JPS6311460Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a type of combustion equipment that forcibly supplies combustion air to perform forced combustion, such as a water heater.
A combustion control device that can automatically maintain the air-fuel ratio at a constant or almost constant level regardless of the adjustment of the air supply amount to adjust the combustion amount. An orifice is provided in the supply path from the forced air supply device to the burner section, and an orifice is provided in the fuel gas supply path connected to the air supply path downstream of the air orifice, and upstream of the air orifice. The mixing ratio of the supply air and the supply gas is maintained constant or almost constant using the pressure difference between the pressure of the air supply passage section and the pressure of the gas supply passage section upstream of the gas orifice as a driving force. This invention relates to a combustion control device equipped with a zero governor that automatically adjusts the amount of gas supplied.

In such a conventional combustion control device, as shown in FIG. 3, the valve 17 in the zero governor 9 is
To operate with a pressure difference between the pressure in the air supply path 4 portion upstream of the air orifice 3 (load pressure) and the pressure in the gas supply path 6 portion upstream of the gas orifice 5 (secondary pressure). diaphragm 1
6 was composed of one diaphragm,
When this is applied to combustion equipment such as water heaters that have a large ratio of maximum input to minimum input, that is, a wide combustion range, it is difficult to maintain the air-fuel ratio at the set value near the minimum input. Ta.

In other words, in general, in combustion equipment, the minimum
Considering the next pressure of 50mmH ₂ O and the internal pressure rise of 15mmH ₂ O in the wind pressure zone of wind speed 15m/S, the maximum load pressure is
If the air-fuel ratio is not set below 35mmH ₂ O, it is not guaranteed that the air-fuel ratio will be maintained at the set value.
In combustion equipment with a wide combustion range, the maximum load pressure is set to 35 mmH ₂ O or less, but in this case,
Minimum load pressure at minimum input is 1-2mm
Therefore, in the case of a conventional device in which the pressure difference on both sides of the diaphragm, which is the driving force for the diaphragm, is the difference between the load pressure and the secondary pressure, as shown in Fig _. 4, the pressure difference is 1 to 2 mmH ₂ O. The pressure difference between both sides of the diaphragm near the minimum load pressure becomes extremely small, and during operation, the load pressure and the secondary pressure are theoretically equal and the pressure difference becomes zero. However, in a zero governor, if the differential pressure on both sides of the diaphragm is small due to curing of the diaphragm over time, heat curing, or even wrinkles that occur during assembly,
There is a characteristic that it is difficult to operate the diaphragm reliably and accurately with such a small pressure difference.
In conventional equipment, the minimum input, that is,
The disadvantage was that the operation of the diaphragm near the minimum load pressure became uncertain and unstable, and the air-fuel ratio inevitably shifted.

In view of this situation, the present invention has an object to ensure reliable and stable diaphragm operation near the minimum input even when the set maximum load pressure is 35 mmH ₂ O or less.

The combustion control device according to the present invention includes a diaphragm for operating the valve in the zero governor with the pressure difference, and two diaphragms having equal or almost equal effective pressure receiving areas, and a combustion control device formed between the two diaphragms. The present invention is characterized in that it is provided with a mechanism for reducing the pressure in the chamber in accordance with the operation of the forced air supply device.

In other words, as will be explained in detail in the examples below, if the effective pressure-receiving areas of both diaphragms are equal, the load pressure and the secondary pressure will be equal, and the pressure change in the chamber formed between the two diaphragms will be controlled by the diaphragm. The pressure in the chambers between both diaphragms was reduced by focusing on the fact that the pressure in the chambers between both diaphragms can be arbitrarily selected, regardless of the drive and the air-fuel ratio.

Therefore, according to the characteristic configuration of the present invention, the pressure difference on both sides of one diaphragm becomes the difference between the load pressure and the pressure in the decompression chamber, and the pressure difference on both sides of the other diaphragm becomes 2.
As the next pressure and the pressure in the decompression chamber can be maintained, a sufficient pressure difference between both diaphragms on both sides can be ensured even at _the minimum load pressure. This has made it possible to minimize the occurrence of wrinkles on the diaphragm surface due to thermal changes and aging, and to ensure the stability of diaphragm operation near the minimum load pressure.

Hereinafter, embodiments of the present invention will be described based on the drawings.

1 controls the burner section 2 based on the combustion amount control signal.
This is a forced air supply device that automatically changes the amount of combustion air supplied to the combustion chamber, and includes a blower 1A, an air volume adjustment damper 1B, and a motor 1C that operates the damper 1B based on a combustion amount control signal. There is.

3 is an orifice provided in the middle of the air supply path 4 from the forced air supply device 1 to the burner section 2; 5 is a fuel gas supply connected to the air supply path 4 on the downstream side of the air orifice 3; An orifice 7 is provided in the air supply passage 4 downstream of the connection part of the fuel gas supply passage 6.
This is an orifice provided in the air supply path 4 between this orifice 7 and the air orifice 3.
A section is formed into a chamber 8 in which air and fuel gas are mixed.

