WO2019009342A1

WO2019009342A1 - Sound-damping system

Info

Publication number: WO2019009342A1
Application number: PCT/JP2018/025410
Authority: WO
Inventors: 美博菅原; 昇吾山添; 真也白田; 暁彦大津
Original assignee: 富士フイルム株式会社
Priority date: 2017-07-05
Filing date: 2018-07-04
Publication date: 2019-01-10
Also published as: JP2019133122A; JP6672390B2

Abstract

Provided is a highly versatile sound-damping system with which it is possible to combine high ventilation performance and sound-proofing performance, and with which it is possible to dampen a plurality of resonant sounds, and which does not require design to be made to correspond to a ventilation sleeve. The sound-damping system has a sound-damping device provided to a ventilation sleeve, and the sound-damping device damps sound having the first resonant frequency of the ventilation sleeve. The sound-damping device is equipped with: a sound damper having a cavity portion and an opening portion, and is positioned one end side surface of a wall; and a sound-absorbing material positioned at a position inside the cavity portion or covering the opening portion. The opening portion of the sound damper is positioned facing the central axis side of the ventilation sleeve, and the depth Ld of the cavity portion in the direction of propagation of sound waves within the sound damper is greater than the width Lo of the opening portion in the width direction of the ventilation sleeve. If the wavelength of the sound waves having the first resonant frequency of the ventilation sleeve is defined as λ, the depth Ld of the cavity portion satisfies the condition 0.011×λ<Ld<0.25×λ.

Description

Silence system

The present invention relates to a noise cancellation system.

In a tubular member such as a ventilation port or a duct for air conditioning, which is provided on a wall separating the room from the room, which penetrates the room from the room, the noise from the room can be suppressed from being transmitted to the room. In order to suppress the transmission of the sound to the outside, a sound absorbing material such as urethane or polyethylene is installed in the tubular member.
However, in the case of using a sound absorbing material such as urethane and polyethylene, the absorptivity of low frequency sound of 800 Hz or less becomes extremely low, so it is necessary to increase the volume in order to increase the absorptivity. Since it is necessary to ensure air permeability of the mouth, air conditioning duct and the like, there is a limit to the size of the sound absorbing material, and there is a problem that it is difficult to achieve both high air permeability and soundproof performance.

Here, as the noise in the tubular member such as the vent and the air conditioning duct, the resonance sound of the tubular member becomes a problem. In particular, the lowest frequency resonance sound is a problem. When the resonance noise is 800 Hz or less, the amount of the sound absorbing material is significantly increased for soundproofing by the sound absorbing material. Therefore, it is generally difficult to obtain sufficient soundproofing performance even at the expense of ventilation. Taking a commercial product as an example, a polyethylene soundproof sleeve (SK-BO75 made by Shin-Kyowa Co., Ltd.), which is a soundproof product of sound absorbing material type inserted into the inside of a housing ventilation sleeve, has an aperture ratio of 36% and significantly ventilation. In spite of reducing the amount, 80% or more of the resonance sound is transmitted.
In order to silence the resonance of such a tubular member, a resonance type silencer that silences a sound of a specific frequency is used.

For example, in Patent Document 1, a ventilation sleeve for ventilating both spaces is provided in a penetrating state in a partition part that divides the first space and the second space, and a resonance type silencer for muffling sound passing through the ventilation sleeve A vent structure in which the mechanism is provided in the venting sleeve, wherein the resonance type sound deadening mechanism is located at a position outside the divider in the axial direction of the vent sleeve and along the divider and the divider. A vent structure is described which is formed on the outer periphery of the venting sleeve, at a position between the facing plate and the decorative board provided in a state of being separated from the surface. Further, as a resonance type noise reduction mechanism, a side branch type silencer and a Helmholtz resonator are described.

Further, Patent Document 2 discloses a muffling tubular body installed and used in a sleeve tube of a natural ventilation port, in which at least one end is closed and an opening is provided in the vicinity of the other end, one end A muffling tubular body is described, having a length from the part to the center of the opening that is approximately half the length of the entire length of the sleeve and inside which the porous material is arranged.
Further, in Patent Document 2, the thickness of the outer wall in a house, an apartment, etc. is about 200 to 400 mm, and the sound insulation performance in the frequency band of the first resonance frequency (400 to 700 Hz) generated in the sleeve tube provided on this outer wall It is described that the decrease of H occurs (see FIG. 15).

Patent No. 4020163 (Japanese Patent Laid-Open No. 2007-169959) JP, 2016-95070, A

However, according to the study of the present inventors, in order to mute the sound of the lowest resonance frequency of the tubular member by using a resonance type silencer, a length of at least 1/4 of the wavelength of the resonance frequency is required. As a result, the size of the silencer increases. Therefore, there is a problem that it is difficult to simultaneously achieve high air permeability and soundproofing performance.
In addition, the resonance type silencer selectively mutes sound of a specific frequency (frequency band). If the length, shape, etc. of the tubular member differ, the resonant frequency of the tubular member also changes. Therefore, there is a problem that the design is required according to the tubular member, and the versatility is low.

Also, although the resonance of the tubular member occurs at a plurality of frequencies, the silencer of the resonance type mutes the sound of a specific frequency. Therefore, there is a problem that the resonance sound of other frequencies can not be silenced because the resonance noise to be silenced is only one frequency, and the frequency band where the resonance type silencer silences is narrow.
Also, although it is effective to arrange the resonance type silencer in the open space, when arranged at the same resonance frequency inside the resonator such as the tubular member, the resonance of the tubular member interacts with the resonance of the silencer. It will As a result, since the original resonance transmitted sound by the tubular member is separated into two frequencies to generate a new resonance transmitted sound, there is a problem that the effect as the silencer is small.

The object of the present invention is to solve the above-mentioned problems of the prior art, to achieve both high air permeability and soundproofing performance, to be able to silence a plurality of resonances, and to be designed in accordance with the tubular member It is an object of the present invention to provide a highly versatile silencing system that does not require

The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, a ventilating sleeve installed through the wall is a noise reduction system in which a noise reducing device is provided to reduce the noise passing through the ventilating sleeve, The muffling apparatus is for muffling sound having a frequency including the frequency of the first resonance generated in the ventilation sleeve, and the muffling apparatus has a cavity and an opening communicating the cavity with the outside, and one of the walls And one or more silencers disposed on the end face side of the sound absorber, and a sound absorbing material disposed at a position covering at least a part of the hollow portion of the silencer or at least a part of the openings of the silencers; The opening of the silencer is disposed toward the central axis of the ventilation sleeve, and the depth L _d of the cavity in the sound wave traveling direction in the silencer is the width L of the opening in the axial direction of the ventilation sleeve. a silencer system that is larger than _o and includes a silencer Assuming that the wavelength of the sound wave at the resonance frequency of the first resonance of the aeration sleeve in the stem is λ, the depth L _d of the cavity satisfies 0.011 × λ <L _d <0.25 × λ, the above problem The present invention has been completed.
That is, it discovered that the said objective could be achieved by the following structures.

[1] A noise reduction system in which a noise reduction device for reducing noise passing through the ventilation sleeve is installed on a ventilation sleeve installed through the wall,
The silencer is for silencing the sound of the frequency including the frequency of the first resonance generated in the ventilation sleeve,
The silencer is
A cavity and an opening communicating between the cavity and the outside, and one or more silencers disposed on one end face side of the wall;
A sound absorbing material disposed at a position covering at least a part of the cavity of the silencer or at least a part of the opening of the silencer;
The opening of the silencer is arranged facing the central axis of the ventilation sleeve,
The depth L _d of the cavity in the direction of travel of the sound wave in the silencer is greater than the width L _o of the opening in the axial direction of the venting sleeve,
The cavity depth L _d satisfies 0.011 × λ <L _d <0.25 × λ, where λ is the wavelength of the sound wave at the resonance frequency of the first resonance of the ventilation sleeve in the silencer system including the silencer. ,
The silencer does not resonate with the sound of the frequency of the first resonance generated in the tubular member, and does not mute the sound of the frequency of the first resonance by the resonance of the silencer alone but muffles it by the conversion mechanism Muffler system.
[2] A muffling system in which a muffling apparatus for muffling the sound passing through the ventilation sleeve is provided on a ventilation sleeve installed through the wall,
The muffling apparatus muffles the sound of the frequency including the frequency of the first resonance generated in the ventilation sleeve,
The silencer is
A cavity and an opening communicating between the cavity and the outside, and one or more silencers disposed on one end face side of the wall;
A sound absorbing material disposed at a position covering at least a part of the cavity of the silencer or at least a part of the opening of the silencer;
The opening of the silencer is arranged facing the central axis of the ventilation sleeve,
The area of the opening of the silencer S _1, when the surface area of the inner wall of the cavity and S _d, the ratio S ₁ / S _d of the area S ₁ to the area S _d is 0 <a S ₁ / S _d <40% Meet
Assuming that the wavelength of the sound wave at the resonance frequency of the first resonance of the aeration sleeve in the muffling system including the muffling device is λ, the depth L _d of the cavity in the traveling direction of the sound wave in the silencer is 0.011 × λ <L. satisfy _d <0.25 × λ,
The silencer does not resonate with the sound of the frequency of the first resonance generated in the tubular member, and does not mute the sound of the frequency of the first resonance by the resonance of the silencer alone but muffles it by the conversion mechanism Muffler system.
[3] Assuming that the frequency of the first resonance generated in the ventilation sleeve is F ₀ and the resonance frequency of the silencer is F ₁ , it is preferable to satisfy 1.15 × F ₀ <F _{1 according} to [1] or [2] Silence system.
[4] In a cross section parallel to the axial direction of the ventilation sleeve, the width L _w of the hollow portion in the direction orthogonal to the depth direction of the hollow portion satisfies 0.001 × λ <L _w <0.061 × λ. The noise reduction system according to any one of 1) to [3].
[5] The flow resistance σ ₁ of the sound absorbing material satisfies (1.25−log (0.1 × L _d )) / 0.24 <log (σ ₁ ) <5.6 [1] to [4] The muffling system according to any of the above.
[6] The flow resistance σ ₁ of the sound absorbing material satisfies (1.32−log (0.1 × L _d )) / 0.24 <log (σ ₁ ) <5.2 [1] to [5] The muffling system according to any of the above.
[7] The flow resistance σ ₁ of the sound absorbing material satisfies (1.39−log (0.1 × L _d )) / 0.24 <log (σ ₁ ) <4.7 [1] to [6] The muffling system according to any of the above.
[8] It has a decorative board provided parallel to the wall,
The noise reduction system according to any one of [1] to [7], wherein the noise reduction device is disposed between the decorative plate and the wall.
[9] In a cross section parallel to the axial direction of the venting sleeve, the silencer is in the axial direction of the venting sleeve, on one side of the axially extending hollow portion of the ventilating sleeve and the hollow portion parallel to the axial direction of the ventilating sleeve. And an opening located on one end side of the
The silencer system according to any one of [1] to [8], wherein the length of the cavity in the axial direction of the ventilation sleeve is the depth L _d of the cavity.
[10] The silencer system according to any one of [1] to [9], wherein the silencer has a plurality of silencers.
[11] The silencer system according to [10], wherein the openings of the plurality of silencers are arranged at at least two or more positions in the axial direction of the insertion portion.
[12] The noise reduction system according to [11], wherein the depth L _d of the cavity portion of the silencer is different for each position of the opening.
[13] The noise reduction system according to [11] or [12], wherein sound absorbing materials having different acoustic characteristics are disposed in the hollow portion of the silencer at each position of the opening.
[14] The silencer has a tubular insert connected within the venting sleeve,
The insertion portion is disposed with the central axis of the insertion portion aligned with the central axis of the ventilation sleeve,
The silencer system according to any one of [1] to [13], wherein the silencer is connected to one end face of the insertion portion.
[15] The noise reduction system according to any one of [1] to [14], wherein the area S ₁ of the opening in the circumferential surface about the central axis of the ventilation sleeve is smaller than the area S _{0 of the} cavity.
[16] have two or more silencers,
The silencer system according to any one of [1] to [15], wherein the openings of the respective silencers are arranged in rotational symmetry with respect to the central axis of the insertion portion.
[17] The noise reduction system according to any one of [1] to [16], which is installed at the indoor end of the ventilation sleeve.
[18] In the cross section perpendicular to the axial direction of the ventilation sleeve, the effective outer diameter D ₀ of the ventilation sleeve and the effective outer diameter D ₁ of the _{_{muffler, D 1 <D 0 + 2}} × a (0.045 × λ + 5mm) The muffling system according to any one of [1] to [17].
[19] The noise reduction system according to any one of [1] to [18], wherein the noise reduction device can be attached to and removed from the ventilation sleeve.
[20] The noise reduction system according to any one of [1] to [19], wherein a silencer of the noise reduction device is separable.
[21] The noise reduction system according to any one of [1] to [20], wherein the noise reduction device is made of a material having higher heat resistance than the flame retardant material.
[22] The silencer system according to any one of [1] to [21], wherein the opening of the silencer is formed in a slit along the circumferential direction of the inner peripheral surface of the insertion portion.
[23] It has a cover member installed on the opposite side to the ventilation sleeve of the silencer, or an air volume adjustment member,
The silencer system according to any one of [1] to [22], wherein the cover member or the air volume adjusting member covers the silencer when viewed from the axial direction of the ventilation sleeve.
[24] a cover member installed at one end of the ventilation sleeve;
An air volume adjustment member installed at the other end of the ventilation sleeve;
Assuming that the wavelength of the sound wave at the resonance frequency of the first resonance of the ventilation sleeve in the silencer system including the silencer, the cover member and the air volume adjusting member is λ, the depth L _d of the cavity is shorter than λ / 4 [1] The muffling system according to any one of [23].
[25] Have a decorative plate provided parallel to the wall,
The muffling system according to any one of [1] to [24], wherein the total thickness of the wall and the decorative plate, including the space between the wall and the decorative plate, is 175 mm to 400 mm.
[26] In the axial direction of the ventilation sleeve, the silencer is disposed between the wall and the decorative plate disposed apart from the wall by being partially inserted through the through holes formed in the decorative plate Yes,
The noise reduction system according to any one of [1] to [25], having a boundary cover that covers the boundary between the decorative plate and the silencer when viewed in the axial direction of the ventilation sleeve.
[27] In the axial direction of the venting sleeve, the silencer is arranged at one end of the venting sleeve,
Furthermore, the noise reduction system according to any one of [1] to [26], further comprising a soundproofing member disposed in the ventilation sleeve.
[28] In the axial direction of the venting sleeve, the silencer is arranged at one end of the venting sleeve,
Further, the noise reduction system according to any one of [1] to [27], further comprising a soundproofing member disposed at the other end of the ventilation sleeve.
[29] The width L _w of the cavity of the silencer is
5.5 mm ≦ L _w ≦ 300 mm
The noise reduction system according to any one of [1] to [28].
[30] The depth L _d of the cavity of the silencer is
25.3 mm ≦ L _d ≦ 175 mm
The noise reduction system according to any one of [1] to [29].
[31] The noise reduction system according to any one of [1] to [30], wherein a plurality of sound absorbing materials are disposed in the hollow portion.

According to the present invention, it is possible to achieve both high air permeability and soundproofing performance, and it is also possible to silence a plurality of resonances, and to provide a highly versatile silencing system that does not require a design matched to the ventilation sleeve. Can be provided.

