JPS609574Y2 - Air blow pressure detection device - Google Patents

Description

[Detailed description of the invention] The present invention relates to an air blowing pressure detection device for a blower, and in particular, air blowing pressure detection in an electrical safety control device that is installed in forced air combustion equipment and that detects air blowing pressure and stops fuel supply. It is related to the device.

In the conventional mechanism of this type, a system as shown in FIG. 1A-9 is commonly used.

In the method (a), an L-shaped detection tube is placed in the discharge path of the blower m, with its open end facing the air flow, and the dynamic pressure received at the opening is directly guided to the action chamber of the wind pressure switch h. The diaphragm is moved to the other atmospheric pressure introduction side to close the electrical circuit contacts.

In addition, the second method has an L-shaped double-structured detection tube facing the discharge path, as in A, and the inner tube side detects the total pressure, and the outer tube side detects the static pressure. their difference (i.e. dynamic pressure)
This is a so-called pitot tube system in which the wind pressure switch h is activated by the pressure switch h.

However, the inventor of the present invention has found through experiments that any of the 49-hole systems described above has the following problems when used in a control mechanism of forced-air combustion equipment.

Below, we will explain the problem based on the characteristic diagram of the blowing pressure H and air volume Q of the blower shown in Figure 2. As shown by the fan characteristic curve X, the relationship between the blowing pressure H and the air volume Q is determined at the time of fan design. Since it is specified to be constant, in forced-air combustion equipment, the air blow resistance (air blow pressure point H□
) is determined, the air volume at that time becomes Q□.

Now, with this air volume Q□ as the boundary, the area between Q1 and Qn is defined as a complete combustion area (within the shaded area in the figure) where the air required for combustion of this equipment is sufficiently supplied, and Q□~.

If the area between
The amount of air required for normal combustion (air volume Q) may be reduced due to deformation of the air passages such as exhaust pipes or exhaust pipes due to burnout, or due to the accumulation of combustion products and char in the heat absorbing parts, reducing the passage area for exhaust gas. If this cannot be supplied, the air blowing pressure H increases as shown in the figure, and when the state shown at the pressure point H2 is reached, the air volume Q decreases as shown by the broken line arrow and shifts from Ql to Q2.

That is, since the burner enters the incomplete combustion region, the burner during combustion eventually goes out due to lack of oxygen, causing a dangerous situation such as releasing raw gas.

In spite of this, in method A, the contacts of the wind pressure switch h cannot be opened due to dynamic pressure detection, and the blower m continues to rotate, which is dangerous, and the power and fuel are reduced. It has the disadvantage of being uneconomical.

In addition, with the differential pressure type at the mouth, when the above situation occurs, the differential pressure decreases, so the wind pressure switch h opens, but the operation is not immediate, the structure is extremely complicated, and the manufacturing process is difficult. The relative positioning of the total pressure and static pressure detection holes and their installation require skill, which has the drawback of extremely high costs.

In view of the above-mentioned cases, the present invention provides an air blowing pressure detection device for a forced ventilation type combustion equipment safety device, which fundamentally solves the above-mentioned disadvantages of conventional devices.

Embodiments of the blowing pressure detection device according to the present invention will be described below with reference to FIGS. 3 to 5.

In the figure, the same reference numerals as those shown in FIG. 1, which will be explained below, indicate the same parts.

FIG. 3 shows a schematic configuration diagram in which the air blowing pressure detection device according to the present invention is applied to a forced air gas water heater. A water supply tap d and a running water switch e are provided on the upstream side, and a hot water tap f is provided at the downstream end.

g is a gas burner disposed at the bottom of the heater a to heat the heat absorbing part; h is a wind pressure switch; the interior is connected by a diaphragm to an atmospheric communication chamber i on one side and a pressure detector 1 to be described later on the other side; It is divided into an action chamber j connected to the connection port 1a.

K is a gas electromagnetic valve disposed in the gas conduit n, and gas supply is stopped in response to the operation of the wind pressure switch h.

S is a power supply, t□ is a contact point of the water flow switch e, cherry blossoms is a contact point of the wind pressure switch h, and M is a water heater casing.

Next, the configuration of the blowing pressure detection device R will be explained based on FIGS. 3 and 4.

Reference numeral 1 denotes a tubular pressure sensor with a closed front end and a small diameter detection hole 2 drilled in the side slightly in front of the tubular pressure sensor 1.
is a predetermined position of the discharge passage 3 near the fan of the blower m,
The opening of the detection hole 2 is inserted perpendicularly to the air flow (at a predetermined interval 1 from the wall surface on the distal side), and is airtightly fixed to the wall of the discharge passage 3 by appropriate means.

Note that it is desirable that the detection hole 2 faces the center position S of the discharge path 3.

1a is the connection port of the pressure detector 1, and 4 is the connection port 1a.
This is a connecting pipe that connects the working chamber j of the wind pressure switch h and the working chamber j of the wind pressure switch h.

