JP6673885B2 - Silencer system - Google Patents

Description

  The present invention relates to a silencing system.

A tubular member, such as a ventilation port or an air-conditioning duct, that is provided on the wall that separates the room from the outside and penetrates between the room and the outside, in order to suppress the transmission of noise from the outside to the room, or to suppress noise from the room In order to suppress the transmission of water to the outside, a sound absorbing material such as urethane, polyethylene, and glass wool is installed in a tubular member.
When a sound absorbing material such as urethane, polyethylene, or glass wool is used, the absorption of low-frequency sound of 800 Hz or less becomes extremely low. Therefore, it is necessary to increase the volume in order to increase the absorption. However, since it is necessary to ensure the air permeability of the ventilation port, the air conditioning duct, and the like, the size of the sound absorbing material is limited, and there is a problem that it is difficult to achieve both high air permeability and soundproof performance.

On the other hand, it has been proposed to arrange a sound absorbing material on the outer peripheral portion of an air conditioning duct to ensure air permeability even when a large sound absorbing material is used.
For example, in Patent Document 1, in a sound-absorbing material for an air-conditioning duct interposed in a flow path of an air-conditioning duct and reducing noise transmitted through the flow path, a peripheral wall facing the flow path has a film stretched outside the sound-absorbing material, A sound-absorbing material for an air-conditioning duct is described, which has a laminated body having a perforated plate provided at intervals on the outside thereof and uses a film that transmits sound and prevents air from leaking.

JP 2001-07302 A

  However, as described in Patent Literature 1, in a configuration in which a sound absorbing material is arranged on the outer peripheral portion of an air conditioning duct, it is necessary to use a large sound absorbing material in order to reduce noise in a low frequency range to noise in a high frequency range. For this reason, there is a problem that the whole system including the sound absorbing material such as the sound absorbing material becomes large.

  An object of the present invention is to solve the above-mentioned problems of the conventional technology, and to provide a noise reduction system that can achieve both high air permeability and soundproofing performance and that can be reduced in size.

Means for Solving the Problems As a result of intensive studies to solve the above problems, the inventors of the present invention have found that a muffling system in which a muffling device for muffling a sound passing through a tubular member is installed in a tubular member provided through a wall separating two spaces. The sound absorbing device has a sound absorbing material and a high-resistance member having a higher acoustic characteristic impedance than the sound absorbing material, and a part of the surface of the sound absorbing material has a first resonance sound of the tubular member in the sound absorbing system. An opening connected to the sound space, at least another part of the surface of the sound absorbing material is covered with a high-resistance member, is blocked from the sound field space, and the sound wave that has entered the sound absorbing material from the opening. the depth L _d of the sound absorbing material in the traveling direction of, greater than the width L _o of the opening portion in the axial direction of the tubular member, the ratio of the acoustic characteristic impedance of the high resistance member with respect to the absolute value of the acoustic characteristic impedance of the sound absorbing material Zr And high resistance material It has been found that the above-mentioned problem can be solved by satisfying log (t × Zr ^2.5 )> 1.99, where t is the thickness of t (mm), and completed the present invention.
That is, it has been found that the above-described object can be achieved by the following configuration.

[1] A muffling system in which a muffling device for muffling a sound passing through a tubular member is installed in a tubular member provided through a wall separating two spaces,
The silencer has a sound absorbing material and a high resistance member having higher acoustic characteristic impedance than the sound absorbing material,
Part of the surface of the sound absorbing material is an opening connected to the first resonance sound field space of the tubular member in the sound deadening system,
At least another part of the surface of the sound absorbing material is covered with a high resistance member, and is isolated from the sound field space,
The depth L _d of the noise absorbing member from opening in the direction of travel of the sound wave that has entered the sound absorbing material is greater than the width L _o of the opening portion in the axial direction of the tubular member,
When the ratio of the acoustic characteristic impedance of the high resistance member to the absolute value of the acoustic characteristic impedance of the sound absorbing material is Zr, and the thickness of the high resistance member is t (mm),
log (t × Zr ^2.5 ) ≧ 1.99
A silencing system that satisfies.
[2] Assuming that the wavelength of the sound wave at the resonance frequency of the first resonance is λ, the depth L _d of the sound absorbing material satisfies 0.011 × λ <L _d <0.25 × λ. system.
[3] The noise reduction system according to [1] or [2], wherein the thickness t of the high-resistance member is 0.01 mm or more and 3.00 mm or less.
[4] The acoustic characteristic impedance of the high resistance member with respect to the absolute value of the acoustic characteristic impedance of the sound absorbing material is not less than 2.4 × 10 ^{4 and not} more than 5 × 10 ⁷ [kg · m ⁻² · s ⁻¹ ] [1]. -The noise reduction system according to any one of [3].
[5] The ratio Zr of the acoustic characteristic impedance of the high resistance member to the absolute value of the acoustic characteristic impedance of the sound absorbing material, and the thickness t (mm) of the high resistance member are:
1.99 ≦ log (t × Zr ^2.5 ) ≦ 11.0
The muffling system according to any one of [1] to [4], which satisfies the following.
[6] In a cross section parallel to the axial direction, the width L _w of the sound absorbing material in a direction orthogonal to the depth direction of the sound absorbing material satisfies 0.001 × λ <L _w <0.061 × λ [1] to The muffling system according to any one of [5].
[7] In a cross section parallel to the axial direction, the sound absorbing material has a rectangular shape extending in the axial direction,
The sound absorbing material, the length in the axial direction is the depth L _d,
A portion of the surface of the sound absorbing material on the central axis side of the tubular member is an opening connected to the first resonance sound field space of the tubular member,
The noise reduction system according to any one of [1] to [6], wherein at least another portion of the surface of the sound absorbing material on the central axis side of the tubular member is covered with a high-resistance member.
[8] The noise reduction system according to [7], wherein the surface of the sound absorbing material other than the surface on the central axis side of the tubular member is covered with a high-resistance member.
[9] The noise reduction system according to [7], wherein the noise reduction device includes a case portion that covers a surface of the sound absorbing material other than a surface on the central axis side of the tubular member.
Silencer system according to any of [10] in the circumferential surface of the central axis and the axis of the tubular member, the area S ₁ of the opening is smaller than the area S ₀ of the sound absorbing material [7-9].
[11] 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 [10] The sound deadening system according to any one of the above.
[12] It has two or more sound absorbing materials,
The noise reduction system according to any one of [1] to [11], wherein the openings of the respective sound absorbing materials are arranged rotationally symmetrically with respect to the central axis of the tubular member.
[13] The sound absorbing material according to any one of [1] to [12], wherein the sound absorbing material is disposed on one end surface side of the wall.
[14] The muffler includes a tubular insertion portion connected to the tubular member,
A case covering the surface of the sound absorbing material other than the surface on the central axis side of the tubular member,
The sound deadening system according to [13], wherein the insertion portion is disposed such that a central axis thereof is aligned with a central axis of the tubular member.
[15] The noise reduction system according to any one of [1] to [12], wherein at least a part of the sound absorbing material is arranged on an outer periphery of the tubular member.
[16] In the axial direction the cross section perpendicular, the effective outer diameter D ₀ of the tubular member, the effective outer diameter D ₁ of the sound-absorbing _{material, D 1 <D 0 + 2} × satisfy (0.045 × λ + 5mm) [ 15 ].
[17] The noise reduction system according to any one of [1] to [13], wherein the sound absorbing material is disposed inside the tubular member.
[18] a plurality of sound absorbing materials,
The noise reduction system according to any one of [1] to [17], wherein the openings of the plurality of sound absorbing materials are arranged at at least two or more positions in the axial direction of the tubular member.
[19] For each position of the opening silencer system according to the depth L _d of the sound absorbing material is different from [18].
[20] The noise reduction system according to [18] or [19], wherein the acoustic characteristics of the sound absorbing material are different for each position of the opening.
[21] A noise reduction system in which a noise reduction device is disposed in a tubular member provided through a wall separating two spaces,
The silencer has a sound absorbing material and a high resistance member having higher acoustic characteristic impedance than the sound absorbing material,
Part of the surface of the sound absorbing material is an opening connected to the first resonance sound field space of the tubular member in the sound deadening system,
At least another part of the surface of the sound absorbing material is covered with a high resistance member, and is isolated from the sound field space,
S ₁ The area of the opening of the sound absorbing material, when the surface area of the inner wall of the sound absorbing material to 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% Fill,
When the ratio of the acoustic characteristic impedance of the high resistance member to the absolute value of the acoustic characteristic impedance of the sound absorbing material is Zr, and the thickness of the high resistance member is t (mm),
log (t × Zr ^2.5 )> 1.99
A silencing system that satisfies.
[22] In the axial direction of the tubular member, the sound absorbing material is disposed between the wall and the decorative plate arranged apart from the wall, with a part of the sound absorbing material being inserted through a through hole formed in the decorative plate. Yes,
The noise reduction system according to any one of [1] to [21], further including a boundary cover that covers a boundary between the decorative plate and the through hole when viewed from the axial direction of the tubular member.
[23] In the axial direction of the tubular member, the sound absorbing material is disposed at one end of the tubular member.
Furthermore, the noise reduction system according to any one of [1] to [22], further including a soundproofing member arranged in the tubular member.
[24] In the axial direction of the tubular member, the sound absorbing material is disposed at one end of the tubular member.
Furthermore, the noise reduction system according to any one of [1] to [23], further including a soundproof member disposed at the other end of the tubular member.

  ADVANTAGE OF THE INVENTION According to this invention, the high air permeability and soundproof performance can be made compatible, and the noise reduction system which can be reduced in size can be provided.

