JPH0258545B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Technical Field The present invention relates to a high ceiling outlet that is installed on a high ceiling in a room or a wall near the high ceiling and blows out air-conditioning air supplied through a duct or the like into the room. It is. (b) Prior Art In places where many people gather, such as music halls, theaters, and hotel lobbies, it is essential to provide so-called air conditioning, such as ventilation and temperature/humidity control. In particular, in music halls and lobbies, the ceiling height is generally 2 to 2 times higher than in normal living rooms.
Since it is four times taller and has an extremely large floor area, the volume of space that must be air-conditioned is also extremely large. Therefore, it is necessary to sufficiently increase the output of the blower used as the air conditioning equipment, and to provide a nozzle with a large diameter or a large number of nozzles with a relatively small diameter as the outlet. However, a large-diameter nozzle is not only difficult to manufacture, but also unsightly because the large hole is exposed directly to the ceiling, etc., and is not desirable. Providing a large number of small-diameter nozzles poses a problem in that the duct system becomes complicated and the cost increases significantly. On the other hand, instead of the above-mentioned nozzle, the air outlet is equipped with a perforated plate, such as a punching grill, in which many small-diameter holes are drilled in close proximity, as was conventionally used as an air-conditioning suction inlet. Another option is to set up a The main purpose of this punching metal is to prevent foreign matter from entering or falling through the suction port, so the hole diameter is small. Therefore,
When used as an air conditioning outlet, the outlet is not directly exposed, so problems with appearance can be solved to some extent. However, when such a punching grill is attached to an air outlet in a high ceiling, a fatal problem arises in that the required amount of air does not reach the human bodies in the room, making it impossible to perform air conditioning satisfactorily. If this problem were to be solved by increasing the speed of the air emitted from the air outlet, equipment such as blowers and ducts would have to have an extremely large capacity.
This measure cannot be adopted at all, since the cost increases significantly and new problems arise, such as the noise emitted from the outlet greatly exceeding the permissible value. (c) Purpose The present invention was made in view of the various circumstances mentioned above, and its purpose is to have a simple configuration, significantly reduce cost compared to a nozzle,
To provide an air outlet for high ceilings that can reach a human body with appropriate air without causing a draft under a predetermined air volume, can suppress the generated noise to a permissible limit value or less, and has a large degree of freedom in design. There is a particular thing. (d) Structure In order to achieve the above-mentioned object, the present invention is installed on a high ceiling in a room or a wall near the high ceiling, and the opening end on the indoor side is covered with a perforated plate having one or more holes. V ₀ is a high-ceiling outlet for blowing out air-conditioning air supplied through a duct or the like into the room, and the blowing wind speed is determined from the allowable noise depending on the use of the room. , Vx is the wind speed at the predetermined position, which is determined on the condition that a human body at a predetermined position a predetermined distance X away from the hole receives the air without causing any discomfort, and Vx is the proportionality constant determined by the shape of the air outlet. K, when the diameter of the hole when the hole is circular or the effective area when the hole is of any shape other than circular is multiplied by 4/π and the square root is taken as D ₀ , The diameter or shape of the hole is set from the value of D ₀ that satisfies the relationship Vx/V ₀ = K・D ₀ /X, and the area and shape of the hole determined from the value of D ₀ are determined from Outlet wind speed
The perforated plate is characterized by having a number of holes formed in the perforated plate approximately corresponding to a value obtained by dividing the amount of air blown from the outlet required for indoor air conditioning by a value multiplied by _V0 . This is what I did. The present invention will be specifically described below based on one embodiment. First, we will discuss the configuration of the present invention while analyzing the general properties of the airflow ejected from the air outlet. The air ejected from the outlet into a space with no airflow gradually reduces its speed as it spreads out. This blowout airflow is sequentially divided into four regions from the blower outlet surface depending on the relationship between the distance X in the blowing direction from the blower outlet and the wind speed Vx at the position of this distance X. First, in the first region, which is approximately 2 to 6 times the diameter D ₀ of the outlet, the wind speed Vx is the outlet wind speed of the ejected air.