9 is the pressure (load pressure) (PL) of the air supply path 4 portion 4A on the upstream side of the air orifice 3;
By using the pressure difference between the pressure (secondary pressure) (P ₂ ) of the portion 6A of the fuel gas supply path 6 upstream of the gas orifice 5 as a driving force, the mixing ratio of the supply air and the supply gas is kept constant. It is a zero governor that automatically adjusts the gas supply amount so that it is maintained, and 10 is a main solenoid valve.

The zero governor 9 communicates with the pressure (PL) in the load pressure chamber 13, which communicates with the air supply passage portion 4A in the governor body 11 via a pressure guide pipe 12, and with the gas supply passage portion 6A via a passage 14. A main diaphragm 16 that is driven with a difference in pressure (P ₃ ) in the secondary pressure chamber 15, and this diaphragm 16.
The valve 17 has an effective pressure receiving area (S ₂ ) that is equal to the effective pressure receiving area (S ₁ ) of the valve 17, and has an upstream pressure (primary pressure) of the valve 17 that acts on the valve 17. A balance diaphragm 18 that offsets the pressure) (P ₁ ), a main diaphragm 16, and a valve 1
7. A spring 19 is provided to offset the weight of the balance diaphragm 18.

The main diaphragm 16 is composed of two diaphragms 16A and 16B with equal effective pressure receiving areas (S ₃ ) and (S ₄ ), and the chamber 20 formed between these two diaphragms 16A and 16B is A pipe 21 is provided which is suctioned and depressurized by the operation of the forced air supply device 1.

The force (F) in the opening direction and the force (F') in the closing direction acting on the valve 17 of the zero governor 9 are as follows.

F=P ₁・S ₁ +P ₃・S ₂ +P ₄・S ₃ +PL・S ₄ +Kχ F′=P ₂・S ₂ +P ₁・S ₂ +P ₃・S ₃ +P ₄・S ₄ +M However, K: Spring constant, χ: spring displacement, M: dead weight of the diaphragm and valve.

Then, when F=F', the valve 17 is stable, and depending on the structural conditions, S ₁ = S ₂ , Kχ = M, P ₂
= P ₃ , so P ₂ = S ₄ /S ₃・PL+S ₃ −S ₄ /S ₃ P ₄ . Here, if S ₃ = S ₄ as in the above embodiment, then P ₂ = PL, and the pressure change inside the decompression chamber 20 is
Since it has nothing to do with the operation of the diaphragms 16A, 16B and the air-fuel ratio, the pressure in the decompression chamber 20 (P ₄ )
can be selected arbitrarily.

Therefore, as in the above embodiment, by lowering the pressure (P ₄ ) inside the decompression chamber 20, the input (IP) can be reduced to a minimum of 1/2 in the conventional device having the driving pressure characteristics as shown in FIG. 5, diaphragm 1
While the pressure difference (△P) on both sides of 6 was about 1.4mmH ₂ O, as is clear from the driving pressure characteristics shown in Figure 2, even when the input (IP) is at least 1/5, , the pressure difference (ΔP) on both sides of the diaphragms 16A, 16B is
Due to the presence of the decompression chamber 20 between B, 11.4
mmH ₂ O.

[Brief explanation of the drawing]

1 and 2 are graphs showing the principle and driving pressure characteristics, and FIGS. 3 and 4 are graphs showing the principle and driving pressure characteristics of the conventional device. 1... Forced air supply device, 2... Burner section,
4...Air supply path, 3...Air orifice, 6...
...Fuel gas supply path, 5...Gas orifice, 9...
...Zero governor, 17...Valve, 16...Diaphragm, 16A, 16B...Diaphragm, 20...
Decompression chamber, 21...decompression mechanism.

Claims (1)

[Scope of utility model registration request] An orifice 3 is provided in a supply path 4 from a forced air supply device 1 capable of changing the amount of combustion air supplied to a burner section 2.
and an orifice 5 is provided in a fuel gas supply passage 6 connected to the air supply passage 4 downstream of the air orifice 3, and a zero governor 9 is provided for automatically adjusting the gas supply amount so that the mixture ratio of the supply air and the supply gas is kept constant or almost constant by using the pressure difference between the pressure in the air supply passage 4 upstream of the air orifice 3 and the pressure in the gas supply passage 6 upstream of the gas orifice 5 as a driving force.
a mechanism for reducing the pressure in a chamber formed between the two diaphragms by operating the forced air supply device, the mechanism comprising: a first diaphragm having an effective pressure receiving area that is equal to or approximately equal to the effective pressure receiving area of the first diaphragm; and a second diaphragm having an effective pressure receiving area that is equal to or approximately equal to the effective pressure receiving area of the first diaphragm.