It is sectional drawing which shows notionally an example of the noise reduction system of this invention. It is a figure for explaining a sound field space of a tubular member. It is a figure for explaining the depth and width of a sound absorbing material. It is a figure for explaining the area of the opening of a sound absorbing material, and the area of a sound absorbing material. It is a graph showing the relationship between depth and width of a sound absorbing material, and vxP. It is a graph showing the relationship between frequency and transmitted sound pressure. It is a graph showing the relationship between the ratio of the opening area and the peak of the transmitted sound pressure. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. FIG. 20 is a sectional view taken along line CC of FIG. 19. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction 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 the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. FIG. 33 is a front view of FIG. 32 as viewed from the air flow adjusting member side. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which shows notionally another example of the noise reduction system of this invention. It is sectional drawing which represents typically the model of the silencing system in a simulation. It is a graph showing the relationship between transmitted sound pressure and frequency. 5 is a graph illustrating a relationship between an impedance ratio Zr and a transmission loss in a 500 Hz octave band. 5 is a graph illustrating a relationship between a thickness t and a transmission loss in a 500 Hz octave band. It is a graph showing the relationship between the parameter PtZ and the effect manifestation rate of the peak sound absorption at 500 Hz. It is a graph showing the relationship between transmitted sound pressure, frequency, and flow resistance. It is a graph showing the relationship between the flow resistance and the peak value of the transmitted sound pressure. It is a graph showing the relationship between the depth, the flow resistance, and the peak value of the transmitted sound pressure. It is a figure for explaining a measuring method of transmitted sound pressure. FIG. 9 is a schematic cross-sectional view for explaining a configuration of a comparative example. FIG. 2 is a schematic cross-sectional view for explaining a configuration of 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 transmission loss of 500 Hz octave band of an Example and a comparative example. It is a graph showing the relationship between the parameter _PtZ and the effect manifestation rate of the peak sound absorption at 500 Hz.

Hereinafter, the present invention will be described in detail.
The description of the components described below is based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
In addition, in this specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit and an upper limit.
Further, in the present specification, “orthogonal” and “parallel” include a range of an error allowable in a technical field to which the present invention belongs. For example, “orthogonal” and “parallel” mean that the angle is within ± 10 ° with respect to strict orthogonal or parallel, and the error with respect to strict orthogonal or parallel is 5 ° or less. And more preferably 3 ° or less.
In this specification, “same” and “same” include an error range generally accepted in the technical field. In this specification, “all”, “all”, “all”, etc., include 100% and include an error range generally accepted in the technical field, for example, 99% or more, It includes the case of 95% or more, or 90% or more.

[Mute system]
The configuration of the noise reduction system of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing an example of a preferred embodiment of the noise reduction system of the present invention.

As shown in FIG. 1, the silencing system 10a has a configuration in which a silencing device 14 is disposed on an outer peripheral surface (outer peripheral surface) of a cylindrical tubular member 12 provided through a wall 16 separating two spaces. Having.
The tubular member 12 is, for example, a ventilation sleeve such as a ventilation port and an air conditioning duct.
In addition, the tubular member 12 is not limited to a ventilation port and an air conditioning duct, and may be a general duct used for various devices.

The silencer 14 includes a sound absorbing material 24, a case 27, and a high resistance member 28.
The sound absorbing material 24 is a conventionally known sound absorbing material that converts sound energy into heat energy to muffle sound. The high resistance member 28 is a film-shaped member made of a material having higher acoustic impedance than the sound absorbing material 24. The case 27 can be regarded as a rigid body, and is a member that blocks sound waves.
As shown in FIG. 1, the noise reduction device 14 is disposed between the tubular member 12 and the wall 16 (in a space provided in the wall 16).

In the example shown in FIG. 1, the case 27 has a substantially rectangular parallelepiped box shape with one surface opened, and the open surface is formed on the peripheral surface of the tubular member 12 toward the central axis of the tubular member 12. Is connected to the peripheral opening 12a. The open surface of the case 27 and the peripheral opening 12a of the tubular member 12 have substantially the same shape and size.
The sound absorbing material 24 is arranged in the case 27. That is, the surface of the sound absorbing material 24 other than the surface on the central axis side of the tubular member 12 is covered with the case portion 27.

On the surface of the sound absorbing material 24 on the central axis side of the tubular member 12, a high resistance member 28 that covers a part of this surface is arranged. The remaining part of the surface of the sound absorbing material 24 on the central axis side of the tubular member 12 communicates with the inside of the tubular member 12. The portion of the sound absorbing material 24 that is not covered with the high resistance member 28 on the central axis side of the tubular member 12 is referred to as an opening 32.
The opening 32, which is a part of the surface of the sound absorbing member 24 on the central axis side of the tubular member 12, is connected to a first resonance sound field space generated in the tubular member 12 in the sound deadening system 10a. In other words, the surface of the sound absorbing material 24 on the central axis side of the tubular member 12 is arranged at a position connected to the sound field space of the first resonance generated in the tubular member 12, and a part of the sound absorbing material 24 has a high resistance. It is covered with the member 28 and is isolated from the sound field space.

Here, the sound field space of the first resonance of the tubular member 12 in the noise reduction system 10a will be described with reference to FIG.
FIG. 2 shows the distribution of sound pressure in the first resonance mode of the tubular member 12 provided through the wall 16 separating two spaces, obtained by simulation. As can be seen from FIG. 2, the sound field space of the first resonance of the tubular member 12 is a space within the tubular member 12 and within the opening 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. In addition, the opening end correction distance in the case of the cylindrical tubular member 12 is given by approximately 1.2 × the pipe diameter.

Further, as shown in FIG. 3, the depth of the sound absorbing material 24 in the direction of travel of the sound wave of the noise absorbing member 24 and L _d, the axial direction of the tubular member 12 (hereinafter, simply referred to as axial direction) of the opening 32 When the width is L _o, depth L _d of the sound absorbing material 24 is greater than the width L _o of the opening 32.
Here, the traveling direction of the sound wave in the sound absorbing material 24 can be obtained by simulation. In the example shown in FIG. 3, since the sound absorbing material 24 extends in the axial direction, the traveling direction of the sound wave in the sound absorbing material 24 is the axial direction (the horizontal direction in the drawing). Therefore, the depth L _d of the sound absorbing material 24, from the opening 32 in the axial direction to the end face of the far side of the sound absorbing member 24 is long. In the case where the depth of the sound absorbing material 24 depending on the position are different, the depth L _d of the sound absorbing material 24 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.
In FIG. 3, the illustration of the wall 16 is omitted for explanation. In the following drawings, the illustration of the wall 16 may be omitted.

Further, in the present invention, the ratio of the acoustic characteristic impedance (Zh) of the high resistance member 28 to the absolute value (Za) of the acoustic characteristic impedance of the sound absorbing material 24 is Zr (= Zh / Za or less, also referred to as “impedance ratio Zr”). Assuming that the thickness of the high resistance member 28 is t (mm), log (t × Zr ^2.5 )> 1.99 is satisfied.
When the ratio Zr of the acoustic characteristic impedance of the high-resistance member 28 to the acoustic characteristic impedance of the sound absorbing material 24 and the thickness t of the high-resistance member 28 satisfy the above expression, sound waves are less likely to propagate in the high-resistance member 28, The portion of the sound absorbing material 24 covered with the high resistance member 28 is cut off from the sound field space, and the sound wave enters the sound absorbing material 24 only from the opening 32. Thus, the width L _o of the opening 32 of the sound absorbing material 24 is smaller than the depth L _d of the sound absorbing material 24.
When the thickness t of the high resistance member 28 differs depending on the position, the thickness t of the high resistance member 28 is an average value of the thickness at each position.

By width L _o of the opening 32 is smaller than the depth L _d of the sound absorbing material 24, when the sound waves of the tubular member 12 flows from the opening 32 in the sound absorbing material 24, the gas while maintaining the sound pressure The movement speed of (air) molecules is increased. The conversion efficiency of sound energy to heat energy by the sound absorbing material 24 depends on the sound pressure and the moving speed of gas molecules. Therefore, the conversion speed of the sound energy to heat energy by the sound absorbing material 24 is increased by increasing the moving speed of the gas molecules while maintaining the sound pressure. Therefore, higher soundproof performance can be obtained than in the case of the sound absorbing material alone.
Further, since a higher soundproofing performance can be obtained than in the case of the sound absorbing material alone, the sound absorbing material 24 (silencer 14) can be made smaller to maintain high air permeability, and the whole system can be downsized. .

Here, even when the surface of the sound absorbing material on the central axis side of the tubular member is covered with a case portion made of a rigid body with a part thereof being opened, when sound waves flow into the sound absorbing material from the opening, Since the moving speed (particle speed) of the gas molecules is increased while maintaining the sound pressure, the conversion efficiency from sound energy to heat energy by the sound absorbing material is increased, and high soundproof performance can be obtained.
However, if the sound absorbing material is to be covered with a case made of a rigid body except for the opening, the case may be made up of a plurality of parts so as to be separable in order to install the sound absorbing material in the case. There is a need. For this reason, there is a possibility that problems such as a complicated structure, complicated assembly, an increase in cost, a gap easily formed, and a decrease in performance may occur.

On the other hand, in the noise reduction system of the present invention, the surface of the sound absorbing material 24 connected to the first resonance sound field space generated in the tubular member 12, in the example shown in FIG. And a film-like high-resistance member 28 that covers a part of this surface is disposed on the surface. Therefore, as in the example shown in FIG. 1, the rigid case portion 27 that houses the sound absorbing material 24 can be integrally formed as a shape with one surface fully opened. The high-resistance member 28 can be easily installed on the sound absorbing material 24. That is, the structure and assembly can be simplified, and the cost can be reduced.
In addition, the cost can be reduced by using an inexpensive film-shaped high-resistance member 28. Further, since the high resistance member 28 is a thin film-shaped member, the entire system can be reduced in size and weight.

Further, since the principle of silencing by the sound absorbing material 24 does not depend on the wavelength of the sound wave, sound in a wide frequency band can be silenced.
In addition, since the principle of silencing by the sound absorbing material 24 does not depend on the wavelength of the sound wave, even when the length and shape of the tubular member 12 are different, the soundproof performance can be exhibited, and the design corresponding to the tubular member 12 is unnecessary. It is highly versatile.