It is a sectional view showing an example of a muffling system of the present invention notionally. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is a figure for demonstrating the area of the opening part of a silencer, and the area of a hollow part. It is a figure for demonstrating the depth and width of the hollow part of a silencer. It is a figure for demonstrating the sound field space of a tubular member. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is a graph showing the relationship between the depth of a hollow part, width, and average sound pressure. It is a graph showing the relationship between the depth of a hollow part, width, and average particle velocity. It is a graph showing the relationship between the depth of a hollow part, width, and vxP. It is a graph showing the relationship between the depth of a hollow part, width, and vxP. It is a figure for demonstrating the method of simulation. It is a graph showing the relation between frequency and transmitted sound pressure. It is a graph showing the relationship between the ratio of opening area, and the peak of transmitted sound pressure. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. FIG. 30 is a cross-sectional view taken along the line CC of FIG. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of a silencer. It is sectional drawing which shows notionally another example of a silencer. It is sectional drawing which shows notionally another example of a silencer. It is sectional drawing which shows notionally another example of a silencer. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is a graph showing the relationship between a transmitted sound pressure and a frequency. It is sectional drawing which represents typically the model of the muffling system of the Example used for simulation. It is a graph showing the relationship between a transmitted sound pressure and a frequency. It is sectional drawing which represents typically the model of the muffling system of the comparative example used for simulation. It is a graph showing the relationship between a transmitted sound pressure and a frequency. It is a graph showing the relation between transmitted sound pressure, frequency, and depth. It is a graph showing the relation between transmitted sound pressure, frequency, and depth. It is a graph showing the relation between transmitted sound pressure, frequency, and depth. It is a graph showing the relation between penetration loss and distance. It is sectional drawing which represents typically the other model of the muffling system of the Example used for simulation. It is sectional drawing which represents typically the other model of the muffling system of the Example used for simulation. It is a graph showing the relationship between a transmitted sound pressure, a frequency, and a position. It is a graph showing the relationship between a transmitted sound pressure and a frequency. It is a graph showing the relation between transmitted sound pressure, frequency and flow resistance. It is a graph showing the relationship between flow resistance and the peak value of transmitted sound pressure. It is a graph showing the relation between depth, flow resistance, and the peak value of transmitted sound pressure. It is a graph showing the relation between frequency and transmitted sound pressure. It is a figure for demonstrating the measuring method of a reference. It is a figure for demonstrating the measuring method of the transmitted sound pressure in an Example. It is a graph showing the relationship between a transmitted sound pressure and a frequency. It is a graph showing the relationship between a transmitted sound pressure and a frequency. It is a graph showing the relationship between a transmitted sound pressure and a frequency. It is a graph showing the relationship between a transmitted sound pressure and a frequency. It is a graph showing the relationship between a transmitted sound pressure and a frequency. It is a graph showing the relationship between a transmitted sound pressure and a frequency. It is a graph showing the relation between frequency and transmission loss. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. FIG. 73 is a front view of FIG. 72 as viewed from the air amount adjustment member side. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is a figure for demonstrating the measuring method of the transmitted sound pressure in an Example. It is a graph showing the relationship between a transmitted sound pressure and a frequency. It is a graph showing the relationship between a transmitted sound pressure and a frequency. It is a graph showing the relationship between a transmitted sound pressure and a frequency. It is a graph showing the relation between the transmission loss and the octave band. It is a graph showing the relationship between a transmitted sound pressure and a frequency. It is a graph showing the relationship between a transmitted sound pressure and a frequency. It is a graph showing the relation between the transmission loss and the octave band. It is a graph showing the relationship between a transmitted sound pressure and a frequency. It is a graph showing the relation between the transmission loss and the octave band. It is sectional drawing which shows typically the bending part of the tubular member which has arrange | positioned the sound transmission wall. It is sectional drawing which shows typically the bending part of the tubular member which has arrange | positioned the sound transmission wall. It is a schematic diagram for demonstrating a simulation model. It is a graph showing the relation between transmitted sound pressure intensity and frequency. It is a graph showing the transmission loss of a 500 Hz band. It is a schematic diagram for demonstrating a simulation model. It is a graph showing the transmission loss of a 500 Hz band. It is a schematic diagram for demonstrating a simulation model. It is a graph showing the transmission loss of a 500 Hz band. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. FIG. 100 is a cross-sectional view taken along line DD of FIG. 100. It is sectional drawing which shows notionally another example of the silencing system of this invention. FIG. 102 is a cross-sectional view taken along the line EE of FIG. 102. It is sectional drawing which shows notionally another example of a silencer. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is sectional drawing which represents typically the model of the muffling system used for simulation. It is a graph showing the relation between flow resistance, opening width / cylinder length, and penetration loss. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is a figure for demonstrating the method of simulation. It is a graph showing the relation between frequency and transmitted sound pressure intensity. It is a conceptual diagram for demonstrating the evaluation method of the calculation model of a comparative example. FIG. 113 is a cross-sectional view taken along the line DD of FIG. It is a graph showing the relation between frequency and transmitted sound pressure intensity. It is a typical side view for explaining composition of a comparative example. It is a graph showing the relation between frequency and transmitted sound pressure intensity.

Hereinafter, the present invention will be described in detail.
Although the description of the configuration requirements described below is made based on the representative embodiments of the present invention, the present invention is not limited to such embodiments.
In the present specification, a numerical range represented using “to” means a range including numerical values described before and after “to” as the lower limit value and the upper limit value.
Moreover, in the present specification, the terms "orthogonal" and "parallel" include the range of allowable errors in the technical field to which the present invention belongs. For example, “orthogonal” and “parallel” mean within ± 10 ° of strictly orthogonal or parallel, etc., and the error with respect to strictly orthogonal or parallel is 5 ° or less Is preferably, and more preferably 3 ° or less.
As used herein, "identical" and "identical" are intended to include error ranges generally accepted in the art. Further, in the present specification, the terms “all”, “all” or “entire” etc. include 100% as well as an error range generally accepted in the technical field, for example, 99% or more, The case of 95% or more, or 90% or more is included.

[Mute system]
The configuration of the noise reduction system of the present invention will be described using the drawings.
The muffling system of the present invention places a silencer, which does not resonate with the sound of the first resonance frequency of the ventilation sleeve, in the vicinity of the ventilation sleeve to muffle the sound of the first resonance frequency generated in the ventilation sleeve. It is a thing.
FIG. 1 is a schematic cross-sectional view showing an example of a preferred embodiment of the noise reduction system of the present invention.

As shown in FIG. 1, the silencer system 10z has a configuration in which the silencer 21 is disposed on the outer peripheral surface (outer peripheral surface) of the cylindrical tubular member 12 provided through the wall 16 separating the two spaces. Have.
The tubular member 12 is, for example, a ventilation sleeve such as a ventilation port and an air conditioning duct.
The silencer 21 mutes the sound of the frequency including the frequency of the first resonance generated in the ventilation sleeve.
The silencer 21 has a substantially rectangular parallelepiped shape extending in the radial direction of the tubular member 12 and has a substantially rectangular parallelepiped hollow portion 30 inside. At the end face of the hollow portion 30 on the side of the tubular member 12, an opening 32 communicating the hollow portion 30 with the outside is formed.
The opening 32 of the silencer 21 is connected to a circumferential opening 12 a formed on the circumferential surface of the tubular member 12. By connecting the opening 32 to the circumferential opening 12a, the opening 32 is connected to the sound field space of the first resonance generated in the tubular member 12 in the noise reduction system 10a.

The tubular member 12 is not limited to the ventilating port and the air conditioning duct, but may be a general duct used for various devices.

Further, as shown in FIG. 1, the depth of the cavity 30 in the direction of travel of the sound wave in the cavity 30 of the silencer 21 is L _d, and the axial direction of the tubular member 12 (hereinafter also referred to simply as the axial direction). Assuming that the width of the opening 32 of the silencer 21 is L _o , the depth L _d of the cavity 30 is larger than the width L _o of the opening 32.
Here, the traveling direction of the sound wave in the hollow portion 30 can be determined by simulation. In the example shown in FIG. 1, since the hollow portion 30 extends in the radial direction, the traveling direction of the sound wave in the hollow portion 30 is the radial direction (vertical direction in the drawing). Therefore, the depth L _d of the cavity 30 is the length from the opening 32 in the radial direction to the upper end of the cavity 30. When the depth of the cavity 30 differs depending on the position, the depth L _d of the cavity 30 is an average value of the depth at each position.
When the width of the opening 32 differs depending on the position, the width L _o of the opening 32 is an average value of the widths at each position.

Further, assuming that the wavelength of the sound wave at the resonance frequency of the first resonance generated in the tubular member 12 in the noise reduction system is λ, the depth L _d of the hollow portion 30 of the silencer 21 is 0.011 × λ <L _d < It satisfies 0.25 × λ. That is, the depth of the cavity portion 30 is L _d, smaller than lambda / 4, the muffler 21 does not silenced by resonance.

As described above, in the case of using the resonance type silencer to mute the sound of the lowest resonance frequency of the tubular member, at least a quarter length of the wavelength λ of the resonance frequency is required, and the size of the silencer is large. It will Therefore, there is a problem that it is difficult to simultaneously achieve high air permeability and soundproofing performance.
In addition, the resonance type silencer selectively mutes sound of a specific frequency (frequency band). Therefore, the design according to the resonant frequency of a tubular member is needed, and there existed a problem that versatility was low.
Also, although the resonance of the tubular member occurs at a plurality of frequencies, the silencer of the resonance type mutes the sound of a specific frequency. Therefore, there is a problem that the resonance noise to be silenced is only one frequency, and since the frequency band where the resonance type silencer silences is narrow, resonance noises of other frequencies can not be silenced.
Also, although it is effective to arrange the resonance type silencer in the open space, when arranged at the same resonance frequency inside the resonator such as the tubular member, the resonance of the tubular member interacts with the resonance of the silencer. It will As a result, since the original resonance transmitted sound by the tubular member is separated into two frequencies to generate a new resonance transmitted sound, there is a problem that the effect as the silencer is small.

On the other hand, the present invention has the cavity 30 and the opening 32, and the depth L _d of the cavity 30 in the sound wave traveling direction in the silencer is the width of the opening in the axial direction of the tubular member. _Assuming that the wavelength of the sound wave at the resonance frequency of the first resonance of the tubular member 12 is λ larger than L _o , the depth L _d of the cavity satisfies 0.011 × λ <L _d <0.25 × λ. The silencer 21 is arranged to be connected to the sound field space of the first resonance of the tubular member 12.
The silencer 21 converts the sound energy into heat energy by the viscosity of the fluid in the vicinity of the wall surface of the silencer 21 and unevenness (surface roughness) of the wall surface or a sound absorbing material 24 disposed in the silencer 21 described later. Convert and mute. The viscosity of the fluid in the vicinity of the wall surface and the unevenness (surface roughness) of the wall surface or the sound absorbing material 24 disposed in the silencer 21 is the conversion mechanism in the present invention.

Here, since the width L _o of the opening 32 of the silencer 21 is smaller than the depth L _d of the hollow portion 30, sound pressure is maintained when the sound wave in the tubular member 12 flows into the silencer 21. The moving speed of gas (air) molecules is increased. The conversion efficiency from sound energy to heat energy by the conversion mechanism depends on the sound pressure and the moving velocity of gas molecules. Therefore, by increasing the moving speed of the gas molecules while maintaining the sound pressure, the conversion efficiency from the sound energy to the heat energy by the conversion mechanism becomes high.
Since the principle of this silencing does not use the resonance of the silencer, high soundproofing performance is obtained even if the depth L _d of the cavity 30 is smaller than 1⁄4 of the wavelength λ at the resonance frequency of the first resonance of the tubular member 12 It can be expressed. Therefore, high soundproof performance can be obtained while downsizing the silencer 21 and maintaining the air permeability of the tubular member 12.

Further, since the resonance of the silencer by the silencer 21 is not used, the wavelength dependency of the sound wave is small, and even when the length and shape of the tubular member 12 are different, the soundproof performance can be exhibited, There is no need to design according to 12 and the versatility is high.
In addition, since the principle of muffling by the muffler 21 does not use resonance of the muffler, it is not muffling sound of only a specific frequency as determined by the structure of the muffling, and muffling a plurality of resonance sounds in a wide frequency band Can.
Moreover, since the principle of muffling by the muffler 21 does not use the resonance of the muffler, interaction with the resonance of the tubular member does not occur, and the original resonant transmitted sound by the tubular member is not separated into two frequencies. Sufficient silencing effect can be obtained.

Here, the case where the resonance type silencer is disposed in the tubular member 12 will be described using simulation.
The simulation used the acoustic module of finite element method calculation software COMSOL ver 5.3 (COMSOL company).
As shown in FIG. 110, in the simulation, the diameter of the ventilation sleeve (tubular member) was 100 mm, the thickness of the wall was 100 mm, the thickness of the decorative plate was 10 mm, and the distance between the wall and the decorative plate was 140 mm. That is, the total thickness of the wall and the decorative plate was 250 mm.

Using such a simulation model, as shown in FIG. 110, a sound wave is made to enter from the hemispherical surface of one space partitioned by walls, and a unit volume of the sound wave reaches the hemispherical surface of the other space. The amplitude was calculated. The hemispherical surface is a hemispherical surface with a radius of 500 mm centered on the central position of the opening surface of the ventilation sleeve. The sound wave to be incident has an amplitude of 1 per unit volume.
Further, it was modeled that a lid of a register (diameter 102 mm) was disposed at a position 32 mm from the end face of the ventilation sleeve on the sound wave detection surface side.

First, calculation was performed for the case where the silencer was not disposed as a reference (hereinafter also referred to as a straight pipe).
FIG. 111 shows the simulation result as a graph of the relationship between frequency and transmitted sound pressure intensity.
From FIG. 111, it can be seen that the frequency of the first resonance of the ventilation sleeve 12 when the silencer is not arranged (in the case of a straight pipe) is about 515 Hz.

Next, an air column resonance type silencer having a resonance frequency of about 515 Hz was designed.
As shown in FIG. 112 and FIG. 113, a model in which an air column resonance type silencer is connected to the outer peripheral portion of an acoustic tube having a length of 1000 mm and a diameter of 100 mm is created The acoustic characteristics were evaluated. A plane wave was incident from one end face of the acoustic tube, and the amplitude per unit volume of the sound wave reaching the other end face was determined. The sound wave to be incident has an amplitude of 1 per unit volume. A value obtained by squaring a value obtained by dividing the integral value of the sound pressure amplitude on the detection surface by the integral value of the sound pressure amplitude on the incident surface was taken as the transmitted sound pressure intensity.

One longitudinal surface of the air column resonance silencer is open and connected to the acoustic pipe. In addition, the position of the air column resonance silencer in the axial direction of the acoustic tube is approximately at the center position.
The air column resonance type silencer was in the form of a rectangular parallelepiped with a cross-sectional size of 45 mm × 45 mm, and the length was variously changed, and the relationship between the frequency and transmitted sound pressure intensity was calculated to determine the resonance frequency. As a result, as shown as Calculation Example 1 in FIG. 114, it was found that the resonance frequency was about 515 Hz at a length of 150 mm.

Next, as shown in FIG. 115, a silencer having this air column resonance type silencer is modeled to create a model connected to a ventilation sleeve, and in the same manner as described above, in one space partitioned by a wall Sound waves were made incident from the hemispherical surface, and the amplitude per unit volume of the sound waves reaching the hemispherical surface of the other space was determined. A cross-sectional view at the position of the air column resonance silencer of FIG. 115 is the same as that of FIG.
As shown in FIGS. 113 and 115, the air column resonance resonance type silencer has two air column resonance tubes with 45 mm × 45 mm prisms and 150 mm in length (depth), A tubular silencer of the same diameter (100 mm) as the ventilation sleeve was arranged at the end of the ventilation sleeve. The axial length of the ventilation sleeve was 130 mm, and the axial length of the tubular portion of the silencer was 120 mm. The axial position of the air column resonance tube was 5 mm from the end face on the aeration sleeve side.
The simulation result is shown in FIG. 111 as a graph of the relationship between the frequency and the transmitted sound pressure intensity (Comparative Example 8). Also, FIG. 116 shows the result of the experiment as a graph of the relationship between frequency and transmitted sound pressure intensity.
In the experiment, a silencer with the above-described shape and dimensions is manufactured using a 5 mm thick acrylic plate, and the relationship between the frequency and the transmitted sound pressure intensity is measured in the same manner as in the example using the simple small soundproof room did.

As shown as Comparative Example 8 in FIGS. 111 and 116, when the resonance type silencer is disposed on the ventilation sleeve, both sides of the first resonance frequency of the ventilation sleeve when the resonance type silencer is not disposed, It can be seen that there is a peak of transmitted sound pressure intensity. That is, peaks occur at two frequencies: a frequency lower than the first resonance frequency and a high frequency when the resonance type silencer is not disposed. This is because the resonance type silencer is placed in the sound field space of the ventilation sleeve which causes resonance, and a strong interaction acts to separate it into two modes of the coupled mode and the anticoupled mode. is there.
As a result, although the sound of the first resonance frequency of the aeration sleeve can be silenced, two new peaks exist.
As described above, when a resonance type silencer is used as the silencer for the aeration sleeve, another new peak of transmitted sound pressure intensity is generated, so that sufficient silencing can not be performed.

In addition, in the example shown in FIG. 1, although the silencer 21 and the internal cavity part 30 set it as substantially rectangular solid shape, it is not limited to this, It can be set as various shapes, such as cylindrical shape. Further, the shape of the opening 32 is also not limited, and can be various shapes such as a rectangular shape, a polygonal shape, a circular shape, and an elliptical shape.

