JP3459619B2 - Silencer for air conditioning duct - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler for an air conditioning duct which is interposed in a channel of an air conditioning duct and reduces noise of a blower or the like transmitted through the channel.

[0002]

2. Description of the Related Art Conventionally, as this type of silencer, a sound absorbing type which absorbs sound energy by a sound absorbing material such as glass wool provided around the flow path or in the flow path to reduce noise and is attached to the flow path. There is a reactance type in which interference and reflection of sound waves are caused by the sudden enlargement of the resonator and the cross section of the flow path, and this is utilized to reduce noise.

[0003]

However, although the sound absorption type can reduce the noise in the high frequency range, it cannot efficiently absorb the noise in the low frequency range, and the reactance type can reduce the noise in the low frequency range. There is a problem that it requires a large installation space.

Therefore, an object of the present invention is to provide a silencer for an air conditioning duct which can reduce noise in a low frequency range to noise in a high frequency range and is compact.

[0005]

In order to solve the above problems, the present invention relates to a silencer for an air conditioning duct which is interposed in a flow channel of an air conditioning duct and reduces noise transmitted through the channel. The peripheral wall facing the structure has a laminated body in which a film is stretched on the outside of the sound absorbing material, and a perforated plate is provided on the outside of the sound absorbing material. As the film, sound is transmitted and air leakage is prevented. I used the one that does.

In this silencer, the noise in the high frequency range is absorbed by the sound absorbing material, and the noise in the low frequency range is radiated to the outside through the holes of the perforated plate and diffused. It can be reduced.

If a cushion material is sandwiched between the film and the perforated plate, the film will not come into close contact with the perforated plate to impair the sound reduction effect.

Further, if the laminated body is attached to the frame as a unit, units of various sizes can be mass-produced to reduce the cost, and the units can be combined to cope with various ducts.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described with reference to FIGS. As shown in the figure, in this silencer, flanges 2 for duct connection are provided at both ends of a tubular body 1 having a quadrangular cross section forming a flow path L, and a laminated body 3 constituting a peripheral wall of the tubular body 1 is formed by a frame 4. It is supported.

The laminated body 3 is formed by inserting a cushion material 6a and a sound absorbing material 6b with a film 7 sandwiched between them inside a perforated plate 5 such as punching metal fitted on each surface of a frame 4. ing. As the film 7, a film that transmits sound and prevents air from leaking is used.

Glass wool is used as the cushion material 6a and the sound absorbing material 6b, and a sheet 8 for preventing scattering of glass wool is stretched on the inner surface of the sound absorbing material 6b facing the flow path L. A glass cloth is used as the sheet 8. Instead of glass wool, the cushion material 6a may be made of another material having a cushioning property such as sponge.

In the silencer as described above, noise in the high frequency range is absorbed by the sound absorbing material 6b, and noise in the low frequency range is radiated to the outside through the holes of the perforated plate 5 and diffused. A sufficient sound reduction effect can be expected and pressure loss is small.

A film 7 for preventing air leakage in the flow path L
Since the cushion material 6a is interposed between the perforated plate 5 and the perforated plate 5, the film 7 does not adhere to the perforated plate 5 to impair the sound reduction effect.

The film 7 and the perforated plate 5 may be fixed to the frame 4 and the cushion material 6a may be omitted.

In the first embodiment, the seat 8 is flush with the opening surface of the flange 2 so that the cross-sectional area of the flow path L is substantially the same over the entire length of the tubular body 1. As in the second embodiment shown in FIGS. 4 and 5, the film 7 is aligned with the opening surface of the flange 2, and the sound absorbing material 6b is provided inside thereof.
May be provided.

Further, as in the third embodiment shown in FIG. 6, when the laminated body 3 is attached as a unit to the frame 4, units of various sizes can be mass-produced to reduce the cost, and the duct Even if the diameter of the frame 4 varies depending on the diameter, a single unit or a plurality of units of each width can be attached in parallel to cope with the difference.

By the way, in each of the above-mentioned embodiments, the laminated body 3 is used on the entire peripheral wall of the cylindrical body 1. However, a part of the surface may be a single layer structure using a normal steel plate.

Further, the sectional shape of the cylindrical body 1 is not limited to a quadrangle, but may be a circular shape, an elliptical shape or the like.

In addition, the above structure can be applied not only to the straight type as illustrated but also to an elbow type and a chamber type.

[0020]

EXAMPLE A noise reduction amount test of the silencer having the above structure was conducted by using the equipment shown in FIG. This equipment generates sound of various frequencies from the speaker 11 of the front room 10, detects the sound radiated to the reverberation room 13 through the duct 12 with the microphone 14, and measures the average sound pressure level with the measuring device 15. Is.

The sound pressure level when the test body S was interposed in the duct 12 was compared with the sound pressure level when the test body S was not present, and the difference was taken as the volume reduction.

As the test piece S, the outer size is 400 mm × 400 mm × 1075 m in width × height × length.
m, an inner diameter of 300 mm × 300 mm, and a film sandwiched between two pieces of glass wool having a thickness of 25 mm on its peripheral wall was used, and a conventional sound absorbing silencer was also measured as a comparative example.

The test results are shown in FIG. As shown in the figure, the conventional muffler has a noise reduction effect of about 5 dB for low frequencies of 250 Hz or less, but the muffler according to the present invention has confirmed noise reduction of about 10 to 15 dB.

[0024]

As described above, in the silencer according to the present invention, noise in the high frequency range is absorbed by the sound absorbing material, and noise in the low frequency range is radiated to the outside through the holes of the perforated plate and diffused.
Even in a small size, noise in a wide band can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing an outer shape of a muffler according to a first embodiment of the present invention.

FIG. 2 is a front view of one side of the same as above.

FIG. 3 is an enlarged sectional view of the main part of the same.

FIG. 4 is a one-sided vertical sectional front view of a muffler according to a second embodiment of the present invention.

FIG. 5 is an enlarged sectional view of the main part of the above.

FIG. 6 is an exploded perspective view of a silencer according to a third embodiment of the present invention.

FIG. 7 is a diagram showing a test facility.

FIG. 8 is a graph showing test results.

[Explanation of symbols] 1 cylinder 2 flange 3 laminate 4 frames 5 Perforated plate 6a Cushion material 6b sound absorbing material 7 Air leakage prevention film 8 Glass wool shatterproof sheet L flow path

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroyuki Tsubaki 1-12-19 Kitahori, Nishi-ku, Osaka City Kurimoto Iron Works Co., Ltd. (72) Inventor Tomoyuki Hasegawa 1-12-19 Kitahori, Nishi-ku, Osaka Kurimoto Iron Works Co., Ltd. (56) Reference JP-A-10-96549 (JP, A) JP-A-10-185288 (JP, A) JP-A-49-81736 (JP, A) Actual development Sho-52-168368 (JP, U) Actual development Sho 46-36290 (JP, U) Actual development Sho 51-84503 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F24F 13/00-13 / 078

Claims (3)

(57) [Claims] 1. In a silencer for an air conditioning duct which is interposed in a flow path of an air conditioning duct and reduces noise transmitted through the flow path, a peripheral wall facing the flow path has a film stretched outside a sound absorbing material, and the outside thereof. A silencer for an air-conditioning duct, characterized in that it has a laminated body in which a perforated plate is provided at intervals, and that the film is made of a material that transmits sound and prevents leakage of air. 2. The silencer for an air conditioning duct according to claim 1, wherein a cushion material is sandwiched between the film and the perforated plate. 3. The unit according to claim 1, wherein the laminated body is attached to a frame as a unit.
The silencer for the air conditioning duct described in.