JPH0336842Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an air supply/exhaust top for a double-pipe duct that reduces pressure loss due to outdoor wind pressure and significantly improves air supply/exhaust efficiency.

[Conventional technology]

In ventilation equipment having a double duct with an exhaust pipe on the inside and an air supply pipe on the outside, conventionally used air supply/exhaust tops include, for example, the 8th,
There is something like the one shown in Figure 9. FIG. 8 is a conceptual diagram of the ventilation equipment, where 1 is a ventilation fan installed in the room 2, 3 is the supply/exhaust part of this ventilation fan, and 4 is a double pipe that passes through another room 5 and leads to the outdoors. It is a duct and is configured with the exhaust pipe 6 on the inside and the air supply pipe 7 on the outside. 8 is an air supply/exhaust top attached to the outdoor open end of the double pipe duct 4.

Exhaust gas generated from a kitchen range or the like in the room 2 is exhausted to the outdoors from a ventilation fan 1 through an exhaust pipe 6 from an air supply/exhaust top 8. Reference numeral 9 denotes exhaust ports provided on both sides of the air supply/exhaust top 8, which communicate with the exhaust pipe 6, from which the exhaust gas is discharged laterally in the left and right directions. Figure 9a is the 8th
A view in the direction of arrow A in the figure, and FIG. 9b is a sectional view taken along line B-B in FIG. 9a. Reference numeral 10 denotes an air supply port communicating with the air supply pipe 7, from which outdoor air is guided to the air supply/exhaust section 3 via the air supply pipe 7 due to the static pressure difference between the indoor and outdoor areas, and the air is discharged into the room 2.
It's like going inward. Numerals 11 and 12 are nets provided to cover the exhaust port 9 and the air supply port 10, respectively, to prevent insects and the like from entering. Reference numeral 13 indicates the outer wall of the room 5 facing outdoors.

[Problem that the invention attempts to solve]

However, in the case of such conventional air supply/exhaust tops, due to the configuration of their exhaust ports, air supply ports, etc., outdoor wind pressure accounts for most of the load applied to the indoor blower (ventilation fan). Due to the large pressure drop, there was a drawback that ventilation was not sufficient, especially when the wind was strong outdoors.

In addition, in the short circuit phenomenon in which the exhaust gas that is once discharged mixes with the outdoor air around the air supply/exhaust top and is then introduced indoors again, the conventional method uses the short circuit both when there is no wind outdoors and when there is wind. The problem was that the ratio was high.

This idea was devised in view of these conventional problems, and by using a supply/exhaust top in which the exhaust gas travels straight along the exhaust pipe axis and is discharged from the tip opening at an increased speed. , aims to solve the above problems.

[Means for solving problems]

This idea is to make the tip of the exhaust pipe larger in diameter than the other parts in the supply/exhaust top of ventilation equipment that has a double-pipe duct with the exhaust pipe on the inside and the air supply pipe on the outside. A bird prevention member for preventing the intrusion of birds is disposed within the large diameter portion, and the tip opening downstream of the large diameter portion is opened in the axial direction of the exhaust pipe and has a smaller diameter than the large diameter portion. An exhaust nozzle is formed in the air supply pipe, and the air supply port of the air supply pipe is provided at least below the supply and exhaust top to serve as a supply and exhaust top for a double pipe duct.

[Effect]

The exhaust gas discharged from the exhaust pipe by the blower is
Since the exhaust port of the supply/exhaust top opens in the axial direction of the exhaust pipe, the fluid travels straight along the exhaust pipe and is discharged at an increased speed as if it were spouted from a nozzle. In addition, since the air supply port is configured to open at least below the supply/exhaust top, the wind pressure applied to the supply/exhaust top when there is wind outdoors is negative at the downwardly facing portion of the exhaust port. Since the air supply port shows a positive wind pressure coefficient, the load on the blower is reduced and ventilation efficiency is improved.