In addition, since the principle of the sound absorption by the sound absorbing material 24 does not depend on the wavelength of the sound wave, it is not necessary to design to muffle the sound of the resonance frequency according to the resonance frequency of the tubular member 12. Therefore, unlike the resonance type sound absorbing material, the size of the sound absorbing material does not need to be set to the size (length of λ / 4) corresponding to the resonance frequency, and the noise reduction device 14 can be downsized.
Therefore, assuming that the wavelength of the sound wave at the resonance frequency of the first resonance generated in the tubular member 12 in the noise reduction system is λ, the depth L _d of the sound absorbing material 24 can be L _d <0.25 × λ. In addition, the silencer 14 can be downsized. It is preferable that 0.011 × λ <L _d <0.25 × λ is satisfied from the viewpoints of miniaturization of the silencer 14 and soundproofing performance.

Further, from the viewpoints that sound waves can easily enter the sound absorbing material 24 from the opening 32, soundproofing performance, miniaturization, air permeability, etc., the impedance ratio Zr and the thickness of the high resistance member 28 are 1 (mm). It preferably satisfies .99 ≦ log (t × Zr ^2.5 ) ≦ 11.0, more preferably satisfies 2.5 ≦ log (t × Zr ^2.5 ) ≦ 10.0, and 3.0 ≦ log (t × Zr ^2.5 ). More preferably, Zr ^2.5 ) ≦ 9.0 is satisfied.
The relationship between the impedance ratio Zr and the thickness t of the high resistance member 28 will be described in detail in a simulation described later.

  In addition, from the viewpoints of rigidity, increase in the volume ratio of the sound absorbing material, production, and the like, the thickness t of the high-resistance member is preferably 0.01 mm or more and 3.00 mm or less, more preferably 0.02 mm or more and 2.50 mm or less, and 0.1 mm or less. 03 mm or more and 2.00 mm or less are more preferable.

From the viewpoint of soundproofing performance, miniaturization, etc., the acoustic characteristic impedance Zc of the high resistance member with respect to the absolute value of the acoustic characteristic impedance of the sound absorbing material is 2.4 × 10 ⁴ [kg · m ⁻² · s ⁻¹ ] or more and 5 ×. It is preferably 10 ⁷ [kg · m ^-2 · s ^-1 ] or less, more preferably 3.0 × 10 ⁴ [kg · m ^-2 · s ^-1 ] or more and 4 × 10 ⁷ [kg · m ^-2 · s]. ⁻¹ ] or less, more preferably 3.4 × 10 ⁴ [kg · m ⁻² · s ⁻¹ ] or more and 1 × 10 ⁷ [kg · m ⁻² · s ⁻¹ ] or less. preferable.

The acoustic characteristic impedance of the sound absorbing material and the high resistance member can be measured as follows.
When the sound-absorbing material and the high-resistance member have a permeability such as a nonwoven fabric, the acoustic characteristic impedance is measured by a transfer function method using four microphones in an aluminum acoustic tube (4 cm inside diameter). . This method complies with "ASTM E2611-09: Standard Test Method for Measurement of Normal Incidence Sound Transmission of Acoustical Materials Based on the Transfer Matrix Method".
As the acoustic tube, for example, one having the same measurement principle as WinZac manufactured by Nitto Bo Acoustic Engineering Co., Ltd. can be used. In this way, sound transmission loss can be measured in a wide spectral band.
An evaluation object having a thickness of 1 cm or more and a diameter of 4 cm is arranged at a measurement site of the acoustic tube, performs a sound transmission loss measurement in a range of 100 Hz to 2000 Hz, calculates an acoustic characteristic impedance, and averages in a range of 355 Hz to 710 Hz. It is assumed that the acoustic characteristic impedance is 500 Hz octave band.

  When the high resistance member is a non-breathable material such as a resin film, the reflection and transmission characteristics of a sample attached to a circular frame having an inner diameter of 40 mm (the same diameter as the acoustic tube) are measured using the above acoustic tube, and the finite element method is used. The acoustic characteristic impedance can be obtained by fitting with numerical calculation using the calculation software COMSOL ver5.3 (COMSOL).

  In the example shown in FIG. 1, the sound absorbing material 24 has a substantially rectangular parallelepiped shape, but is not limited thereto, and may have various shapes such as a cylindrical shape. 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.

The position of the opening 32 in the axial direction is not limited. Depending on the position of the opening 32, it is possible to control the frequency band in which the sound is more appropriately muted.
For example, when the sound wave of the first resonance frequency of the tubular member 12 is silenced, the opening 32 is arranged at a position where the sound pressure of the sound wave of the first resonance frequency becomes high, that is, at the center of the tubular member in the axial direction. Thus, the sound pressure and the moving speed of the gas molecules can be increased, and higher soundproof performance can be exhibited.

Here, as shown in FIG. 4, the area of sound absorbing material 24 as S _0, and the area of the opening 32 and S _1, the area S ₁ of the openings 32 is smaller than the area S ₀ of the sound absorbing material 24 Is preferred. By making the area S ₁ of the opening 32 smaller than the area S ₀ of the sound absorbing material 24, when sound waves in the tubular member 12 flow into the sound absorbing material 24, gas (air) is maintained while maintaining sound pressure. Since the moving speed of the molecule can be increased, the conversion efficiency of sound energy to heat energy by the sound absorbing material 24 can be further increased.
Here, each area S ₁ of the area S ₀ and the opening 32 of the sound absorbing material 24 is the area in the circumferential surface of the axial center axis of the tubular member 12 through the sound absorbing material 24 or opening 32.
When the area of the sound absorbing material 24 varies depending on the radial position of the tubular member 12, the area S ₀ of the sound absorbing material 24 is an average value of the area at each position.
The area S ₁ of the opening 32 is the area in which the opening is minimized.

From the viewpoint of increasing the moving speed of the gas molecules, the smaller the area S ₁ of the opening 32 is, the better. However, if the area S ₁ of the opening 32 is too small, the sound wave hardly flows into the sound absorbing material 24, and the soundproofing performance is low. 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 sound absorbing material 24, and 0.3% <S ₁ / S ₀ <35%. It is more preferable, and more preferably _{0.5% <S 1 / S 0} <30%.

From the viewpoint of sound insulation performance and breathability, the depth L _d of the sound absorbing material 24 is preferably satisfy _{0.011 × λ <L d <0.25} × λ, 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.
In a section parallel to the axial direction, the width L _w (see FIG. 3) of the sound absorbing material 24 in a direction orthogonal to the depth direction of the sound absorbing material 24 is 0.001 × λ <L _w <0.061 × λ. Is preferably satisfied, more preferably 0.001 × λ <L _w <0.051 × λ, and even more preferably 0.001 × λ <L _w <0.041 × λ.
In the case where the width L _w of the noise absorbing member 24 differs depending on the position, the width L _w of the noise absorbing member 24 is the average value of the width at each location.

  This will be described with reference to FIG. FIG. 5 shows a result of a simulation in a case where the silencer as shown in FIG. 1 is used.

FIG. 5 shows (depth L _d of sound absorbing material 24 / wavelength λ of sound wave to be silenced), (width L _w of sound absorbing material 24 / wavelength λ of sound wave to be silenced), and average particle velocity v of gas molecules. 7 is a graph showing a relationship between the average sound pressure P and a multiplied value (| v | × | P |). (| V | × | P |) is a value proportional to the absorption per volume of the sound absorbing material 24.

Particle velocity v and sound pressure P, using an acoustic module FEM calculation software COMSOL ver5.3 (COMSOL Inc.), and a width L _w of depth L _d and sound absorbing material 24 of the noise absorbing member 24 with various modifications I asked. In the simulation, the length of the tubular member was 300 mm, the diameter was 100 mm, the sound absorbing material 24 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. The high-resistance member 28 was arranged in a region of the sound absorbing material 24 other than the opening 32 on the central axis side surface of the tubular member. A rigid body (case portion) was arranged on a surface of the sound absorbing material 24 other than the surface on the central axis side of the tubular member.
The lowest resonance frequency of the tubular member 12 was 460 Hz. The frequency of the sound wave to be silenced was 460 Hz. The acoustic characteristic impedance of the sound absorbing material 24 was 6304 [kg / (s · m ² )]. The acoustic characteristic impedance of the high resistance member 28 was 5 × 10 ⁷ [kg / (s · m ² )] and the thickness was 1 mm.
That is, log (t × Zr ^2.5 ) is 10.4.

  As shown in FIG. 38 to be described later, a sound wave was made incident from a hemispherical surface in one space partitioned by a wall, and the amplitude per unit volume of the sound wave reaching the hemispherical surface in the other space was determined. 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 sound wave to be incident had an amplitude of 1 per unit volume.

From Figure 5, is proportional to the absorption (| v | × | P | ) value of the extent that there is a range L _w and depth L _d of the sound absorbing material 24, it is understood that high.

Further, the noise reduction system according to the present invention sets the ratio S ₁ / S _d of the area S ₁ of the opening 32 to the surface area S _d of the sound absorbing material 24 to be 0 <S ₁ / S _d <40%, so that the sound absorbing material 24 is formed. The ratio of the area of the surface on which the sound wave is incident to the surface area of the sound absorbing member 24 is reduced, and the moving speed of the gas molecules corresponding to the sound wave flowing into the sound absorbing material 24 is increased while maintaining the high sound pressure P to enhance the soundproofing performance. be able to.
From the viewpoint of increasing the moving speed of the gas molecules, the smaller the area S ₁ (ratio S ₁ / S _d ) of the opening 32 is, the better. However, if the area S ₁ of the opening 32 is too small, the sound wave flows into the sound absorbing material 24. The soundproofing performance is reduced because it is difficult to perform. In view of the above, the area S ₁ of the openings 32 to the surface area S _d of the inner wall of the sound absorbing material 24 is preferably _{0.1% <S 1 / S d} <40%, 0.3% <S 1 / S d < more preferably 35%, more preferably _{0.5% <S 1 / S d} <30%.
Incidentally, the surface area S _d of the sound absorbing material 24 measures the resolution as 1 mm. That is, when having a fine uneven structure such as less than 1mm does this may be determined the surface area S _d by averaging. For example, modeled using CAD software COMSOL, it is possible to obtain the surface area S _d by calculating the surface area COMSOL.

