JP2019133122A - Sound damping system - Google Patents

Abstract

To provide a sound damping system with which it is possible to achieve both high air permeability and soundproof performance and silence a plurality of resonance sounds, and which does not require design tailored to a ventilation sleeve making it highly suitable for general purposes.SOLUTION: Provided is a sound damping system 10k having a silencing device 14 installed in a ventilation sleeve 12, the silencing device being designed to silence sounds of first resonance frequency of the ventilation sleeve and provided with a silencer 22 having a cavity 30 and an opening 32 and arranged on one end face side of a wall and a sound absorber arranged at a position covering the cavity or the opening. The opening of the silencer is arranged facing the center axis side of the ventilation sleeve, in which the ratio S/Sof an area Sto an area S, satisfies 0<S/S<40%, where Srepresents the area of the opening of the silencer and Srepresents the surface area of inner wall of the cavity, and the depth Lof the cavity satisfies 0.011×λ<L<0.25×λ, where λ represents the wavelength of sound wave at the resonance frequency of first resonance of the ventilation sleeve.SELECTED DRAWING: Figure 33

Description

  The present invention relates to a silencing system.

In order to prevent noise from the outside from being transmitted to the room, or to prevent noise from the room in a tubular member that penetrates the room and the room, such as ventilation openings and air-conditioning ducts. In order to suppress the transmission of noise 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 absorption rate of low frequency sound of 800 Hz or less is extremely low. Therefore, in order to increase the absorption rate, it is necessary to increase the volume. Since it is necessary to ensure the air permeability of the mouth, the air conditioning duct, etc., 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 sound insulation performance.

Here, resonance noise of the tubular member becomes a problem as noise in the tubular member such as the ventilation port and the air conditioning duct. In particular, the lowest frequency resonance is a problem. When the resonance noise is 800 Hz or less, the amount of the sound absorbing material is remarkably increased in order to prevent the sound absorbing material. For this reason, it is generally difficult to provide sufficient soundproofing performance even at the expense of ventilation. Taking a commercial product as an example, the soundproofing sleeve made of polyethylene (SK-BO75, manufactured by Shin-Kyowa Co., Ltd.), which is a sound-absorbing material-type soundproofing product that is inserted into the ventilation sleeve for residential use, has an aperture ratio of 36% and is greatly ventilated. Despite reducing the amount, more than 80% of the resonance sound is transmitted.
In order to mute the resonance sound of such a tubular member, a resonance type silencer that mutes a sound of a specific frequency is used.

  For example, Patent Document 1 discloses a resonance type silencer that silences a passage sound of a ventilation sleeve by providing a ventilation sleeve that allows ventilation between the two spaces in a partition that partitions the first space and the second space. The mechanism is a ventilation hole structure provided in the ventilation sleeve, and the resonance type silencing mechanism is located at a position outside the partition part in the cylinder axis direction of the ventilation sleeve, and along the partition part and the partition part. A ventilation hole structure formed in the outer peripheral portion of the ventilation sleeve is described at a position between the decorative board and the decorative plate provided in a state of being separated from the surface. Further, a side branch type silencer and a Helmholtz resonator are described as the resonance type silencer mechanism.

Patent Document 2 discloses a muffler tubular body that is installed and used in a sleeve tube of a natural ventilation port, and at least one end is closed and an opening is provided near the other end. A silencer tubular body is described in which the length from the center to the center of the opening is approximately half the total length of the sleeve tube, and a porous material is disposed inside.
In Patent Document 2, the thickness of the outer wall in a house, a condominium or the like 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 the outer wall. Is described (see FIG. 15).

Japanese Patent No. 4820163 (Japanese Patent Laid-Open No. 2007-169959) JP-A-2006-95070

However, according to the study by the present inventors, when the sound of the lowest resonance frequency of the tubular member is silenced using a resonance type silencer, at least a quarter 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 achieve both high air permeability and soundproof performance.
In addition, the resonance type silencer selectively silences sound of a specific frequency (frequency band). When the length and shape of the tubular member are different, the resonance frequency of the tubular member is also changed. For this reason, there is a problem that the design according to the tubular member is required, and the versatility is low.

In addition, resonance of the tubular member occurs at a plurality of frequencies, but a resonance type silencer silences sound of a specific frequency. For this reason, the resonance sound to be silenced is only one frequency, and the frequency band in which the resonance type silencer silences is narrow, so that there is a problem that resonance sounds of other frequencies cannot be silenced.
In addition, it is effective to arrange a resonance type silencer in an open space, but when arranged at the same resonance frequency inside a resonator such as a tubular member, the resonance of the tubular member and the resonance of the silencer interact. End up. As a result, the original resonance transmission sound by the tubular member is separated into two frequencies and a new resonance transmission sound is generated, so that there is a problem that the effect as a silencer is small.

  An 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 mute a plurality of resonance sounds, and to be designed according to a tubular member It is an object of the present invention to provide a highly versatile muffler system that is unnecessary.

As a result of intensive investigations to achieve the above object, the present inventors are a silencing system in which a silencing device for silencing the sound passing through the vent sleeve is installed in the vent sleeve installed through the wall, The silencer silences a sound having a frequency including the frequency of the first resonance generated in the ventilation sleeve. The silencer has an opening that communicates the cavity and the cavity with the outside. 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 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 side of the ventilation sleeve. When the area of the opening of the silencer is S ₁ and the surface area of the inner wall of the cavity is S _d , the area S relative to the area S _{d 1} ratio S ₁ / S _{d is, 0 <S 1 / S d} <40% Filled, and the wavelength of the sound wave at the resonant frequency of the first resonance ventilation sleeve in silencer system including a muffler and lambda, the depth L _d of the _{cavity, 0.011 × λ <L d <} 0.25 × λ By satisfying the above, it was found that the above problems can be solved, and the present invention has been completed.
That is, it has been found that the above object can be achieved by the following configuration.

[1] A silencer system in which a silencer that silences a sound passing through a ventilation sleeve is installed in a ventilation sleeve installed through a wall,
The silencer silences the sound of the frequency including the frequency of the first resonance generated in the ventilation sleeve,
The silencer is
One or more silencers having a cavity and an opening that communicates the cavity with the outside, and disposed on one end face side of the wall;
A sound absorbing material disposed in 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 side 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,
When the wavelength of the sound wave at the resonance frequency of the first resonance of the ventilation sleeve in the muffler system including the muffler is λ, the depth L _d of the cavity in the sound wave traveling direction in the muffler is 0.011 × λ <L. satisfies _d <0.25 × λ,
The muffler 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 muffler alone, but muffles with the sound absorbing material. Is a silencer system.
[2] The muffler system according to [1], wherein 1.15 × F ₀ <F ₁ is satisfied, where F ₀ is a frequency of the first resonance generated in the ventilation sleeve and F ₁ is a resonance frequency of the silencer.
[3] In the cross section parallel to the axial direction of the ventilation sleeve, the width L _w of the cavity in the direction orthogonal to the depth direction of the cavity satisfies 0.001 × λ <L _w <0.061 × λ. The muffler system according to [1] or [2].
[4] 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 [3]. The mute system according to any one of the above.
[5] 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 [4]. The mute system according to any one of the above.
[6] 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 [5]. The mute system according to any one of the above.
[7] Having a decorative board provided parallel to the wall,
The muffler device according to any one of [1] to [6], wherein the muffler is disposed between the decorative board and the wall.
[8] In the cross section parallel to the axial direction of the ventilation sleeve, the silencer includes a cavity extending in the axial direction of the ventilation sleeve and an axial direction of the ventilation sleeve of one surface of the cavity parallel to the axial direction of the ventilation sleeve. An opening located on one end side of the
Silencer system according to any one of the length of the cavity portion in the axial direction of the ventilation sleeve, the depth L _d of the cavity [1] to [7].
[9] The silencer system according to any one of [1] to [8], wherein the silencer includes a plurality of silencers.
[10] The silencer system according to [9], wherein the openings of the plurality of silencers are arranged at at least two positions in the axial direction of the insertion portion.
Silencer system according to [11] for each position of the opening, is different from the depth L _d of the hollow portion of the muffler [10].
[12] The silencing system according to [10] or [11], in which a sound absorbing material having different acoustic characteristics is disposed in the cavity of the silencer for each position of the opening.
[13] The silencer has a cylindrical insertion portion connected to the ventilation sleeve,
The insertion part is arranged so that the central axis of the insertion part coincides with the central axis of the ventilation sleeve,
The silencer system according to any one of [1] to [12], wherein the silencer is connected to one end face of the insertion portion.
[14] The silencing system according to any one of [1] to [13], wherein an area S ₁ of the opening is smaller than an area S _{0 of the} cavity on the circumferential surface about the central axis of the ventilation sleeve.
[15] having two or more silencers,
The silencer system according to any one of [1] to [14], wherein the opening of each silencer is disposed rotationally symmetrically with respect to the central axis of the insertion portion.
[16] The silencing system according to any one of [1] to [15], which is installed at an indoor end of the ventilation sleeve.
[17] 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 silencing system according to any one of [1] to [16], which is satisfied.
[18] The silencing system according to any one of [1] to [17], wherein the silencing device can be attached to and detached from the ventilation sleeve.
[19] The silencer system according to any one of [1] to [18], wherein the silencer of the silencer is separable.
[20] The silencer system according to any one of [1] to [19], wherein the silencer is made of a material having higher heat resistance than the flame retardant material.
[21] The silencer system according to any one of [1] to [20], wherein the opening of the silencer is formed in a slit shape along the circumferential direction of the inner circumferential surface of the ventilation sleeve.
[22] A cover member installed on the side opposite to the ventilation sleeve of the silencer, or an air volume adjusting member,
The silencer system according to any one of [1] to [21], wherein the cover member or the air volume adjusting member covers the silencer when viewed from the axial direction of the ventilation sleeve.
[23] a cover member installed at one end of the ventilation sleeve;
An air volume adjusting member installed at the other end of the ventilation sleeve,
When the wavelength of the sound wave at the resonance frequency of the first resonance of the ventilation sleeve in the silencing 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] to [22] The silencing system according to any one of [22].
[24] having a decorative board provided parallel to the wall;
The silencing system according to any one of [1] to [23], in which 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.
[25] In the axial direction of the ventilation sleeve, the silencer is disposed between a wall and a decorative plate disposed away from the wall and partially inserted through a through hole formed in the decorative plate. And
The silencing system according to any one of [1] to [24], which includes a boundary cover that covers a boundary between the decorative plate and the silencer when viewed from the axial direction of the ventilation sleeve.
[26] In the axial direction of the ventilation sleeve, the silencer is disposed at one end of the ventilation sleeve,
Furthermore, the noise reduction system in any one of [1]-[25] which has a soundproof member arrange | positioned in a ventilation sleeve.
[27] In the axial direction of the ventilation sleeve, the silencer is disposed at one end of the ventilation sleeve,
Furthermore, the noise reduction system in any one of [1]-[26] which has a soundproof member arrange | positioned at the other edge part of a ventilation sleeve.
[28] The width L _w of the cavity of the silencer is
5.5 mm ≦ L _w ≦ 300 mm
The silencing system according to any one of [1] to [27], which satisfies
[29] The depth L _d of the cavity of the silencer is
25.3 mm ≦ L _d ≦ 175 mm
The silencing system according to any one of [1] to [28], wherein
[30] The muffler system according to any one of [1] to [29], wherein a plurality of sound absorbing materials are disposed in the cavity.
[31] A silencing system in which a silencing device for silencing a sound passing through a ventilation sleeve is installed in a ventilation sleeve installed through a wall,
The silencer is
One or more silencers having a cavity and an opening communicating with the cavity and the outside, and disposed on one end surface of the wall;
A sound absorbing material disposed in 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 side of the ventilation sleeve,
The depth L _d of the cavity in the traveling direction of the sound wave in the silencer is larger than the width L _o of the opening in the axial direction of the ventilation sleeve,
When the wavelength of the sound wave at the resonance frequency of the first resonance of the ventilation sleeve in the silencing system including the silencing device is λ, the depth L _d of the cavity satisfies 0.011 × λ <L _d <0.25 × λ. Silencer system.

  According to the present invention, it is possible to achieve both high breathability and soundproofing performance, to mute a plurality of resonance sounds, and to eliminate the need for a design tailored to the ventilation sleeve and to provide a highly versatile silencing system. Can be provided.

