a predetermined time elapses from the ignition time t2 when ignition is detected by the flame rod 18 until time t3, and thereafter, according to the determined combustion amount, Controls the blower 25 and proportional control valve 61.

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.

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 spark discharge is performed at the sparker electrode 17 as an ignition operation, the air-fuel mixture supplied into the combustion chamber 14 is ignited. At this time, vibration with a natural frequency f1 corresponding to the slow ignition combustion amount is generated due to the ignition pressure and is transmitted to the supply section 20, but the natural frequency f2 of the supply section 20 is , 31f acoustically matches the natural frequency f1 of the combustion section 10, vibrations caused by ignition pressure are released to the outside of the supply section 20.

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 at time t1, the combustion amount Qi at the time of ignition is maintained for a predetermined period of time (for example, 5 seconds) until the temperature of the combustor 2 stabilizes, as shown by the solid line A in FIG. Ru.

Therefore, the temperature of the combustor 2 such as the burner plate 12 is
As shown by the solid line B in the figure, the natural frequency f2 of the supply section 20 can be made to match the natural frequency f1 of the combustion section 10 even immediately after ignition, which has not yet risen sufficiently, so that noise is generated. Never.

Thereafter, at time t3, the combustion amount is changed to the combustion amount determined based on the controller 71 etc., and the blower 25 and the proportional control valve 61 are controlled based on it.

Further, as shown in FIG. 6, the damper 38 swings to each position as follows, depending on the amount of air sucked in.

The combustion amount of the combustor 2 is small, and the rotation speed of the blower 25 is at the sixth
In the figure, between N1 and N2, the damper 38 comes into contact with the inner wall 31g and exhibits an opening state where the opening area is the minimum, as shown by the broken line E.

The combustion amount is increased, and the rotation speed of the blower 25 is increased from N2 to N2.
3, the damper 38 exhibits an opening degree that corresponds to the amount of air blown.

The combustion amount is further increased, and the rotation speed of the blower 25 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 natural frequency f1 of the combustion section 10 changes depending on the combustion amount. Accordingly, the natural frequency f2 of the supply section 20 changes in the same way, and even if the combustion amount changes, noise can be reduced. Note that at this time, the combustion amount of the combustor 2 changes as indicated by the solid line F.

As described above, according to the present invention, no abnormal sound or noise is generated during ignition, immediately after ignition, and during steady combustion, making it possible to provide a low-noise combustion apparatus.

[Brief explanation of the drawing]

1 to 4 show a gas water heater according to a first embodiment of the present invention, FIG. 1 is a front view showing a schematic configuration of the gas water heater, FIG. 2 is a side sectional view of the supply section, 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 shows the control by the control device of this embodiment,
FIG. 6 is a characteristic diagram showing the amount of combustion and the opening degree of the damper according to this embodiment. In the figure, 2... combustor (burner), 18... flame rod (ignition detection means), 22... blower case (blower casing), 25... blower, 31... air supply case, 38... Damper, 70... Control device (combustion control device, combustion amount determining means).

Claims (1)

[Claims] 1) A blower for supplying combustion air to the burner;
A combustion control device comprising a combustion amount determining means for determining a combustion amount of the burner, and performing an ignition operation with a combustion amount different from the combustion amount determined by the combustion amount determining means at the time of ignition, It is characterized by comprising an ignition detection means for detecting ignition, and changing the combustion amount of the burner to the combustion amount determined by the combustion amount determining means after a predetermined time after the ignition detection means detects the ignition of the burner. combustion control device.