In this regard, as in the case of FIG. 5, a simulation was performed for the silencing system as shown in FIG.
In the simulation, the length of the tubular member was 300 mm, the diameter was 100 mm, the sound absorbing material 24 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 is 80 mm, the width L _w of the noise absorbing member 24 was set to 10 mm. The opening 32 was disposed at the center of the tubular member 12 in the axial direction. The high-resistance member 28 was arranged in a region of the sound absorbing material 24 other than the opening 32 on the central axis side surface of the tubular member. A rigid body (case portion) was arranged on a surface of the sound absorbing material 24 other than the surface on the central axis side of the tubular member.
The flow resistance of the sound absorbing material 24 was 13000 [Pa · s / m ² ], and the acoustic characteristic impedance was 6304 [kg / (s · m ² )]. The flow resistance of the high-resistance member 28 was Δ (non-ventilating membrane), the acoustic characteristic impedance was 5 × 10 ⁷ [kg / (s · m ² )], and the thickness was 1 mm.
That is, log (t × Zr ^2.5 ) is 10.4.

By changing the width L _o of the opening to 10mm (1cm) ~70mm (7cm) , by changing the area ratio S ₁ / S _d to 5.3% ～54.7%, calculated respectively transmitted sound pressure did.
The results are shown in FIGS.
In FIG. 6, 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. Note that the transmitted sound pressure was normalized by setting the peak of the transmitted sound pressure (transmitted sound pressure of the first resonance frequency) when the muffler 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.

FIG. 6 is a graph showing the relationship between the frequency and the transmitted sound pressure, and FIG. 7 is a graph showing the relationship between the ratio of the opening area and the peak of the transmitted sound pressure.
As can be seen from FIGS. 6 and 7, the volume of the sound absorbing material despite the same, as the area ratio S ₁ / S _d of the opening is small, the transmitted sound pressure of the resonance frequency is found to be smaller. In addition, the reason why the resonance frequency when the sound absorbing material is installed is shifted to the lower frequency side in comparison with the case without the sound absorbing material is that the volume in which the sound wave can exist is increased.

  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, soft urethane foam, wood, ceramic particle sintered material, phenol foam, etc., and materials containing minute air; glass wool, rock wool, microfibers (such as 3M company thinsulate), floor mats, carpets Melt and blown non-woven fabrics, metal non-woven fabrics, polyester non-woven fabrics, fibers and non-woven materials such as metal wool, felt, insulation boards and glass non-woven fabrics; wood wool cement boards; nanofiber materials such as silica nanofibers; gypsum boards; Sound absorbing material is available.

The flow resistance σ ₁ of the sound absorbing material 24 is such that the sound absorbing material 24 easily flows into the sound absorbing material 24 through the opening 32, and has a flow resistance per unit thickness from the viewpoint of soundproofing performance, miniaturization, and air permeability. σ ₁ [Pa · s / m ² ] preferably satisfies (1.25−log (L _d )) / 0.24 <log (σ ₁ ) <5.6, and (1.32−log (L) _d )) / 0.24 <log (σ ₁ ) <5.2 is more preferably satisfied, and (1.39−log (L _d )) / 0.24 <log (σ ₁ ) <4.7 is satisfied. It is more preferable to satisfy. In the above formulas, the unit of L _d is [mm], log is a natural logarithm.
The flow resistance of the sound absorbing material is measured by measuring the normal incidence sound absorption coefficient of a 1 cm thick sound absorbing material and fitting with a Miki model (J. Acoustic. Soc. Jpn., 11 (1) pp. 19-24 (1990)). Can be evaluated. Alternatively, the evaluation may be performed according to “ISO 9053”.

  The thickness of the sound absorbing material 24 is not limited. From the viewpoints of sound absorbing performance, miniaturization, 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.

  The high resistance member 28 is not particularly limited as long as it has a higher acoustic characteristic impedance than the sound absorbing material 24. For example, resin materials that can be made into films, metal materials that can be made into foils, other materials that can be used as fibrous films, nonwoven fabrics, films containing nano-sized fibers, thin porous materials, and carbon materials that have been processed into thin film structures And a material or structure capable of forming a thin structure such as a rubber material. Specifically, as the metal material, aluminum, titanium, nickel, permalloy, 42 alloy, kovar, nichrome, copper, beryllium, phosphor bronze, brass, nickel silver, tin, zinc, iron, tantalum, niobium, molybdenum, zirconium And various metals such as gold, silver, platinum, palladium, steel, tungsten, lead, and iridium, and alloys of these metals. As the resin material, PET (polyethylene terephthalate), TAC (triacetylcellulose), polyvinyldene chloride, polyethylene, polyvinyl chloride, polymethylbenten, COP (cycloolefin polymer), polycarbonate, zeonoa, PEN (polyethylene naphthalate) ), Polypropylene, and resin materials such as polyimide can be used. Other examples of the material for the fibrous film include paper and cellulose. Examples of the thinly processed porous material include thinly processed urethane and thinsulate. Further, a glass material such as a thin film glass and a fiber reinforced plastic material such as CFRP (Carbon Fiber Reinforced Plastics) and GFRP (Glass Fiber Reinforced Plastics) can be used. Examples of the rubber material include silicone rubber and natural rubber.

  The area of the high-resistance member 28 that covers the sound absorbing material 24 is not particularly limited, but it is preferable that the area of the sound absorbing material that is equal to or larger than the area of the opening 32 connected to the sound field is covered with the high resistance member.

The material of the case portion 27 is not limited as long as it can be regarded as a rigid body and can shield sound waves, and examples thereof include a metal material, a resin material, a reinforced plastic material, and a carbon fiber. . Examples of the metal material include metal materials such as aluminum, titanium, magnesium, tungsten, iron, steel, chromium, chromium molybdenum, nichrome molybdenum, and alloys thereof. As the resin material, for example, acrylic resin, polymethyl methacrylate, polycarbonate, polyamideide, polyarylate, polyetherimide, polyacetal, polyetheretherketone, polyphenylene sulfide, polysulfone, polyethylene terephthalate, polybutylene terephthalate, Resin materials such as polyimide and triacetyl cellulose can be used. Examples of the reinforced plastic material include carbon fiber reinforced plastics (CFRP: Carbon Fiber Reinforced Plastics) and glass fiber reinforced plastics (GFRP: Glass Fiber Reinforced Plastics).
Here, it is preferable that the case 27 be made of a material having higher heat resistance than the flame-retardant material because it can be used for an exhaust port or the like. The heat resistance can be defined, for example, by a time that satisfies Article 108-2 of the Building Standard Law Enforcement Order. The case where the time to satisfy Article 108-2 of the Building Standards Law enforcement order is 5 minutes or more and less than 10 minutes is a flame retardant material, and the case where the time is 10 minutes or more and less than 20 minutes is a quasi-nonflammable material, and 20 minutes The above cases are non-combustible materials. However, heat resistance is often defined for each field. Therefore, the case 27 may be made of a material having heat resistance equal to or higher than the flame retardancy defined in the field in accordance with the field in which the noise reduction system is used.

Here, in the example illustrated in FIG. 1, the silencer 14 is configured to be disposed on the outer peripheral portion of the tubular member 12. However, the configuration is not limited thereto. May be arranged at a position connected to the first resonance sound field space. For example, as in the noise reduction system 10c shown in FIG. 8, the noise reduction device 14 may be disposed inside the tubular member 12. Alternatively, as in a sound deadening system 10k shown in FIG. 22 described below, the sound deadening device 14 (sound absorbing material 24) may be arranged on one end face side of the wall 16, that is, outside the open end face of the tubular member 12. .
In the noise reduction system 10c shown in FIG. 8 and the noise reduction system 10k shown in FIG. 22, the noise reduction device 14 is arranged such that the opening 32 faces the central axis of the tubular member 12.

  Further, in the example illustrated in FIG. 1, the surface of the sound absorbing material 24 other than the surface on the central axis side of the tubular member 12 is configured to be covered with the case portion 27, but is not limited thereto. 8, the surface of the sound absorbing material 24 other than the surface on the central axis side of the tubular member 12 may be covered with the high-resistance member 28. Further, the sound absorbing material 24 may be configured so that a part of the surface other than the surface on the central axis side of the tubular member 12 is covered with the high resistance member 28 and the remaining part is covered with the case 27.

  Further, in the example shown in FIG. 1, the silencer 14 has a configuration in which one sound absorbing material 24 is partially covered with the high-resistance member 28, but the present invention is not limited to this. It may be configured to have two or more sound absorbing members 24 covered with 28. For example, as in a noise reduction system 10f shown in FIG. 9, two sound absorbing members 24 are arranged on the outer peripheral surface of the tubular member 12, and the surface having the opening 32 and the high-resistance member 28 is attached to the peripheral surface of the tubular member 12. It is good also as a structure arrange | positioned at the formed peripheral surface opening part 12a. Alternatively, a sound absorbing material 24 whose periphery is covered with a high-resistance member 28 except for the opening 32 may be arranged inside the tubular member 12, as in a sound deadening system 10g shown in FIG.