It is sectional drawing which shows notionally an 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 area of the opening part of a silencer, and the area of a cavity part. It is a figure for demonstrating the depth and width | variety of the cavity 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 and width of a cavity part, and an average sound pressure. It is a graph showing the relationship between the depth and width of a cavity part, and an average particle velocity. It is a graph showing the relationship between the depth of a hollow part, width | variety, and vxP. It is a graph showing the relationship between the depth of a hollow part, width | variety, and vxP. It is a figure for demonstrating the method of simulation. It is a graph showing the relationship between a frequency and a transmitted sound pressure. It is a graph showing the relationship between the ratio of an 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. It is CC sectional view taken on the line 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 transmitted sound pressure and frequency. It is sectional drawing which represents typically the model of the silencing system of the Example used for simulation. It is a graph showing the relationship between transmitted sound pressure and frequency. It is sectional drawing which represents typically the model of the silencing system of the comparative example used for simulation. It is a graph showing the relationship between transmitted sound pressure and frequency. It is a graph showing the relationship between transmitted sound pressure, frequency, and depth. It is a graph showing the relationship between transmitted sound pressure, frequency, and depth. It is a graph showing the relationship between transmitted sound pressure, frequency, and depth. It is a graph showing the relationship between transmission loss and distance. It is sectional drawing which represents typically the other model of the silencing system of the Example used for simulation. It is sectional drawing which represents typically the other model of the silencing system of the Example used for simulation. It is a graph showing the relationship between transmitted sound pressure, frequency, and position. It is a graph showing the relationship between transmitted sound pressure and frequency. It is a graph showing the relationship 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 relationship between depth, flow resistance, and the peak value of transmitted sound pressure. It is a graph showing the relationship between a frequency and a 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 transmitted sound pressure and frequency. It is a graph showing the relationship between transmitted sound pressure and frequency. It is a graph showing the relationship between transmitted sound pressure and frequency. It is a graph showing the relationship between transmitted sound pressure and frequency. It is a graph showing the relationship between transmitted sound pressure and frequency. It is a graph showing the relationship between transmitted sound pressure and frequency. It is a graph showing the relationship between a 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. It is the front view which looked at FIG. 72 from the air volume 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 transmitted sound pressure and frequency. It is a graph showing the relationship between transmitted sound pressure and frequency. It is a graph showing the relationship between transmitted sound pressure and frequency. It is a graph showing the relationship between transmission loss and an octave band. It is a graph showing the relationship between transmitted sound pressure and frequency. It is a graph showing the relationship between transmitted sound pressure and frequency. It is a graph showing the relationship between transmission loss and an octave band. It is a graph showing the relationship between transmitted sound pressure and frequency. It is a graph showing the relationship between transmission loss and an 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 relationship 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. It is the DD sectional view taken on the line of FIG. It is sectional drawing which shows notionally another example of the silencing system of this invention. It is the EE sectional view taken on the line of FIG. 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 silencing system used for simulation. It is a graph showing the relationship between flow resistance, opening width / cylinder length, and transmission 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 relationship between a frequency and a transmitted sound pressure intensity | strength. It is a conceptual diagram for demonstrating the evaluation method of the calculation model of a comparative example. It is the DD sectional view taken on the line of FIG. It is a graph showing the relationship between a frequency and a transmitted sound pressure intensity | strength. It is a typical side view for demonstrating the structure of a comparative example. It is a graph showing the relationship between a frequency and a transmitted sound pressure intensity | strength.

Hereinafter, the present invention will be described in detail.
The description of the constituent elements described below is made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
In this specification, “orthogonal” and “parallel” include a range of errors allowed in the technical field to which the present invention belongs. For example, “orthogonal” and “parallel” mean that the angle is within ± 10 ° with respect to strict orthogonality or parallelism, and an error with respect to strict orthogonality or parallelism is 5 ° or less. Preferably, it is 3 ° or less.
In the present specification, “same” and “same” include an error range generally allowed in the technical field. In addition, in the present specification, when “all”, “any” or “entire surface” is used, it includes an error range generally allowed in the technical field in addition to the case of 100%, for example, 99% or more, The case of 95% or more, or 90% or more is included.

[Silence system]
The configuration of the silencer system of the present invention will be described with reference to the drawings.
In the silencing system of the present invention, a silencer that does not resonate with the sound of the first resonance frequency of the ventilation sleeve is disposed in the vicinity of the ventilation sleeve to mute the sound of the first resonance frequency generated in the ventilation sleeve. Is.
FIG. 1 is a schematic cross-sectional view showing an example of a preferred embodiment of the silencing system of the present invention.

As shown in FIG. 1, the silencer system 10 z is configured such that a silencer 21 is disposed on the outer peripheral surface (outer peripheral surface) of a cylindrical tubular member 12 provided through a wall 16 that separates two spaces. Have
The tubular member 12 is, for example, a ventilation sleeve such as a ventilation opening and an air conditioning duct.
The silencer 21 silences a sound having a 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 hollow portion 30 having a substantially rectangular parallelepiped shape therein. An opening 32 that communicates the cavity 30 with the outside is formed on the end surface of the cavity 30 on the tubular member 12 side.
The opening 32 of the silencer 21 is connected to the circumferential surface opening 12 a formed on the circumferential surface of the tubular member 12. When the opening 32 is connected to the circumferential surface opening 12a, the opening 32 is connected to the sound field space of the first resonance generated in the tubular member 12 in the silencing system 10a.

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

Further, as shown in FIG. 1, the depth of the cavity 30 in the traveling direction 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 simply referred to as the axial direction). When the width of the opening 32 of the silencer 21 is L _o , the depth Ld 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 cavity 30 can be obtained by simulation. In the example shown in FIG. 1, since the cavity 30 extends in the radial direction, the traveling direction of the sound wave in the cavity 30 is the radial direction (vertical direction in the figure). Therefore, the depth L _d of the cavity 30 is the length from the opening 32 to the upper end of the cavity 30 in the radial direction. In the case where the depth of the cavity 30 by the position are different, the depth L _d of the cavity 30 is the average value of the depth at each position.
When the width of the opening 32 differs depending on the position, the width _Lo of the opening 32 is an average value of the width at each position.

Further, when the wavelength of the sound wave at the resonance frequency of the first resonance generated in the tubular member 12 in the silencing system is λ, the depth L _d of the cavity 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, when the sound of the lowest resonance frequency of the tubular member is silenced using the resonance type silencer, at least a quarter of the wavelength λ of the resonance frequency is required, and the size of the silencer is large. It will become. Therefore, there is a problem that it is difficult to achieve both high air permeability and soundproof performance.
In addition, the resonance type silencer selectively silences sound of a specific frequency (frequency band). For this reason, there is a problem that the design according to the resonance frequency of the tubular member is required, and the versatility is low.
In addition, resonance of the tubular member occurs at a plurality of frequencies, but a resonance type silencer silences sound of a specific frequency. For this reason, the resonance sound to be silenced has only one frequency, and the frequency band in which the resonance type silencer silences is narrow, so that there is a problem that resonance sounds of other frequencies cannot be silenced.
In addition, it is effective to arrange a resonance type silencer in an open space, but when arranged at the same resonance frequency inside a resonator such as a tubular member, the resonance of the tubular member and the resonance of the silencer interact. End up. As a result, the original resonance transmission sound by the tubular member is separated into two frequencies and a new resonance transmission sound is generated, so that there is a problem that the effect as a 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 traveling direction of the sound wave in the silencer is the width of the opening in the axial direction of the tubular member. If the wavelength of the sound wave at the resonance frequency of the first resonance of the tubular member 12 is greater than L _o and λ, the depth L _d of the cavity portion satisfies 0.011 × λ <L _d <0.25 × λ. The silencer 21 is configured 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 thermal energy by the viscosity of the fluid in the vicinity of the wall surface of the silencer 21 and the unevenness (surface roughness) of the wall surface, or the 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 are the conversion mechanism in the present invention.

Here, when the width L _o of the opening 32 of the silencer 21 is smaller than the depth L _d of the cavity 30, the 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 increases. The conversion efficiency from sound energy to heat energy by the conversion mechanism depends on the sound pressure and the moving speed of gas molecules. Therefore, the efficiency of conversion from sound energy to heat energy by the conversion mechanism is increased by increasing the moving speed of the gas molecules while maintaining the sound pressure.
Since the silencer principle does not use the resonance of the silencer, even if the depth L _d of the cavity 30 is smaller than ¼ of the wavelength λ at the resonance frequency of the first resonance of the tubular member 12, high soundproof performance can be obtained. Can be expressed. Therefore, it is possible to obtain a high soundproofing performance while reducing the size of the silencer 21 and maintaining the air permeability of the tubular member 12.

In addition, since the silencer resonance of the silencer by the silencer 21 is not used, even when the length and shape of the tubular member 12 are different, the soundproofing performance can be exhibited, and the tubular member can be expressed. The design according to 12 is unnecessary, and versatility is high.
Further, since the silencer principle by the silencer 21 does not use the resonance of the silencer, the sound of only a specific frequency as determined by the structure of the silencer is not silenced, and a plurality of resonance sounds in a wide frequency band are silenced. Can do.
In addition, since the silencer principle by the silencer 21 does not use the resonance of the silencer, there is no interaction with the resonance of the tubular member, and the original resonance transmitted sound by the tubular member is not separated into two frequencies. A sufficient silencing effect can be obtained.

Here, the case where the resonance type silencer is arranged in the tubular member 12 will be described using simulation.
For the simulation, an acoustic module of finite element method calculation software COMSOL ver5.3 (COMSOL) was used.
As shown in FIG. 110, in the simulation, the diameter of the ventilation sleeve (tubular member) was 100 mm, the wall thickness was 100 mm, the decorative board thickness was 10 mm, and the distance between the wall and the decorative board was 140 mm. That is, the total thickness of the wall and the decorative board was 250 mm.

Using such a simulation model, as shown in FIG. 110, a sound wave is incident from a hemispherical surface of one space partitioned by a wall and reaches a hemispherical surface of the other space. The per-turn amplitude was obtained. The hemispherical surface is a hemispherical surface having a radius of 500 mm centered on the center position of the opening surface of the ventilation sleeve. The incident sound wave has an amplitude of 1 per unit volume.
In addition, a resistor (diameter: 102 mm) lid was arranged at a position 32 mm from the end face of the ventilation sleeve on the sound wave detection surface side.

First, as a reference, calculation was performed for a case where a silencer was not disposed (hereinafter also referred to as a straight tube).
FIG. 111 shows simulation results 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 disposed (in the case of a straight tube) is about 515 Hz.

Next, an air column resonance type silencer having a resonance frequency of about 515 Hz was designed.
As shown in FIGS. 112 and 113, a model in which an air column resonance silencer is connected to the outer periphery 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 incident sound wave has an amplitude of 1 per unit volume. The value obtained by dividing the integrated value of the sound pressure amplitude on the detection surface by the square of the integrated value of the sound pressure amplitude on the incident surface was taken as the transmitted sound pressure intensity.

One surface in the longitudinal direction of the air column resonance silencer is opened and connected to the acoustic tube. In addition, the position of the air column resonance silencer in the axial direction of the acoustic tube was set to a substantially central position.
The air column resonance type silencer has a rectangular parallelepiped shape with a cross-sectional size of 45 mm × 45 mm, the length is variously changed, and the relationship between the frequency and the transmitted sound pressure intensity is calculated to obtain 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 with a length of 150 mm.

Next, as shown in FIG. 115, the silencer having this air column resonance silencer is modeled to create a model connected to the ventilation sleeve, and in the same manner as described above, one of the spaces partitioned by the wall is created. A sound wave was incident from a hemispherical surface, and the amplitude per unit volume of the sound wave reaching the hemispherical surface of the other space was determined. 115 is the same as FIG. 113 in cross section at the position of the air column resonance silencer.
As shown in FIG. 113 and FIG. 115, the model of the air column resonance resonance type silencer has two air column resonance tubes having a prismatic shape of 45 mm × 45 mm and a length (depth) of 150 mm on the side surface. A tubular silencer having the same diameter (100 mm) as the ventilation sleeve is 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 position of the air column resonance tube in the axial direction was 5 mm from the end surface on the ventilation sleeve side.
FIG. 111 shows simulation results as a graph of the relationship between frequency and transmitted sound pressure intensity (Comparative Example 8). FIG. 116 shows experimental results as a graph of the relationship between frequency and transmitted sound pressure intensity.
In the experiment, the silencer having the shape and dimensions described above was produced using an acrylic plate having a thickness of 5 mm, and the relationship between the frequency and the transmitted sound pressure intensity was measured in the same manner as in the example using a simple small soundproof room described later. did.