Moreover, the frequency of the first resonance occurring within tubular member 12 and F _0, the resonance frequency of the silencer 21 and F _1, preferably satisfies 1.15 × F ₀ <F _1. By setting the relationship between the frequency F ₀ of the first resonance generated in the tubular member 12 and the resonant frequency F ₁ of the silencer 21 in the above range, the _first frequency generated in the tubular member 12 at the resonant frequency F ₁ of the silencer 21 Since the transmission sound pressure intensity of one resonance is 25% or less of the peak value, the interaction between the first resonance and the resonance of the silencer in the tubular member 12 is reduced.
The frequency F _{0 of} the first resonance generated in the tubular member 12 from the viewpoint that the transmitted sound pressure intensity of the first resonance generated in the tubular member 12 can be made smaller at the resonance frequency F ₁ of the silencer 21 to make the interaction smaller. And the resonance frequency F ₁ of the silencer 21 preferably satisfies 1.17 × F ₀ <F ₁ , more preferably 1.22 × F ₀ <F ₁ and 1.34 × F ₀ < It is further preferable to satisfy F ₁ . By satisfying the above condition, the transmitted sound pressure strength of the first resonance occurring within tubular member 12 at the resonant frequencies F ₁ of the muffler 21 is 20% or less with respect to the peak value, 15% or less, of 10% or less.

In the example shown in FIG. 1, the hollow portion 30 of the silencer 21 extends in the radial direction, and the traveling direction of the sound wave in the hollow portion 30 is the radial direction. For example, as shown in FIG. 2, as the hollow portion 30 extends in the axial direction, the traveling direction of the sound wave in the hollow portion 30 may be the axial direction. In the following description, the silencer 21 as shown in FIG. 1 is also referred to as a vertical cylindrical silencer.
FIG. 2 is a schematic sectional view showing an example of a preferred embodiment of the noise reduction system of the present invention. Moreover, FIG. 3 is a figure for demonstrating area S ₀ of the hollow part of the silencer of a silencer system, and area S _{1 of an} opening part. FIG. 4 is a diagram for explaining the depth L _d and the width L _w of the hollow portion of the silencer. In FIG. 3 and FIG. 4, illustration of the wall 16 is omitted. Also in the subsequent drawings, the illustration of the wall 16 may be omitted.

As shown in FIG. 2, the silencer system 10 a has a configuration in which the silencer 22 is disposed on the outer peripheral surface (outer peripheral surface) of the cylindrical tubular member 12 provided through the wall 16 separating the two spaces. Have.
The tubular member 12 is, for example, a ventilation sleeve such as a ventilation port and an air conditioning duct.
The silencer 22 extends in the axial direction in a cross section parallel to the axial direction, has a substantially rectangular parallelepiped shape curved along the outer peripheral surface of the tubular member 12, and has a substantially rectangular hollow portion axially extending in the inner direction. It has 30. In addition, an opening 32 communicating the hollow portion 30 with the outside is provided on one end side in the axial direction of the surface on the tubular member 12 side of the silencer 22. That is, the silencer 22 has an L-shaped space. The opening 32 is connected to a circumferential opening 12 a formed on the circumferential surface of the tubular member 12. By connecting the opening 32 to the circumferential opening 12a, the opening 32 is connected to the sound field space of the first resonance generated in the tubular member 12 in the noise reduction system 10a.

Here, in the example shown in FIG. 2, since the hollow portion 30 extends in the axial direction, the traveling direction of the sound wave in the hollow portion 30 is the axial direction (left and right direction in the drawing). Therefore, as shown in FIG. 4, the depth L _d of the cavity 30 is the length from the central position of the opening 32 in the axial direction to the end face on the far side of the cavity 30.

Similar to the silencer 21 shown in FIG. 1, the silencer 22 is disposed in the viscosity of the fluid in the vicinity of the wall surface of the silencer 22 and the unevenness (surface roughness) of the wall surface or in the silencer 22 described later. Sound energy is converted into heat energy by the sound absorbing material 24 or the like (conversion mechanism) to perform muffling.

Thus, even when the silencer 22 is shaped to have an L-shaped space, as in the case of the configuration of FIG. 1, when the sound wave in the tubular member 12 flows into the silencer 22, the sound pressure Since the transfer speed of gas (air) molecules can be increased while maintaining the pressure, the transfer speed of gas molecules can be increased while maintaining the sound pressure, so that the conversion efficiency from sound energy to heat energy by the conversion mechanism is Get higher. Therefore, even if the depth L _d of the cavity 30 is smaller than 1⁄4 of the wavelength λ at the resonance frequency of the first resonance of the tubular member 12, high soundproofing performance can be exhibited. Therefore, high soundproof performance can be obtained while downsizing the silencer 22 and maintaining the air permeability of the tubular member 12. In the following description, the silencer 22 as shown in FIG. 2 is also referred to as an L-shaped silencer.

Further, by forming the silencer 22 in a shape having an L-shaped space, the effective outer diameter of the silencer 22, that is, the outer diameter of the silencer system can be further reduced, and high soundproof performance is maintained. Higher breathability can be obtained. The effective outer diameter will be described in detail later.

Here, the sound field space of the first resonance of the tubular member 12 in the noise reduction system 10a will be described with reference to FIG.
FIG. 5 is a simulation of the distribution of sound pressure in the first resonance mode of the tubular member 12 provided through the wall 16 separating the two spaces. As can be seen from FIG. 5, the sound field space of the first resonance of the tubular member 12 is a space within the tubular member 12 and within the open end correction distance. As known, the antinodes of the standing waves of the sound field protrude outside the tubular member 12 by the distance of the open end correction. The open end correction distance in the case of the cylindrical tubular member 12 is given by approximately 1.2 × the tube diameter.

The silencer 22 may be disposed at a position where the opening 32 is connected to the first resonance sound field space of the tubular member 12. Therefore, the opening 32 of the silencer 22 may be disposed outside the open end face of the tubular member 12 as in the noise reduction system 10b shown in FIG. Alternatively, the silencer 22 may be disposed inside the tubular member 12 as in the noise reduction system 10 c shown in FIG. 7.
In the noise reduction system 10 b shown in FIG. 6 and the noise reduction system 10 c shown in FIG. 7, the silencer 22 is disposed such that the opening 32 faces the central axis of the tubular member 12. The central axis of the tubular member 12 is an axis passing through the center of gravity in the cross section of the tubular member 12.

Here, the position of the opening 32 of the silencer 22 in the axial direction is not limited. Depending on the position of the opening 32, it is possible to control the frequency band to mute more preferably.
For example, when the sound wave of the first resonance frequency of the tubular member 12 is to be silenced, the opening 32 of the silencer 22 is located at the position where the sound pressure of the sound wave of the first resonance frequency is high, ie By disposing, the sound pressure and the moving speed of gas molecules can be increased, and higher soundproofing performance can be expressed.
This point will be described in more detail in the examples.

Here, as shown in FIG. 3, and the area of the cavity portion 30 of the muffler 22 and S _0, the area of the opening 32 and S _1, the area S ₁ of the opening 32, the area of the cavity 30 S Preferably it is less than _zero . By making the area S ₁ of the opening 32 smaller than the area S ₀ of the hollow portion 30, when the sound wave in the tubular member 12 flows into the silencer 22, the gas (air) is maintained while maintaining the sound pressure. Since the moving speed of the molecule can be increased, the conversion efficiency from sound energy to heat energy by the conversion mechanism can be further increased.
Here, each area S ₁ of the area S ₀ and the opening 32 of the cavity 30 is the area in the circumferential surface of the central axis of the tubular member 12 passing through the hollow portion 30 or the opening 32 and the shaft.
When the area of the cavity 30 differs depending on the radial position of the tubular member 12, the area S ₀ of the cavity 30 is an average value of the areas at the respective positions.
The area S ₁ of the opening 32 is the area in which the opening is minimized.

Is preferably as the area S ₁ of the openings 32 is small in terms of the moving speed of the gas molecules, the area S ₁ of the openings 32 is too small waves low soundproof performance since less likely to flow into the cavity 30 turn into. From the above viewpoints, the area S ₁ of the opening 32 is preferably 0.1% <S ₁ / S ₀ <40% of the area S ₀ of the cavity 30, 0.3% <S ₁ / S ₀ <35% Is more preferably 0.5% <S ₁ / S ₀ <30%.

Further, from the viewpoint of soundproof performance and air permeability, the depth L _d of the hollow portion 30 of the silencer 22 satisfies 0.011 × λ <L _d <0.25 × λ, and 0.016 × λ <L _d. It is preferable to satisfy <0.25 × λ, and it is more preferable to satisfy 0.021 × λ <L _d <0.25 × λ.
Further, in the cross section parallel to the axial direction, the width L _w (see FIG. 4) of the hollow portion 30 in the direction orthogonal to the depth direction of the hollow portion 30 is 0.001 × λ <L _w Is preferably satisfied, 0.001 × λ <L _w <0.051 × λ is preferable, and 0.001 × λ <L _w <0.041 × λ is more preferable. Note that, in FIG. 1, the width of the hollow portion 30 is the length in the left-right direction in the drawing, and matches the width L _w of the opening 32.

This point will be described with reference to FIGS. 8 to 10 and 11. FIGS. 8 to 10 show the results of simulation in the case of using the vertical cylindrical silencer as shown in FIG. 1, and FIG. 11 shows the case of using an L-shaped silencer as shown in FIG. Simulation results of

FIG. 8 shows (the depth L _d of the cavity 30 / the wavelength λ of the sound wave to be muffled), (the width L _w of the cavity 30 / the wavelength λ of the sound wave to be muffled), and the average sound in the cavity 30 It is a graph showing the relation with pressure P. FIG. 9 shows (the depth L _d of the cavity 30 / the wavelength λ of the sound wave to be silenced), (the width L _w of the cavity 30 / the wavelength λ of the sound wave to be silenced), and gas molecules in the cavity 30 Is a graph showing the relationship between the average particle velocity v and. FIG. 10 shows (the depth L _d of the cavity 30 / the wavelength λ of the sound wave to be silenced), (the width L _w of the cavity 30 / the wavelength λ of the sound wave to be silenced), and the average particle velocity v of gas molecules And it is a graph showing the relation with the log value of the multiplication value (| v | x | P |) of average sound pressure P. (| V | × | P |) is a value proportional to the absorption per volume of the cavity 30.
The log in FIGS. 9 to 11 is a common logarithm.

The particle velocity v and the sound pressure P are changed variously for the depth L _d of the cavity 30 and the width L _{w of the} cavity 30 using the acoustic module of the finite element method calculation software COMSOL ver 5.3 (COMSOL) I asked for. In the simulation, the tubular member had a length of 300 mm and a diameter of 100 mm, and the hollow portion 30 of the silencer 22 was annularly installed on the outer periphery of the tubular member 12. The openings 32 were arranged in the shape of a slit in the circumferential direction of the tubular member. The width of the opening 32 is the same as the width of the cavity 30. The opening 32 is located at the center of the tubular member 12 in the axial direction. The lowest resonant frequency of the tubular member 12 was 460 Hz. The frequency of the sound wave to be silenced was 460 Hz. Further, the sound absorbing material 24 having a flow resistance of 13000 [Pa · s / m ² ] is disposed in the entire area of the hollow portion 30.

As shown in FIG. 12, the sound wave was made to enter from the hemispherical surface of one space partitioned by the wall, and the amplitude per unit volume of the sound wave reaching the hemispherical surface of the other space was determined. The hemispherical surface is a hemispherical surface with a radius of 500 mm centered on the central position of the opening surface of the tubular member. The sound wave to be incident has an amplitude of 1 per unit volume.

As shown in FIGS. 8 to 10, it can be seen that there is a preferred range between the depth L _d of the cavity 30 and the width L _w of the cavity 30. It can be seen from FIG. 8 that the sound pressure is higher as the width L _w and the depth L _d of the cavity 30 are smaller. It can be seen from FIG. 9 that the particle velocity is higher as the width L _w of the cavity 30 is smaller and the depth L _d is in a certain range. From FIG. 10, it can be seen that the value of (| v | × | P |), which is proportional to the absorption, becomes high as long as the width L _w and the depth L _d of the cavity 30 are present.

Similarly, FIG. 11 shows (Depth L _d of cavity 30 / Wavelength λ of sound wave to be silenced) of the L-shaped silencer as shown in FIG. It is a graph showing the relation between L _w / wavelength λ of sound wave to be silenced and the log value of the average particle velocity v of gas molecules and the average sound pressure P multiplied by (| v | × | P |).
In the simulation, the tubular member had a length of 300 mm and a diameter of 100 mm, and the hollow portion 30 of the silencer 22 was annularly installed on the outer periphery of the tubular member 12, and the axial direction was the depth direction. The openings 32 were arranged in the shape of a slit in the circumferential direction of the tubular member. The width of the opening 32 was 10 mm. The opening 32 is located at the center of the tubular member 12 in the axial direction. Further, in the hollow portion 30, the sound absorbing material 24 having a flow resistance of 13000 [Pa · s / m ² ] is disposed.

From FIG. 11, also in the L-shaped silencer, the value of (| v | × | P |), which is proportional to absorption, increases in the range where the width L _w and the depth L _d of the cavity 30 are present I understand that. Moreover, it turns out that a suitable range is the same as that of the vertical cylinder type silencer.

Further, in the noise reduction system of the present invention, the ratio S ₁ / S _d of the area S ₁ of the opening 32 to the surface area S _d of the inner wall of the hollow portion 30 of the silencer 22 is 0 <S ₁ / S _d <40%. Thus, the ratio of the area of the surface on which the sound wave is incident to the surface area of the sound absorbing material 24 or the like conversion mechanism is reduced to correspond to the sound waves flowing into the sound absorbing material 24 etc. converting mechanism while maintaining the high sound pressure P. The moving speed of gas molecules can be increased to enhance the soundproofing performance.
The area S ₁ (ratio S ₁ / S _d ) of the opening 32 is preferably as small as possible from the viewpoint of increasing the moving speed of gas molecules, but if the area S ₁ of the opening 32 is too small, sound waves flow into the cavity 30 Soundproof performance is lowered because it becomes difficult to do. From the above viewpoint, the area S ₁ of the opening 32 with respect to the surface area S _d of the inner wall of the cavity 30 is preferably 0.1% <S ₁ / S _d <40%, and 0.3% <S ₁ / S _d < 35% is more preferable, and 0.5% <S ₁ / S _d <30% is more preferable.
The surface area S _d of the inner wall of the hollow portion 30 is measured with a resolution of 1 mm. That is, in the case of having a microstructure such as unevenness less than 1 mm, this may be averaged to obtain the surface area S _d .

About this point, it simulated similarly to the case of FIG. 11 using the L-shaped silencer as shown in FIG.
In the simulation, the tubular member had a length of 300 mm and a diameter of 100 mm, and the hollow portion 30 of the silencer 22 was annularly installed on the outer periphery of the tubular member 12, and the axial direction was the depth direction. The openings 32 were arranged in the shape of a slit in the circumferential direction of the tubular member. The depth L _d of the hollow portion 30 was 80 mm, and the width L _w was 10 mm. The opening 32 is located at the center of the tubular member 12 in the axial direction. Further, in the hollow portion 30, the sound absorbing material 24 having a flow resistance of 13000 [Pa · s / m ² ] is disposed.
By changing the width _{Lo of the} opening to 10 mm (1 cm) to 70 mm (7 cm), the area ratio S ₁ / S _d is changed to 5.3% to 54.7%, and the transmitted sound pressure is calculated respectively. did. In FIG. 13, the area ratio 5.3% corresponds to 1 cm, 17.9% corresponds to 3 cm, 25.3% corresponds to 4 cm, 33.8% corresponds to 5 cm, 54.7% It corresponds to 7 cm. In addition, the transmission sound pressure normalized the peak (transmission sound pressure of 1st resonance frequency) of the transmission sound pressure in case the silencer was not installed as one. Since the first resonance frequency in the tubular member when the silencer is not installed is 460 Hz, the transmitted sound pressure at 460 Hz is the peak sound pressure.
The results are shown in FIG. 13 and FIG.

FIG. 13 is a graph showing the relationship between the frequency and the transmitted sound pressure, and FIG. 14 is a graph showing the relationship between the ratio of the aperture area and the peak of the transmitted sound pressure.
As can be seen from FIGS. 13 and 14, it can be seen that, even though the volume of the sound absorbing material is the same, the smaller the area ratio S ₁ / S _{d of} the opening, the smaller the transmitted sound pressure at the resonance frequency. In addition, the resonant frequency at the time of installing a silencer shifts to a low frequency side compared with the case without a silencer because the volume in which a sound wave can exist increased.