It is almost the same as V ₀ and can be considered constant. In the next second region, the wind speed Vx decreases in proportion to 1/X ^1/2 , but within an extremely narrow range. The third region is a range of tens to hundreds of times the aperture D ₀ , and in this region, Vx/V ₀ =K・D ₀ /X (1) =K・(4A ₀ /π) ^1/2 / There is a relationship of Here, equation (1) is a relational expression when the shape of the air outlet is circular, and K is a proportionality constant, generally referred to as an air outlet constant, and is a value determined experimentally. In addition, equation (2) is a relational expression when the shape of the outlet is arbitrary, where A ₀ is the effective area of the outlet, and the area of the outlet, the outflow coefficient (generally 0.65 to 0.9), and the free area It is expressed as the product of the ratio. Next, the fourth region is a region in which the wind speed Vx is affected by the general airflow in the space and rapidly decreases in a range several times the diameter of the outlet compared to the third region. From the above, the relationship between the distance X from the outlet of the airflow blown into the room from the outlet and the wind speed Vx can generally be sufficiently described by the relationship of equation (1) or equation (2) alone. The relationship in equation (1) or equation (2) above relates to one air outlet, and for example, the indoor opening end of the air outlet is covered with a perforated plate in which a plurality of holes are bored close to each other. In this case, the individual small airflows from each hole will merge after passing a certain distance and interfere with each other. However, in this case as well, it is known that the airflow can be treated as a blowout from one large opening, and by simply changing the outlet constant K instead of the diameter D ₀ , the relationship in equation (1) or (2) can be applied as is. be able to. A more specific explanation of the relationship in equation (1) is as follows. That is, the higher the wind speed Vx, the more quickly the air conditioning will be performed, but if this airflow hits a human body in the room, it will cause discomfort to that person. Therefore, it is desirable that the magnitude of the wind speed Vx is set so as not to cause discomfort to people and to allow just enough diffusion of the blown airflow into the room. Specifically, the air ejected from the air outlet installed in the ceiling reaches a height of 1.5 m above the floor (approximately the height of a person's face when standing upright on the floor) (at this time, the distance (called the reach distance), the wind speed Vx is
For example, set it to 0.5m/s. This wind speed Vx of 0.5 m/s is a value determined on the condition that a human body at the reaching distance X does not feel a draft, that is, discomfort when receiving the air blown out from the air outlet. Next, the value of the outlet constant K can be obtained by substituting the experimental value into the relationship in equation (1). For example, in a perforated plate with multiple holes drilled in a flat plate, K = 7.1. Data is available. These data (1)
The relational expression 0.5/V ₀ =7.1・D ₀ /X (3) obtained by substituting it into the equation is plotted against several representative initial air velocities V ₀ as shown in Figure 4. It is a graph. From this graph {or equation (3)}, we can determine that the reach distance
Once the distance X obtained by subtracting _the
The diameter D ₀ of the two holes is determined. Next, in order to determine the outlet wind speed V ₀ , the noise caused by the airflow emitted from the outlet will be considered. There are various methods for evaluating noise, but here we analyze noise with a continuous frequency spectrum into octaves, plot the sound pressure level for each octave on an NC curve, and calculate the noise level. Use evaluation methods. For example, as shown in Figure 5, this NC curve corresponds to the sound pressure level of a reference octave band (1200 to 2400 Hz in this case) and the NC value (for example, 20 dB =
(NC20, 30dB = NC30...), and for sounds in other octave bands, each octave band is filtered using a bandpass filter, and the test subject listens to it. It is obtained by measuring the sound pressure level with a sound level meter and tying up the sound pressure level values. (The NC curve was proposed by Beranek et al. in the United States in 1957). This NC value was devised so that noise as physical energy can be expressed in numerical values that are close to human sensations. The table below shows the allowable noise NC values for various room applications as NC curve values:
Its value varies depending on the purpose of the room.