Since the blowing pressure detection device of the present invention is constructed as described above, it operates as described below.

As shown in FIGS. 3 to 5, when the pilot burner is ignited by an appropriate means and the hot water tap f is opened after confirming the pilot flame, water flows through the water conduit pipe and the water supply switch e is turned on.
senses the water pressure and closes the contact t1, the fan starts rotating and forcibly sends the air necessary for combustion in the gas burner g into the heater a.

At this time, the air sucked into the blower m by the rotation of the fan flows along the inner circumference of the casing and is sent to the discharge passage 3, and the air distribution flow within the discharge passage 3 is directed toward the centrifugal side as shown in the streamlines. Flowing along the wall is faster.

Therefore, as a fast air flow passes through the front surface of the detection hole 2, the inside of the pressure detector 1 becomes negative pressure.

This relationship can be explained using the generally known Bernoulli theorem as follows.

Flow velocity of the two fluids p: Fluid pressure γ: Weight of original fluid unit volume g: Gravitational acceleration force Water head 1 Static pressure) Hl (total pressure) is the sum of ) and Z (position water head). Indicates that it is constant regardless of location.

Now, if the horizontal plane of the flow path is taken as the reference horizontal plane for convenience, the positional water head 2 becomes zero, so equation (1) can be expressed by the following equation, which is generally applied to a planar flow.

can be done.

Therefore, the inside of the operating chamber j of the wind pressure switch h becomes a negative pressure state, so that the diaphragm is pulled in the direction of the solid arrow, the operating rod moves forward, the contact point t□ is closed, and the gas solenoid valve k is opened.

As a result, gas is supplied to the gas burner g, which is ignited by the pilot flame of the pilot burner to start combustion.

The combustion gas generated by this combustion rises in the heater a, heats the heat absorption part, becomes exhaust gas, and is discharged from the exhaust stack.

Next, during this combustion, if for example the opening of the exhaust stack is blocked for some reason and the exhaust gas is suppressed, in this case, naturally the blowing pressure H in the heater a increases, and the pressure detector 1 Since the total positive pressure H1 received at the interval 1 part of the discharge passage 3 is immediately applied to the detection hole 2 of , the operating rod is retracted and the contacts are also opened.

Therefore, the gas solenoid valve k is closed, and combustion in the gas burner g is immediately stopped.

It is preferable that the pressure detector 1 has a cylindrical shape, so that the flow rate of the air in the detection hole 2 can be adjusted as described above. is obtained.

The device of the present invention is equipped with a pressure detector that constantly detects negative pressure during normal air blowing at a specified position on the blower discharge path, especially on the centrifugal wall side near the fan and where the air blowing speed is high. Because it has a switch-operated structure, compared to conventional dynamic pressure detection type devices, when applied to safety devices for forced-air combustion equipment, for example, the amount of ventilation required for normal combustion in gas burners is inhibited. (Positive pressure will be applied to the detection hole)
This can immediately block the gas supply path and prevent the danger of releasing carbon monoxide or raw gas caused by incomplete combustion or extinguishing of the gas burner, making the safety device extremely reliable. .

In addition, the structure is simpler than conventional ones, and
It has excellent effects such as being easy to install and disassemble and can be manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1A9 is a partially cutaway side view showing an example of a conventional blowing pressure detection device, and FIG. 2 is a diagram illustrating the characteristics of the blowing pressure and air volume of the blower. Fig. 3 is a schematic configuration diagram showing an embodiment in which the device according to the present invention is applied to a forced air water heater, Fig. 4 is a cutaway front view of the main part of Fig. 3, and Fig. 5 is a partially enlarged view of the main part. It is a notch side view. a... Heater, b... Endothermic part, C...
... Water supply pipe, d ... Water supply valve, e ...
...Water switch, f...Hot water tap, g...
...Gas burner h...Wind pressure switch, i...
...atmospheric communication chamber, j...action chamber, k...
...Gas solenoid valve, n...Gas conduit, m...
...Blower, S...Power supply, tl, t2...
...Contact, M...Water heater body, R...
...Blow pressure detection device, 1...Pressure detector, 1
a...Connection port, 2...Detection hole, 3...
...Discharge pipe, 4...Connection pipe, H...
・Blowing pressure, Q... Air volume.

Claims (1)

[Scope of utility model registration request] In the air blow pressure detection device of the electric safety control device installed in forced air combustion equipment, which detects the air blow pressure of the blower and stops the fuel supply, the front end is closed and a detection hole is formed in the front side. The drilled pressure detector is inserted at a predetermined position in the discharge path of the blower at a specified distance from the wall surface on the centrifugal side, with the detection hole facing the wall surface and perpendicular to the air flow, and the pressure sensor A blowing pressure detection device characterized in that a detector is connected to an action chamber of a wind pressure switch to detect negative pressure.