Further, as described above, the conversion mechanism for converting sound energy into heat energy is disposed in the viscosity of the fluid in the vicinity of the wall surface of the silencer and the unevenness (surface roughness) of the wall surface of the silencer or in the silencer. It is preferable to use a sound absorbing material.
The sound absorbing material 24 may be disposed in at least a part of the hollow portion 30 of the silencer 22 as in the noise reduction system 10 d shown in FIG. 15. Alternatively, as in the noise reduction system 10 e shown in FIG. 16, the sound absorbing material 24 may be disposed so as to cover at least a part of the opening 32 of the silencer 22.

The sound absorbing material 24 has a flow resistance per unit thickness σ ₁ [Pa · s / m ² ] of (1.25−log (0.1 × L _d )) / 0.24 <log (σ ₁ ) <5 Preferably satisfies (1.32-log (0.1 × L _d )) / 0.24 <log (σ ₁ ) <5.2, more preferably (1.39-log). It is further preferable to satisfy (0.1 × L _d )) / 0.24 <log (σ ₁ ) <4.7. In the above equation, the unit of L _d is [mm], and log is a common logarithm. To measure the flow resistance of a sound absorbing material, measure the normal incidence sound absorption coefficient of a 1 cm thick sound absorbing material, and fit it with the Miki model (J. Acoust. Soc. Jpn., 11 (1) pp. 19-24 (1990)). It evaluated by. Or it may be evaluated according to "ISO 9053".

Further, assuming that the ratio of the length of the cavity 30 (hereinafter also referred to as a cylinder length) in the depth direction of the cavity 30 to the width of the opening (opening width / tube length) is K _rate (%), sound absorption The flow resistance σ ₁ [Pa · s / m ² ] per unit length of the material 24 is (K _rate +165) /62.5 <log σ ₁ <(K _rate +319.) When 0 <K _rate ≦ 50%. 6) /76.9 is preferable, and it is preferable to satisfy 3.45 <log σ ₁ <(K _rate +484) /111.1 when 50% <K _rate . Further, it is more preferable to satisfy (K _rate +175) /62.5 <log σ ₁ <(K _rate +315.3) /76.9 when 0 <K _rate ≦ 50%, and when 50% <K _rate It is more preferable to satisfy 3.6 <log σ ₁ <(K _rate +478) /111.1. Further, it is more preferable to satisfy (K _rate +182) /62.5 <log σ ₁ <(K _rate +311.3) /76.9 when 0 <K _rate ≦ 50%, and when 50% <K _rate More preferably, 3.72 <log σ ₁ <(K _rate +472) / 11 _{1 1} is satisfied. In the above equation, log is a common logarithm.

The simulation results of the relationship between the ratio K _{rate of the} cylinder length to the opening width and the flow resistance σ ₁ [Pa · s / m ² ] per unit length of the sound absorbing material 24 will be described.
FIG. 107 is a cross-sectional view schematically showing a model of the noise reduction system used for the simulation.
As shown in FIG. 107, the thickness of the wall 16 was 212.5 mm, and the diameter of the tubular member 12 was 100 mm. The silencer 22 was disposed at a distance of 100 mm from the wall on the incident side (left side in FIG. 107). The silencer 22 was disposed in a tubular shape on the outer periphery of the tubular member 12, and the axial direction was in the depth direction. The length (cylinder length) of the hollow portion 30 of the silencer 22 was 42 mm. The width was 37 mm. The opening 32 was arranged in the shape of a slit in the circumferential direction of the tubular member 12. The opening 32 is formed on the incident side (left side in FIG. 107) in the axial direction. The sound absorbing material 24 was disposed in the entire area of the hollow portion 30 of the silencer 22.
Further, a gullet (cover member) is disposed at the opening of the tubular member 12 on the incident side of the sound wave, and a register (air volume adjustment member) is disposed at the opening on the emission side of the sound wave.
Galari and resistors were modeled with reference to commercially available products.

In addition, the flow resistance σ ₁ of the sound absorbing material 24 and the width of the opening were variously changed, and a simulation was performed on the sound waves transmitted through the tubular member. The transmission loss was calculated from the sound pressure of the sound wave transmitted through the tubular member and propagating from one space (left side in FIG. 107) to the other space (right side in FIG. 107) by simulation.
The results are shown in FIG. FIG. 108 is a graph showing the relationship between the flow resistance, the opening width / tube length, and the normalized transmission loss. The normalized transmission loss is a value normalized with a value at which the transmission loss is maximum as 1.

From FIG. 108, it can be seen that the flow resistance has an optimum range depending on the opening width / tube length. The area inside the dotted line in FIG. 108 is an area where the normalized transmission loss is about 0.8 or more. When this region is expressed by a formula, when 0 <K _rate ≦ 50% mentioned above, (K _rate +165) /62.5 <log σ ₁ <(K _rate +319.6) /76.9, 50% <K _{When rate} , 3.45 <log σ ₁ <(K _rate +484) /111.1.

The sound absorbing material 24 is not particularly limited, and a conventionally known sound absorbing material can be appropriately used. For example, foamed urethane, flexible urethane foam, wood, sintered material of ceramic particles, foamed material such as phenol foam, and material containing minute air; glass wool, rock wool, micro fiber (such as 3M manufactured Thinsulate), floor mat, carpet Fibers and non-wovens materials such as meltblown non-woven fabric, metal non-woven fabric, polyester non-woven fabric, metal wool, felt, insulation board and glass non-woven fabric; Wood cement board; Nanofiber-based material such as silica nanofibers; Sound absorbing material is available.

The thickness of the sound absorbing material 24 is not limited as long as it can be disposed in the cavity 30 or in the vicinity of the opening. From the viewpoint of sound absorption performance and the like, the thickness of the sound absorbing material 24 is preferably 0.01 mm to 500 mm, and more preferably 0.1 mm to 100 mm.

When the sound absorbing material is disposed in the hollow portion of the silencer, it is preferable that the shape of the sound absorbing material be formed in conformity with the shape of the hollow portion. By making the shape of the sound absorbing material conform to the shape of the hollow portion, it becomes easy to uniformly fill the sound absorbing material in the hollow portion, cost can be reduced, and maintenance can be simplified. Become.

Moreover, although it was set as the structure which has one silencer 22 in the example shown in FIG. 2, it is not limited to this, It is good also as a structure which has two or more silencers 22. FIG. For example, as in the noise reduction system 10 f shown in FIG. 17, two silencers 22 are disposed on the outer peripheral surface of the tubular member 12 and connected to the peripheral surface opening 12 a formed on the peripheral surface of the tubular member 12. It may be Alternatively, two silencers 22 may be disposed inside the tubular member 12 as in a silencer system 10g shown in FIG.

When two or more silencers 22 are provided, the two or more silencers 22 are preferably disposed in rotational symmetry with respect to the central axis of the tubular member 12.
For example, as shown in FIG. 19, three silencers 22 may be provided, and the three silencers 22 may be arranged on the outer circumferential surface of the tubular member 12 at equal intervals in the circumferential direction to be rotationally symmetric. . Alternatively, as shown in FIG. 20, six silencers 22 may be provided, and the six silencers 22 may be arranged at equal intervals on the outer peripheral surface of the tubular member 12 to be rotationally symmetrical. In addition, the number of silencers 22 is not limited to these, for example, a configuration in which two silencers 22 are disposed in rotational symmetry may be employed, or a configuration in which four silencers 22 are disposed in rotational symmetry It may be

Also when the silencer 22 is disposed inside the tubular member 12, it is preferable that two or more silencers 22 be disposed in rotational symmetry.
For example, as shown in FIG. 21, even if four silencers 22 are arranged at equal intervals in the circumferential direction on the inside of the tubular member 12 (inner circumferential surface (inner circumferential surface)), they have rotational symmetry. Good.

Further, in the case of the configuration in which the plurality of silencers 22 are arranged in the circumferential direction on the outer peripheral surface of the tubular member 12, the plurality of silencers 22 may be connected. For example, as shown in FIG. 22, eight silencers 22 may be connected in the circumferential direction.

Similarly, when the silencers 22 are disposed in the tubular member 12, in the case where the plurality of silencers 22 are arranged in the circumferential direction on the inner peripheral surface of the tubular member 12, the plurality of silencers are arranged. The vessels 22 may be connected. For example, as shown in FIG. 23, eight silencers 22 may be connected in the circumferential direction.

Further, in the example shown in FIG. 1, the silencer 22 has a substantially cubic shape along the outer peripheral surface of the tubular member 12. However, the present invention is not limited thereto, and various types of three-dimensional shapes having hollow portions may be used. Alternatively, as shown in FIG. 24, the silencer 22 may be annular along the entire circumference of the outer circumferential surface of the tubular member 12 in the circumferential direction. In this case, the opening 32 is formed in a slit shape along the circumferential direction of the inner peripheral surface of the tubular member 12.

Similarly, when the silencer 22 is disposed in the tubular member 12, as shown in FIG. 25, the silencer 22 is annular along the entire circumference of the inner circumferential surface of the tubular member 12 in the circumferential direction. May be

When the silencer 22 is disposed on the outer peripheral surface of the tubular member 12, the outer diameter of the silencer 22 in the circumferential direction is assumed to cover the entire periphery of the outer peripheral surface of the tubular member 12 ( Assuming that the effective outer diameter is D ₁ and the outer diameter (effective outer diameter) of the tubular member 12 is D ₀ (see FIG. 24), it is preferable to satisfy D ₁ <D ₀ + 2 × (0.045 × λ + 5 mm) . The unit of D ₁ , D ₀ and λ in the formula is mm.
Thereby, high soundproof performance can be expressed, suppressing the enlargement of a silencer system.
In addition, an effective outside diameter is a circle equivalent diameter, and when a cross section is not circular, the diameter of the same circle as the cross-sectional area was made into the effective outside diameter.

When the silencer 22 is disposed on the inner circumferential surface of the tubular member 12, the inner diameter of the silencer 22 is assumed to cover the entire circumference of the inner circumferential surface of the tubular member 12 in the circumferential direction. Where D ₂ and the inner diameter of the tubular member 12 is D ₀ (see FIG. 18), it is preferable to satisfy 0.75 × D ₀ <D ₂ .
As a result, it is possible to exhibit high soundproofing performance while suppressing the upsizing of the noise reduction system to secure air permeability.

In the examples shown in FIGS. 17 to 23, the plurality of silencers 22 are arranged in the circumferential direction of the tubular member 12. However, the present invention is not limited to this. It may be arranged in the axial direction. In other words, the openings 32 of the plurality of silencers 22 may be disposed at at least two or more positions in the axial direction of the tubular member 12.

For example, the noise reduction system 10h shown in FIG. 26 includes a silencer 22a connected to the circumferential opening 12a of the tubular member 12 at a substantially central portion of the tubular member 12 in the axial direction, and one end of the tubular member 12 And a silencer 22b connected to the circumferential opening 12a in the vicinity.

Further, in the example shown in FIG. 26, two silencers are disposed in rotational symmetry in the circumferential direction respectively. Thus, two or more silencers may be arranged in the circumferential direction and in the axial direction, respectively.

In the example shown in FIG. 26, although two silencers are arranged in the axial direction, the present invention is not limited to this, and three or more silencers may be arranged in the axial direction.

Further, in the case of the construction of arranging the plurality of silencer in the axial direction is preferably a length L _d of the cavity for each position of the opening to position different muffler.
For example, in the noise reduction system 10i shown in FIG. And a silencer 22b connected to the circumferential opening 12a in the vicinity. The depth L _d of the hollow portion 30a of the central portion of the muffler 22a, the depth L _d of the hollow portion 30b of the end portion of the muffler 22b are different from each other.

When a plurality of silencers are arranged in the axial direction, it is preferable to arrange sound absorbing materials having different acoustic characteristics in the hollow portion for each position of the opening.
For example, the noise reduction system 10j shown in FIG. 28 has a silencer 22a connected to the circumferential surface opening 12a of the tubular member 12 at a substantially central portion of the tubular member 12 in an axial direction, And a silencer 22b connected to the circumferential opening 12a in the vicinity. The sound absorbing material 24 a is disposed in the hollow portion 30 a of the silencer 22 a on the central portion side, and the sound absorbing material 24 b is disposed in the hollow portion 30 b of the silencer 22 b on the end side. The sound absorbing characteristics of the sound absorbing material 24a and the sound absorbing characteristics of the sound absorbing material 24b are different from each other.

As will be described in detail later, in the noise reduction system according to the present invention, the wavelength that can be favorably damped changes depending on the arrangement position of the silencer (opening) in the axial direction. Therefore, by arranging a plurality of silencers in the axial direction, sounds in different wavelength ranges can be muffled and muffled in a wider band. In addition, it is possible to more preferably mute by adjusting the depth L _d of the cavity and the sound absorption characteristics of the sound absorber according to the wavelength that can be preferably muffled for each position of the opening in the axial direction. .

Further, in the example shown in FIG. 1, the hollow portion 30 of the silencer 21 is configured to have a depth L _d in the radial direction from the opening, and in the example shown in FIG. Although the depth L _d is provided in the axial direction from the above, the present invention is not limited to this, and the depth 32 may be provided in the circumferential direction from the opening 32.

FIG. 29 is a cross-sectional view schematically showing another example of the noise reduction system of the present invention, and FIG. 30 is a cross-sectional view taken along the line CC in FIG.
The silencer system shown in FIGS. 29 and 30 has two silencers 23 arranged along the outer peripheral surface of the tubular member 12. The cavity 30 of the silencer 23 extends from the opening 32 along the circumferential direction of the tubular member 12. That is, the silencer 23 has a depth in the circumferential direction from the opening 32.
With such a configuration, the axial length of the silencer can be shortened.

In addition, although it was set as the structure which has two silencers 23 in the example shown in FIG. 30, it is not limited to this, You may have three or more silencers 23. FIG. For example, as shown in an example shown in FIG. 31, five silencers 23 may be provided.

Moreover, in the example shown in FIG. 2, although the depth of the hollow part 30 of the silencer 22 was set as the structure extended in one direction, it is not limited to this. For example, as shown in FIG. 32, the hollow portion 30 may have a substantially C shape in which the depth direction is folded. The sound wave that has entered the hollow portion 30 shown in FIG. 32 proceeds from the opening 32 in the right direction in the drawing, and then turns back and proceeds in the left direction in the drawing. The depth L _d of the cavity 30, since it is the length along the traveling direction of the sound wave, the depth L _d of the cavity 30 shown in FIG. 32 is a length along the folded shape.

Here, the noise reduction system of the present invention may be configured such that a portion of the noise reduction device having the noise reduction device and the insertion portion is inserted and disposed in the tubular member (vent sleeve).
FIG. 33 shows a schematic cross-sectional view of another example of the noise reduction system of the present invention.
The muffling system 10k shown in FIG. 33 has a configuration in which a muffling device 14 for muffling the sound passing through the tubular member 12 is installed on one end face side of the tubular member 12.

The silencer 14 has an insertion portion 26 and a silencer 22. The insertion portion 26 is a cylindrical member whose both ends are open, and the silencer 22 is connected to one end face. Further, the outer diameter of the insertion portion 26 is smaller than the inner diameter of the tubular member 12 and can be inserted into the tubular member 12.
The silencer 22 has the same configuration as the above-described L-shaped silencer 22 except that the silencer 22 is disposed on the end face of the insertion portion 26. Further, the silencer 22 is disposed along the circumferential surface of the insertion portion 26 so as not to block the inner diameter of the insertion portion 26. Further, the silencer 22 is disposed such that the opening 32 thereof faces the central axis of the insertion portion 26 (the central axis of the tubular member 12).
The central axis of the insertion portion 26 is an axis passing through the center of gravity in the cross section of the insertion portion 26.

The silencer 14 is inserted and installed in the tubular member 12 from the end face side where the silencer 22 of the insertion portion 26 is not disposed. Since the effective outer diameter of the silencer 22 is larger than the inner diameter of the tubular member 12, the insertion portion 26 is inserted to a position where the silencer 22 contacts the end face of the tubular member 12. Thus, the silencer 22 is disposed in the vicinity of the open end face of the tubular member 12. That is, the opening 32 of the silencer 22 is disposed in the space within the opening end correction distance of the tubular member 12. Thus, the opening 32 of the silencer 22 is connected to the sound field space of the first resonance of the tubular member 12.

As described above, by installing the silencer having the silencer and the insertion portion into the tubular member and installing it, the installation can be easily performed on the existing ventilating port, the air conditioning duct, etc. without performing the large-scale construction and the like. It is possible to Therefore, replacement when the silencer is deteriorated or damaged is easy. Moreover, when using for the ventilation sleeve etc. of a house, it is not necessary to change the through-hole diameter of a concrete wall, and construction is simple. In addition, it is easy to retrofit at the time of renovation.