When two or more sound absorbing members 24 are provided, the two or more sound absorbing members 24 are preferably arranged rotationally symmetrically with respect to the central axis of the tubular member 12.
For example, as shown in FIG. 11, three sound absorbing members 24 may be provided, and the three sound absorbing members 24 may be arranged on the outer peripheral surface of the tubular member 12 at equal intervals in the circumferential direction to be rotationally symmetric. . Alternatively, as shown in FIG. 12, six sound absorbing members 24 may be provided at equal intervals on the outer peripheral surface of the tubular member 12 so as to be rotationally symmetric. The number of the sound absorbing members 24 is not limited to these. For example, a configuration in which two sound absorbing members 24 are arranged rotationally symmetrically, or a structure in which four sound absorbing members 24 are arranged rotationally symmetrically. It may be.

Similarly, when the sound absorbing material 24 is arranged inside the tubular member 12, it is preferable that two or more sound absorbing materials 24 are arranged rotationally symmetrically.
For example, as shown in FIG. 13, a configuration in which four sound absorbing members 24 are arranged inside 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 of a configuration in which a plurality of sound absorbing materials 24 are arranged in the circumferential direction, the case portions 27 accommodating the respective sound absorbing materials 24 may be connected. For example, as shown in FIG. 14, eight sound absorbing members 24 may be connected in the circumferential direction.

Further, in the example shown in FIG. 1, the sound absorbing material 24 has a substantially cubic shape. However, the sound absorbing material 24 is not limited to this, and may have any three-dimensional shape.
For example, as shown in FIG. 15, the sound absorbing material 24 may be annular along the entire circumference of the outer peripheral surface of the tubular member 12 in the circumferential direction. In this case, the high resistance member 28 covers, for example, the entire inner peripheral surface of the sound absorbing material 24 except for a part in the axial direction. Thereby, 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 sound absorbing material 24 is disposed in the tubular member 12, as shown in FIG. 16, the sound absorbing material 24 has an annular shape along the entire circumference of the inner peripheral surface of the tubular member 12 in the circumferential direction. You may. Also in this case, the high resistance member 28 covers the entire inner peripheral surface of the sound absorbing material 24 except for a part in the axial direction, for example. The opening 32 is formed in a slit shape along the circumferential direction of the inner peripheral surface of the tubular member 12.

Further, when the sound absorbing material 24 is disposed on the outer peripheral surface of the tubular member 12, the outer diameter of the sound absorbing material 24 assuming that the sound absorbing material 24 covers the entire circumference of the outer peripheral surface of the tubular member 12 in the circumferential direction ( Assuming that the effective outer diameter is D ₁ and the outer diameter (effective outer diameter) of the tubular member 12 is D ₀ (see FIG. 15), it is preferable to satisfy D ₁ <D ₀ + 2 × (0.045 × λ + 5 mm). . The units of D ₁ , D ₀ and λ in the formula are mm.
Thereby, high soundproofing performance can be exhibited while suppressing an increase in the size of the silencing system.
The effective outer diameter is a diameter equivalent to a circle, and when the cross section is not circular, the diameter of the circle having the same cross-sectional area as the effective outer diameter was used.

Further, when the sound absorbing material 24 is disposed on the inner peripheral surface of the tubular member 12, the inner diameter of the sound absorbing material 24 when it is assumed that the sound absorbing material 24 covers the entire circumference of the inner peripheral surface of the tubular member 12 in the circumferential direction. Is set to D ₂ and the inner diameter of the tubular member 12 is set to D ₀ (see FIG. 10), it is preferable to satisfy 0.75 × D ₀ <D ₂ .
Thereby, high soundproofing performance can be exhibited while suppressing the increase in size of the silencing system and securing air permeability.

  9 to 14, the plurality of sound absorbing members 24 are arranged in the circumferential direction of the tubular member 12. However, the present invention is not limited to this. It may be configured to be arranged in the axial direction. In other words, the configuration may be such that the openings 32 of the plurality of sound absorbing members 24 are arranged at at least two or more positions in the axial direction of the tubular member 12.

  For example, the noise reduction system 10h illustrated in FIG. 17 includes a sound absorbing material 24a disposed substantially at the center of the tubular member 12 and a sound absorbing material 24b disposed near one end of the tubular member 12 in the axial direction. . A part of the surface of the tubular member 12 on the central axis side of each of the sound absorbing material 24a and the sound absorbing material 24b is covered with a high resistance member (28a and 28b), and the remaining part is an opening (32a and 32b). I have. A peripheral surface opening 12a is formed in each of the positions where the sound absorbing material 24a and the sound absorbing material 24b are arranged on the tubular member 12, and the surface of the sound absorbing material 24 having the opening 32 and the high-resistance member 28 is Are arranged in the peripheral surface opening 12a formed on the peripheral surface of the hologram.

  In the example shown in FIG. 17, two sound absorbing materials are also arranged rotationally symmetrically in the circumferential direction. Thus, two or more sound absorbing materials may be arranged in each of the circumferential direction and the axial direction.

  In the example shown in FIG. 17, two sound absorbing materials are arranged in the axial direction. However, the present invention is not limited to this, and three or more sound absorbing materials may be arranged in the axial direction.

Further, in the case of the construction of arranging the plurality of sound absorbing material in the axial direction is preferably a length L _d of the sound absorbing material is arranged different sound-absorbing material for each position of the opening.
For example, the noise reduction system 10i illustrated in FIG. 18 includes a sound absorbing material 24a arranged substantially at the center of the tubular member 12 and a sound absorbing material 24b connected near one end of the tubular member 12 in the axial direction. . The depth L _d of the sound absorbing material 24a of the central portion, the depth L _d of the sound absorbing material 24b of the end-side differ from each other.

When a plurality of sound absorbing materials are arranged in the axial direction, the acoustic characteristics of the sound absorbing materials may be different for each position of the opening.
For example, in the example shown in FIG. 17, the sound absorbing properties of the sound absorbing material 24a and the sound absorbing material 24b may be different from each other.

In the noise reduction system of the present invention, the wavelength at which the noise can be properly reduced changes according to the position of the sound absorbing material (opening) in the axial direction. Therefore, by arranging a plurality of sound absorbing materials in the axial direction, sounds in different wavelength ranges can be silenced, and the sound can be silenced in a wider band. In addition, by adjusting the depth L _d of the sound absorbing material and the sound absorbing characteristics of the sound absorbing body in accordance with the wavelength that can be appropriately muffled for each position of the opening in the axial direction, the sound can be more appropriately muffled. .

Further, in the example shown in FIG. 1, although the sound absorbing material 24 was configured to have a depth L _d from the opening 32 in the axial direction, this is not the sole, has a depth from the opening 32 in the circumferential direction It may be configured.

FIG. 19 is a cross-sectional view schematically illustrating another example of the noise reduction system of the present invention, and FIG. 20 is a cross-sectional view taken along line CC of FIG.
In the noise reduction system shown in FIGS. 19 and 20, two peripheral openings are formed along the circumferential direction of the tubular member 12, and two sound absorbing members 24 are provided at the positions of the peripheral openings. 12 are arranged along the outer peripheral surface. A part of the surface of the sound absorbing material 24 on the central axis side of the tubular member 12 is formed as an opening 32 in the circumferential direction, and the remaining part is covered with a high-resistance member 28.
Therefore, the sound absorbing material 24 extends from the opening 32 along the circumferential direction of the tubular member 12. That is, the sound absorbing material 24 has a depth from the opening 32 in the circumferential direction.
With such a configuration, the length of the sound absorbing material in the axial direction can be reduced.

  In the example illustrated in FIG. 20, the configuration includes two sound absorbing members 24, but is not limited thereto, and may include three or more sound absorbing members 24. For example, as shown in an example shown in FIG.

Here, in the sound deadening system of the present invention, when the sound absorbing material is arranged on one end surface side of the wall 16 (the tubular member 12), a part of the sound absorbing device is inserted and arranged in the tubular member (the ventilation sleeve). It is good also as a structure which performs.
FIG. 22 shows a schematic cross-sectional view of another example of the sound deadening system of the present invention.
The silencing system 10k illustrated in FIG. 22 has a configuration in which a silencer 14 that silences a sound passing through the tubular member 12 is provided on one end surface side of the wall 16 (the tubular member 12).

The noise reduction device 14 includes an insertion portion 26, a sound absorbing material 24, a case 27 that houses the sound absorbing material 24, a high-resistance member 28 that covers a part of the surface of the sound absorbing material 24 on the central axis side of the tubular member 12. And
The insertion portion 26 is a cylindrical member having both ends opened, and a case portion 27 is fixed to one end surface. The outer diameter of the insertion portion 26 is substantially the same as the inner diameter of the tubular member 12 and can be inserted into the tubular member 12.
The case 27 has the same configuration as the case 27 of FIG. 1 except that the case 27 is fixed to the end face of the insertion section 26. The case 27 is arranged along the peripheral surface of the insertion section 26 so as not to block the inner diameter of the insertion section 26. The case portion 27 is fixed to the insertion portion 26 such that the open surface faces the center axis of the insertion portion 26 (the center axis of the tubular member 12).
The sound absorbing material 24 is disposed in the case portion 27, and a part of the surface of the sound absorbing material 24 on the central axis side of the tubular member 12 (that is, the surface on the open surface side of the case portion 27) is a high resistance member 28. Covered with.

  The silencer 14 is inserted into the tubular member 12 from the end face of the insertion portion 26 where the case 27 is not arranged, and is installed. Since the outer diameter of the case portion 27 is larger than the inner diameter of the tubular member 12, the insertion portion 26 is inserted to a position where the case portion 27 contacts the end surface of the tubular member 12. Thereby, the sound absorbing material 24 is arranged near the opening end face of the tubular member 12. That is, the opening 32 of the sound absorbing material 24 is arranged in a space within the opening end correction distance of the tubular member 12. Therefore, the opening 32 of the sound absorbing material 24 is connected to the first resonance sound field space of the tubular member 12.