As shown as Comparative Example 8 in FIGS. 111 and 116, when the resonance type silencer is arranged in the ventilation sleeve, on both sides of the first resonance frequency of the ventilation sleeve when the resonance type silencer is not arranged, It can be seen that a peak of transmitted sound pressure intensity occurs. That is, peaks occur at two frequencies, a frequency lower than the first resonance frequency and a higher frequency when no resonance type silencer is arranged. This is due to a phenomenon in which a strong interaction acts to separate into two modes, a coupled mode and an anti-coupled mode, by arranging a resonant silencer in the sound field space of the ventilation sleeve that generates resonance. is there.
As a result, although the sound of the first resonance frequency of the ventilation sleeve can be silenced, two new peaks exist.
As described above, when a resonance-type silencer is used as a silencer for the ventilation sleeve, another new transmitted sound pressure intensity peak is generated, so that it cannot be sufficiently silenced.

  In the example shown in FIG. 1, the silencer 21 and the internal cavity 30 are substantially rectangular parallelepiped shapes, but the present invention is not limited thereto, and can be various shapes such as a cylindrical shape. Further, the shape of the opening 32 is not limited, and may 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. A first resonance frequency F ₀ caused within tubular member 12, the relationship between the resonant frequencies F ₁ of the muffler 21 in the above range, the resulting tubular member 12 at the resonant frequencies F ₁ of the muffler 21 Since the transmitted sound pressure intensity of one resonance is 25% or less with respect to the peak value, the interaction between the first resonance generated in the tubular member 12 and the silencer resonance is reduced.
From the viewpoint that the transmitted sound pressure intensity of the first resonance generated in the tubular member 12 at the resonance frequency F ₁ of the silencer 21 can be further reduced to reduce the interaction, the frequency F _{0 of} the first resonance generated in the tubular member 12 can be reduced. The resonance frequency F ₁ of the silencer 21 preferably satisfies 1.17 × F ₀ <F ₁ , more preferably satisfies 1.22 × F ₀ <F ₁ , and 1.34 × F ₀ < More preferably, F ₁ is satisfied. By satisfying the above conditions, the transmitted sound pressure intensity of the first resonance generated in the tubular member 12 at the resonance frequency F ₁ of the silencer 21 is 20% or less, 15% or less, and 10% or less with respect to the peak value.

In the example shown in FIG. 1, the cavity 30 of the silencer 21 is assumed to extend in the radial direction, and the traveling direction of the sound wave in the cavity 30 is assumed to be the radial direction. However, the present invention is not limited to this. For example, as illustrated in FIG. 2, the cavity 30 may extend in the axial direction, and the traveling direction of the sound wave in the cavity 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 cross-sectional view showing an example of a preferred embodiment of the silencing system of the present invention. FIG. 3 is a diagram for explaining the area S ₀ of the cavity and the area S _{1 of the} opening of the silencer of the silencing system. FIG. 4 is a diagram for explaining the depth L _d and the width L _w of the cavity of the silencer. 3 and 4, the illustration of the wall 16 is omitted. 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 a silencer 22 is disposed on the outer peripheral surface (outer peripheral surface) of the cylindrical tubular member 12 provided through the wall 16 that separates the two spaces. Have
The tubular member 12 is, for example, a ventilation sleeve such as a ventilation opening and an air conditioning duct.
The silencer 22 has a substantially rectangular parallelepiped shape extending in the axial direction and curved along the outer peripheral surface of the tubular member 12 in a cross section parallel to the axial direction, and having a substantially rectangular parallelepiped shape extending in the axial direction inside. 30. In addition, an opening 32 that communicates the cavity 30 with the outside is provided on one axial end side of the surface of the silencer 22 on the tubular member 12 side. That is, the silencer 22 has an L-shaped space. The opening 32 is connected to a peripheral surface opening 12 a formed on the peripheral surface of the tubular member 12. When the opening 32 is connected to the circumferential surface opening 12a, the opening 32 is connected to the sound field space of the first resonance generated in the tubular member 12 in the silencing system 10a.

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

  Similar to the silencer 21 shown in FIG. 1, the silencer 22 is disposed in the silencer 22, which will be described later, or the viscosity of the fluid near the wall surface of the silencer 22 and the unevenness (surface roughness) of the wall surface. Sound absorption is performed by converting sound energy into heat energy by the sound absorbing material 24 or the like (conversion mechanism).

Thus, even when the silencer 22 has a shape having an L-shaped space, the sound pressure when the sound wave in the tubular member 12 flows into the silencer 22 is the same as in the configuration of FIG. Since the moving speed of gas molecules can be increased while maintaining sound pressure, the moving speed of gas molecules can be increased while maintaining sound pressure. Get higher. Therefore, even if the depth L _d of the cavity 30 is smaller than ¼ of the wavelength λ at the resonance frequency of the first resonance of the tubular member 12, high soundproof performance can be expressed. Therefore, it is possible to obtain a high soundproof performance while reducing the size of 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.

  Moreover, by making the silencer 22 into 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, while maintaining high soundproof performance, 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 silencing system 10a will be described with reference to FIG.
FIG. 5 shows the distribution of sound pressure in the first resonance mode of the tubular member 12 provided through the wall 16 separating the two spaces, by simulation. 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 is well known, the antinode of the standing wave of the sound field protrudes outside the tubular member 12 by the distance of the opening end correction. Note that the opening end correction distance in the case of the cylindrical tubular member 12 is approximately 1.2 × tube diameter.

The silencer 22 only needs to be arranged at a position where the opening 32 is connected to the sound field space of the tubular member 12 in the first resonance. Therefore, the opening part 32 of the silencer 22 may be arrange | positioned on the outer side of the opening end surface of the tubular member 12 like the silencing system 10b shown in FIG. Or the silencer 22 may be arrange | positioned inside the tubular member 12 like the silence system 10c shown in FIG.
In the silencer system 10 b shown in FIG. 6 and the silencer system 10 c shown in FIG. 7, the silencer 22 is arranged so that the opening 32 faces the central axis side of the tubular member 12. The central axis of the tubular member 12 is an axis that passes through the center of gravity in the cross section of the tubular member 12.

Here, there is no limitation on the position of the opening 32 of the silencer 22 in the axial direction. Depending on the position of the opening 32, it is possible to control the frequency band to be silenced more suitably.
For example, when the sound wave of the first resonance frequency of the tubular member 12 is 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, that is, in the center of the tubular member in the axial direction. By arranging, the sound pressure and the moving speed of gas molecules can be increased, and higher soundproof performance can be expressed.
This point will be described in more detail in the embodiments.

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 cavity 30, when sound waves in the tubular member 12 flow into the silencer 22, gas (air) is maintained while maintaining the sound pressure. Since the moving speed of the molecules 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 is different depending on the radial position of the tubular member 12, the area S ₀ of the cavity 30 is an average value of the area at each position.
The area S ₁ of the opening 32 is an area where 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 viewpoint, 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, and 0.3% <S ₁ / S ₀ <35%. Is more preferable, and 0.5% <S ₁ / S ₀ <30% is more preferable.

Further, from the viewpoint of soundproof performance and air permeability, the depth L _d of the cavity 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 cavity 30 in the direction orthogonal to the depth direction of the cavity 30 is 0.001 × λ <L _w <0.061 × λ. Preferably, 0.001 × λ <L _w <0.051 × λ is satisfied, and more preferably 0.001 × λ <L _w <0.041 × λ. In FIG. 1, the width of the cavity 30 is the length of the horizontal direction in the drawing coincides with the width L _w of the opening 32.

  This point will be described with reference to FIGS. 8 to 10 and FIG. 8 to 10 show simulation results when the vertical cylindrical silencer as shown in FIG. 1 is used, and FIG. 11 shows the case where the L-shaped silencer as shown in FIG. 2 is used. It is the result of simulation.

FIG. 8 shows (depth L _d of the cavity 30 / wavelength λ of the sound wave to be silenced), (width L _w of the cavity 30 / wavelength λ of the sound wave to be silenced), and average sound in the cavity 30. 3 is a graph showing the relationship with pressure P. 9 shows (depth L _d of cavity 30 / wavelength λ of sound wave to be muffled), (width L _w of cavity 30 / wavelength λ of sound wave to be muffled), and gas molecules in the cavity 30. It is a graph showing the relationship with the average particle velocity v. FIG. 10 shows (depth L _d of cavity 30 / wavelength λ of sound wave to be muffled), (width L _w of cavity 30 / wavelength λ of sound wave to be muffled), and average particle velocity v of gas molecules. 4 is a graph showing the relationship between the log value of the multiplication value (| v | × | P |) of the average sound pressure P. (| V | × | P |) is a value proportional to the absorption per volume of the cavity 30.
In addition, log in FIGS. 9-11 is a common logarithm.

The particle velocity v and the sound pressure P can be varied by changing the depth L _d of the cavity 30 and the width L _{w of the} cavity 30 using an acoustic module of the finite element method calculation software COMSOL ver5.3 (COMSOL). Asked. In the simulation, the length of the tubular member was 300 mm and the diameter was 100 mm, and the cavity 30 of the silencer 22 was annularly installed on the outer periphery of the tubular member 12. The opening 32 was arranged in a slit shape 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 was disposed at the center of the tubular member 12 in the axial direction. The lowest resonance frequency of the tubular member 12 was 460 Hz. The frequency of the sound wave to be muffled was 460 Hz. In addition, the sound absorbing material 24 having a flow resistance of 13000 [Pa · s / m ² ] is disposed in the entire cavity 30.

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

As shown in FIGS. 8 to 10, it can be seen that there is a suitable range for the depth L _d of the cavity 30 and the width L _w of the cavity 30. 8, sound pressure, as the width L _w and depth L _d of the cavity 30 is small, it can be seen that high. 9, the particle velocity, the more the width L _w of the cavity 30 small, in range of the depth L _d, it can be seen that high. From FIG. 10, it can be seen that the value of (| v | × | P |) proportional to the absorption increases in a range where 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) and (width of cavity 30) when an L-shaped silencer as shown in FIG. 2 is used. It is a graph showing the relationship between L _w / wavelength λ of sound wave to be muffled and log value of product value (| v | × | P |) of average particle velocity v of gas molecules and average sound pressure P.
In the simulation, the length of the tubular member was 300 mm, the diameter was 100 mm, the cavity 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 opening 32 was arranged in a slit shape in the circumferential direction of the tubular member. The width of the opening 32 was 10 mm. The opening 32 was disposed at the center of the tubular member 12 in the axial direction. Further, the sound absorbing material 24 having a flow resistance of 13000 [Pa · s / m ² ] is disposed in the cavity 30.

From FIG. 11, also in the case of the L-shaped silencer, the value of (| v | × | P |) proportional to the absorption increases in a 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 a vertical cylinder type silencer.

In the silencing 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 cavity 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 conversion mechanism such as the sound absorbing material 24 is reduced, and the sound wave flowing into the conversion mechanism such as the sound absorbing material 24 is maintained while maintaining the high sound pressure P. The moving speed of gas molecules can be increased to improve the soundproofing performance.
From the viewpoint of increasing the moving speed of the gas molecules, the area S ₁ (ratio S ₁ / S _d ) of the opening 32 is preferably as small as possible. However, if the area S ₁ of the opening 32 is too small, the sound wave flows into the cavity 30. The soundproofing performance is lowered because it is difficult to perform. From the above viewpoint, the area S ₁ of the opening 32 relative 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 cavity 30 is measured with a resolution of 1 mm. That is, when it has a fine structure such as unevenness of less than 1 mm, the surface area S _d may be obtained by averaging this.

In this regard, as in the case of FIG. 11, a simulation was performed using an L-shaped silencer as shown in FIG.
In the simulation, the length of the tubular member was 300 mm, the diameter was 100 mm, the cavity 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 opening 32 was arranged in a slit shape in the circumferential direction of the tubular member. The depth L _d of the cavity 30 was 80 mm, and the width L _w was 10 mm. The opening 32 was disposed at the center of the tubular member 12 in the axial direction. Further, the sound absorbing material 24 having a flow resistance of 13000 [Pa · s / m ² ] is disposed in the cavity 30.
By changing the width L _{o 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. 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, and 54.7%. Corresponds to 7 cm. The transmitted sound pressure was normalized with the peak of the transmitted sound pressure (transmitted 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 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 frequency and transmitted sound pressure, and FIG. 14 is a graph showing the relationship between the ratio of the opening area and the peak of transmitted sound pressure.
As can be seen from FIG. 13 and FIG. 14, it can be seen that the transmitted sound pressure at the resonance frequency decreases as the area ratio S ₁ / S _{d of} the opening decreases, even though the volume of the sound absorbing material is the same. Note that the resonance frequency when the silencer is installed is shifted to the low frequency side compared to the case without the silencer because the volume in which sound waves can exist is increased.