In addition, the wall of a house such as an apartment is configured to have, for example, a concrete wall, a gypsum board, a heat insulating material, a decorative plate, and a wallpaper, etc., and a ventilation sleeve is provided through them. . When the muffling device 14 as shown in FIG. 33 is installed in such a wall ventilation sleeve, the wall 16 in the present invention corresponds to a concrete wall, and the muffler 22 portion of the muffling device 14 is outside the concrete wall. And between the concrete wall and the decorative board (see FIG. 70).

In the example shown in FIG. 33, although the insertion portion 26 of the silencer 14 is inserted into the tubular member 12 and the silencer 14 is disposed at the opening of the tubular member 12, the present invention is not limited thereto.
For example, as in the noise reduction system 10 n shown in FIG. 67, the noise reduction device 14 may be configured to be attached to the wall 16 with an adhesive or the like without having the insertion portion.
Alternatively, inside the insertion portion 26 of the silencer 14 with the inside diameter of the insertion portion 26 of the silencer 14 substantially the same as the outside diameter of the tubular member 12 disposed on the wall 16 as in the silencer system 10p shown in FIG. The tubular member 12 may be inserted to install the silencer 14. The insert 26 is disposed between the tubular member 12 and the wall 16.
Alternatively, as in the noise reduction system 10 q shown in FIG. 69, the inner diameter of the insertion portion 26 of the noise reduction device 14 may be larger than the outer diameter of the tubular member 12, and the insertion portion 26 may be disposed in the wall 16. .
With the configuration as shown in FIGS. 67 to 69, it is possible to suppress the decrease in the aperture ratio due to the insertion of the insertion portion 26 into the tubular member 12, and the air permeability of the tubular member 12 can be improved.

When the insertion portion 26 is arranged in the wall 16 as shown in FIGS. 68 and 69, the insertion portion 26 is arranged on the wall 16 in accordance with the size and shape of the insertion portion 26. It is sufficient to form a groove for Alternatively, when the wall 16 is manufactured, the muffling device 14 (and the tubular member 12) may be installed in advance, and concrete may be poured into the wall 16.

In the example shown in FIG. 33, the silencer 14 is configured to have the L-shaped silencer 22. However, the present invention is not limited to this, and may be configured to have the vertical cylindrical silencer 21. Alternatively, the silencer 23 may have a depth in the circumferential direction.

Also in the noise reduction device 14 of the noise reduction system 10k as shown in FIG. 33, it is preferable that the sound absorbing material 24 be disposed in the hollow portion 30 or in the vicinity of the opening 32.

Moreover, it is preferable that the silencer 14 has a plurality of silencers 22.
When a plurality of silencers 22 are provided, they may be arranged at equal intervals in the circumferential direction to be rotationally symmetrical.
Alternatively, as in the noise reduction system 10l shown in FIG. 34, a plurality of silencers 22 are provided in the axial direction, and the openings 32 of the plurality of silencers 22 are disposed at at least two or more axial positions It is also good.

Further, in the case of the construction of arranging the plurality of silencer in the axial direction is preferably the depth L _d of the cavity for each position of the opening to position different muffler.
For example, the silencer shown in FIG. 35 has the silencer 22a and the silencer 22b in the axial direction from the insertion portion 26 side. The depth L _d of the cavity 30 a of the silencer 22 a is different from the depth L _d of the cavity 30 b of the silencer 22 b.

When a plurality of silencers are arranged in the axial direction, it is preferable to arrange sound absorbing materials having different acoustic characteristics in the hollow portion for each position of the opening.
For example, the silencer shown in FIG. 36 has the silencer 22a and the silencer 22b in the axial direction from the insertion portion 26 side. The sound absorbing material 24a is disposed in the hollow portion 30a of the silencer 22a, and the sound absorbing material 24b is disposed in the hollow portion 30b of the silencer 22b. The sound absorbing characteristics of the sound absorbing material 24a and the sound absorbing characteristics of the sound absorbing material 24b are different from each other.

Moreover, when it is set as the structure which arrange | positions a sound absorbing material in the hollow part of a silencer, it is good also as a structure which arrange | positions several sound absorbing materials in one hollow part.
The silencer shown in FIG. 104 has a silencer 22a and a silencer 22b in the axial direction from the insertion portion 26 side. Three

sound absorbing materials

24c, 24d and 24e are disposed in the cavity 30a and the cavity 30b of the silencer 22a, respectively. In each hollow portion, the sound absorbing materials 24c to 24e are stacked in the depth direction of the hollow portion.
By arranging a plurality of sound absorbing materials in the cavity, the sound absorbing material can be easily filled from the opening into the cavity at the time of manufacture, and the sound absorbing material can be easily replaced at the time of maintenance.
Further, it is more preferable that the sound absorbing material molded in accordance with the shape of the hollow portion be divided into a plurality of parts.

The plurality of sound absorbing members 24c to 24e disposed in the same hollow portion may be the same type of sound absorbing members, or at least one is a different type of sound absorbing member, that is, sound absorbing performance (flow resistance, material, structure, etc.) The sound absorbing material may be different.
By arranging a plurality of different types of sound absorbing materials in the hollow portion, it becomes easy to control the muffling by the muffler to the sound absorbing performance suitable for the shape of the muffler (hollow portion) and the sound etc. of the sound absorbing object. .

For example, as shown in Drawing 37 and Drawing 38, a silencer may be constituted so that a silencer can be separated. By making the silencers separable, it becomes easy to manufacture the silencers in which the size, number, etc. of the silencers are changed. In addition, installation and replacement of the sound absorbing material in the hollow portion is facilitated.
For example, the distance between the concrete wall and the decorative panel varies, and even the same apartment may differ depending on the location or may differ depending on the construction company. Depending on the distance between the concrete wall and the veneer, it is costly to design and manufacture the silencer each time. Also, if the silencer is designed to be thin enough to be applied to all distances, the soundproofing performance will be lowered. Therefore, when installing the silencer between the concrete wall and the decorative plate, it is possible to reduce the cost by installing a plurality of silencers separated according to the distance between the concrete wall and the decorative plate as appropriate Soundproofing performance can be maximized.

Further, as shown in FIG. 39, the silencer 14 is preferably installed on the tubular member 12 so as to be removable. Thereby, replacement | exchange of the muffling apparatus 14, or reform etc. can be performed easily.
Moreover, although the silencer 14 may be installed on either the end face on the indoor side of the tubular member 12 or the end face on the outdoor side, it is preferable to be installed on the end face on the indoor side.

In addition, the noise reduction system may have at least one of a cover member installed on any one end surface of the tubular member and an air volume adjustment member installed on the other end. The cover member is a conventionally known louver, gully, etc. installed in a ventilating port, an air conditioning duct, etc. Further, the air flow rate adjustment member is a conventionally known register or the like.
Further, the cover member and the air flow rate adjusting member may be installed on the end face of the tubular member on the side where the muffling device is installed, or may be installed on the end face of the side where the muffling device is not installed.
Further, for example, as shown in FIG. 40, when the air volume adjusting member 20 is installed on the side of the silencer 14, the air volume adjusting member 20 is installed so as to cover all the silencer 14 when viewed from the axial direction. Is preferred. The same applies to the case where the cover member is installed on the side of the silencer 14.

Here, in a general house such as a condominium, a concrete wall and a decorative plate are installed separately from each other, and a heat insulating material or the like is disposed between the concrete wall and the decorative plate. The silencer 14 is preferably installed in the space between the concrete wall and the decorative board. At that time, as shown in FIG. 70, the silencer 14 may be configured such that the end face on the decorative plate 40 side is disposed closer to the wall 16 than the surface on the wall 12 side of the decorative plate 40. Alternatively, as shown in FIG. 71, the silencer 14 may be configured such that the end face on the decorative plate 40 side is flush with the surface on the opposite side to the wall 12 of the decorative plate 40. That is, the through holes formed in the decorative plate 40 may be substantially the same as the outer diameter of the silencer 14, and the silencer 14 may be inserted into the through holes of the decorative plate 40. In the example shown in FIG. 71, the silencer 14 has a configuration in which the end face on the decorative plate 40 side is flush with the surface on the opposite side of the wall 12 of the decorative plate 40, but the invention is not limited thereto. The part of the muffling device 14 may be configured to exist on the plane on which the decorative plate 40 is located.
The configuration in which the silencer 14 is inserted into the through hole of the decorative plate 40 facilitates installation, replacement and the like of the silencer.

As the size of the silencer 22 of the silencer 14 is larger, the muffling performance becomes higher.
Here, as shown in FIG. 71, in the case where the silencer 14 has a configuration in which the end face on the decorative plate 40 side is disposed flush with the surface on the opposite side to the wall 12 of the decorative plate 40, the silencer 22 is If the air flow rate adjusting member 20 such as a register is installed on the side of the decorative plate 40, the through hole (the boundary between the silencer 14 and the decorative plate 40) formed in the decorative plate 40 is visually recognized There is a risk of Therefore, as shown in FIG. 72, it is preferable to place the boundary cover 42 between the air flow rate adjusting member 20 and the decorative plate 40 and the muffling device 14. Thereby, when viewed from the indoor side (air volume adjustment member 20 side), as shown in FIG. 73, the through hole of the decorative plate 40 is hidden by the boundary cover 42, so that the design can be enhanced.

In the example shown in FIG. 72, although the silencer 14 and the boundary cover 42 are separate members, the silencer 14 and the boundary cover 42 may be integrally formed. That is, the silencer 14 may be provided with a fringe.

Moreover, in the example shown in FIG. 70 etc., although the internal diameter of the muffling device 14 was made uniform with substantially the same diameter as the tubular member 12, limitation is not carried out to this. As in the noise reduction system 10r shown in FIG. 74, the inner diameter of the silencer 22 may be larger than the inner diameter of the insertion portion 26, ie, larger than the inner diameter of the tubular member 12.
By making the inner diameter of the silencer 22 part larger than the inner diameter of the tubular member 12, a large air flow adjusting member 20 for a tubular member having a diameter larger than the diameter of the tubular member 12 can be used. By using the large air flow rate adjusting member 20, the through hole of the decorative plate 40 is hidden by the air flow rate adjusting member 20, so that the design can be enhanced.

Further, as in the noise reduction system 10s shown in FIG. 75, the noise reduction device 14 and the air volume adjustment member 20 may be integrated.
As shown in FIG. 71 etc., the air flow rate adjusting member 20 such as a commercially available register has an insertion portion, and the insertion portion is inserted into the silencer 14 and installed. However, the insertion portion of a commercially available register has a length of about 5 cm to secure rigidity and sealing at the time of connection, which may limit the design of the silencer 14. On the other hand, as shown in FIG. 75, integrating the muffling apparatus 14 and the air volume adjusting member 20 is preferable in that the design freedom of the muffling apparatus 14 is increased and the construction is simplified.

In the case where the noise reduction system has the cover member and the air flow rate adjustment member, the first resonance occurring in the tubular member is the first resonance of the tubular member in the sound reduction system including the cover member, the air flow rate adjustment member and the noise reduction device. . Therefore, the length L _d of the hollow portion of the silencer is shorter than 1⁄4 of the wavelength λ of the sound wave at the resonance frequency of the first resonance of the tubular member in the muffling system including the cover member, the air volume adjusting member and the muffling device.

Further, in the example shown in FIG. 70 and the like, the silencer 14 is arranged such that the central axis of the silencer 14 coincides with the central axis of the tubular member 12. That is, the silencer 14 is the center of the tubular member 12. Although it is formed in the shape of rotational symmetry with respect to the axis, it is not limited to this.
As in the noise reduction system shown in FIG. 105 and the noise reduction system shown in FIG. 106, the silencer 14 is disposed such that the central axis of the silencer 14 is offset from the central axis of the tubular member 12 in the direction perpendicular to the central axis. It may be done.
A configuration in which the central axis of the silencer 14 coincides with the central axis of the tubular member 12 is preferable in terms of air permeability. On the other hand, when the central axis of the muffling device 14 and the central axis of the tubular member 12 deviate from each other, reflection of sound increases, which is preferable in that the soundproofing performance is improved. In particular, it is effective in a high frequency region where the linearity is high.

Here, the thickness of the wall for housing, that is, the total thickness of the concrete wall and the decorative plate including the space between the concrete wall and the decorative plate (hereinafter also referred to as the total thickness of the wall and the decorative plate) is , About 175 mm to 400 mm. Therefore, the length of the ventilating sleeve (annular member) used for residential use is 175 mm to 400 mm. The first resonance frequency of the resonance generated by the ventilation sleeve having a length in this range is about 355 Hz to 710 Hz.

In addition, when considering the sound insulation of the ventilation sleeve used for the wall for housing, the total thickness of the concrete wall and the decorative plate, that is, the length of the ventilation sleeve is 175 mm to 400 mm. Given that the wavelength is the shortest (when the length of the aeration sleeve is 175 mm, λ = 497 mm), the width L _{w of the} cavity is 5.5 mm or more from the viewpoint of obtaining sufficient soundproofing performance. Preferably, it is 15 mm or more, more preferably 25 mm or more.
On the other hand, the wall for a house has a total thickness (total thickness of concrete wall and decorative plate) of at most 400 mm, and the concrete wall is at least 100 mm, so the width L _{w of the} cavity is the concrete wall of the house It is preferable that it is 300 mm or less from a viewpoint which can be arrange | positioned to the space between and a decorative board, Furthermore, it is more preferable from a viewpoint of versatility that it is 200 mm or less, More preferably, it is 150 mm or less.

Similarly, considering the case where the first resonance wavelength of the ventilation sleeve is the shortest (when the length of the ventilation sleeve is 175 mm, λ = 497 mm), the depth L of the cavity is sufficient in terms of obtaining sufficient soundproofing performance _d is preferably 25.3 mm or more, more preferably 27.8 mm or more, and still more preferably 30.3 mm or more.
On the other hand, the silencer is disposed radially between the pillars of the house. The maximum distance between the housing pillars is about 450 mm, and the ventilation sleeve is at least about 100 mm. Therefore, the depth L _d of the hollow portion is preferably 175 mm or less (= (450 mm-100 mm) / 2) and 130 mm or less from the viewpoint of being able to be disposed in the space between the pillars of the house Is more preferable, and 100 mm or less is more preferable.

Moreover, when it is set as the structure which has a sound absorbing material in a part in hollow part 30 of silencer 22, it is preferable to arrange so that opening 32 may be covered or opening 32 may be narrowed. That is, it is preferable that the sound absorbing material be disposed at a position near the opening 32 in the cavity 30. Further, it is preferable to dispose the sound absorbing material at a position away from the end face of the hollow portion 30 on the side far from the opening 32 in the depth direction.

The difference in the soundproofing performance due to the difference in the position of the sound absorbing material in the hollow portion 30 was examined by the following simulation.
FIG. 91 shows a schematic diagram of a simulation model.
As shown in FIG. 91, in the simulation, the tubular member had a length of 200 mm and a diameter of 100 mm. The silencer 22 was installed in a tubular shape on the outer periphery of the tubular member 12. The distance between the end face of the sound wave incident side of the tubular member 12 and the silencer 22 in the axial direction was 100 mm. The opening 32 of the silencer 22 was arranged in a slit shape in the circumferential direction of the tubular member. The width of the opening 32 was 15 mm. The axial length of the hollow portion 30 was 60 mm, and the width in the direction perpendicular to the axial direction was 33 mm.
As shown in FIG. 91, when viewed in a cross section parallel to the axial direction, the cavity 30 is divided into 9 parts, and the flow resistance is 13000 [Pa · s / m ^{2] in} each of the 9 divided areas The simulation was performed on the assumption that the sound absorbing material 24 is disposed. p1 is the area closest to the opening 32, and p2 and p3 are areas farther from the opening 32 than p1 in the radial direction. Also, p4 and p7 are regions farther from the opening 32 than p1 in the axial direction. p5 and p8 are regions farther from the opening 32 than p2 in the axial direction. p6 and p9 are regions farther from the opening 32 than p3 in the axial direction.

FIG. 92 shows a graph showing the relationship between the transmission sound pressure intensity and the frequency when the sound absorbing material is arranged in each of the regions p1, p2, p3, p5 and p9. The transmission sound pressure intensity was standardized with the peak of the transmission sound pressure (transmission sound pressure at the first resonance frequency) when the silencer was not installed as 1. Since the first resonance frequency in the tubular member when the silencer is not installed is 630 Hz, the transmitted sound pressure at 630 Hz is the peak sound pressure.
Further, FIG. 93 shows a graph showing the transmission loss of the 500 Hz band when the sound absorbing material is disposed in each of the regions p1 to p9. The transmission loss in the 500 Hz band is obtained by averaging the transmission loss at a frequency of 354 Hz to 707 Hz.