  In this manner, by adopting a configuration in which the insertion portion of the silencer having the insertion portion is inserted into the tubular member and installed, the large-scale construction or the like can be easily performed on the existing ventilation ports and air conditioning ducts. It is possible to install a silencer. Therefore, replacement when the sound absorbing material is deteriorated or damaged is easy. In addition, when used as a ventilation sleeve of a house, it is not necessary to change the diameter of the through hole in the concrete wall, and the construction is simple. In addition, it is easy to install it later during renovation.

  In addition, a wall of a house such as an apartment is configured to have, for example, a concrete wall, a plaster board, a heat insulating material, a decorative board, and wallpaper, and a ventilation sleeve is provided therethrough. . When the silencer 14 as shown in FIG. 22 is installed on the ventilation sleeve of such a wall, the wall 16 in the present invention corresponds to a concrete wall, and the sound absorbing material 24 of the silencer 14 is located outside the concrete wall. Is preferably installed between the concrete wall and the decorative panel (see FIG. 30).

In the example shown in FIG. 22, the insertion portion 26 of the silencer 14 is inserted into the tubular member 12, and the silencer 14 is arranged at the opening of the tubular member 12, but the present invention is not limited to this.
For example, as in the sound muffling system 10n shown in FIG. 23, the sound muffling device 14 may have no insertion portion, and may be attached to the wall 16 with an adhesive or the like.
Alternatively, as in the silencing system 10p shown in FIG. 24, the inner diameter of the insertion portion 26 of the silencer 14 is set to be substantially the same as the outer diameter of the tubular member 12 arranged on the wall 16, and the inside of the insertion portion 26 of the silencer 14 is A configuration in which the tubular member 12 is inserted and the silencer 14 is installed may be adopted. The insertion section 26 is disposed between the tubular member 12 and the wall 16.
Alternatively, as in the noise reduction system 10q shown in FIG. 25, the inner diameter of the insertion portion 26 of the noise reduction device 14 may be larger than the outer diameter of the tubular member 12, and the insertion portion 26 may be disposed in the wall 16. .
With the configuration as shown in FIGS. 23 to 25, a decrease in the aperture ratio due to the insertion of the insertion portion 26 into the tubular member 12 can be suppressed, and the air permeability of the tubular member 12 can be improved.

  As shown in FIGS. 24 and 25, when the insertion section 26 is arranged in the wall 16, the insertion section 26 is arranged on the wall 16 according to the size and shape of the insertion section 26. May be formed. Alternatively, when producing the wall 16, the muffler 14 (and the tubular member 12) may be installed in advance, and the wall 16 may be produced by pouring concrete.

Further, also in a case where the sound absorbing material 24 is arranged on one end surface side of the wall 16, the sound absorbing device 14 preferably includes a plurality of sound absorbing materials 24.
In the case where a plurality of sound absorbing members 24 are provided, the sound absorbing members 24 may be arranged at equal intervals in the circumferential direction to be rotationally symmetric.
Alternatively, as in the noise reduction system 101 shown in FIG. 26, a plurality of sound absorbing materials 24 (24 a and 24 b) are provided in the axial direction, and the openings 32 ( 32a and 32b) may be arranged.

Further, in the case of the construction of arranging the plurality of sound absorbing material in the axial direction is preferably the depth L _d of the sound absorbing material is arranged different sound-absorbing material for each position of the opening.
For example, the sound deadening device shown in FIG. 27 has a sound absorbing material 24a and a sound absorbing material 24b in the axial direction from the insertion portion 26 side. The depth L _d of the sound absorbing material 24a, the depth L _d of the noise absorbing member 24b different from each other.

When a plurality of sound absorbing materials are arranged in the axial direction, the acoustic characteristics of the sound absorbing materials may be different for each position of the opening.
For example, in the sound deadening device shown in FIG. 26, the sound absorbing characteristics of the sound absorbing material 24a and the sound absorbing material 24b may be different from each other.

  Further, the muffling device may be configured so that the case portion can be separated. By making the case part separable, it becomes easy to manufacture a noise reduction device in which the size and number of the case part (sound absorbing material) are changed.

In addition, as shown in FIG. 28, it is preferable that the silencer 14 is detachably installed on the tubular member 12. This makes it possible to easily replace or remodel the silencer 14.
Further, the silencer 14 may be installed on either the indoor end surface or the outdoor end surface of the tubular member 12, but is preferably installed on the indoor end surface.

In addition, the muffling system may include at least one of a cover member installed on one end surface of the tubular member and an air volume adjustment member installed on the other end. The cover member is a conventionally known louver, rattle, 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 face of the tubular member on which the silencer is installed, or may be installed on the end face on which the silencer is not installed.
Also, for example, as shown in FIG. 29, when the air volume adjustment member 20 is installed on the muffler 14 side, the air volume adjustment member 20 is installed so as to cover the entire muffler 14 when viewed from the axial direction. Preferably. The same applies to the case where the cover member is installed on the muffler 14 side.

Here, in a general house such as an apartment, a concrete wall and a decorative panel are installed separately from each other, and a heat insulating material and the like are disposed between the concrete wall and the decorative panel. It is preferable that the silencer 14 is installed in a space between the concrete wall and the decorative panel. At that time, as shown in FIG. 30, the sound deadening device 14 may be configured such that the end face on the decorative board 40 side is disposed closer to the wall 16 than the face of the decorative board 40 on the wall 16 side. Alternatively, as shown in FIG. 31, the silencer 14 may have a configuration in which the end surface on the decorative plate 40 side is arranged flush with the surface of the decorative plate 40 on the side opposite to the wall 16. That is, the through-hole formed in the decorative board 40 may be made substantially the same as the outer diameter of the muffler 14 so that the muffler 14 is inserted through the through-hole of the decorative board 40. In the example shown in FIG. 31, the silencer 14 has a configuration in which the end face on the decorative board 40 side and the face of the decorative board 40 on the opposite side to the wall 16 are flush, but the present invention is not limited to this. Alternatively, a configuration in which a part of the muffler 14 is present on a plane where the decorative board 40 is located may be used.
The configuration in which the silencer 14 is inserted through the through hole of the decorative plate 40 facilitates installation, replacement, and the like of the silencer.

The larger the size of the sound absorbing material 24 of the noise reduction device 14, the higher the noise reduction performance.
Here, as shown in FIG. 31, when the end surface on the decorative plate 40 side is arranged flush with the surface of the decorative plate 40 on the opposite side to the wall 16, as shown in FIG. Is large, the through-hole (the boundary between the muffler 14 and the decorative panel 40) formed in the decorative panel 40 is visually recognized from the room even when the air volume adjusting member 20 such as a register is installed on the decorative panel 40 side. There is a risk that it will. Therefore, as shown in FIG. 32, it is preferable to install a boundary cover 42 between the air volume adjusting member 20 and the decorative board 40 and the muffler 14. Thereby, as seen from the indoor side (the air flow adjusting member 20 side), as shown in FIG. 33, the through-hole of the decorative board 40 is hidden by the boundary cover 42, so that the design can be enhanced.

  In the example shown in FIG. 32, the muffler 14 and the boundary cover 42 are separate members, but the muffler 14 and the boundary cover 42 may be formed integrally. That is, a fringe may be provided in the case 27 of the silencer 14 to form the boundary cover 42.

In the example shown in FIG. 30 and the like, the inner diameter of the silencer 14 is substantially the same as the diameter of the tubular member 12 and is uniform, but the present invention is not limited to this. 34, the inner diameter of the case 27 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 case 27 larger than the inner diameter of the tubular member 12, a large air volume adjusting member 20 for a tubular member having a diameter larger than the diameter of the tubular member 12 can be used. By using the large air 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 enhanced.

Further, as in the silencing system 10s shown in FIG. 36, the silencing device 14 and the air volume adjusting member 20 may be integrated.
As shown in FIG. 31 and the like, the air volume adjusting member 20 such as a commercially available register has an insertion portion, and the insertion portion is inserted into the muffler 14 and installed. However, the insertion portion of a commercially available register has a length of about 5 cm for securing rigidity and airtightness at the time of connection, and there is a possibility that the design of the silencer 14 may be limited. On the other hand, as shown in FIG. 36, by integrating the silencer 14 and the air volume adjusting member 20, it is preferable in that the degree of freedom of design of the silencer 14 is increased and the construction is simplified.

When the noise reduction system has the cover member and the air volume adjustment member, the first resonance generated in the tubular member is the first resonance of the tubular member in the noise reduction system including the cover member, the air volume adjustment member, and the noise reduction device. . Accordingly, the length L _d of the sound absorbing material, the cover member, a short is preferred than 1/4 of the air flow rate adjusting member and the wavelength of the sound wave at the resonant frequency of the first resonance of the tubular member in a silencer system including a muffler lambda.

Further, in the example shown in FIG. 1 and the like, the surface of the sound absorbing material 24 other than the opening 32 is covered with the high-resistance member 28 and the case 27, but the present invention is not limited thereto. The sound absorbing material 24 may be disposed in at least a part of the space surrounded by the space 28 or the space surrounded by the high-resistance member 28 and the case 27. That is, the sound absorbing space including the sound absorbing material 24 and the space may be covered with the high-resistance member 28 (and the case 27).
In addition, even in the case of a configuration in which the sound absorbing space including the sound absorbing material 24 and the space is covered with the high resistance member 28 (and the case portion 27), the high resistance member 28 covers at least a part of the sound absorbing material 24.

Further, in the sound deadening system of the present invention, another commercially available sound insulating member may be provided.
For example, as shown in FIG. 36, at one end of the tubular member 12, the silencer 14 according to the present invention is arranged, and inside the tubular member 12, an insertion type silencer 50 is arranged. Is also good.
Further, as shown in FIG. 37, a sound deadening device 14 of the present invention is disposed at one end of the tubular member 12, and a field-installed soundproof hood 52 is disposed at the other end of the tubular member 12. May be adopted.
Alternatively, the muffler 14 according to the present invention is arranged at one end of the tubular member 12, and an insertion silencer 50 is arranged inside the tubular member 12, and the other end of the tubular member 12 is arranged at the other end of the tubular member 12. May be configured such that an outdoor installation type soundproof hood 52 is arranged.
As described above, by combining with another soundproofing member, high soundproofing performance can be obtained in a wider band.