In addition, as described above, the conversion mechanism that converts sound energy into heat energy is arranged in the silencer wall, the fluid viscosity in the vicinity of the silencer wall surface, and the silencer wall surface unevenness (surface roughness). It is preferable to use a sound absorbing material.
The sound absorbing material 24 may be configured to be disposed in at least a part of the cavity 30 of the silencer 22 as in the silencer system 10d shown in FIG. Or it is good also as a structure arrange | positioned so that the sound absorption material 24 may cover at least one part of the opening part 32 of the silencer 22 like the silence system 10e shown in FIG.

The sound absorbing material 24 has a flow resistance σ ₁ [Pa · s / m ² ] per unit thickness of (1.25−log (0.1 × L _d )) / 0.24 <log (σ ₁ ) <5. .6, preferably (1.32-log (0.1 × L _d )) / 0.24 <log (σ ₁ ) <5.2], and more preferably (1.39− More preferably, log (0.1 × L _d )) / 0.24 <log (σ ₁ ) <4.7 is satisfied. In the above formula, the unit of L _d is [mm], and log is a common logarithm. The flow resistance of the sound absorbing material is determined by measuring the normal incident sound absorption coefficient of the sound absorbing material having a thickness of 1 cm and fitting with the Miki model (J. Acoust. Soc. Jpn., 11 (1) pp. 19-24 (1990)). It was evaluated with. Alternatively, evaluation may be performed according to “ISO 9053”.

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

The result of having performed simulation about the relationship between the ratio K _rate between the tube length and 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 muffler system model used in 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 position 100 mm away 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 the depth direction. The length (cylinder length) of the cavity 30 of the silencer 22 was 42 mm. The width was 37 mm. The opening 32 was arranged in a slit shape 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. A sound absorbing material 24 is disposed in the entire area of the cavity 30 of the silencer 22.
In addition, the tubular member 12 is configured such that a louver (cover member) is disposed at the opening on the sound wave incident side and a register (air volume adjusting member) is disposed at the opening on the sound wave emitting side.
The gallery and the register 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 simulation was performed for sound waves transmitted through the tubular member. Through simulation, the transmission loss was calculated from the sound pressure of a sound wave that passed through the tubular member and propagated from one space (left side in FIG. 107) to the other space (right side in FIG. 107).
The results are shown in FIG. FIG. 108 is a graph showing the relationship among flow resistance, opening width / cylinder length, and normalized transmission loss. Note that the normalized transmission loss is a value normalized with the value at which the transmission loss is maximized being 1.

It can be seen from FIG. 108 that the flow resistance has an optimum range according to the opening width / cylinder length. In FIG. 108, the area inside the dotted line is an area where the normalized transmission loss is about 0.8 or more. When this region is expressed by an equation, when 0 <K _rate ≦ 50%, (K _rate +165) /62.5 <logσ ₁ <(K _rate +319.6) /76.9, 50% <K _{At rate} , 3.45 <logσ 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 materials such as urethane foam, flexible urethane foam, wood, ceramic particle sintered material, phenol foam, and materials containing minute air; glass wool, rock wool, microfiber (such as 3M synthalate), floor mat, carpet , Melt blown nonwoven fabric, metal nonwoven fabric, polyester nonwoven fabric, metal wool, felt, insulation board and glass nonwoven fabric and other nonwoven materials; wood wool cement board; nanofiber materials such as silica nanofiber; gypsum board; 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.

  Moreover, when it is set as the structure which arrange | positions a sound absorption material in the cavity part of a silencer, it is preferable that the shape of a sound absorption material shall be shape | molded according to the shape of the cavity part. By making the shape of the sound-absorbing material to match the shape of the cavity, it becomes easy to uniformly fill the cavity with the sound-absorbing material, which can reduce costs and simplify maintenance. Become.

  In the example illustrated in FIG. 2, the configuration includes one silencer 22. However, the configuration is not limited thereto, and the configuration may include two or more silencers 22. For example, as in the silencing system 10 f shown in FIG. 17, two silencers 22 are arranged on the outer circumferential surface of the tubular member 12 and connected to the circumferential surface opening 12 a formed on the circumferential surface of the tubular member 12. It is good. Or it is good also as a structure which arrange | positions the two silencers 22 inside the tubular member 12 like the silencer system 10g shown in FIG.

When two or more silencers 22 are provided, the two or more silencers 22 are preferably arranged rotationally symmetrically 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 on the outer peripheral surface of the tubular member 12 at equal intervals to be rotationally symmetric. The number of silencers 22 is not limited to these. For example, two silencers 22 may be arranged in a rotationally symmetrical manner, or four silencers 22 are arranged in a rotationally symmetrical manner. It may be.

Similarly, when the silencer 22 is arranged inside the tubular member 12, it is preferable that two or more silencers 22 are arranged rotationally symmetrically.
For example, as shown in FIG. 21, four silencers 22 are arranged in the tubular member 12 (inner circumferential surface (inner circumferential surface)) at equal intervals in the circumferential direction and are rotationally symmetric. Good.

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

  Similarly, when the silencer 22 is arranged in the tubular member 12, a plurality of silencers 22 are arranged in the configuration in which the plurality of silencers 22 are arranged on the inner circumferential surface of the tubular member 12 in the circumferential direction. The vessel 22 may be connected. For example, as in the example shown in FIG. 23, eight silencers 22 may be connected in the circumferential direction.

  In the example illustrated in FIG. 1, the silencer 22 has a substantially cubic shape along the outer peripheral surface of the tubular member 12, but is not limited thereto, and may be any three-dimensional shape having a hollow portion. Alternatively, as shown in FIG. 24, the silencer 22 may be an annular shape along the entire outer circumference 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 circumferential 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 has an annular shape along the entire circumference of the inner circumferential surface of the tubular member 12 in the circumferential direction. May be.

In addition, when the silencer 22 is disposed on the outer peripheral surface of the tubular member 12, the outer diameter of the silencer 22 assuming that the silencer 22 covers the entire circumference of the outer peripheral surface of the tubular member 12 in the circumferential direction ( When 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 that D ₁ <D ₀ + 2 × (0.045 × λ + 5 mm) is satisfied. . 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 silencing system.
The effective outer diameter is an equivalent circle diameter, and when the cross section is not circular, the diameter of the same circle as the cross sectional area was taken as the effective outer diameter.

Further, when the silencer 22 is arranged on the inner peripheral surface of the tubular member 12, the inner diameter of the silencer 22 is assumed when the silencer 22 covers the entire circumference of the inner peripheral surface of the tubular member 12 in the circumferential direction. was a D _2, when the inner diameter of the tubular member 12 and D ₀ (see FIG. 18), preferably satisfy 0.75 × D ₀ <D _2.
Thereby, high soundproof performance can be expressed, suppressing the enlargement of a silencer system and ensuring air permeability.

  Moreover, in the example shown in FIGS. 17-23, it was set as the structure which arranged the several silencer 22 in the circumferential surface direction of the tubular member 12, However, It is not limited to this, The several silencer 22 of the tubular member 12 is used. It is good also as a structure arranged in the axial direction. In other words, the openings 32 of the plurality of silencers 22 may be arranged at at least two positions in the axial direction of the tubular member 12.

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

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

  In addition, in the example shown in FIG. 26, it was set as the structure which arrange | positions two silencers in an axial direction, However It is not limited to this, It is good also as a structure which arranges three or more silencers in an 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, the muffler system 10i shown in FIG. 27 includes a muffler 22a connected to the circumferential surface opening 12a of the tubular member 12 and one end of the tubular member 12 at the substantially central portion of the tubular member 12 in the axial direction. And a silencer 22b connected to the peripheral opening 12a in the vicinity. The depth L _d of the cavity 30a of the silencer 22a on the center side is different from the depth L _d of the cavity 30b of the silencer 22b on the end side.

Moreover, when it is set as the structure which arrange | positions a several silencer in an axial direction, it is preferable to arrange | position the sound-absorbing material from which an acoustic characteristic differs in a cavity part for every position of an opening part.
For example, a silencer system 10j shown in FIG. 28 includes a silencer 22a connected to the circumferential surface opening 12a of the tubular member 12 at one of the ends of the tubular member 12 at the substantially central portion of the tubular member 12 in the axial direction. And a silencer 22b connected to the peripheral opening 12a in the vicinity. A sound absorbing material 24a is arranged in the cavity 30a of the silencer 22a on the center side, and a sound absorbing material 24b is arranged in the cavity 30b of the silencer 22b 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 silencer system of the present invention, the wavelength that can be suitably silenced varies depending on the arrangement position of the silencer (opening) in the axial direction. Therefore, by arranging a plurality of silencers in the axial direction, it is possible to mute sounds in different wavelength ranges, and to mute in a wider band. Further, the sound can be more suitably silenced by adjusting the depth L _d of the cavity and the sound absorption characteristics of the sound absorber in accordance with the wavelength that can be suitably silenced for each position of the opening in the axial direction. .

In the example shown in FIG. 1, the cavity 30 of the silencer 21 has a depth L _d in the radial direction from the opening. In the example shown in FIG. 2, the cavity 30 of the silencer 22 has the opening 32. it is configured to have a depth L _d in the axial direction from this is not the sole may be configured to have a depth from the opening 32 in the circumferential direction.

29 is a sectional view schematically showing another example of the silencing system of the present invention, and FIG. 30 is a sectional view taken along the line CC of FIG.
29 and 30, two silencers 23 are 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.
By setting it as such a structure, the axial length of a silencer can be shortened.

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

Moreover, in the example shown in FIG. 2, although the depth of the cavity 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 shape of the cavity 30 may be a substantially C shape with the depth direction turned back. The sound wave that has entered the cavity 30 shown in FIG. 32 travels in the right direction in the figure from the opening 32, then turns back and proceeds in the left direction in the figure. 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 silencer system of the present invention may be configured such that a part of the silencer having a silencer and an insertion part is inserted into a tubular member (a ventilation sleeve).
FIG. 33 shows a schematic cross-sectional view of another example of the silencing system of the present invention.
A silencing system 10k shown in FIG. 33 has a configuration in which a silencing device 14 for silencing the sound passing through the tubular member 12 is installed on one end face side of the tubular member 12.

The silencer 14 includes an insertion portion 26 and a silencer 22. The insertion portion 26 is a cylindrical member having both ends open, and the silencer 22 is connected to one end face. 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. The silencer 22 is arranged along the circumferential surface of the insertion portion 26 so as not to block the inner diameter of the insertion portion 26. The silencer 22 is arranged such that the opening 32 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 that passes through the center of gravity in the cross section of the insertion portion 26.

  The silencer 14 is installed by being inserted into 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 surface of the tubular member 12. Accordingly, the silencer 22 is disposed in the vicinity of the opening end surface of the tubular member 12. That is, the opening 32 of the silencer 22 is disposed in a space within the opening end correction distance of the tubular member 12. Accordingly, the opening 32 of the silencer 22 is connected to the sound field space of the first resonance of the tubular member 12.

  In this way, a silencer and a silencer having an insertion part are inserted and installed in the tubular member, so that it can be easily installed without carrying out large-scale construction etc. in existing ventilation openings and air conditioning ducts. It becomes possible to do. Therefore, replacement when the silencer is deteriorated or damaged is easy. Moreover, when used for a ventilation sleeve of a house, it is not necessary to change the diameter of the through hole of the concrete wall, and the construction is simple. Moreover, it is easy to install retrofitting during renovation.

  In addition, a wall of a house such as an apartment has, for example, a concrete wall, a gypsum board, a heat insulating material, a decorative board, wallpaper, and the like, and a ventilation sleeve is provided therethrough. . When the silencer 14 as shown in FIG. 33 is installed on such a ventilation sleeve, the wall 16 in the present invention corresponds to a concrete wall, and the silencer 22 portion of the silencer 14 is outside the concrete wall. It is preferable to be installed between the concrete wall and the decorative board (see FIG. 70).