Furthermore, since the exhaust gas is normally discharged almost perpendicularly to the outer wall surface of the chamber and at an increased speed, it is blown far away, so that the proportion of the air mixed in with the supply air sucked in from the vicinity of the outer wall surface is extremely small.

In addition, the bird prevention member can prevent birds from entering, and the exhaust flow area, which is reduced by the bird prevention member, can be secured by making the diameter large, thereby reducing exhaust resistance as much as possible. There is.

〔Example〕

This invention will be explained below based on the drawings. Figures 1, 2, 4 and 5 are diagrams showing an embodiment of this invention. FIG. 1a is a front view of the embodiment, and FIG. 1b is a longitudinal sectional view thereof. FIG. 2 is a schematic diagram showing a cross section of a double pipe duct.

First, the structure will be explained. Reference numeral 14 is an air supply/exhaust top, which is connected to a double pipe duct 15 on the outer wall surface 13 of the chamber. 16 is an exhaust pipe on the inside of the double pipe duct 15, and 17 is an air supply pipe on the outside thereof. Reference numeral 18 denotes an exhaust port, which opens in the axial direction of the exhaust pipe 16 and is provided at the supply/exhaust top 14;
The exhaust gas is discharged straight in the direction of arrow A. Reference numeral 19 is a net provided inside the exhaust port 18 to prevent insects, birds, etc. from entering, and constitutes the bird prevention member of the present invention, but instead of the net, a plurality of rods are used in a planar shape. It may be placed in 20
is an air supply port, and the air supply/exhaust top 14 is in communication with the air supply pipe 17, more specifically, with the air supply passage which is the space between the exhaust pipe 16 and the air supply pipe 17 having a larger diameter than the exhaust pipe. It is located at the bottom of the . Reference numeral 21 denotes a net for preventing insects or birds, which is provided to cover the air supply port 20. Also, this double pipe 1
5 has an oval cross section made by flattening a circular pipe, and this is because when this double pipe is arranged, the dimension under the slab of the building is reduced, so that the indoor space is not narrowed.

Furthermore, the supply and exhaust top 14 has an exhaust pipe 16
A large diameter portion 14a is formed, the diameter of which is enlarged by another portion, and the net 19 is disposed within this large diameter portion 14a. The large diameter portion 14 compensates for the reduction in the exhaust flow area due to the net 19.
Compensate by setting a. In addition, the large diameter portion 14
The exhaust port 18, which is the tip opening on the downstream side of a, is
An exhaust nozzle 14b is formed here to have a smaller diameter than the large diameter portion 14a.

Next, the action will be explained.

Factors that affect the ventilation efficiency of ventilation equipment include the problem of wind pressure applied to the top of the air supply and exhaust during windy conditions outdoors, and the problem of the short circuit where exhaust air mixes with the air supply.

First, regarding wind pressure, if strong wind pressure is applied during strong winds, air supply and exhaust may be obstructed.

Here, the wind pressure acting on the air supply/exhaust top acts as a pressure loss that accounts for a large portion of the load applied to the indoor blower, and the degree of this loss varies depending on the shape and configuration of the air supply/exhaust top. FIG. 4 is a graph showing actual measured values of the pressure loss in the present embodiment, and FIG. 5 is a graph showing the measured values of the pressure loss in the conventional example. It is clear from these graphs that the pressure loss in the embodiment is small.

Further, when the degree of the wind pressure is expressed by a wind pressure coefficient Cp, this coefficient differs depending on each part of the air supply/exhaust top. Now, as shown in Fig. 1a, the actual measured values of the wind pressure coefficient are shown in Fig. 6 (example) and Fig. 7 (conventional Example). As is clear from FIG. 6, the coefficient Cp of the exhaust port 18 has a negative value over its entire circumference (see a in the same figure), which indicates that it is advantageous for exhausting air. , the positive coefficient Cp is maximized immediately below it (see b in the same figure), which is extremely advantageous for air supply.

