JP3044736B2 - Air conditioning duct noise attenuator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an air conditioning duct noise attenuator in a hall, an audio-visual room, a recording studio, and other various buildings. The present invention relates to a simple structure for controlling noise transmitted through a duct. The sound can be effectively reduced.

[Conventional technology]

In the design of halls, audio-visual rooms, recording studios, etc., sufficient measures must be taken against noise entering through air-conditioning ducts, in addition to sound-insulating structures on the walls.

In the past, building design and equipment design were performed separately, so sound insulation measures for air-conditioning ducts were either passed through the duct space provided in the building design as it was or a damping device was installed in the duct space. (Sound-absorbing elbows, sound-absorbing chambers, muffler-type silencers, etc.) were arranged to secure the required sound absorption volume.

FIG. 2 shows a conventional sound insulation measure for an air conditioning duct. In this building 10, in addition to the main space such as the stage, the room, and the corridor, the surroundings are surrounded by a boundary wall 12 and a closed duct space 14 is formed, in which an air conditioning duct 16, made of iron plate duct, 18 passes through a hole 19 formed in the boundary wall 12. In duct space 14, air conditioning duct
A straight pipe type silencer (muffler type silencer) 20 is inserted in 16. This silencer 20 has a cross-sectional area S larger than the cross-sectional area ρ of the air-conditioning duct 16,
The noise transmitted through the air conditioning duct 16 is reduced by the expansion type noise reduction and the absorption type sound absorption.

In the duct space 14, the air conditioning duct 18 is provided with two-stage sound absorbing elbows 22, 24. These sound absorbing elbows 22 and 24 each have a flow path bent at a right angle, and a sound absorbing material is lined. The sound absorbing elbows 22 and 24 reduce noise transmitted through the air conditioning duct 18 due to reflection by the right-angled bending and sound absorption by the lined sound absorbing material.

[Problems to be solved by the invention]

In the sound reduction by the silencer 20, since the sound reduction is proportional to S / ρ, in order to increase the sound reduction, the cross-sectional area of the silencer 20 must be increased, and in order to obtain the necessary sound reduction, The size of the silencer 20 increases, the cost increases, and the duct space 14 requires a wide area. In addition, the attenuation of the bass is small, and particularly in the case of the high-frequency sound type, the attenuation in the low frequency range is at most about 5 to 10 dB. In addition, it was easily affected by installation conditions, such as the inability to secure experimental data (catalog values) at the construction site.

Further, in the sound reduction by the sound absorbing elbows 22 and 24, the sound reduction was small, and only about several dB was obtained particularly in a low frequency range.
In addition, a sound absorbing elbow is added to the air conditioning duct 18 in the duct space 14.
Installation of 22,24 was not easy.

SUMMARY OF THE INVENTION An object of the present invention is to solve the drawbacks of the prior art and to provide an air conditioning duct noise attenuating device that can achieve a large noise reduction effect with a simple configuration and a small installation space.

[Means for solving the problem]

The present invention relates to a plurality of air conditioning ducts that are piped through a common boundary wall surrounding portion surrounded by a boundary wall of a building, wherein the plurality of duct bodies are located within the boundary wall surrounding portion. A part or the whole is made of a material that is substantially impermeable to air and acoustically substantially permeable, and the space in the boundary wall surrounding portion is not partitioned into spaces to be individually accommodated for each of the ducts. It is characterized by comprising.

[Action]

This invention realizes a sound reduction structure by combining architectural design and equipment design, and uses the space itself surrounded by the building walls such as duct space and dead space provided in advance to reduce sound. It is what you do. In other words, the air flowing through the duct passes through the portion made of acoustically almost transparent material as it is, but the sound that has propagated through the duct is almost acoustically transmitted through the surrounding wall. Since it is leaked out of the duct and diffused in the portion made of the conductive material, the inflatable noise reduction is performed there. In this case, the sound absorption volume is proportional to [cross-sectional area of diffusion part] ÷ [cross-sectional area of duct]. However, since the cross-sectional area of the part where diffusion occurs is the same as the cross-sectional area of the surrounding area of the boundary wall, the conventional silencer (FIG. A very large cross-sectional area can be ensured as compared with the reference numeral 20), and a large volume reduction can be obtained. In particular, a large amount of attenuation in a low sound range can be ensured as compared with the conventional one.

Also, since it is only necessary to construct a part of the duct with a material that is almost acoustically transparent (for example, glass wool duct),
It can be easily and easily constructed, and requires a small installation space.

In addition, even if there are multiple ducts (multiple ducts), the same volume reduction can be obtained for each system as when placed alone, so even if the number of systems increases, the installation space remains the same, The more the number of lines, the more effective.

In addition, when the acoustically substantially transparent material is made of glass wool, the glass wool also functions as a sound absorbing material in the duct space, so that the sound that has flowed out and diffused into the duct space is further attenuated and returned to the duct again. Energy can be sufficiently reduced, which is more effective.

〔Example〕

One embodiment of the present invention is shown in FIG. This building 30
Is a closed so-called duct space 31 which is provided in advance for a duct pipe or the like or is a dead space and is surrounded by a boundary wall 32 (a driving wall made of concrete, a slab, etc.). (Partition wall surrounding portion) is formed therein, through which four systems of air conditioning ducts 34 to 37 (duct main body) are passed.