In the example shown in FIG. 33, the insertion portion 26 of the silencer 14 is inserted into the tubular member 12, and the silencer 14 is disposed in the opening of the tubular member 12. However, the present invention is not limited to this.
For example, as in the silencing system 10n shown in FIG. 67, the silencing device 14 may have a configuration in which the silencing device 14 does not have an insertion portion and is attached to the wall 16 with an adhesive or the like.
Alternatively, as in the silencing system 10p shown in FIG. 68, the inner diameter of the insertion portion 26 of the silencing device 14 is set to be substantially the same as the outer diameter of the tubular member 12 disposed on the wall 16, and is inserted into the insertion portion 26 of the silencing device 14. The silencer 14 may be installed by inserting the tubular member 12. The insertion portion 26 is disposed between the tubular member 12 and the wall 16.
Alternatively, as in the silencing system 10q shown in FIG. 69, the inner diameter of the insertion portion 26 of the silencing device 14 may be made larger than the outer diameter of the tubular member 12, and the insertion portion 26 may be arranged in the wall 16. .
67 to 69, a decrease in the aperture ratio caused by inserting the insertion portion 26 into the tubular member 12 can be suppressed, and the air permeability of the tubular member 12 can be improved.

  68 and 69, when the insertion portion 26 is arranged in the wall 16, the insertion portion 26 is arranged on the wall 16 in accordance with the size and shape of the insertion portion 26. For this purpose, a groove may be formed. Alternatively, when the wall 16 is produced, the silencer 14 (and the tubular member 12) may be installed in advance, and the wall 16 may be produced by pouring concrete.

  In the example shown in FIG. 33, the silencer 14 is configured to include the L-shaped silencer 22, but is not limited thereto, and may be configured to include the vertical cylindrical silencer 21. Or it is good also as a structure which has the silencer 23 which has a depth in the surrounding surface direction.

  In addition, in the silencer 14 of the silencer system 10k as shown in FIG. 33, it is preferable that the sound absorbing material 24 is disposed in the cavity 30 or in the vicinity of the opening 32.

The silencer 14 preferably includes a plurality of silencers 22.
When it has a plurality of silencers 22, it is good also as composition which is arranged at equal intervals in the peripheral surface direction and serves as rotational symmetry.
Alternatively, as in the silencing 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 arranged at at least two positions in the axial direction. 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 includes a silencer 22a and a silencer 22b in the axial direction from the insertion portion 26 side. The depth L _d of the cavity 30a of the silencer 22a is different from the depth L _d of the cavity 30b of the silencer 22b.

Moreover, when it is set as the structure which arrange | positions a several silencer in an axial direction, it is preferable to arrange | position the sound-absorbing material from which an acoustic characteristic differs in a cavity part for every position of an opening part.
For example, the silencer shown in FIG. 36 includes a silencer 22a and a silencer 22b from the insertion portion 26 side in the axial direction. A sound absorbing material 24a is disposed in the cavity 30a of the silencer 22a, and a sound absorbing material 24b is disposed in the cavity 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 cavity part of a silencer, it is good also as a structure which arrange | positions a several sound-absorbing material in one cavity 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 arranged in the cavity 30a and the cavity 30b of the silencer 22a, respectively. Within each cavity, the sound absorbing materials 24c to 24e are stacked in the depth direction of the cavity.
By adopting a configuration in which a plurality of sound absorbing materials are arranged in the hollow portion, it becomes easy to fill the sound absorbing material into the hollow portion from the opening during manufacture, and it is easy to replace the sound absorbing material during maintenance.
Moreover, it is more preferable that the sound absorbing material molded in accordance with the shape of the cavity is divided into a plurality of parts.

The plurality of sound absorbing materials 24c to 24e arranged in the same cavity may be the same type of sound absorbing material, or at least one different type of sound absorbing material, that is, sound absorbing performance (flow resistance, material, structure, etc.). Different sound absorbing materials may be used.
By disposing a plurality of different types of sound absorbing materials in the cavity, it becomes easy to control the silencing by the silencer to the sound absorbing performance suitable for the shape of the silencer (cavity) and the sound to be absorbed. .

Further, for example, as shown in FIGS. 37 and 38, the silencer may be configured so that the silencer can be separated. By making the silencer separable, it becomes easy to produce a silencer in which the size and number of silencers are changed. In addition, it is easy to install and replace the sound absorbing material in the cavity.
For example, the distance between the concrete wall and the decorative board varies, and even in the same apartment, it varies depending on the location and varies depending on the construction company. It is costly to design and produce a silencer each time according to the distance between the concrete wall and the decorative board. If the silencer is designed to be thin so that it can be applied to all distances, the soundproofing performance will be lowered. Therefore, when installing a silencer between a concrete wall and a decorative board, a plurality of silencers separated according to the distance between the concrete wall and the decorative board can be installed in an appropriate combination to reduce the cost. Can maximize the soundproofing performance.

Moreover, as shown in FIG. 39, it is preferable that the silencer 14 is detachably installed on the tubular member 12. As a result, the silencer 14 can be easily replaced or reformed.
Moreover, although the silencer 14 may be installed in any of the indoor side end surface and the outdoor side end surface of the tubular member 12, it is preferable to install in the indoor side end surface.

The silencing system may have at least one of a cover member installed on one end surface of the tubular member and an air volume adjusting member installed on the other end. The cover member is a conventionally known louver, louver or the like installed in a ventilation port, an air conditioning duct, or the like. The air volume adjusting member is a conventionally known register or the like.
Further, the cover member and the air volume adjusting member may be installed on the end surface of the tubular member on the side where the silencer is installed, or may be installed on the end surface on the side where the silencer is not installed.
For example, as shown in FIG. 40, when the air volume adjusting member 20 is installed on the silencer 14 side, the air volume adjusting member 20 is installed so as to cover the silencer 14 when viewed from the axial direction. It is preferred that The same applies when the cover member is installed on the silencer 14 side.

Here, in a general house such as a condominium, a concrete wall and a decorative board are installed apart from each other, and a heat insulating material or the like is disposed between the concrete wall and the decorative board. It is preferable to install the silencer 14 in the space between the concrete wall and the decorative board. At that time, as shown in FIG. 70, the silencer 14 may have a configuration in which the end surface 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. Or as shown in FIG. 71, the silencer 14 is good also as a structure by which the end surface by the side of the decorative board 40 is arrange | positioned flush with the surface on the opposite side to the wall 12 of the decorative board 40. FIG. That is, the silencer 14 may be inserted into the through hole of the decorative plate 40 by making the through hole formed in the decorative plate 40 substantially the same as the outer diameter of the silencer 14. In the example shown in FIG. 71, the silencer 14 is configured such that the end surface on the decorative plate 40 side and the surface opposite to the wall 12 of the decorative plate 40 are flush with each other. However, the present invention is not limited to this. A configuration in which a part of the silencer 14 exists on a plane on which the decorative plate 40 is located may be employed.
By adopting a configuration in which the silencer 14 is inserted through the through hole of the decorative plate 40, installation, replacement, etc. of the silencer are facilitated.

The silencer 22 of the silencer 14 has a higher silencing performance as the size is larger.
Here, as shown in FIG. 71, when the silencer 14 has a configuration in which the end face on the decorative plate 40 side is arranged flush with the surface of the decorative plate 40 opposite to the wall 12, the silencer 22. If the size is large, a through-hole (boundary between the silencer 14 and the decorative plate 40) formed in the decorative plate 40 from the room is visually recognized even if the air volume adjusting member 20 such as a register is installed on the decorative plate 40 side. There is a risk that. Therefore, as shown in FIG. 72, it is preferable to install a boundary cover 42 between the air volume adjusting member 20, the decorative board 40, and the silencer 14. Thereby, when viewed from the indoor side (air volume adjusting 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 improved.

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

In addition, in the example shown in FIG. 70 and the like, the inner diameter of the silencer 14 is substantially the same as the tubular member 12, but the present invention is not limited to this. As in the silencing 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, that is, larger than the inner diameter of the tubular member 12.
By making the inner diameter of the silencer 22 portion larger than the inner diameter of the tubular member 12, the large air volume adjusting member 20 for the tubular member having a diameter larger than the diameter of the tubular member 12 can be used. By using the large air volume adjusting member 20, the through hole of the decorative plate 40 is hidden by the air volume adjusting member 20, so that the design can be improved.

Moreover, you may integrate the silencer 14 and the air volume adjusting member 20 like the silencer system 10s shown in FIG.
As shown in FIG. 71 and the like, the air volume adjusting member 20 such as a commercially available register has an insertion portion, and is installed by inserting the insertion portion into the silencer 14. However, the insertion part of a commercially available resistor has a length of about 5 cm in order to ensure rigidity and sealing at the time of connection, and the design of the silencer 14 may be limited. On the other hand, as shown in FIG. 75, integrating the silencer 14 and the air volume adjusting member 20 is preferable in that the design freedom of the silencer 14 is increased and the construction is simplified.

When the silencing system has a cover member and an air volume adjusting member, the first resonance generated in the tubular member is the first resonance of the tubular member in the silencing system including the cover member, the air volume adjusting member and the silencing device. . Accordingly, the length L _d of the silencer cavity is shorter than ¼ of the wavelength λ of the sound wave at the resonance frequency of the first resonance of the tubular member in the silencing system including the cover member, the air volume adjusting member and the silencing device.

In the example shown in FIG. 70 and the like, the silencer 14 is arranged so that the center axis of the silencer 14 coincides with the center axis of the tubular member 12, that is, the silencer 14 is the center of the tubular member 12. Although it is formed in a rotationally symmetric shape with respect to the axis, it is not limited to this.
105 and the silencer system shown in FIG. 106, the silencer 14 is arranged such that the center axis of the silencer 14 is shifted from the center axis of the tubular member 12 in a direction perpendicular to the center axis. May be.
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 center axis of the silencer 14 and the center axis of the tubular member 12 are deviated, sound reflection is increased, which is preferable in terms of improving soundproof performance. This is particularly effective in a high-frequency region with high straightness.

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

In addition, when considering the soundproofing of the ventilation sleeve used for the wall for the house, the total thickness of the concrete wall and the decorative board, that is, the length of the ventilation sleeve is 175 mm to 400 mm. Considering the case where the wavelength is the shortest (λ = 497 mm when the length of the ventilation sleeve is 175 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 of a housing, the overall thickness (total thickness of the concrete wall and the decorative plate) is 400mm in maximum, because the concrete wall is at least 100 mm, the width L _w of the cavity housing the concrete wall It is preferably 300 mm or less from the viewpoint that it can be placed in the space between the decorative plate and the decorative board, more preferably 200 mm or less, and even more preferably 150 mm or less from the viewpoint of versatility.

Similarly, considering the case where the wavelength of the first resonance of the ventilation sleeve is the shortest (λ = 497 mm when the length of the ventilation sleeve is 175 mm), the depth L of the cavity portion is obtained from the viewpoint of obtaining sufficient soundproofing performance. _d is preferably 25.3 mm or more, more preferably 27.8 mm or more, and further preferably 30.3 mm or more.
On the other hand, the silencer is arranged between the pillars of the house in the radial direction. The maximum distance between the pillars of the house is about 450 mm, and the ventilation sleeve is at least about 100 mm. Therefore, the depth L _d of the cavity is preferably 175 mm or less (= (450 mm−100 mm) / 2), and preferably 130 mm or less, from the viewpoint that it can be arranged in the space between the columns of the house. Is more preferably 100 mm or less.

  Moreover, when it is set as the structure which has a sound-absorbing material in a part in the cavity part 30 of the silencer 22, it is preferable to arrange | position so that the opening part 32 may be covered or the opening part 32 may be made narrow. In other words, the sound absorbing material is preferably disposed at a position close to the opening 32 in the cavity 30. Moreover, it is preferable to arrange the sound absorbing material at a position away from the end face on the side far from the opening 32 in the depth direction of the cavity 30.