As the interpolation silencer 50, various known interpolation silencers can be used. For example, Shinkyowa 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.), Inc. Unix: Silencer (UPS100SA etc.), Kento Corporation: Silent Sleeve P (HMS-K etc.), etc. can be used.
Various known soundproof hoods can be used as the outdoor-installed soundproof hood 52. For example, a soundproofing hood (such as SSFW-A10M) manufactured by Unix Corporation, a soundproofing hood (such as BON-TS) manufactured by Sylpher, Inc. can be used.

  Hereinafter, the present invention will be described in more detail with reference to examples. Materials, usage amounts, ratios, processing contents, processing procedures, and the like shown in the following examples can be appropriately changed 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, a result of a simulation performed on the sound deadening system of the present invention will be described.
The simulation was performed using an acoustic module of the finite element method calculation software COMSOL ver5.3 (COMSOL).

FIG. 38 shows a simulation model. As shown in FIG. 38, the thickness of the wall 16 was 209 mm, and the diameter of the tubular member 12 was 100 mm. The sound absorbing material 24 was annularly arranged on the outer periphery of the tubular member 12, the axial direction was the depth direction, the axial length was 60 mm, and the width L _{w of the} sound absorbing material was 10 mm. The opening 32 was arranged in a slit shape in the circumferential direction of the tubular member 12. The width of the opening 32 was 12 mm. The depth L _d of the sound absorbing material is 54 mm. The distance from the surface of the wall on the sound wave incident side to the opening 32 was 102 mm. The opening 32 is formed at the end of the sound absorbing material 24 on the sound wave incident side. The high-resistance member 28 was arranged in a region of the sound absorbing material 24 other than the opening 32 on the central axis side surface of the tubular member. The surface of the sound absorbing material 24 other than the surface on the central axis side of the tubular member was in contact with the rigid body.
The flow resistance of the sound absorbing material 24 was 27000 [Pa · s / m ² ], and the acoustic characteristic impedance was 826 [kg / (s · m ² )]. The acoustic characteristic impedance of the high resistance member 28 was set to 5 × 10 ⁷ [kg / (s · m ² )].
The thickness is. 5 mm.

Further, the tubular member 12 has a configuration in which a louver (cover member) is disposed in an opening on the sound wave incident side and a register (air volume adjusting member) is disposed in the opening on the sound wave emitting side.
The model and the register were modeled with reference to commercially available products.

[Reference example]
First, as a reference, a simulation was performed on a sound wave transmitted through a tubular member when no muffler was installed (in the case of a straight tube). The relationship between the sound pressure (transmitted sound pressure) and the frequency of the sound wave transmitted from one space to the other space through the tubular member was calculated by simulation. The results are shown in FIG.
As shown in FIG. 39, when the silencer is not installed, the transmitted sound pressure is high at the resonance frequency of the resonance generated in the tubular member. The first resonance frequency is 510 Hz.

[Simulation 1]
Next, as a simulation 1, as shown in FIG. 38, regarding a configuration in which the sound absorbing material 24 (the sound absorbing device 14) is arranged on the outer peripheral surface of the tubular member 12, the high resistance member with respect to the absolute value of the acoustic characteristic impedance of the sound absorbing material 24 is used. The simulation was performed by variously changing the ratio Zr of the acoustic characteristic impedance, and the relationship between the frequency and the transmission loss was calculated. Specifically, simulations were performed for the cases where the impedance ratio Zr was 1.04, 1.85, 3.41, 7.00, 13.75, 29.08, and 57.97.
The results are shown in FIG. The transmitted sound pressure is a value normalized by setting the transmitted sound pressure of the primary resonance frequency in the reference to 1.
Further, from the relationship between the transmitted sound pressure and the frequency shown in FIG. 39, the average value of the transmission loss at the frequency of 350 Hz or more and 710 Hz or less was determined as the transmission loss of the 500 Hz octave band. FIG. 40 shows the relationship between the transmission loss in the 500 Hz octave band and the impedance ratio Zr.

As shown in FIGS. 39 and 40, it can be seen that the higher the impedance ratio Zr, that is, the higher the acoustic characteristic impedance of the high resistance member 28, the lower the transmitted sound pressure and the higher the soundproofing performance.
From FIG. 39, it can be seen that the transmitted sound pressure is selectively low particularly near the first resonance frequency, and the soundproofing performance in this frequency band is high. In the noise reduction system of the present invention, the sound absorbing effect of the sound absorbing material 24 depends on the sound pressure and the particle velocity of gas molecules. Therefore, the sound deadening system of the present invention has high soundproofing performance in the vicinity of the first resonance frequency at which the sound pressure increases due to the resonance phenomenon of the tubular member.
In addition, FIG. 40 shows transmission loss values in a 500 Hz octave band when the high resistance member is a rigid body and when there is no high resistance member, by broken lines.

[Simulation 2]
Next, as a simulation 2, in the case of each impedance ratio Zr, a simulation is performed by variously changing the thickness t of the high-resistance member 28, a relationship between a frequency and a transmission loss is calculated, and a transmission loss of a 500 Hz octave band is obtained. Was.
The results are shown in FIG.

  From FIG. 41, it can be seen that as the thickness t of the high resistance member 28 increases, the transmission loss in the 500 Hz octave band increases. On the other hand, when the impedance ratio Zr and the thickness t are sufficiently high, the transmission loss in the 500 Hz octave band has a substantially constant value. From the above, it is understood that the transmission loss depends on the impedance ratio Zr and the thickness t.

Therefore, the parameter P _tZ including the thickness t of the impedance ratio Zr and the high resistance member 28, is defined as _{P tZ = log (t × Zr} 2.5), the thickness t of the impedance ratio Zr and the high resistance member 28 by variously changing A simulation was performed to determine the _relationship between the parameter _PtZ and the effect manifestation rate of peak sound absorption at 500 Hz (hereinafter, also simply referred to as “effect manifestation rate”) [%].
The effect manifestation rate R of the peak sound absorption at 500 Hz means that the transmission loss when there is no high resistance member is TL _min , the transmission loss when the high resistance member is a rigid body is TL _mmax , and the high resistance member has an arbitrary impedance _Let TLX _denote the transmission loss of
_{R = 100 × (TL X -TL} min) / (TL mmax -TL min)

From FIG. 42, it can be seen that a certain relationship is established between the parameter P _tZ and the effect onset. When a relational expression between the parameter _PtZ and the effect expression rate Ye was obtained by fitting, it was found that the following relational expression was established.
Ye = 100 / (1 + exp (-( _PtZ- 1.961) /0.4390))

From this relational expression, it is understood that the parameter P _tZ (= log (t × Zr ^2.5 )) needs to be 1.99 or more in order to make the effect expression rate Ye 50% or more. Further, the parameter _PtZ is preferably 2.62 or more from the viewpoint that the effect expression rate Ye can be 80% or more, and the parameter _PtZ is 3.88 or more from the point that the effect expression rate Ye can be almost 100%. Is more preferred.

[Simulation 3]
Next, the result of a simulation of the flow resistance of the sound absorbing material 24 will be described.
FIG. 43 shows the result of a simulation in which the flow resistance of the sound absorbing material 24 was variously changed in the model of the simulation 1. The impedance ratio Zr was set to 57.97.
It can be seen from FIG. 43 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 inside of the sound absorbing material 24, and the conversion efficiency of sound energy to heat energy by the sound absorbing material 24 decreases.

Further, based on the above simulation results, the combination of the flow resistance of the depth L _d and sound absorbing material 24 of the sound absorbing material 24, a result of the transmitted sound pressure was measured is shown in FIGS. 44 and 45. Figure 44 is a graph depth L _d of the sound absorbing material 24 is represented in each case 10mm (1cm) ~140mm (14cm) , the relationship between the peak value of the flow resistance and the transmission sound pressure of the sound absorbing material 24. Figure 45 is a graph showing the peak value of the transmitted sound pressure to the flow resistance of the depth L _d and sound absorbing material 24 of the sound absorbing material 24.
As shown in FIGS. 44 and 45, the flow resistance of the sound absorbing material 24, it can be seen that there is a preferable range according to the depth L _d of the sound absorbing material 24. 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 (log (0.1 × L _d ) −1.25) /0.24 <log (σ ₁ ) <. 5.6 is preferable, (log ((0.1 × L _d )) − 1.32) /0.24 <log (σ ₁ ) <5.2 is more preferable, and (log ((0.1 × L _d )) is less than 5.2. _d ))-1.39) /0.24 <log (σ ₁ ) <4.7 is more preferable. In the above formulas, the unit of L _d is [mm], the unit of flow resistance σ1 is ^{[Pa · s / m 2]} , log is a natural logarithm.

[Results]
Next, a description will be given of a result of evaluating a soundproofing performance by producing a sound deadening system.
For performance evaluation, a simple small soundproof room as shown in FIG. 46 was used.