[Table] On the other hand, the noise generated from the outlet varies depending on the shape of the outlet, such as whether it is a nozzle or a perforated plate, but if the shape is the same, , has a certain relationship to the value of the initial velocity V ₀ . FIG. 6 shows experimentally determined data for this perforated plate, and is a diagram showing the relationship between the NC value as a noise value and the air velocity (initial velocity) V ₀ from the outlet. That is, the sound pressure level of noise at a certain wind speed is measured through an octave band pass filter, each measured value is plotted on the NC curve shown in Figure 5, and the NC value in the band showing the maximum NC value is calculated as the noise level at that wind speed. The size of (NC value) is determined. The graph shown in FIG. 6 is obtained by plotting the NC values for each wind speed thus obtained on a graph with the initial velocity V ₀ on the horizontal axis and the NC value on the vertical axis. From the above, first, once the purpose of the room is determined, the allowable noise NC value is determined from the table above, and from this NC value, the initial velocity of air at the outlet is determined using Figure ₆ . be done. Then, if the reach distance of the airflow (for example, the distance from the ceiling to 1.5 meters above the floor) X is set from the structure of the room, the diameter D ₀ of the hole in the perforated plate can be determined from Figure 4 or equation (1). It happens. For example, if the purpose of the room is residential, its maximum NC value is 35, so from Figure 6, the blowing wind speed V ₀ is 9 m/s, and if the reach distance X is 5 m, the hole diameter D ₀ is determined to be 40 mm from equation (3). Then, the initial velocity V ₀ and the hole diameter D ₀
If you set it like this, a human body standing upright on the floor in this room will be able to adjust the NC value without feeling any draft.
Appropriate air conditioning will be performed at low noise levels below 35. By the way, in order to perform optimal air conditioning, it is also necessary to send out an appropriate amount of airflow from each outlet. To do this, if the air volume to be blown from one outlet is set, the air volume from one hole is determined as (V ₀ × area of one hole), so the air volume is By dividing by the air volume, the number of holes to be bored in the perforated plate that covers one outlet opening end can be determined. For example, if the air volume is 720m ³ /hr and the hole area is 0.0012m ²
(D ₀ ≒ 40 mm), the number of holes is 17. Therefore, the results of the above example can be summarized as follows. In other words, the allowable indoor noise level for residential use is NC
The value is 35, the ceiling height of this room is 6.5 m, the wind speed Vx at which a person does not feel a draft at a height of 1.5 m from the floor is 0.5 m/s, and a perforated plate with circular holes is used. When the outlet constant K is 7.1 and the air volume required for air conditioning this room is 720 m ³ /hr, the perforated plate has a diameter D ₀ .
It is a good idea to drill 17 40mm holes. Figure 1 shows a plan view of the perforated plate 1 set according to the above procedure when it is attached to a ceiling surface in a room, and Figure 2 shows a part of Figure 1. FIG. 2 is an enlarged partial cross-sectional view taken along the line A-A, which is shown enlarged and broken. In FIG. 1, a perforated plate 1 is a square flat plate, on which a predetermined number of holes 2 having a diameter D ₀ set based on equation (1) are formed under the above-mentioned conditions. are drilled evenly. On the other hand, an opening 4 for air conditioning is provided in a wall 3 such as the ceiling of the room, and a chamber 5 connected to a duct is fitted into the opening 4.
6 is a mounting frame, and this mounting frame 6 has a slit 6a, and a claw piece formed at the tip of the chamber 5 is inserted into this slit 6a and bent, thereby being fixed to the chamber 5. be done. and,
A supporting metal fitting 7 having a hook-shaped cross section and having a horizontal portion and a vertical portion connected to each other is fixed to the mounting frame 6 by spot welding or the like. 8 is a perforated plate frame attached to cover the peripheral edge of the opening 4, and the perforated plate 1 is
It is integrated with the perforated plate frame 8 by spot welding or the like, and its four corners are fixedly held together with the perforated plate frame 8 to the support fitting 7 by set screws 9. In this embodiment, the perforated plate 1 and the chamber 5 are the main components of the outlet. In this way, the perforated plate 1 having a predetermined diameter D ₀ and a predetermined number of holes 2 can be easily attached to the air outlet 4.