The difference in the soundproof performance due to the difference in the position of the sound absorbing material in the cavity 30 was examined by the following simulation.
FIG. 91 shows a schematic diagram of a simulation model.
As shown in FIG. 91, the length of the tubular member was 200 mm and the diameter was 100 mm in the simulation. The silencer 22 was installed in a tubular shape on the outer periphery of the tubular member 12. In the axial direction, the distance between the sound wave incident side end face of the tubular member 12 and the silencer 22 was set to 100 mm. The opening 32 of the silencer 22 was arranged in a slit shape in the circumferential surface direction of the tubular member. The width of the opening 32 was 15 mm. The length of the cavity 30 in the axial direction 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 inside of the cavity 30 is divided into nine parts, and a flow resistance of 13,000 [Pa · s / m ^{2] is} formed in each of the nine divided areas p1 to p9. The simulation was performed on the assumption that the sound absorbing material 24 is disposed. p1 is a region closest to the opening 32, and p2 and p3 are regions farther from the opening 32 than p1 in the radial direction. Further, 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 is a graph showing the relationship between the transmitted 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 transmitted sound pressure intensity was normalized by setting the peak of the transmitted sound pressure (transmitted 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 muffler is not installed is 630 Hz, the transmitted sound pressure at 630 Hz is the peak sound pressure.
FIG. 93 is a graph showing transmission loss in the 500 Hz band when a sound absorbing material is arranged in each region of p1 to p9. The transmission loss in the 500 Hz band is an average value of 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 arranged in the region of p1 closest to the opening 32, that is, the configuration covering the opening 32 has the lowest transmitted sound pressure intensity and transmission loss in the 500 Hz band. It can be seen that the soundproofing performance is high. In addition, it can be seen that the configuration in which the sound absorbing material is arranged in the regions p2 and p4 close to the opening 32 has a low transmitted sound pressure intensity and a high transmission loss in the 500 Hz band and a high soundproofing performance compared to 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 cavity 30 is divided into three in the axial direction, and the flow resistance 13000 [ The simulation was performed on the assumption that the sound absorbing material 24 of Pa · s / m ² ] is disposed. pz1 is a region closest to the opening 32, and pz2 and pz3 are regions farther from the opening 32 than pz1 in the axial direction.
FIG. 95 shows a graph representing transmission loss in the 500 Hz band when a sound absorbing material is disposed in each of the regions pz1 to pz3.

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

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

  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 sectional view conceptually showing another example of the silencing system of the present invention.
In the silencing system shown in FIG. 98, the second cavity 38 is provided on the surface of the wall constituting the cavity 30 of the silencer 22 that faces the surface having the opening 32. By configuring 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 reduced. Sound waves can easily enter the cavity 30. As a result, sound energy is easily converted into heat energy in the cavity 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 reduced in size.

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

  Here, in the case of the configuration in which 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 penetrates into the wall, or from the wall into the cavity. There is a risk that water or moisture may enter the product. Therefore, as in the example shown in FIG. 99, the second opening of the silencing system shown in FIG. 98 may be covered with the film member 46. The film-like member 46 is a film-like member that allows sound waves to pass therethrough and does not allow water to pass therethrough, and a thin resin film such as Saran Wrap (registered trademark), a water-repellent non-woven fabric, or the like can be used. Thereby, it is possible to prevent water and moisture from entering while lowering the acoustic impedance in the cavity 30. As a material of the film-like member 46, the same material as that of a windproof film 44 described later can be used.

Moreover, it is good also as a structure which has the intrusion prevention board 34 in the tubular member 12 like the example shown to FIG. 100 and FIG.
FIG. 100 is a schematic cross-sectional view of another example of the silencing system of the present invention. 101 is a cross-sectional view taken along the line DD of FIG.
As shown in FIGS. 100 and 101, the intrusion prevention plate 34 is a plate-like member erected in the radial direction of the tubular member 12 below the vertical direction in the tubular member 12.

  Since the ventilation sleeve (tubular member) installed on the wall of the house is connected to the outdoors, rainwater may enter the ventilation sleeve through an external louver or an external hood during a strong wind such as a typhoon. In the silencing system of the present invention, since the silencer having a hollow portion is connected to the ventilation sleeve, there is a possibility that rainwater that has entered the ventilation sleeve enters the hollow portion and accumulates.

On the other hand, as shown in FIGS. 100 and 101, by providing an infiltration prevention plate 34 in the tubular member 12, rainwater that has entered the tubular member 12 from the outside enters the cavity 30 of the silencer 22. Can be prevented.
The vertical height 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 cavity 30 of the silencer 22, as shown in FIGS. 102 and 103, a region below the vertical direction of the opening 32 of the silencer 22 is covered with a lid 36. It is good also as a structure closed with.
FIG. 102 is a schematic cross-sectional view of another example of the silencing system of the present invention. FIG. 103 is a cross-sectional view taken along line EE of FIG.
As shown in FIGS. 102 and 103, rainwater that has entered the tubular member 12 from the outside is silenced by covering the area below the vertical direction of the opening 32 of the silencer 22 with a lid 36. Intrusion into the hollow portion 30 of 22 can be prevented.

  Further, as shown in FIG. 109, the member that forms the surface on the opening 32 side of the silencer 22 may be a separate member (partition member 54), and the partition member 54 may be replaceable. By making the partition member 54 replaceable, the size of the opening 32 can be easily changed, so that the resonance frequency of the silencer 22 can be set as appropriate. Moreover, the sound absorbing material 24 installed in the cavity 30 can be easily replaced.

Examples of the material for forming the silencer 22 and the silencer 14 include metal materials, resin materials, reinforced plastic materials, and carbon fibers. Examples of the metal material include metal materials such as aluminum, titanium, magnesium, tungsten, iron, steel, chromium, chromium molybdenum, nichrome molybdenum, and alloys thereof. Examples of the resin material include acrylic resin, polymethyl methacrylate, polycarbonate, polyamideide, polyarylate, polyetherimide, polyacetal, polyetheretherketone, polyphenylene sulfide, polysulfone, polyethylene terephthalate, polybutylene terephthalate, Examples of the resin material include polyimide and triacetyl cellulose. Examples of the reinforced plastic material include carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (GFRP).
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 that it can be used for an exhaust port or the like. The heat resistance can be defined, for example, by the time that satisfies each item of Article 108-2 of the Building Standard Law Enforcement Order. Article 108-2 of the Building Standards Law Enforcement Ordinance, when the time to satisfy each item is 5 minutes or more and less than 10 minutes is a flame-retardant material, and when it is 10 minutes or more and less than 20 minutes is a quasi-incombustible material, 20 minutes The above cases are incombustible materials. However, heat resistance is often defined for each field. Therefore, the silencer 22 and the silencer 14 may be made of a material having heat resistance equivalent to or higher than the flame retardancy defined in the field in accordance with the field in which the silencer system is used.

In addition, as in the silencing system 10t shown in FIG. 76, it is preferable that the opening 32 of each silencer 22 is covered with a windproof film 44 that transmits sound waves and shields air (wind).
In the configuration in which air can flow into the cavity 30 of the silencer 22, the pressure loss of the entire silencer system is greater than in the case of a straight pipe. Therefore, there is a possibility that the amount of ventilation will decrease. On the other hand, because the windproof film 44 transmits sound waves by covering the opening 32 of each silencer 22 with the windproof film 44, the effect of silencing by the silencer 22 is obtained, and Since the windproof film 44 shields the air, the pressure loss can be reduced by suppressing the air from flowing into the cavity 30.

The windproof film 44 may be a non-breathable film or a film having low air permeability.
The material of the non-ventilated windproof film 44 includes acrylic resin such as polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate, polyamideide, polyarylate, polyetherimide, polyacetal, polyetheretherketone, polyphenylene. Resin materials such as sulfide, polysulfone, polybutylene terephthalate, polyimide, and triacetyl cellulose can be used.
Examples of the material for the low-breathable windproof film 44 include porous films made of the above resins, porous metal foils (porous aluminum foil, etc.), non-woven fabrics (resin bond non-woven fabrics, thermal bond non-woven fabrics, spun bond non-woven fabrics, spun lace non-woven fabrics) , Nanofiber nonwoven fabric), woven fabric, paper and the like 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 obtained by the through-hole part which they have. That is, they also function as a conversion mechanism that converts sound energy into heat energy.
The thickness of the windproof film 44 depends on the material, but is preferably 1 μm to 500 μm, more preferably 3 μm to 300 μm, and more preferably 5 μm to 100 μm.

Moreover, the silencer system of this invention may have another commercially available soundproofing member.
For example, as shown in FIG. 77, the silencer 14 according to the present invention is arranged at one end of the tubular member 12, and the insertion-type silencer 50 is arranged inside the tubular member 12. Also good.
As shown in FIG. 78, the silencer 14 according to 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 is good also as a structure to be made.
Alternatively, the silencer 14 according to the present invention is disposed at one end of the tubular member 12, and the interpolated silencer 50 is disposed inside the tubular member 12, and is disposed at the other end of the tubular member 12. May be configured such that an outdoor soundproof hood 52 is disposed.
Thus, by combining with other soundproofing members, high soundproofing performance can be obtained in a wider band.

As the interpolating silencer 50, various known interpolating silencers can be used. 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.) Made by Unix: Silencer (UPS100SA, etc.), manufactured by Kenyu Co., Ltd .: Silent sleeve P (HMS-K, etc.) can be used.
As the outdoor-installed soundproof hood 52, various known soundproof sleeves can be used. For example, a soundproof hood (SSFW-A10M, etc.) manufactured by Unix Co., Ltd., a soundproof hood (BON-TS, etc.) manufactured by Sylfer Corporation can be used.

Here, the tubular member 12 is not limited to a straight tubular member, and may have a bent structure. When the tubular member 12 has a bent structure, wind (air flow) and sound waves are reflected upstream at the bent portion, so that it is difficult for the wind and sound waves to pass through. In order to ensure air permeability, it is possible to change the direction of wind flow by changing the angle of the wall by making the bent part curved, etc., or by providing a baffle plate at the bent part, etc. Conceivable.
However, when the bent portion is curved or a rectifying plate is provided at the bent portion, the air permeability is improved, but the sound wave transmittance is also increased.

  Therefore, as shown in FIG. 89, an acoustic transmission wall 60 that does not allow wind to pass through (is difficult to pass through) and transmits sound waves is disposed at the bent portion of the tubular member 12. 89, the tubular member 12 has a bent portion that bends approximately 90 °. The sound transmitting wall 60 is disposed at the bent portion of the tubular member 12 with a surface inclined by about 45 ° with respect to the longitudinal direction of the incident-side tubular member 12 and the longitudinal direction of the emitting-side tubular member 12. 89 and 90, the upper end side in the figure is the incident side, and the right end side is the emission side.

  As shown in FIG. 89, since the sound transmission wall 60 transmits sound waves, the sound waves incident from the upstream side pass through the sound transmission wall 60 at the bent portion and are 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 wind does not pass through the sound transmission wall 60, the wind incident from the upstream side is bent by the sound transmission wall 60 at the bent portion and flows downstream. As described above, by disposing the sound transmission wall 60 in the bent portion, it is possible to improve the air permeability while keeping the sound transmittance low.

As the sound transmission wall 60, a non-woven fabric having a low density and a film having a small thickness and density can be used.
Examples of the non-woven fabric having a low density include Yodogawa Paper Co., Ltd .: stainless fiber sheet (TOMY FIREC SS), ordinary tissue paper, and the like. Examples of the film having a small thickness and density include various commercially available wrap films, silicone rubber films, and metal foils.

  Hereinafter, the present invention will be described in more detail based on examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the following examples.

[simulation]
First, the result of having performed simulation about the silencing system of the present invention is explained.
The simulation was performed using the acoustic module of the finite element method calculation software COMSOL ver5.3 (COMSOL).

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

[Example 1]
Next, as Example 1, a simulation was performed on a configuration in which the silencer 22 was arranged on the outer peripheral surface of the tubular member 12 as shown in FIG.
The silencer 22 is an L-shaped silencer and 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 arranged in the cavity 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 opening 32 in the axial direction is 10 mm, the wall thickness of the tubular member 12 is 3 mm, the area S ₁ of the opening 32 and the cavity The ratio S ₁ / S _{d to} the surface area S _d of 30 inner walls was 7.4%, and the center position of the opening 32 in the axial direction was 150 mm from the end face on the sound source side.
Further, the sound absorbing material 24 is filled in the entire area of the cavity 30. The flow resistance of the sound absorbing material 24 was set to 13000 [Pa · s / m ² ]. In the following examples, unless otherwise specified, the sound absorbing material 24 was filled in the entire area of the cavity 30 and the flow resistance of the sound absorbing material 24 was set to 13000 [Pa · s / m ² ]. .
The results are shown in FIG. FIG. 43 also shows the result when the depth L _d is 0 mm as a reference example, that is, when the silencer 22 is not arranged. The transmitted sound pressure is a value normalized by assuming that the transmitted sound pressure at the primary resonance frequency is 1.
As shown in FIG. 43, compared with the reference example, in Example 1, the transmitted sound pressure is selectively low particularly in the vicinity of the first resonance frequency and the third resonance frequency. It can be seen that the soundproofing performance is high. This is because the sound absorption effect in the silencing system of the present invention increases as the sound pressure inside the tubular member increases due to the resonance phenomenon of the tubular member.