As shown in FIGS. 92 and 93, the configuration in which the sound absorbing material is disposed in the region of p1 closest to the opening 32, that is, the configuration that covers the opening 32, has the lowest transmitted sound pressure intensity and a transmission loss of the 500 Hz band. High and the soundproofing performance is high. In addition, it is understood that the configuration in which the sound absorbing material is disposed in the region of p2 and p4 close to the opening 32 has a low transmitted sound pressure intensity and high transmission loss in the 500 Hz band and high soundproof performance compared to the other regions other than p1. .

Next, as shown in FIG. 94, when viewed in a cross section parallel to the axial direction, the inside of the hollow portion 30 is axially divided into three, and the flow resistance is 13000 [in each of three divided regions The simulation was performed assuming that the sound absorbing material 24 of Pa · s / m ² ] is disposed. pz1 is the area closest to the opening 32, and pz2 and pz3 are areas farther from the opening 32 than pz1 in the axial direction.
FIG. 95 shows a graph showing the transmission loss of the 500 Hz band when a sound absorbing material is arranged in each of the regions pz1 to pz3.

Further, as shown in FIG. 96, when viewed in a cross section parallel to the axial direction, the inside of the hollow portion 30 is divided into three in the radial direction, and the flow resistance is 13000 [Pa Simulation was performed assuming that the sound absorbing material 24 of s / m ² ] is disposed. Ph1 is the area closest to the opening 32, and ph2 and ph3 are areas farther from the opening 32 than ph1 in the radial direction.
FIG. 97 shows a graph showing the transmission loss of the 500 Hz band when the sound absorbing material is disposed in each of the ph1 to ph3.

As shown in FIGS. 95 and 97, it can be seen that the transmission loss of the 500 Hz band increases and the soundproofing performance increases as the area where the sound absorbing material is disposed is closer to the opening 32.

In addition, the silencer 22 may have a second opening 38 communicating with the cavity 30 at a position not connected to the sound field space of the first resonance generated in the tubular member 12.

FIG. 98 is a cross sectional view conceptually showing another example of the silencing system of the present invention.
In the noise reduction system shown in FIG. 98, the second hollow portion 38 is provided on the surface of the wall surface of the hollow portion 30 of the silencer 22 facing the surface having the opening 32. By providing the second opening 38 communicating with the cavity 30 at a position not connected to the sound field space of the first resonance generated in the tubular member 12, the acoustic impedance in the cavity 30 is lowered, Sound waves can easily enter the cavity 30. As a result, sound energy is easily converted into heat energy in the hollow portion 30, and soundproof performance can be further improved. Moreover, since the acoustic impedance in the cavity 30 can be lowered without increasing the volume of the cavity 30, the silencer can be miniaturized.

The formation position of the second opening 38 is not limited as long as it is a position not connected to the sound field space of the first resonance generated in the tubular member 12. Also, the size of the second opening 38 is not limited, but is preferably large.

Here, in the case where the second opening 38 is formed at a position not connected to the sound field space of the first resonance generated in the tubular member 12, water or moisture intrudes into the wall, or the cavity is formed from the wall Water and moisture may get into the Therefore, as in the example shown in FIG. 99, the second opening of the muffling system shown in FIG. 98 may be covered with the film-like member 46. The film-like member 46 is a film-like member that easily passes sound waves and does not pass water, and may be a thin resin film such as Saran Wrap (registered trademark), a non-woven fabric treated with water repellant, or the like. Thereby, it is possible to prevent water and moisture from entering while reducing the acoustic impedance in the hollow portion 30. As a material of the film-like member 46, the same material as the material of the windproof film 44 described later can be used.

Further, as in the example shown in FIG. 100 and FIG. 101, the penetration prevention plate 34 may be provided in the tubular member 12.
FIG. 100 is a schematic cross-sectional view of another example of the noise reduction system of the present invention. FIG. 101 is a cross-sectional view taken along the line DD in FIG.
As shown in FIGS. 100 and 101, the penetration preventing plate 34 is a plate-like member which is provided in the radial direction of the tubular member 12 below the vertical direction in the tubular member 12.

Since the aeration sleeve (tubular member) installed on the wall of the house leads to the outside, rainwater may pass through the outer girari, the outer hood, etc. and intrude into the aeration sleeve during strong wind such as a typhoon. In the noise reduction system of the present invention, since the silencer having the hollow portion is connected to the ventilation sleeve, there is a possibility that the rainwater which has entered the ventilation sleeve may infiltrate into the hollow portion and be accumulated.

On the other hand, as shown in FIGS. 100 and 101, by providing the intrusion prevention plate 34 in the tubular member 12, the rainwater which has entered the tubular member 12 from the outside enters the hollow portion 30 of the silencer 22 You can prevent
The height in the vertical direction of the intrusion prevention plate 34 is preferably 5 mm or more and 40 mm or less.

Further, as a configuration for preventing rainwater from entering the hollow portion 30 of the silencer 22, as shown in FIG. 102 and FIG. 103, the region on the lower side in the vertical direction of the opening 32 of the silencer 22 is covered. It may be configured to be closed.
FIG. 102 is a schematic cross-sectional view of another example of the noise reduction system of the present invention. FIG. 103 is a cross-sectional view taken along the line EE of FIG.
As shown in FIG. 102 and FIG. 103, by configuring the region below the opening 32 of the silencer 22 in the vertical direction with the lid 36, the rainwater that has entered the tubular member 12 from the outside is a silencer It can be prevented from entering the hollow portion 30 of 22.

Further, as shown in FIG. 109, the partition member 54 may be replaceable by using a member forming the surface on the opening 32 side of the silencer 22 as a separate member (partition member 54). Since the size of the opening 32 can be easily changed by making the partition member 54 replaceable, the resonance frequency of the silencer 22 can be set appropriately. Moreover, the sound absorbing material 24 installed in the hollow portion 30 can be easily replaced.

Examples of materials for forming the silencer 22 and the silencer 14 include metal materials, resin materials, reinforced plastic materials, carbon fibers, and the like. As a metal material, metal materials, such as aluminum, titanium, magnesium, tungsten, iron, steel, chromium, chromium molybdenum, nichrome molybdenum, and these alloys can be mentioned, for example. Moreover, as the resin material, for example, acrylic resin, methyl polymethacrylate, polycarbonate, polyamideid, polyarylate, polyetherimide, polyacetal, polyetheretherketone, polyphenylene sulfide, polysulfone, polyethylene terephthalate, polybutylene terephthalate, Resin materials such as polyimide and triacetyl cellulose can be mentioned. Moreover, as a reinforced plastic material, carbon fiber reinforced plastics (CFRP: Carbon Fiber Reinforced Plastics) and glass fiber reinforced plastics (GFRP: Glass Fiber Reinforced Plastics) can be mentioned.
Here, the silencer 22 and the silencer 14 are preferably made of a material having higher heat resistance than the flame retardant material, from the viewpoint of being usable for an exhaust port or the like. The heat resistance can be defined, for example, as a time satisfying the items of Article 108-2 of the Building Standard Act Enforcement Order. If the time required to satisfy Article 108-2 of the Building Standard Act Enforcement Order is 5 minutes or more and less than 10 minutes, it is a flame retardant material, and if it is 10 minutes or more and less than 20 minutes, it is a semicombustible material; The above cases are noncombustible materials. However, heat resistance is often defined in each field. Therefore, the silencer 22 and the silencer 14 may be made of a material having heat resistance equal to or higher than the flame retardancy that is defined in the field according to the field using the silencer system.

Further, as in the noise reduction system 10t shown in FIG. 76, it is preferable that the openings 32 of the silencers 22 are covered with a windproof film 44 that transmits sound waves and shields air (wind).
In the case of a configuration in which air can flow into the hollow portion 30 of the silencer 22, the pressure loss as a whole of the silencer system is larger than in the case of a straight pipe. Therefore, the amount of ventilation may be reduced. On the other hand, by covering the openings 32 of the respective silencers 22 with the windproof films 44, the windproof films 44 transmit sound waves, so that the muffling effect by the silencers 22 can be obtained, and Since the windproof film 44 shields the air, the flow of air into the hollow portion 30 can be suppressed to reduce the pressure loss.

The windproof film 44 may be a non-air-permeable film or a low air-permeable film.
The material of the non-ventilated windproof film 44 is acrylic resin such as polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate, polyamideid, polyarylate, polyetherimide, polyacetal, polyetheretherketone, polyphenylene Resin materials such as sulfide, polysulfone, polybutylene terephthalate, polyimide, triacetyl cellulose and the like can be used.
The material of the low air-permeable windproof film 44 is a porous film made of the above resin, porous metal foil (porous aluminum foil etc.), non-woven fabric (resin-bonded non-woven fabric, thermal-bonded non-woven fabric, spun-bonded non-woven fabric, spunlace non-woven fabric (Nanofiber non-woven fabric), woven fabric, paper, etc. can be used.
In addition, when a porous film, porous metal foil, a nonwoven fabric, and a woven fabric are used, the sound absorption effect can be acquired by the through-hole part which they have. That is, they also function as a conversion mechanism that converts sound energy into heat energy.
Although depending on the material, the thickness of the windproof film 44 is preferably 1 μm to 500 μm, more preferably 3 μm to 300 μm, and still more preferably 5 μm to 100 μm.

Moreover, you may have another commercially available soundproof member in the noise reduction system of this invention.
For example, as shown in FIG. 77, the silencer 14 according to the present invention is disposed at one end of the tubular member 12, and the insertion silencer 50 is disposed inside the tubular member 12. It is also good.
Further, as shown in FIG. 78, the muffling device 14 of the present invention is disposed at one end of the tubular member 12, and the outdoor soundproof hood 52 is disposed at the other end of the tubular member 12. It may be configured as
Alternatively, the silencer 14 of the present invention is disposed at one end of the tubular member 12, and the insertion type silencer 50 is disposed inside the tubular member 12 at the other end of the tubular member 12. Alternatively, the outdoor soundproof hood 52 may be disposed.
Thus, high soundproofing performance can be obtained in a wider band by combining with other soundproofing members.

Various known interpolation silencers can be used as the interpolation silencer 50. For example, Shin Kyowa Co., Ltd .: Soundproof sleeve (SK-BO100, etc.), Daiken Plastics Co., Ltd .: Soundproof sleeve (100NS2, etc.), Saiho Kogyo Co., Ltd., Natural ventilation silencer (SEIHO NPJ100, etc.), Ltd. Product made by Unix: Silencer (UPS100SA etc.), product made by Kentoh Co., Ltd .: Silent sleeve P (HMS-K etc.) etc. can be used.
Various known soundproof sleeves can be used as the outdoor soundproof hood 52. For example, a soundproofing hood (SSFW-A10M or the like) manufactured by Unix Co., Ltd., a soundproofing hood (BON-TS or the like) manufactured by Silfer Co., Ltd., or the like can be used.

Here, the tubular member 12 is not limited to a straight tubular one, and may have a bent structure. In the case where the tubular member 12 has a bending structure, the air (flow of air) and the sound waves are also reflected to the upstream side at the bending portion, so that neither the wind nor the sound waves pass. In order to secure air permeability, the angled change of the wall may be made gentle by making curved parts to be curved or the like, and a flow straightening plate may be provided at the bent parts to change air flow direction to ensure air permeability. Conceivable.
However, when the bent portion is formed into a curved surface or a straightening vane is provided to the bent portion, although the air permeability is improved, the sound wave transmission rate is also increased.

Therefore, as shown in FIG. 89, an acoustic transmission wall 60 which transmits a sound wave while preventing wind from passing therethrough is disposed at the bent portion of the tubular member 12. In FIG. 89, the tubular member 12 has a bent portion that bends approximately 90 °. The sound transmitting wall 60 is disposed at the bend of the tubular member 12 with its surface inclined by about 45 ° with respect to the longitudinal direction of the tubular member 12 on the incident side and the longitudinal direction of the tubular member 12 on the outgoing side. In FIGS. 89 and 90, the upper end in the drawing is the incident side, and the right end is the emission side.

As shown in FIG. 89, since the sound transmission wall 60 transmits the sound wave, the sound wave incident from the upstream side transmits the sound transmission wall 60 at the bending portion and is reflected upstream by the wall of the tubular member 12. That is, the characteristics of the original tubular member 12 are maintained. On the other hand, as shown in FIG. 90, since the sound transmission wall 60 does not pass the wind, the wind incident from the upstream side is bent in the traveling direction by the sound transmission wall 60 at the bent portion and flows downstream. As described above, by disposing the sound transmission wall 60 at the bent portion, it is possible to improve the air permeability while maintaining the low sound transmittance.

As the sound transmission wall 60, a non-woven fabric with low density and a membrane with low thickness and density can be used.
As a non-woven fabric having a low density, Yodogawa Paper Mill Co., Ltd .: stainless fiber sheet (Tomy Filec SS), ordinary tissue paper and the like can be mentioned. As a film with a small thickness and density, various commercially available lap films, silicone rubber films, metal foils and the like can be mentioned.

Hereinafter, the present invention will be described in more detail based on examples. The materials, amounts used, proportions, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Accordingly, the scope of the present invention should not be construed as limited by the following examples.

[simulation]
First, the simulation results of the noise reduction system of the present invention will be described.
The simulation was performed using an acoustic module of finite element method calculation software COMSOL ver 5.3 (COMSOL).

[Reference example]
First, a simulation was performed on the sound waves transmitted through the tubular member when the silencer is not installed. The thickness of the wall was 300 mm, and the diameter of the tubular member was 100 mm. By simulation, the relationship between the sound pressure (transmitted sound pressure) and the frequency of the sound wave transmitted through the tubular member and propagating from one space to the other space was calculated. The results are shown in FIG.
As shown in FIG. 41, when the silencer is not installed, the transmission sound pressure is high at the resonance frequency of the resonance generated in the tubular member. The first resonant frequency is 460 Hz, the second resonant frequency is 950 Hz, the third resonant frequency is 1470 Hz, and the fourth resonant frequency is 2000 Hz.

Example 1
Next, as Example 1, as shown in FIG. 42, simulation was performed about the structure which has arrange | positioned the silencer 22 in the outer peripheral surface of the tubular member 12. FIG.
The silencer 22 is an L-shaped silencer, and has an annular shape along the entire circumference of the outer circumferential surface of the tubular member 12 in the circumferential direction, and the opening 32 is formed in a slit shape along the circumferential direction Shape (see FIG. 24). Further, the sound absorbing material 24 is disposed in the hollow portion 30 of the silencer 22.
The depth L _d of the cavity 30 is 60 mm, the width L _w is 10 mm, the width of the axial opening 32 is 10 mm, the thickness of the tubular member 12 is 3 mm, and the area S ₁ of the opening 32 and the cavity The ratio S ₁ / S _{d to} the surface area S _d of the inner wall of 30 was 7.4%, and the central position of the opening 32 in the axial direction was 150 mm from the end face on the sound source side.
In addition, the sound absorbing material 24 is to be filled in the entire area of the hollow portion 30. The flow resistance of the sound absorbing material 24 was 13000 [Pa · s / m ² ]. Also in the following examples, the sound absorbing material 24 is assumed to be filled in the entire area of the hollow portion 30 and the flow resistance of the sound absorbing material 24 is simulated as 13000 [Pa · s / m ² ] unless otherwise specified. .
The results are shown in FIG. FIG. 43 also shows the result in the case where the depth L _d is 0 mm as a reference example, that is, in the case where the silencer 22 is not disposed. Note that the transmission sound pressure is a value normalized with the transmission sound pressure of the first resonance frequency as 1.
As shown in FIG. 43, compared with the reference example, particularly in Example 1, the transmission sound pressure is selectively lowered in the vicinity of the first resonance frequency and the third resonance frequency, and in these frequency bands, It can be seen that the soundproofing performance is high. This is because the sound absorption effect in the noise reduction system of the present invention becomes higher as the sound pressure inside the tubular member becomes higher due to the resonance phenomenon of the tubular member.

Comparative Example 1
Next, as Comparative Example 1, as shown in FIG. 44, a simulation was performed on a configuration in which the silencer 122 is disposed on the outer peripheral surface of the tubular member 12. In the silencer 122, the depth L _d of the hollow portion 130 is 10 mm, the width L _w is 60 mm, the width of the opening 60 mm, and the area ratio S ₁ / S _d is 76.3%. It is the same configuration as the configuration. This configuration is an example in which the sound absorption effect is different because the area of the opening is different although the volume of the cavity is the same as that of the first embodiment.
The results are shown in FIG. FIG. 45 also shows the result in the case where the width of the opening is 0 mm, that is, in the case where the silencer 122 is not disposed, as a reference example.
As shown in FIG. 45, in Comparative Example 1, compared to the reference example, the transmission sound pressure is low in a wide frequency band, particularly in a high frequency band of 800 Hz or more. However, compared to Example 1, it can be seen that the transmitted sound pressure of the resonance sound is not selectively lowered, and the soundproofing performance on the low frequency side near the first resonance frequency is not sufficient.