In the air-conditioning ducts 34 to 37, portions 34a to 37a outside the duct space 31 (generally connecting to a main space such as a room or a stage) are constituted by iron plate ducts, and the opening ends thereof are boundaries. It is fixed to the outer surface of the boundary wall 32 by bolting or the like so as to communicate with a hole 40 having the same cross-sectional area formed in the wall 32.

Also, the air conditioning ducts 34 to 37 are formed by glass wool ducts at portions 34 a to 37 a inside the duct space 31, and bolted to the inner surface of the boundary wall 32 so that the open end thereof communicates with the hole 40. Fixed. The glass wool ducts 34b to 37b are formed by molding a relatively hard glass wool board or the like into a pipe shape. In some cases, the outer cover is provided with an aluminum cover (substantially transmitting low frequencies). The glass wool duct is substantially impermeable to air and acoustically substantially permeable.

In the air-conditioning ducts 34 to 37, air flowing to each main space is flown. In addition, noise from a blower or the like is also transmitted therethrough.

According to the configuration of FIG. 1 described above, the air conditioning ducts 34 to
The air flowing inside 37 is a glass wool duct 34b-37b
Pass through the inside as it is. Also, noise transmitted through the air conditioning ducts 34 to 37 leaks through the wall surfaces of the glass wool ducts 34b to 37b in the duct space 31, and
Spread into 31. Due to this diffusion, inflatable noise reduction is performed. In addition, the glass wool ducts 34b to 37b also perform absorption type sound absorption.

FIG. 3 conceptually shows the sound absorbing operation of the single air conditioning duct 34 shown in FIG. 1 by the expansion type sound absorbing. Assuming that the cross-sectional area of the duct space 31 is S ₀ and the cross-sectional area of the air-conditioning duct 34 is ρ, a volume reduction proportional to S ₀ / ρ is obtained by the expanded sound absorption. S ₀ is the conventional silencer 20 (Fig. 2)
Is very large as compared with the cross-sectional area S, so that a large volume reduction can be obtained especially in a low frequency range. In addition, with respect to sounds in the mid-range and treble range, the material itself of the glass wool ducts 34b to 37b becomes a sound-absorbing material and can be effectively reduced.

In addition, even if the number of systems (the number of ducts) increases, the same sound reduction can be obtained for each system as in the case where they are arranged alone. Therefore, the noise reduction effect increases as the number of systems increases. That is,
If the volume reduction when only one duct is placed is A,
The total sound reduction when n ducts are arranged is nA, which is 1 / per unit compared to when only one duct is arranged.
In the duct space of n, the same volume reduction can be obtained for each duct.

Due to the above-described noise reduction and sound absorption effects, according to the embodiment of FIG.
criteria) Low noise of -15 or less can be easily realized.

If a sound absorbing material such as glass wool is lined on the inner wall surface of the duct space 31 in FIG. 1, the sound reducing effect can be further enhanced.

[Modification example]

In the above embodiment, the air-conditioning ducts 34 to 37 are constituted by the glass wool ducts 34b to 37b over the entire duct space 31, but as shown in FIG. 34b-3
7b can also be comprised.

Further, in the above embodiment, the inner diameter of the glass wool ducts 34b to 37b is substantially the same as the inner diameter of the iron plate ducts 34b to 37b.
The inner diameters do not necessarily have to be the same.

Further, in the above-described embodiment, glass wool is used as the material that is acoustically substantially transparent. However, various materials that are almost impermeable to air and acoustically substantially transparent can be used.

〔The invention's effect〕

As described above, according to the present invention, the sound propagated through the duct leaks out of the duct and diffuses at the portion made of an acoustically substantially transmissive material in the boundary wall surrounding portion. As a result, the inflatable noise reduction is performed, and the noise can be eliminated. In this case, the cross-sectional area of the portion where the diffusion occurs is the same as the cross-sectional area of the boundary wall surrounding portion, so that a wider cross-sectional area can be secured as compared with the conventional silencer, and a large volume reduction can be obtained. Can be remarkably increased as compared with the conventional one.

Further, since only a part of the duct needs to be made of a material that is almost acoustically permeable, it can be simply and easily constructed, and the installation space is small.

In addition, even if there are multiple ducts (multiple ducts), the same volume reduction can be obtained for each system as when placed alone, so even if the number of systems increases, the installation space remains the same, The more the number of lines, the more effective.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing a conventional apparatus. FIG. 3 is a conceptual diagram showing the sound reduction effect of the apparatus of FIG. FIG. 4 is a longitudinal sectional view showing another embodiment of the present invention. 30 ……………………………………………………………………………………………………… ………………………………………………………………………………………………………………………. Material).

Claims (1)

(57) [Claims] 1. A plurality of air-conditioning ducts that are piped through a common wall surrounding portion surrounded by a wall of a building,
A part or all of the plurality of duct bodies located in the boundary wall surrounding portion are each made of a material that is substantially impermeable to air and acoustically substantially transparent, and An air-conditioning duct noise attenuating device, wherein a space inside the air-conditioning duct is configured without partitioning into a space for accommodating the duct individually.