[Comparative Example 1]
Next, as Comparative Example 1, a simulation was performed on a configuration in which a silencer 122 was disposed on the outer peripheral surface of the tubular member 12 as shown in FIG. In the silencer 122, the depth L _d of the cavity 130 is 10 mm, the width L _w is 60 mm, the width of the opening is 60 mm, and the area ratio S ₁ / S _d is 76.3%. The configuration is the same as the configuration. This configuration is an example in which the sound absorbing 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 when the width of the opening is 0 mm as a reference example, that is, when the silencer 122 is not disposed.
As shown in FIG. 45, compared with the reference example, Comparative Example 1 has a low transmitted sound pressure in a wide frequency band, particularly in a high frequency band of 800 Hz or higher. However, as compared with Example 1, it is understood 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 Example 1 with various changes in the depth L _d of the cavity 30. The width of the opening 32 was 10 mm.
Similarly, in Comparative Example 1 above, the results of simulation with various widths of the opening are shown in FIG.
Further, FIG. 48 shows the result of simulation by variously changing the depth L _d of the cavity 30 in the same manner as in Example 1 except that a vertical cylindrical silencer is used. The width L _w of the cavity 30 (the width of the opening 32) was 10 mm.
The sound absorbing material was changed according to the size of the cavity. The center position of the opening was fixed at the center of the tubular member. In FIGS. 46 to 48, the value of λ / 4 for each frequency is also indicated by a bold line for comparison.
Figure 46 is different, the effect of silencing the depth L _d of the cavity from, it can be seen that obtain high silencing effect even in a low frequency side. Since the opening is arranged in the center, the first resonance sound and the third resonance sound having a high sound pressure are rapidly absorbed in the center portion. Further, the required length is shorter than λ / 4, and its specificity is clear. Similarly, when the FIG. 48 of the vertical tubular, the depth L _d of the cavity have different effect of silencing, it can be seen that obtain high silencing effect even in a low frequency side. Since the opening is arranged in the center, the first resonance sound and the third resonance sound having a high sound pressure are rapidly absorbed in the center portion. Further, 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 the sound absorbing material is simply disposed, the length of about λ / 4 is necessary for absorbing the resonance sound, and in this case, the soundproofing performance on the low frequency side can be improved. I find it difficult.

Moreover, about the said Example 1, the transmission loss in the 1st resonance frequency when the depth of a cavity part is changed variously, and the 1st resonance frequency when the width | variety of an opening part is changed about the said Comparative Example 1 variously Transmission loss was calculated. The higher the transmission loss, the higher the performance.
The results are shown in FIG. Note that ¼ 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, 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 characteristic depending on the surface area and volume of the sound absorbing material in contact with the sound wave. Such a characteristic is obtained when the sound absorbing material is used in a general usage method of increasing the surface area in contact with the sound wave.

[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 transmitted sound pressure was calculated by variously changing the position of the opening 32 of the silencer 22 in the axial direction of the tubular member. As shown in FIG. 50, the case where the center of the opening 32 is at the axial center position of the tubular member was used as a reference (position 0 mm). Except for the position of the opening 32, the second embodiment is the same as the first embodiment. As shown in FIG. 50, the configuration in which the opening 32 is arranged in the center is referred to as Example 2. As shown in FIG. 51, the configuration in which the opening 32 is arranged near one end surface (position 140 mm) is as Example 3. To 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 a graph showing the relationship between the frequency and the transmitted sound pressure in Examples 2 and 3 is shown in FIG. FIG. 53 shows a case where no silencer is arranged 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 center in the axial direction, the sound pressure at the center in the axial direction such as the first resonance frequency and the third resonance frequency. It can be seen that sound waves having a frequency of increasing can be more suitably silenced. In addition, it can be seen that changing the position of the opening 32 changes the silencing effect for each resonance frequency. For example, it can be seen that by disposing the opening 32 at a position 90 mm from the center, the silencing effect for the second resonance frequency at which the sound pressure increases at this position can be further increased.
As described above, the mode for silencing can be controlled by the position of the opening 32 of the silencer 22.

Next, the result of having performed simulation about the flow resistance of the sound absorbing material 24 arranged in the cavity 30 of the silencer 22 will be described.
In the model of Example 1, the result of having performed simulation by changing the flow resistance of the sound absorbing material 24 is 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%, and the position of the opening in the axial direction is the center It is.
FIG. 54 shows that the flow resistance has an optimum range. This is because if the flow resistance becomes too large, it becomes difficult to pass through the sound absorbing material 24, and the conversion efficiency from the sound energy to the heat energy by the sound absorbing material 24 becomes low.

Moreover, based on the above simulation results, the results of measuring the transmitted sound pressure with respect to the combination of the depth L _d of the cavity 30 and the flow resistance of the sound absorbing material are shown in FIGS. 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 FIG. 55 and FIG. 56, it can be seen that the flow resistance of the sound absorbing material 24 has a suitable range according to the depth L _d of the cavity 30. From this result, the range of the 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, (1.32-log ((0.1 × L _d ))) / 0.24 <log (σ ₁ ) <5.2 is more preferable, and (1.39-log ((0 0.1 × L _d ))) / 0.24 <log (σ ₁ ) <4.7. In the above formula, the unit of L _d is [mm], and log is a common logarithm.

[Example 4]
Next, the result of simulation when a plurality of silencers 22 are arranged in the axial direction will be described.
As shown in FIG. 27, the silencing system has a silencer 22a having an opening 32a at the center position (position 150 mm from the end face) of the tubular member 12 in the axial direction and the vicinity of the end section (position 25 mm from the end face). And a silencer 22b having an opening 32b.
The wall thickness was 300 mm, and the diameter of the tubular member was 100 mm.
The muffler 22a and the muffler 22b are L-shaped mufflers, are circular in the circumferential direction along the entire circumference of the outer peripheral surface of the tubular member 12, and the opening 32 is a slit along the circumferential direction. The shape was formed into a shape. The depth L _d of the hollow portion 30a of the muffler 22a is 80 mm, the width L _w 10 mm, the width L _o of the opening portion 32a is 10 mm, the area ratio S ₁ / S _d is set to 5.5%. The depth L _d of the cavity 30b of the silencer 22b was 50 mm, the width L _w was 10 mm, the width L _o of the opening 32b was 10 mm, and the area ratio S ₁ / S _d was 8.9%.
In addition, the sound absorbing material 24 is arranged in the cavity 30 of the silencer 22a and the silencer 22b. The flow resistance of the sound absorbing material 24 was set to 13000 [Pa · s / m ² ].
Using such a muffler system model, the relationship between frequency and transmitted sound pressure was calculated. The results are shown in FIG. In addition, in FIG. 57, the result of Example 1 was also shown as a structure which has one silencer in the axial direction when there is no silencer as a reference example.

  As shown in FIG. 57, in Example 1 having a single silencer, the transmitted sound pressure at the first resonance frequency and the third resonance frequency can be reduced, but the transmitted sound at the second resonance frequency and the fourth resonance frequency is reduced. The pressure is relatively high. On the other hand, in Example 4, in addition to the silencer 22a arranged at a position (center) where the sound pressure of the first resonance is high, it is arranged at a position where the sound pressure of the second resonance is high (position 25 mm from the end face). Since the silencer 22b is provided, the transmitted sound pressure of the second resonance can be reduced. Therefore, a soundproof effect can be obtained over a wider band. In addition, at the position where the silencer 22b is disposed, the sound pressure of the third resonance and the fourth resonance is not zero, so that a soundproofing effect can be obtained for these resonance frequencies.

[Measurement results]
Next, a description will be given of the result of producing a muffler system and evaluating the soundproofing performance.
First, using a simple small soundproof room as shown in FIG. 58 as a reference, the transmitted sound pressure was measured without a silencer.
58 is surrounded by a sound-absorbing urethane foam W ₃ (thickness 100 mm, U00F2 manufactured by Fuji Rubber Sangyo Co., Ltd.), and the other surface is sound-absorbing urethane foam W ₂ (sound-absorbing urethane foam W). ₃ (Fuji Rubber Sangyo Co., Ltd. U00F2) is surrounded by a wall member in which an acrylic plate W ₁ having a thickness of 5 mm is arranged on both sides. Further, among the five sound absorbing urethane foams W ₃ , corrugated sound absorbing urethane foam W ₄ (maximum thickness 35 mm, U00F6 manufactured by Fuji Rubber Sangyo Co., Ltd.) is provided on the inner surfaces of the three surfaces arranged on the left and right surfaces. Arranged. The size of the soundproof room was 400 mm × 500 mm × 500 mm.
The wall member having the sound absorbing urethane foam W ₂ and the two acrylic plates W ₁ was provided with a vinyl chloride ventilation sleeve (tubular member) 12 having an inner diameter of 10 cm, penetrating the wall member.
A horizontal louver (SG-CB made by UNIX Co., Ltd.) is attached to the end surface of the ventilation sleeve 12 in the soundproof chamber as a cover member 18, and a register (KRP-made by UNIX Co., Ltd.) is installed on the outer end surface of the ventilation sleeve 12 as an air volume adjusting member 20. BWF) was attached.

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

  First, the register 20 was closed, white noise was generated from the two speakers SP, and the sound pressure was measured with the measurement microphone MP at a sampling rate of 25000 Hz for 10 seconds. The frequency spectrum was calculated by performing Fourier transform on the measured sound pressure data. The data after Fourier transform was 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, Fourier transform is performed on the sound pressure data, the frequency spectrum is calculated, and the difference from the background data is obtained as reference data. .

[Example 5]
As Example 5, as shown in FIG. 59, a 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 a difference from the background data was obtained to obtain transmitted sound pressure data.
The results are shown in FIG.
In addition, the silencer 22 of Example 5 is 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. Yes (see FIG. 24). Further, the sound absorbing material 24 is arranged in the cavity 30 of the silencer 22.
The cavity portion 30 has a depth L _d of 80 mm, a width L _w of 14 mm, an axial opening portion 32 width of 15 mm, an area ratio S ₁ / S _d of 8.3%, and an axial opening portion 32. The center position of was set at a position 113 mm from the end face on the sound source side. Further, as the sound absorbing material 24, bean charcoal or rock wool for replacement (manufactured by Mitsuuroko) was used. The flow resistance of the sound absorbing material 24 is 40000 [Pa · s / m ² ], and the entire cavity 30 is filled.

[Comparative Example 2]
As Comparative Example 2, the transmitted sound pressure was obtained in the same manner as in Example 4 except that a soundproof sleeve made of polyethylene (SK-BO75 manufactured by Shin Kyowa Co., Ltd.) was placed in the ventilation sleeve 12 instead of the silencer 22. .
The results are shown in FIG.

[Comparative Example 3]
As Comparative Example 3, in place of the silencer 22, the transmitted sound pressure was the same as in Example 4 except that a silent sleeve P (HMS100K manufactured by Kenyu Co., Ltd.), which is a resonance type silencer, was disposed in the ventilation sleeve 12. Asked.
The results are shown in FIG.

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

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

[Comparative Example 4]
Instead of the silencer 22, the transmitted sound pressure was determined in the same manner as in Example 6 except that a silent sleeve P (HMS100K manufactured by Kenyu Co., Ltd.), which is a resonance type silencer, was disposed in the ventilation sleeve 12.
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 in the embodiment 5 is applied to the ventilation sleeve having a different first resonance frequency even if the length of the ventilation sleeve is changed. It can be seen that a high soundproofing performance can be obtained by using and the versatility is high.
On the other hand, from the comparison between FIG. 62 and FIG. 64, it can be seen that in the resonance type silencer, if the first resonance frequency of the ventilation sleeve is different, the soundproof performance is lowered and the versatility is low.

[Example 7]
As Example 7, 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 a difference from the background data was obtained to obtain transmitted sound pressure data.
The results are shown in FIGS. 65 and 66. FIG. 66 shows the average value of transmission loss for each frequency band (octave band frequency). When the octave band frequency is 500 Hz, the average value of transmission loss at a frequency of 354 Hz or more and less than 707 Hz is obtained. For 1000 Hz, the average value of transmission loss at a frequency of 707 Hz or more and less than 1414 Hz is obtained. In the case of 2000 Hz, the average value of transmission loss at a frequency of 1414 Hz or more and less than 2829 Hz is obtained. 65 and 66 also show the results of Example 5.

In addition, the silencer 22a and the silencer 22b according to the seventh embodiment have 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 arranged in the cavity 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 32a is 14 mm, the area ratio S ₁ / S _d is 15.7%, The center position of the opening 32a in the axial direction was 113 mm from the end surface 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 32b is 15 mm, the area ratio S ₁ / S _d is 11.4%, The center position of the opening 32b in the axial direction was 156 mm from the end surface on the sound source side.
The sound absorbing material 24 was bean charcoal or rock wool for replacement (manufactured by Mitsuuroko). The flow resistance of the sound absorbing material 24 is 40000 [Pa · s / m ² ], and the entire cavity 30 is filled.