On the other hand, in the conventional example shown in FIG. 7, the exhaust port 9 is oriented horizontally and opens at 90 degrees.
The coefficient Cp is a positive value centering on 90 degrees (a in the same figure), indicating that there is a resistance of that magnitude to the exhaust air, and the air supply port 10 is opened vertically downward, and the direction is 0 degrees. The coefficient Cp is a negative value (b in the figure), indicating that there is a resistance of that magnitude to the air supply. To summarize this, it can be seen that in the conventional example, both the air supply and exhaust air are resisted by the outdoor wind pressure, and the ventilation efficiency deteriorates to a considerable extent.

Next, regarding the problem of short circuits, even if the ventilation efficiency is good, if a large amount of the exhaust gas that has been discharged is mixed in with the supply air, in other words, short circuits are created, it is difficult to ensure good ventilation. It is not.

It is known that this short circuit phenomenon is closely related to the shape of the air supply and exhaust top. The results of an experiment in which this phenomenon was quantified and compared for the conventional example and the example are shown below, with the ratio of exhaust gas included in the intake air being the short circuit ratio. In the example, the value is 9 in both windless and windy conditions.
% or less, and this is because the exhaust speed is increased by the exhaust nozzle and the gas is blown far away from the wall surface. In the conventional example, the short circuit ratio was rather large when the outdoor wind was strong, and it was 17.8% at an outdoor wind speed of 3.2 m/s. This is because the exhaust gas blown out laterally is returned to the wind.

Furthermore, as other conventional examples, a full-circle pan type top showed a value of 36.6% when there was no wind, and a bottom blowing pan type top also showed a value of 24.3% when there was no wind.

FIG. 3 shows another embodiment.

This is the case of the circular double pipe before the double pipe is flattened in the above embodiment, and although the ceiling duct space becomes larger when this ventilation equipment is installed, the ventilation characteristics are the same as in the above embodiment. This will be further improved. Each symbol shown here indicates the same member as shown in the previous embodiment.

[Effect of idea]

As explained above, according to this invention, since the configuration is as described above, it is not easily affected by the wind pressure of outdoor wind, the ventilation efficiency is good, and the short circuit ratio is low in both windy and non-windy conditions. It is extremely small and provides benefits such as high-quality ventilation.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of an embodiment of the present invention, in which Fig. a is a front view, Fig. b is a vertical cross-sectional view, Fig. 2 is a cross-sectional view taken in Fig. 1 b, and Fig. 3 is a diagram showing another embodiment. Figure 4 is a diagram showing the pressure drop of the air supply and exhaust top in the embodiment, and Figure 5 shows the similar pressure drop in the conventional example. Figure 6 is a diagram showing the wind pressure at the air supply and exhaust top of the embodiment, where a is the exhaust port and b is the diagram showing the wind pressure at the air supply and exhaust top of the embodiment.
are based on actual measurements at the air supply port, Figures 7a and b are diagrams based on actual measurements similar to Figure 6 in the conventional example, and Figure 8 is a schematic diagram of the ventilation equipment in the conventional example.
FIG. 9 is a schematic view of a conventional air supply/exhaust top, with FIG. 9a being a front view thereof and FIG. 9b being a longitudinal sectional view thereof. 14,8...Supplement/exhaust top, 15,4...Double pipe duct, 16,6...Exhaust pipe, 17,7...Air supply pipe, 18,9...Exhaust port, 20,10...Air supply Mouth, 14a...large diameter part.

Claims (1)

[Scope of utility model registration request] In the supply/exhaust top of ventilation equipment having a double-pipe duct with the exhaust pipe on the inside and the air supply pipe on the outside, the diameter of the tip of the exhaust pipe is made larger than other parts to make it a large diameter part, and this large diameter A bird prevention member for preventing the intrusion of birds is arranged inside the part, and the tip opening downstream of the large diameter part is opened in the axial direction of the exhaust pipe and has a smaller diameter than the large diameter part, and an exhaust nozzle is installed here. 1. An air supply/exhaust top for a double pipe duct, characterized in that the air supply/exhaust pipe has an air supply port provided at least on the lower side of the air supply/exhaust top.