This large opening 4 is covered in a good manner. Further, according to the air outlet formed by attaching this perforated plate 1, the airflow blown into the room from the holes 2 can perform efficient air conditioning with low noise and without making the people in the room feel a draft. Can be done. Figures 3a, b, and c show other embodiments of the perforated plate, in which 12 holes 2 are arranged near the periphery of the perforated plate 10 in figure a and the perforated plate shown in figure b. 1
1 has 12 holes 2 arranged in an asymmetrical pattern, and FIG. here,
What should be noted is that in any of the embodiments a, b, and c of the same figure, as long as it has a predetermined number of holes 2 and a predetermined diameter D ₀ or shape, the first
This means that the same effects as those of the embodiment shown in the figure can be achieved. In other words, the high ceiling air outlet of the present invention has the advantage that the shape of the holes 2 and the arrangement pattern of the holes 2 can be changed arbitrarily, so there is a large degree of freedom in design. Furthermore, in the past, when determining the diameter of a nozzle, it was a matter of trial and error, such as manufacturing a large number of prototypes and performing various measurements, but according to the present invention, the diameter of the nozzle can be determined easily by the above-mentioned procedure. can be determined. Therefore, according to the present invention, a desired air outlet can be designed and manufactured without much expense. Note that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the scope of the invention. For example, although we have explained an example using the NC curve as a noise evaluation method, it is possible to achieve the desired effect by selecting other evaluation methods depending on the purpose and situation of the room in which the air outlet is installed. can. In addition, in the above example, the wind speed Vx at a position a distance Since the level of discomfort differs depending on whether you are working in the office or doing some kind of work, you can change the value as appropriate. Furthermore, the shape of the hole 2 is not limited to a circle, but may be oval, oval, rectangular, or any other shape as long as it has an area determined from the effective area A ₀ in equation (2). Can be set. (e) Effects As is clear from the above detailed description, according to the present invention, the configuration is simple, and the shape and number of holes can be easily determined by a rational procedure without trial and error. The cost can be significantly reduced compared to conventional nozzles, and it is possible to deliver properly conditioned air without creating a draft under a specified air volume to a person at a specified position, while also reducing the noise generated to an allowable limit. It can be kept below,
Moreover, it is possible to provide an air outlet for high ceilings with a large degree of freedom in design.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the configuration of an embodiment of the present invention, FIG. 2 is an enlarged sectional view taken along the line A-A in FIG. 1, and FIGS. A plan view showing the configuration of other embodiments that are different from those shown in the drawings,
Fig. 4 is a diagram showing the relationship between _{the diameter D 0 of} each hole and the reach distance FIG. 3 is a diagram showing the relationship between the blowing wind speed V ₀ and the NC value. 1, 10, 11, 12...perforated plate, 2...hole,
3... Wall, 4... Opening, 5... Chamber, 6...
Mounting plate, 7... Support metal fittings, 8... Perforated plate frame, 9...
...Set screw.

Claims (1)

[Scope of Claims] 1. It is installed on a high ceiling in a room or a wall near the high ceiling, and the opening end on the indoor side is covered with a perforated plate having one or more holes, and is supplied through a duct, etc. A high-ceiling outlet for blowing out air conditioning air into the room, where V ₀ is the blowing wind speed determined from the allowable noise according to the use of the room, and a predetermined distance X from the hole. The wind speed at the predetermined position is determined on the condition that a human body in a predetermined position far away receives the air without causing discomfort.
Vx, K is the proportionality constant determined by the shape of the air outlet, the diameter of the hole when it is circular, or the effective area when the hole is of any shape other than circular, multiplied by 4/π and the square root. D ₀
The diameter or shape of the hole is set from the value of D ₀ that satisfies the relationship Vx/V ₀ = K・D ₀ /X, and the area of the hole determined from the value of D ₀ is and the blowing wind speed from the hole
The perforated plate is characterized by having a number of holes formed in the perforated plate approximately corresponding to a value obtained by dividing the amount of air blown from the outlet required for indoor air conditioning by a value multiplied by _V0 . Air outlet for high ceilings.