Next, FIG. 46 shows the result of simulation in which the depth L _d of the hollow portion 30 was variously changed in the first embodiment. The width of the opening 32 was 10 mm.
Similarly, FIG. 47 shows the result of simulation in which the width of the opening was variously changed in the comparative example 1 described above.
Furthermore, FIG. 48 shows the result of simulation in which the depth L _d of the cavity 30 was variously changed in the same manner as in Example 1 except that the vertical cylindrical silencer was used. The width L _w (the width of the opening 32) of the hollow portion 30 was 10 mm.
The sound absorbing material was changed in accordance with the size of the hollow portion. Also, the central position of the opening was fixed at the center of the tubular member. Further, in FIGS. 46 to 48, the value of λ / 4 for each frequency is also indicated by a thick line for comparison.
It can be seen from FIG. 46 that the muffling effect differs depending on the depth L _{d of the} hollow portion, and a high muffling effect can be obtained even on the low frequency side. Since the opening is disposed at the center, the first resonance sound and the third resonance sound, which have high sound pressure at the center, are rapidly absorbed. Also, the required length is shorter than λ / 4, and its specificity is clear. Similarly, in the case of the vertical cylinder type, it is understood from FIG. 48 that the muffling effect is different depending on the depth L _d of the hollow portion, and a high muffling effect can be obtained even on the low frequency side. Since the opening is disposed at the center, the first resonance sound and the third resonance sound, which have high sound pressure at the center, are rapidly absorbed. Also, the required length is shorter than λ / 4, and its specificity is clear.
On the other hand, it can be seen from FIG. 47 that in the configuration in which a sound absorbing material is simply disposed, a length of about λ / 4 is required for sound absorption of resonance sound, and in this case, soundproof performance on the low frequency side is enhanced. I understand that it is difficult.

In addition, in Example 1, the transmission loss at the first resonance frequency when the depth of the cavity is variously changed, and for the comparison example 1, the width at the first resonance frequency when the width of the opening is variously changed. The transmission loss was calculated. The higher the transmission loss, the higher the performance.
The results are shown in FIG. Note that 1⁄4 of the wavelength λ of the first resonance frequency is about 170 mm.
As can be seen from FIG. 49, in Example 1 of the present invention, the transmission loss peaks at a depth shorter than λ / 4. On the other hand, in Comparative Example 1, the transmission loss increases as the width of the opening increases. This is a surface area in contact with the sound wave of the sound absorbing material, and a property dependent on volume. Such characteristics are obtained when the sound absorbing material is used in a general use method of increasing the surface area in contact with sound waves.

[Examples 2 and 3]
Next, the result of having performed simulation about the position of the opening part 32 of the silencer 22 is demonstrated.
As shown in FIGS. 50 and 51, the position of the opening 32 of the silencer 22 was variously changed in the axial direction of the tubular member to calculate the transmitted sound pressure. As shown in FIG. 50, the case where the center of the opening 32 is at the axial center position of the tubular member is taken as a reference (position 0 mm). The second embodiment is the same as the first embodiment except for the position of the opening 32. As shown in FIG. 50, the configuration in which the opening 32 is disposed at the center is referred to as Example 2, and as shown in FIG. 51, the configuration (position 140 mm) in which the opening 32 is disposed in the vicinity of one end face Do.
A graph showing the relationship between the position of the opening, the frequency, and the transmitted sound pressure is shown in FIG. 52, and the graph showing the relationship between the frequency and the transmitted sound pressure in Examples 2 and 3 is shown in FIG. Moreover, in FIG. 53, the case where a silencer is not arrange | positioned is shown as a reference example.

As shown in FIGS. 52 and 53, by arranging the opening 32 of the silencer 22 at a position close to the axial center, the sound pressure at the axial center such as the first resonance frequency and the third resonance frequency is obtained. It can be seen that sound waves of a frequency at which is increased can be muted more suitably. In addition, it can be seen that changing the arrangement position of the opening 32 changes the muffling effect on each resonance frequency. For example, by arranging the opening 32 at a position of 90 mm from the center, it can be seen that the muffling effect on the second resonance frequency at which the sound pressure becomes high at this position can be further enhanced.
Thus, the mode of noise cancellation can be controlled by the position of the opening 32 of the noise suppressor 22.

Next, results of simulation of the flow resistance of the sound absorbing material 24 disposed in the hollow portion 30 of the silencer 22 will be described.
In the model of the first embodiment, the flow resistance of the sound absorbing material 24 was changed variously and simulation results are shown in FIG. The depth L _d of the cavity is 80 mm, the width L _{w of the} cavity is 10 mm, the width L _{o of the} opening is 10 mm, the area ratio S ₁ / S _d is 5.5%, the position of the opening in the axial direction is the center It is.
It can be seen from FIG. 54 that the flow resistance has an optimum range. This is because when the flow resistance becomes too large, the passage of the inside of the sound absorbing material 24 is difficult, and the conversion efficiency from the sound energy to the heat energy by the sound absorbing material 24 becomes low.

Further, based on the above simulation results, the combination of the flow resistance of the cavity 30 depth L _d and sound absorbing material, the results of the transmitted sound pressure was measured is shown in FIGS. 55 and 56. FIG. 55 is a graph showing the relationship between the flow resistance of the sound absorbing material 24 and the peak value of the transmitted sound pressure when the depth L _d of the cavity 30 is 10 mm (1 cm) to 140 mm (14 cm). FIG. 56 is a graph showing the peak value of the transmitted sound pressure with respect to the depth L _d of the cavity 30 and the flow resistance of the sound absorbing material 24.
As shown in FIGS. 55 and 56, it can be seen that the flow resistance of the sound absorbing material 24 has a suitable range depending on the depth L _d of the cavity 30. From this result, the range of flow resistance in which the effect of selectively absorbing the resonance sound of the present invention appears is (1.25−log (0.1 × L _d )) / 0.24 <log (σ ₁ ) < 5.6 is preferable, and (1.32-log ((0.1 x L _d ))) / 0.24 <log (σ ₁ ) <5.2 is more preferable, (1.39-log ((0 More preferably, 1 × L _d )) / 0.24 <log (σ ₁ ) <4.7. In the above equation, the unit of L _d is [mm], and log is a common logarithm.

Example 4
Next, the result of simulation will be described for the case where a plurality of silencers 22 are arranged in the axial direction.
The configuration of the muffling system is as shown in FIG. 27: a silencer 22a having an opening 32a at the central position (position 150 mm from the end face) in the axial direction in the axial direction; And a silencer 22b having an opening 32b.
The thickness of the wall was 300 mm, and the diameter of the tubular member was 100 mm.
The silencer 22a and the silencer 22b are L-shaped silencers, and have an annular shape along the entire circumference of the outer peripheral surface of the tubular member 12 in the circumferential direction, and a slit in which the opening 32 extends along the peripheral direction In the shape of a circle. The depth L _d of the hollow portion 30 a of the silencer 22 a is 80 mm, the width L _w is 10 mm, the width L _o of the opening 32 a is 10 mm, and the area ratio S ₁ / S _d is 5.5%. The depth L _d of the hollow portion 30 b of the silencer 22 b is 50 mm, the width L _w is 10 mm, the width L _o of the opening 32 b is 10 mm, and the area ratio S ₁ / S _d is 8.9%.
Further, the sound absorbing material 24 is disposed in the hollow portion 30 of the silencer 22a and the silencer 22b. The flow resistance of the sound absorbing material 24 was 13000 [Pa · s / m ² ].
The relationship between the frequency and the transmitted sound pressure was calculated using such a model of the noise reduction system. The results are shown in FIG. FIG. 57 also shows the results of Example 1 as a reference example in the case where there is no silencer and in a configuration having one silencer in the axial direction.

As shown in FIG. 57, in Example 1 of the configuration having one silencer, the transmission sound pressure at the first resonance frequency and the third resonance frequency can be reduced, but the transmission sound at the second resonance frequency and the fourth resonance frequency The pressure is relatively high. On the other hand, in the fourth embodiment, in addition to the silencer 22a disposed at the position (center) where the sound pressure of the first resonance is high, the sound pressure of the second resonance is disposed at a position (25 mm from the end face) Since the silencer 22 b is provided, the transmitted sound pressure of the second resonance can also be lowered. Therefore, the soundproof effect can be obtained in a wider band. Further, at the position where the silencer 22b is disposed, the sound pressure of the third resonance and the fourth resonance is also not zero, so that the soundproof effect can be obtained also for these resonance frequencies.

[Measurement result]
Next, the result of having produced a noise reduction system and evaluated soundproof performance is explained.
First, using a simple small-sized soundproof room as shown in FIG. 58 as a reference, transmission sound pressure was measured in the case where no silencer was disposed.
In the simple small-sized soundproof room shown in FIG. 58, five sides are surrounded by sound absorbing urethane foam W ₃ (thickness 100 mm, U00F2 manufactured by Fuji Rubber Sangyo Co., Ltd.), and the remaining one side is sound absorbing urethane foam W ₂ (sound absorbing urethane foam W ₃ two sheets (Fuji rubber industry Co. U00F2), is surrounded by a wall member disposed acrylic plate W ₁ having a thickness of 5mm on both sides of the total thickness 205 mm). Also, the five surfaces of the sound-absorbing urethane foam W _3, the inner surface of the three faces are disposed on the left and right surfaces, corrugated acoustical polyurethane foam W ₄ (maximum thickness 35 mm, Fuji rubber industry Co., Ltd. U00F6) a Placed. The size of the soundproof room was 400 mm × 500 mm × 500 mm.
On the wall member having the sound absorbing urethane foam W ₂ and the two acrylic plates W ₁ , a ventilation sleeve (tubular member) 12 made of vinyl chloride having an inner diameter of 10 cm was installed through the wall member.
A lateral glaring (SG-CB manufactured by Unix Co., Ltd.) is attached to the end face of the soundproof room of the aeration sleeve 12 as a cover member 18 and a register (made by Unix Co., Ltd. KRP- BWF) attached.

In the soundproof room, two speakers SP (KOSPI set KANSPI-8 manufactured by FOSTEX Co., Ltd.) for generating white noise were arranged. In addition, a measurement microphone MP for acoustic wave detection (TYPE 4152N manufactured by Accor Corporation) was disposed at a position 50 cm away from the register 20 outside the soundproofing room.

First, the register 20 was closed, white noise was generated from the two speakers SP, and the sound pressure was measured for 10 seconds at a sampling rate of 25000 Hz with the measurement microphone MP. Fourier transform was performed on the measured sound pressure data to calculate a frequency spectrum. Data after Fourier transform were averaged at 10 Hz intervals. This data is used as background data.

Next, the register 20 is fully opened, the sound pressure is measured in the same manner as described above, the data of the sound pressure is subjected to Fourier transform, the frequency spectrum is calculated, and the difference with the background data is calculated as reference data .

[Example 5]
As Example 5, as shown in FIG. 59, the silencer 22 is installed in the ventilation sleeve 12, the register 20 is fully opened, and the sound pressure is measured in the same manner as described above. Fourier transform was performed to calculate a frequency spectrum, and the difference with background data was obtained to obtain data of transmitted sound pressure.
The results are shown in FIG.
The silencer 22 according to the fifth embodiment has an annular shape along the entire circumference of the outer peripheral surface of the tubular member 12 in the circumferential direction, and the opening 32 is formed in a slit shape along the circumferential direction. (See FIG. 24). Further, the sound absorbing material 24 is disposed in the hollow portion 30 of the silencer 22.
The depth L _d of the cavity 30 is 80 mm, the width L _w is 14 mm, the width of the axial opening 32 is 15 mm, the area ratio S ₁ / S _d is 8.3%, and the opening 32 in the axial direction The center position of was at a position of 113 mm from the end face on the sound source side. Further, as the sound absorbing material 24, rock wool (made by Mitsuroko Co., Ltd.) was used. The flow resistance of the sound absorbing material 24 is 40,000 [Pa · s / m ² ], and the entire area of the hollow portion 30 is filled.

Comparative Example 2
As Comparative Example 2, the transmitted sound pressure was determined in the same manner as in Example 4 except that a soundproof sleeve made of polyethylene (SK-BO 75, manufactured by Shin-Kyowa Co., Ltd.) was disposed in the ventilation sleeve 12 instead of the silencer 22. .
The results are shown in FIG.

Comparative Example 3
As Comparative Example 3, the transmitted sound pressure is the same as in Example 4 except that a silent sleeve P (HMS100K manufactured by Kentomo Co., Ltd.), which is a resonance type silencer, is disposed in the ventilation sleeve 12 instead of the silencer 22. I asked for.
The results are shown in FIG.

From the comparison between Example 5 and Comparative Examples 2 and 3, it is understood that the Example of the present invention can significantly reduce the transmitted sound pressure of the first resonance frequency on the low frequency side as compared with the Comparative Example.

[Example 6]
As Example 6, the thickness of the sound absorbing urethane foam W ₂ on which the ventilation sleeve 12 is installed was set to 265 mm, and the transmission sound pressure was determined in the same manner as in Example 5 except that the length of the ventilation sleeve 12 was changed.
The results are shown in FIG.

Comparative Example 4
The transmitted sound pressure was determined in the same manner as in Example 6 except that a silent sleeve P (HMS 100K manufactured by Kentomo Co., Ltd.), which is a resonance type silencer, was disposed in the ventilation sleeve 12 instead of the silencer 22.
The results are shown in FIG.

From the comparison between FIG. 60 and FIG. 63, in the embodiment of the present invention, the same silencer 22 as the fifth embodiment is used even if the length of the ventilating sleeve is changed, that is, for ventilating sleeves having different first resonance frequencies. It can be seen that high soundproofing performance can be obtained by using
On the other hand, it can be understood from the comparison between FIG. 62 and FIG. 64 that, in the resonance type silencer, when the first resonance frequency of the aeration sleeve is different, the soundproofing performance is lowered and the versatility is low.

[Example 7]
In the seventh embodiment, the silencer 22a and the silencer 22b are arranged in the axial direction on the ventilation sleeve 12, the register 20 is fully opened, and the sound pressure is measured in the same manner as described above. Fourier transform was performed to calculate a frequency spectrum, and the difference with background data was obtained to obtain data of transmitted sound pressure.
The results are shown in FIGS. 65 and 66. FIG. 66 shows the average value of transmission loss determined for each frequency band (octave band frequency). The octave band frequency of 500 Hz is the average of transmission loss at 354 Hz and less than 707 Hz, and that of 1000 Hz is the average of transmission loss at 707 Hz and less than 1414 Hz. In the case of 2000 Hz, the average value of the transmission loss at a frequency of 1414 Hz or more and less than 2829 Hz is obtained. 65 and 66 also show the result of the fifth embodiment.

The silencer 22a and the silencer 22b of Example 7 are annular along the entire circumference of the outer circumferential surface of the tubular member 12 in the circumferential direction, and the opening 32 is formed in a slit shape along the circumferential direction. The shape is as shown in FIG. Further, the sound absorbing material 24 is disposed in the hollow portion 30 of the silencer 22.
The depth L _d of the cavity 30a of the silencer 22a is 40 mm, the width L _w is 14 mm, the width L _o of the axial opening 32 a is 14 mm, and the area ratio S ₁ / S _d is 15.7%, The central position of the opening 32a in the axial direction was 113 mm from the end face on the sound source side. The depth L _d of the cavity 30b of the silencer 22b is 60 mm, the width L _w is 14 mm, the width L _o of the axial opening 32 b is 15 mm, and the area ratio S ₁ / S _d is 11.4%, The central position of the opening 32b in the axial direction was 156 mm from the end face on the sound source side.
Further, as the sound absorbing material 24, rock wool (made by Mitsuroko Co., Ltd.) for replacement with charcoal was used. The flow resistance of the sound absorbing material 24 is 40,000 [Pa · s / m ² ], and the entire area of the hollow portion 30 is filled.

From FIG. 65 and FIG. 66, it can be understood that arranging two silencers in the axial direction can provide a wider band and high soundproofing effect.

[Example 8]
Next, the result of having evaluated the soundproofing performance by producing a sound deadening system combined with a commercially available soundproofing member will be described.
For the performance evaluation, a simple small-sized soundproof room as shown in FIG. 79 was used.