  From FIG. 65 and FIG. 66, it can be seen that by arranging two silencers in the axial direction, a higher soundproofing effect can be obtained in a wider band.

[Example 8]
Next, a description will be given of the result of producing a noise reduction system combined with a commercially available sound insulation member and evaluating the sound insulation performance.
For performance evaluation, a simple small soundproof room as shown in FIG. 79 was used.

The simple soundproof room shown in FIG. 79 is surrounded on five sides by a sound-absorbing urethane foam W ₃ (thickness 100 mm, U00F2 manufactured by Fuji Rubber Sangyo Co., Ltd.) and an acrylic plate W ₁ having a thickness of 5 mm arranged outside thereof, and the remaining 1 The surface is a wall member (wall 16 of the present invention) composed of an aluminum plate W ₅ (thickness 3 mm), glass wool W ₆ (32501211 density 32 kg / m ³ non-formaldehyde manufactured by Shojo Tsusho Co., Ltd.) and an acrylic plate W ₁ from the soundproof room side. Is equivalent). 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 arranged parallel to the wall member at a distance of 110 mm from the wall member.
Of the five sound-absorbing urethane foams W ₃ , corrugated sound-absorbing urethane foams W ₄ (maximum thickness 35 mm, U00F6 manufactured by Fuji Rubber Sangyo Co., Ltd.) are provided on the inner surfaces of the three surfaces arranged on the left and right surfaces. Has been placed. The size of the soundproof room was 800 mm × 800 mm × 900 mm.
A wall member made of aluminum plate W ₅ , glass wool W ₆ and acrylic plate W ₁ was provided with a vinyl chloride ventilation sleeve (tubular member) 12 having an inner diameter of 100 mm and a length of 100 mm penetrating the wall member. The decorative board (acrylic board 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.
The acrylic plate W ₁ and the aluminum plate W ₅ were supported by fixing the end portions to a 30 mm square aluminum frame Fr.

  A horizontal louver (SG-CB made by UNIX Co., Ltd.) is attached to the end surface of the ventilation sleeve 12 in the soundproof chamber as a cover member 18, and a register (KRP-made by UNIX Co., Ltd.) is installed on the outer end surface of the ventilation sleeve 12 as an air volume adjusting member 20. BWF) was attached.

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

  First, 10 circular acrylic plates (thickness 5 mm) having the same size (100 mm diameter) as the inner diameter were placed in the ventilation sleeve 12 as a reference sound insulating material. Thereby, the sound 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 with the measurement microphone MP at a sampling rate of 25000 Hz for 10 seconds. The frequency spectrum was calculated by performing Fourier transform on the measured sound pressure data. The data after Fourier transform was 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, Fourier transform is performed on the sound pressure data, the frequency spectrum is calculated, and the difference from the background data is obtained as reference data. .

  Next, as Example 8, the reference sound insulating material and the resistor 20 are removed, the silencer 14 is installed on the outer end face of the ventilation sleeve 12 (between the wall member and the decorative plate), and the resistor 20 is silenced 14. It was attached to the end surface of the decorative board side.

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

The sound pressure is measured in the same manner as described above with the register 20 fully opened, and the frequency spectrum is calculated by performing Fourier transform on the sound pressure data, and the difference from the background data is obtained to obtain the transmitted sound pressure data. .
The results are shown in FIG.
The opening ratio of the silencer 14 is 88% with respect to the inner diameter of the ventilation sleeve 12.

[Comparative Example 5]
As Comparative Example 5, in place of the silencer 14, a polyethylene soundproof sleeve (SK-BO100, manufactured by Shin Kyowa Co., Ltd.) was used in the ventilation sleeve 12 as an interpolated silencer. The transmitted sound pressure was obtained.
The results are shown in FIG.
The opening ratio of the soundproof sleeve is 35.7% with respect to the inner diameter of the ventilation sleeve 12.

[Example 9]
As Example 9, the transmitted sound pressure was determined in the same manner as in Example 8 except that a soundproof sleeve made of polyethylene (SK-BO100 manufactured by Shin Kyowa Co., Ltd.) was disposed in the ventilation sleeve 12.
The results are shown in FIG.
FIG. 83 shows the result of obtaining the average value of transmission loss for each frequency band (octave band frequency) of Examples 8 and 9 and Comparative Example 5. For the octave band frequency of 500 Hz, the average value of transmission loss at a frequency of 354 Hz or more and less than 707 Hz is obtained, and for 1000 Hz, the average value of transmission loss at a frequency of 707 Hz or more and less than 1414 Hz is obtained. is there.

  From FIG. 80 to FIG. 83, it can be seen that the eighth embodiment in which the silencer 14 is arranged can obtain a higher soundproofing performance in the low frequency range (around 500 Hz) than the fifth comparative example. Furthermore, it can be seen from Example 9 that the soundproofing performance in the frequency region around 1000 Hz can be improved in addition to the low frequency region by combining the soundproofing sleeve.

[Comparative Example 6]
As Comparative Example 6, in place of the silencer 14, a soundproof hood (SSFW-A10M manufactured by Unix Co., Ltd.) was placed at the end of the ventilation sleeve 12 on the soundproof room side in the same manner as in Example 8 to transmit the transmitted sound pressure. Asked.
The results are shown in FIG.
The opening ratio of the soundproof hood is 50.2% with respect to the inner diameter of the ventilation sleeve 12.

[Example 10]
As 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 ventilation sleeve 12 on the soundproof room side.
The results are shown in FIG.
FIG. 86 shows the result of obtaining the average value of transmission loss for each frequency band (octave band frequency) of Examples 8, 10 and Comparative Example 6.

  From FIGS. 80 and 84 to 86, Example 8 in which the muffler 14 is arranged has an aperture ratio higher than that of Comparative Example 7, but the same soundproofing performance can be obtained in the low frequency range (around 500 Hz). I understand that. Furthermore, it can be seen from Example 10 that the soundproofing performance in the frequency range around 1000 Hz can be improved in addition to the low frequency range by combining the soundproof hood.

[Example 11]
As Example 11, a soundproof sleeve made of polyethylene (SK-BO100, manufactured by Shin Kyowa Co., Ltd.) is disposed in the ventilation sleeve 12, and a soundproof hood (SSFW-A10M, manufactured by Unix Co., Ltd.) is disposed inside the soundproof chamber. The transmitted sound pressure was determined in the same manner as in Example 8 except that it was arranged at the end of the above.
The results are shown in FIG.
Further, FIG. 88 shows the result of obtaining the average value of transmission loss for each frequency band (octave band frequency) of Examples 8 and 11 and Comparative Examples 5 and 6.

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

10a to 10t Silencer system 12 Tubular member 14 Silencer 16 Wall 18 Cover member 20 Air volume adjusting member 21, 22, 22a, 22b, 23 Silencer 24, 24a-24e Sound absorbing material 26 Insertion part 30, 30a, 30b Cavity part 32, 32a, 32b Opening 34 Infiltration prevention plate 36 Lid 38 Second opening 40 Decorative plate 42 Boundary cover 44 Non-breathing film 46 Film-like member 50 Interpolated silencer 52 Soundproof hood 54 Partition member 60 Sound transmission wall

Claims (30)

A silencing system in which a silencing device for silencing the sound passing through the ventilation sleeve is installed in the ventilation sleeve installed through the wall,
The silencer silences a sound having a frequency including the frequency of the first resonance generated in the ventilation sleeve,
The silencer is
One or more silencers having a hollow portion and an opening communicating the hollow portion and the outside, and disposed on one end surface 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 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,
If the wavelength of the sound wave at the resonance frequency of the first resonance of the ventilation sleeve in the sound deadening system including the sound deadening device is λ, the depth L _d of the cavity in the traveling direction of the sound wave in the silencer is 0. Satisfy 011 × λ <L _d <0.25 × λ,
The muffler 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 resonance of the muffler alone, but by the sound absorbing material. A mute system that is designed to mute. 2. The silencing system according to claim 1, wherein a frequency of a first resonance generated in the ventilation sleeve is F _0, and a resonance frequency of the silencer is F ₁ , wherein 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} cavity in a direction perpendicular to the depth direction of the cavity satisfies 0.001 × λ <L _w <0.061 × λ. Item 3. The mute system according to item 1 or 2. 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 mute system according to item. 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 mute system according to item. 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 mute system according to item. Having a decorative board provided parallel to the wall;
The silencer system according to any one of claims 1 to 6, wherein the silencer is disposed between the decorative plate and the wall. In the cross section parallel to the axial direction of the ventilation sleeve, the silencer includes the cavity portion extending in the axial direction of the ventilation sleeve and one surface of the cavity portion parallel to the axial direction of the ventilation sleeve. The opening located on one end side in the axial direction of the sleeve,
Silencer system according to the length of said cavity in the axial direction of the ventilation sleeve, any one of claims 1 to 7, the depth L _d of the cavity.   The silencer system according to any one of claims 1 to 8, wherein the silencer includes a plurality of silencers.   The silencing system according to claim 9, wherein the openings of the plurality of silencers are arranged at at least two positions in the axial direction of the ventilation sleeve. The silencing system according to claim 10, wherein a depth L _{d of the} hollow portion of the silencer is different for each position of the opening.   The noise reduction system according to claim 10 or 11, wherein a sound absorbing material having different acoustic characteristics is disposed in the cavity of the silencer for each position of the opening. The silencer has a cylindrical insertion portion connected to the ventilation sleeve,
The insertion portion is arranged 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 claims 1 to 12, wherein the silencer 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 small claims 1-13 than the area S ₀ of the cavity. Having two or more silencers,
The silencer system according to any one of claims 1 to 14, wherein the opening of each silencer is disposed rotationally symmetrically with respect to a central axis of the ventilation sleeve.   The silencing system according to any one of claims 1 to 15, wherein the silencing system is installed at an end portion on the indoor side 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) The muffler system according to any one of claims 1 to 16, which is satisfied.   The silencer system according to any one of claims 1 to 17, wherein the silencer is detachable from the ventilation sleeve.   The silencer system according to any one of claims 1 to 18, wherein the silencer of the silencer is separable.   The silencer system according to any one of claims 1 to 19, wherein the silencer is made of a material having higher heat resistance than a flame retardant material.   The silencer system according to any one of claims 1 to 20, wherein the opening of the silencer is formed in a slit shape along a circumferential direction of an inner circumferential surface of the ventilation sleeve. A cover member installed on the side opposite to the ventilation sleeve of the silencer, or an air volume adjusting member;
The silencing system according to any one of claims 1 to 21, wherein the cover member or the air volume adjusting member covers the silencing device when viewed from the axial direction of the ventilation sleeve. A cover member installed at one end of the ventilation sleeve;
An air volume adjusting member installed at the other end of the ventilation sleeve,
When the wavelength of the sound wave at the resonance frequency of the first resonance of the ventilation sleeve in the silencing system including the silencing device, the cover member, and the air volume adjusting member is λ, the depth L _d of the cavity portion is larger than λ / 4. 23. A muffler system according to any one of the preceding claims. Having a decorative board provided parallel to the wall;
The silencing system according to any one of claims 1 to 23, 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 ventilation sleeve, the silencer is arranged such that a part thereof is inserted through a through-hole formed in the decorative plate between the wall and the decorative plate arranged apart from the wall. Has been
The silencing system according to any one of claims 1 to 24, further comprising a boundary cover that covers a boundary between the decorative plate and the silencer when viewed from the axial direction of the ventilation sleeve. In the axial direction of the ventilation sleeve, the silencer is disposed at one end of the ventilation sleeve,
Furthermore, the noise reduction system as described in any one of Claims 1-25 which has a soundproof member arrange | positioned in the said ventilation sleeve. In the axial direction of the ventilation sleeve, the silencer is disposed at one end of the ventilation sleeve,
Furthermore, the noise reduction system as described in any one of Claims 1-26 which has a soundproof member arrange | positioned at the other edge part of the said ventilation sleeve. The width L _{w of the} cavity of the silencer is
5.5 mm ≦ L _w ≦ 300 mm
The muffler system according to any one of claims 1 to 27, wherein: The depth L _d of the cavity of the silencer is:
25.3 mm ≦ L _d ≦ 175 mm
The silencing system according to any one of claims 1 to 28, wherein The silencing system according to any one of claims 1 to 29, wherein a plurality of the sound absorbing materials are disposed in the hollow portion.