The simple soundproof room shown in FIG. 79 has five sides surrounded by the sound absorbing urethane foam W ₃ (thickness 100 mm, U00F2 manufactured by Fuji Rubber Sangyo Co., Ltd.) and the acrylic plate W ₁ with a thickness of 5 mm disposed outside thereof. Wall member (wall 16 of the present invention) made of aluminum plate W ₅ (thickness 3 mm), glass wool W ₆ (32501121 density 32 kg / m ³ non-formaldehyde) and acrylic plate W ₁ from the soundproof room side Blockade). The total thickness of the wall members was 100 mm. Further, an acrylic plate W ₁ (corresponding to the decorative plate of the present invention) is disposed in parallel to the wall member at a distance of 110 mm from the wall member.
Also, among the sound-absorbing urethane foam W ₃ of five surfaces, the inner surface of the three faces are disposed on the left and right surfaces, corrugated acoustical polyurethane foam W ₄ (maximum thickness 35 mm, Fuji rubber industry Co., Ltd. U00F6) is It is arranged. The size of the soundproof room was 800 mm × 800 mm × 900 mm.
On a wall member made of aluminum plate W ₅ , glass wool W ₆ and acrylic plate W ₁ , a ventilation sleeve (tubular member) 12 made of vinyl chloride having an inner diameter of 100 mm and a length of 100 mm was installed through the wall member. The decorative plate (acrylic plate W ₁ ) was provided with an opening of 100 mm at the same position as the ventilation sleeve when viewed from the axial direction of the ventilation sleeve.
Incidentally, acrylic plate W ₁ and the aluminum plate W ₅ is supported by fixing the ends in an aluminum frame Fr of 30mm square.

A lateral glaring (SG-CB manufactured by Unix Co., Ltd.) is attached to the end face of the soundproof room of the aeration sleeve 12 as a cover member 18 and a register (made by Unix Co., Ltd. KRP- BWF) attached.

In the soundproof room, two speakers SP (KOSPI set KANSPI-8 manufactured by FOSTEX Co., Ltd.) generating pink noise were arranged. In addition, a measurement microphone MP for acoustic wave detection (TYPE 4152N manufactured by Accor Corporation) was disposed at a position 50 cm away from the register 20 outside the soundproofing room.

First, ten circular acrylic plates (5 mm in thickness) having the same size (100 mm in diameter) as the inner diameter of the air-permeable sleeve 12 were disposed as a sound insulation material for reference. Thereby, the noise passing through the ventilation sleeve 12 was almost completely shielded. In this state, noise was generated from the two speakers SP, and the sound pressure was measured for 10 seconds at a sampling rate of 25000 Hz with the measurement microphone MP. Fourier transform was performed on the measured sound pressure data to calculate a frequency spectrum. Data after Fourier transform were averaged at 10 Hz intervals. This data is used as background data.

Next, as the eighth embodiment, the sound insulation material for reference and the resistor 20 are removed, and the silencer 14 is installed on the outer end face of the aeration sleeve 12 (between the wall member and the decorative plate). It was attached to the end face of the decorative board side of.

The silencer 14 has an L-shaped silencer 22 connected to the insertion portion 26 with an outer diameter of 100 mm and an inner diameter of 94 mm and one end face of the insertion portion 26. Two silencers 22 are arranged in the axial direction. Each of the silencers 22 has an annular shape along the circumferential surface of the insertion portion 26, and the opening 32 is shaped like a slit along the circumferential direction (see FIG. 24). Further, the sound absorbing material 24 is disposed in the hollow portion 30 of the silencer 22.
The depth L _d of the hollow portion 30 of the silencer 22a is 41 mm, the width L _w is 16 mm, the width of the opening 32 in the axial direction is 12 mm, and the area ratio S ₁ / S _d is 11.6%. The depth L _d of the hollow portion 30b of the silencer 22b is 60 mm, the width L _w is 15 mm, the width of the axial opening 32 b is 12.5 mm, and the area ratio S ₁ / S _d is 8.6%. . Further, as the sound absorbing material 24, Thinsulate (manufactured by 3M) was used. The flow resistance of the sound absorbing material 24 is 27000 [Pa · s / m ² ], and the entire area of the hollow portion 30 is filled.

With the register 20 fully open, the sound pressure is measured in the same manner as described above, the sound pressure data is subjected to Fourier transform to calculate the frequency spectrum, and the difference with the background data is determined to be the transmitted sound pressure data .
The results are shown in FIG.
The opening ratio of the silencer 14 is 88% of the inner diameter of the ventilation sleeve 12.

Comparative Example 5
As Comparative Example 5, the same procedure as in Example 8 was carried out except that a soundproof sleeve made of polyethylene (SK-BO 100, manufactured by Shin-Kyowa Co., Ltd.) was disposed in the ventilation sleeve 12 as an insertion type silencer instead of the silencer 14. Sound pressure was determined.
The results are shown in FIG.
Also, the opening ratio of the soundproof sleeve is 35.7% with respect to the inner diameter of the aeration sleeve 12.

[Example 9]
In Example 9, the transmitted sound pressure was determined in the same manner as in Example 8 except that a polyethylene soundproof sleeve (SK-BO 100, manufactured by Shin-Kyowa Co., Ltd.) was disposed in the ventilation sleeve 12.
The results are shown in FIG.
Moreover, in FIG. 83, the result of having calculated | required the average value of the transmission loss for every frequency band (octave band frequency) of Example 8, 9 and the comparative example 5 is shown. The octave band frequency of 500 Hz is the average of transmission loss at frequencies of 354 Hz to 707 Hz, and that of 1000 Hz is the average of transmission loss at frequencies of 707 Hz to less than 1414 Hz. is there.

From FIGS. 80 to 83, it can be seen that Example 8 in which the silencer 14 is disposed can obtain high soundproofing performance in a low frequency range (about 500 Hz) as compared with Comparative Example 5. Furthermore, it can be seen that by combining the soundproof sleeve from Example 9, in addition to the low frequency band, the soundproofing performance in the frequency band around 1000 Hz can also be enhanced.

Comparative Example 6
As Comparative Example 6, the transmission sound pressure was changed in the same manner as in Example 8 except that a soundproof hood (SSFW-A10M manufactured by Unix Co., Ltd.) was disposed at the end of the aeration sleeve 12 in the soundproof room side I asked.
The results are shown in FIG.
In addition, the opening ratio of the soundproof hood is 50.2% with respect to the inner diameter of the aeration sleeve 12.

[Example 10]
In Example 10, the transmitted sound pressure was determined in the same manner as in Example 8 except that a soundproof hood (SSFW-A10M manufactured by Unix Co., Ltd.) was disposed at the end of the aeration sleeve 12 on the soundproof room side.
The results are shown in FIG.
Moreover, in FIG. 86, the result of having calculated | required the average value of the transmission loss for every frequency band (octave band frequency) of Example 8, 10 and the comparative example 6 is shown.

From FIGS. 80 and 84 to 86, Example 8 in which the silencer 14 is disposed is able to obtain the same soundproofing performance in the low frequency range (about 500 Hz) although the aperture ratio is high compared to Comparative Example 7. I understand that. Furthermore, it can be seen that by combining the soundproof hood from Example 10, in addition to the low frequency band, the soundproofing performance in the frequency band around 1000 Hz can also be enhanced.
[Example 11]
As Example 11, further, a soundproof sleeve made of polyethylene (SK-BO 100, manufactured by Shin-Kyowa Co., Ltd.) is disposed in the aeration sleeve 12, and a soundproof hood (SSFW-A10M, manufactured by Unix, Inc.) The transmitted sound pressure was determined in the same manner as in Example 8 except that it was arranged at the end of the.
The results are shown in FIG.
Moreover, in FIG. 88, the result of having calculated | required the average value of the transmission loss for every frequency band (an octave band frequency) of Example 8, 11 and Comparative Example 5, 6 is shown.

From FIGS. 87 to 88, it can be understood that the soundproof performance in the frequency range around 1000 Hz can be enhanced in addition to the low frequency range by combining the soundproof sleeve and the soundproof hood.
The effect of the present invention is clear from the above results.

10a to 10t Silencer system 12 Tubular member 14 Silencer 16 Wall 18 Cover member 20 Air

volume adjustment member

21, 22, 22a, 22b, 23

Silencer

24, 24a to 24e Sound absorbing material 26

Insertion part

30, 30a,

30b Hollow part

32, 32a, 32b Opening 34 Intrusion prevention plate 36 Cover 38 Second opening 40 Decorative plate 42 Boundary cover 44 Non-pervious film 46 Membrane member 50 Interpolated silencer 52 Soundproof hood 54 Partition member 60 Sound transmission wall

Claims

A muffling system in which a muffling apparatus for muffling the sound passing through the aeration sleeve is provided on an aeration sleeve installed through a wall.
The muffling apparatus muffles the sound of the frequency including the frequency of the first resonance generated in the ventilation sleeve,
The silencer is
A cavity and an opening communicating the cavity with the outside, and one or more silencers disposed on one end face side of the wall;
A sound absorbing material disposed at a position covering at least a part of the hollow portion of the silencer or at least a part of the opening of the silencer;
The opening of the silencer is disposed facing the central axis side of the ventilation sleeve,
The depth L d of the cavity in the sound wave traveling direction in the silencer is greater than the width L o of the opening in the axial direction of the venting sleeve,
Assuming that the wavelength of the sound wave at the resonance frequency of the first resonance of the ventilation sleeve in the sound reduction system including the sound reduction device is λ, the depth L d of the cavity is 0.011 × λ <L d <0.25 Satisfy × λ,
The silencer does not resonate with the sound of the first resonance frequency generated in the ventilation sleeve, and does not mute the sound of the first resonance frequency by the resonance of the silencer alone, but by the sound absorbing material Silence system that is to mute.
A muffling system in which a muffling apparatus for muffling the sound passing through the aeration sleeve is provided on an aeration sleeve installed through a wall.
The muffling apparatus muffles the sound of the frequency including the frequency of the first resonance generated in the ventilation sleeve,
The silencer is
A cavity and an opening communicating the cavity with the outside, and one or more silencers disposed on one end face side of the wall;
A sound absorbing material disposed at a position covering at least a part of the hollow portion of the silencer or at least a part of the opening of the silencer;
The opening of the silencer is disposed facing the central axis side of the ventilation sleeve,
S 1 The area of the opening of the muffler, when the surface area of the inner wall of the cavity and S d, the ratio S 1 / S d of the area S 1 to the area S d, 0 <S 1 / S d <40 %The filling,
Assuming that the wavelength of the sound wave at the resonance frequency of the first resonance of the ventilation sleeve in the sound reduction system including the sound reduction apparatus is λ, the depth L d of the cavity in the sound wave traveling direction in the sound silencer is 0. Satisfy 011 × λ <L d <0.25 × λ,
The silencer does not resonate with the sound of the first resonance frequency generated in the ventilation sleeve, and does not mute the sound of the first resonance frequency by the resonance of the silencer alone, but by the sound absorbing material Silence system that is to mute.
The noise reduction system according to claim 1 or 2, wherein when the frequency of the first resonance generated in the ventilation sleeve is F 0 and the resonance frequency of the silencer is F 1 , 1.15 × F 0 <F 1 is satisfied.
In a cross section parallel to the axial direction of the ventilation sleeve, the width L w of the hollow portion in the direction orthogonal to the depth direction of the hollow portion satisfies 0.001 × λ <L w <0.061 × λ The noise reduction system according to any one of Items 1 to 3.
The flow resistance σ 1 of the sound absorbing material satisfies (1.25−log (0.1 × L d )) / 0.24 <log (σ 1 ) <5.6. The muffling system according to the paragraph.
The flow resistance σ 1 of the sound absorbing material satisfies (1.32−log (0.1 × L d )) / 0.24 <log (σ 1 ) <5.2. The muffling system according to the paragraph.
The flow resistance σ 1 of the sound absorbing material satisfies (1.39−log (0.1 × L d )) / 0.24 <log (σ 1 ) <4.7. The muffling system according to the paragraph.
Having a decorative board provided parallel to the wall,
The noise reduction system according to any one of claims 1 to 7, wherein the noise reduction device is disposed between the decorative plate and the wall.
In a cross section parallel to the axial direction of the ventilation sleeve, the silencer comprises the ventilation of the cavity extending in the axial direction of the ventilation sleeve and one surface of the cavity parallel to the axial direction of the ventilation sleeve. And an opening located at one axial end of the sleeve;
Said length of said cavity in the axial direction of the ventilation sleeve, silencing system as claimed in any one of claims 1 to 8, the depth L d of the cavity.
The noise reduction system according to any one of claims 1 to 9, wherein the noise reduction device has a plurality of the noise reduction devices.
The silencer system according to claim 10, wherein the openings of the plurality of silencers are disposed at at least two or more axial positions of the ventilation sleeve.
For each position of the opening, silencer system according to claim 11, the depth L d of the hollow portion is different of the muffler.
The noise reduction system according to claim 11 or 12, wherein sound absorbing materials having different acoustic characteristics are disposed in the hollow portion of the silencer at each position of the opening.
The muffling apparatus has a cylindrical insertion part connected in the ventilation sleeve,
The insertion portion is disposed with the central axis of the insertion portion aligned with the central axis of the ventilation sleeve,
The muffling system according to any one of claims 1 to 13, wherein the muffler is connected to one end face of the insertion portion.
Silencer system according to any one of the vent in the circumferential surface of the central axis and the axis of the sleeve, the opening area S 1 is the hollow portion of the area S small claim 1 than 0-14.
With two or more of the silencers,
The noise reduction system according to any one of claims 1 to 15, wherein the opening of each of the silencers is disposed in rotational symmetry with respect to a central axis of the ventilation sleeve.
The noise reduction system according to any one of claims 1 to 16, which is installed at the indoor end of the ventilation sleeve.
In a cross section perpendicular to the axial direction of the ventilation sleeve, and said vent effective outer diameter D 0 of the sleeve, the A muffler effective outer diameter D 1 of the, D 1 <D 0 + 2 × a (0.045 × λ + 5mm) A noise reduction system according to any one of the preceding claims, wherein:
19. A muffling system according to any of the preceding claims, wherein the muffling device is removable from the venting sleeve.
A system according to any of the preceding claims, wherein the silencer of the silencer is separable.
The noise reduction system according to any one of claims 1 to 20, wherein the noise reduction device is made of a material having higher heat resistance than the flame retardant material.
The noise reduction system according to any one of claims 1 to 21, wherein the opening of the silencer is formed in a slit shape along the circumferential direction of the inner peripheral surface of the ventilation sleeve.
It has a cover member or an air volume adjustment member installed on the opposite side to the ventilation sleeve of the silencer.
The noise reduction system according to any one of claims 1 to 22, wherein the cover member or the air volume adjustment member covers the noise reduction device when viewed in the axial direction of the ventilation sleeve.
A cover member installed at one end of the ventilation sleeve;
An air volume adjustment member installed at the other end of the ventilation sleeve;
Assuming that the wavelength of the sound wave at the resonance frequency of the first resonance of the ventilation sleeve in the silencer system including the silencer, the cover member, and the air volume adjusting member is λ, the depth L d of the cavity is more than λ / 4 A system according to any one of the preceding claims, wherein the system is short.
Having a decorative board provided parallel to the wall,
The noise reduction system according to any one of claims 1 to 24, wherein a total thickness of the wall and the decorative plate, including a space between the wall and the decorative plate, is 175 mm to 400 mm.
In the axial direction of the ventilating sleeve, the silencer is disposed by being inserted through a through hole formed in the decorative plate between the wall and the decorative plate disposed apart from the wall. Has been
The noise reduction system according to any one of claims 1 to 25, further comprising a boundary cover covering a boundary between the decorative plate and the silencer when viewed in the axial direction of the ventilation sleeve.
In the axial direction of the venting sleeve, the silencer is arranged at one end of the venting sleeve,
The noise reduction system according to any one of claims 1 to 26, further comprising a soundproofing member disposed within the ventilation sleeve.
In the axial direction of the venting sleeve, the silencer is arranged at one end of the venting sleeve,
A noise suppressor system according to any of the preceding claims, further comprising a soundproofing member arranged at the other end of the ventilating sleeve.
The width L w of the hollow portion of the silencer is
5.5 mm ≦ L w ≦ 300 mm
A noise reduction system according to any one of the preceding claims, wherein
The depth L d of the hollow portion of the silencer is
25.3 mm ≦ L d ≦ 175 mm
The noise reduction system according to any one of claims 1 to 29, wherein
The noise reduction system according to any one of claims 1 to 30, wherein a plurality of the sound absorbing materials are disposed in the hollow portion.