The simple soundproof room shown in FIG. 46 is surrounded on five sides by a sound-absorbing urethane foam W ₃ (thickness: 100 mm, U00F2 manufactured by Fuji Rubber Industries Co., Ltd.) and an acrylic plate W ₁ having a thickness of 5 mm disposed outside thereof. a face, an aluminum plate W ₅ (thickness 3mm) from the soundproof chamber side wall in the glass wool W ₆ (Seishiro Trade Ltd. 32501211 density 32 kg / m ³ non formaldehyde) and wall members (present invention made of an acrylic plate W ₁ 16 ). The total thickness of the wall members was 100 mm. Further, an acrylic plate W ₁ (corresponding to a decorative plate in the present invention) is arranged at a distance of 110 mm from the wall member and parallel to the wall member.
Also, among the sound-absorbing urethane foam W ₃ of five surfaces, the inner surface of the three faces are disposed on the left and right surfaces, corrugated acoustical polyurethane foam W ₄ (maximum thickness 35 mm, Fuji rubber industry Co., Ltd. U00F6) is Are located. The size of the soundproof room was 800 mm x 800 mm x 900 mm.
A ventilation sleeve (tubular member) 12 made of vinyl chloride and having an inner diameter of 100 mm and a length of 100 mm was installed in the wall member made of the aluminum plate W ₅ , the glass wool W _6, and the acrylic plate W ₁ , penetrating the wall member. The decorative plate (acrylic plate W ₁ ) has an opening of 100 mm at the same position as the ventilation sleeve when viewed from the axial direction of the ventilation sleeve.
Incidentally, acrylic plate W ₁ and the aluminum plate W ₅ is supported by fixing the ends in an aluminum frame Fr of 30mm square.

  A horizontal gutter (SG-CB manufactured by Unix Corporation) is attached as a cover member 18 to the end surface of the ventilation sleeve 12 in the soundproof room, and a register (KRP- manufactured by Unix Corporation) is provided on the outer end surface of the ventilation sleeve 12 as an air volume adjusting member 20. BWF).

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

  First, ten circular acrylic plates (thickness: 5 mm) having the same size (diameter: 100 mm) as the inner diameter of the reference sound insulating material were placed in the ventilation sleeve 12. Thus, 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 measuring microphone MP at a sampling rate of 25000 Hz for 10 seconds. Fourier transform was performed on the measured sound pressure data to calculate a frequency spectrum. The data after Fourier transform was averaged at 10 Hz intervals. This data is used as background data.

  Next, the register 20 was fully opened, the sound pressure was measured in the same manner as above, a Fourier transform was performed on the sound pressure data, a frequency spectrum was calculated, and a difference from the background data was obtained as reference data. .

[Comparative Example 1]
Next, as Comparative Example 1, the sound insulating material for reference was removed, and the sound absorbing material 24 was installed in the ventilation sleeve 12. As the sound-absorbing material 24, a sound-absorbing urethane (Calmflex F-2 manufactured by Inoac Corporation) was used in a cylindrical shape (see FIG. 47). The length in the axial direction was 70 mm, the outer diameter was 100 mm, and the inner diameter was 70 mm. When the acoustic characteristic impedance of the sound absorbing material 24 was measured by the method described above, it was 6304 [kg / (s · m ² )].

With the register 20 fully opened, the sound pressure is measured in the same manner as described above, a Fourier transform is performed on the sound pressure data, a frequency spectrum is calculated, and a difference from the background data is obtained to obtain transmitted sound pressure data. .
The results are shown in FIG.

[Example 1]
As Embodiment 1, as shown in FIG. 48, the inner peripheral surface of the sound absorbing material 24 is covered with a high resistance member 28 with an axial width _Lo of 12 mm, and all other surfaces of the sound absorbing material 24 have high resistance. A silencing system was produced in the same manner as in Comparative Example 1 except that the structure was covered with the member 28, and data on transmitted sound pressure was obtained.
As the high resistance member 28, a PET film (Lumirror manufactured by Toray Industries, Inc.) having a thickness of 50 μm was used. The acoustic characteristic impedance was 2.9 × 10 ⁶ [kg / (s · m ² )]. That is, the parameter P _tZ (= log (t × Zr ^2.5 )) was 7.99.
The results are shown in FIG.

[Example 2]
Except that a 350 μm-thick PET film (Lumirror manufactured by Toray Industries, Inc.) was used as the high-resistance member, a noise reduction system was prepared in the same manner as in Example 1, and data on transmitted sound pressure was obtained. The parameter P _tZ (= log (t × Zr ^2.5 )) was 8.83.
The results are shown in FIG.
Further, from the relationship between the transmitted sound pressure and the frequency shown in FIGS. 49 to 51, the average value of the transmission loss at a frequency of 350 Hz or more and 710 Hz or less was determined as the transmission loss of a 500 Hz octave band. The results are shown in FIG.

From FIG. 49 to FIG. 52, it can be seen that the embodiment of the noise reduction system of the present invention has higher transmission loss and higher soundproofing performance as compared with the comparative example, though the sound absorbing material 24 is the same.
Further, it can be seen from FIGS. 49 to 51 that the transmission loss increases in the example, particularly near the first resonance frequency.

FIG. 53 is a graph in which the positions of the parameter P _tZ of Example 1 and Example 2 are plotted on a graph showing the relationship between the parameter P _tZ and the effect expression rate Ye of FIG. As shown in FIG. 53, Example 1 and Example 2 are conditions under which substantially the same (approximately 100%) effect expression rate can be obtained. From the comparison between the first embodiment and the second embodiment in FIGS. 50 to 52, the same effect is obtained with respect to the transmitted sound pressure and the transmission loss, although the thickness of the high resistance member 28 is different by 7 times. You can see that.
The effects of the present invention are clear from the above results.

10a to 10s Silencer system 12 Tubular member 12a Peripheral opening 14 Silencer 16 Wall 18 Cover member 20 Air flow adjusting member 24, 24a, 24b Sound absorbing material 26 Insertion part 27, 27a, 27b Case part 28, 28a, 28b High resistance member 32, 32a, 32b Opening 40 Decorative plate 42 Boundary cover 50 Interpolation type silencer 52 Soundproof hood

Claims (24)

A muffling system in which a muffling device for muffling a sound passing through the tubular member is installed on a tubular member provided through a wall separating two spaces,
The silencer includes a sound absorbing material and a high resistance member having a higher acoustic characteristic impedance than the sound absorbing material,
A part of the surface of the sound absorbing material is an opening connected to a first resonance sound field space of the tubular member in the sound deadening system,
At least another portion of the surface of the sound absorbing material is covered with the high-resistance member, and is isolated from the sound field space.
The depth L _d of the noise absorbing member in the travel direction of sound waves entering into the noise absorbing member from said opening is larger than the width L _o of the opening portion in the axial direction of the tubular member,
When the ratio of the acoustic characteristic impedance of the high resistance member to the absolute value of the acoustic characteristic impedance of the sound absorbing material is Zr, and the thickness of the high resistance member is t (mm),
log (t × Zr ^2.5 ) ≧ 1.99
A silencing system that satisfies. 2. The noise reduction system according to claim 1, wherein, assuming that the wavelength of the sound wave at the resonance frequency of the first resonance is λ, the depth L _d of the sound absorbing material satisfies 0.011 × λ <L _d <0.25 × λ. .   The noise reduction system according to claim 1, wherein a thickness t of the high-resistance member is 0.01 mm or more and 3.00 mm or less. The acoustic characteristic impedance of the high resistance member with respect to the absolute value of the acoustic characteristic impedance of the sound absorbing material is not less than 2.4 × 10 ^{4 and not} more than 5 × 10 ⁷ [kg · m ⁻² · s ⁻¹ ]. 4. The sound deadening system according to any one of items 3 to 5. The ratio Zr of the acoustic characteristic impedance of the high resistance member to the absolute value of the acoustic characteristic impedance of the sound absorbing material, and the thickness t (mm) of the high resistance member are:
1.99 ≦ log (t × Zr ^2.5 ) ≦ 11.0
The muffling system according to any one of claims 1 to 4, which satisfies the following. In a cross section parallel to the axial direction, the width L _w of the sound absorbing material in a direction orthogonal to the depth direction of the sound absorbing material, 0.001 × lambda <claim 1 satisfying L _w <0.061 × λ The noise reduction system according to any one of claims 5 to 13. In a cross section parallel to the axial direction, the sound absorbing material has a rectangular shape extending in the axial direction,
Wherein the sound absorbing material is the length of the axial depth L _d,
A part of the surface of the sound absorbing material on the central axis side of the tubular member is the opening connected to the first resonance sound field space of the tubular member,
The noise reduction system according to any one of claims 1 to 6, wherein at least another part of the surface of the sound absorbing material on the central axis side of the tubular member is covered with the high-resistance member.   The noise reduction system according to claim 7, wherein a surface of the sound absorbing material other than a surface on the central axis side of the tubular member is covered with the high resistance member.   The noise reduction system according to claim 7, wherein the noise reduction device has a case portion that covers a surface of the sound absorbing material other than a surface on the central axis side of the tubular member. Silencer system according in the circumferential surface, the area S ₁ of the openings in any one of smaller claims 7-9 than the area S ₀ of the sound absorbing material to the axial center axis of the tubular member. 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 silencing system according to the section. Having two or more said sound absorbing materials,
The noise reduction system according to any one of claims 1 to 11, wherein the openings of each of the sound absorbing members are arranged rotationally symmetrically with respect to a central axis of the tubular member.   The noise reduction system according to any one of claims 1 to 12, wherein the sound absorbing material is disposed on one end surface side of the wall. The muffling device, a cylindrical insertion portion connected to the tubular member,
A case portion for covering the surface of the sound absorbing material other than the surface on the central axis side of the tubular member,
The noise reduction system according to claim 13, wherein the insertion portion is arranged such that a central axis thereof is aligned with a central axis of the tubular member.   The noise reduction system according to claim 1, wherein at least a part of the sound absorbing material is arranged on an outer periphery of the tubular member. In a cross section perpendicular to the axial direction, said the effective outer diameter D ₀ of the tubular member, wherein a is the effective outer diameter D ₁ of the sound-absorbing material, D ₁ <claims D ₀ + 2 × satisfy (0.045 × λ + 5mm) 15. The noise reduction system according to item 15.   The noise reduction system according to any one of claims 1 to 13, wherein the sound absorbing material is disposed inside the tubular member. Having a plurality of said sound absorbing materials,
The noise reduction system according to any one of claims 1 to 17, wherein the openings of the plurality of sound absorbing materials are arranged at at least two positions in an axial direction of the tubular member. For each position of the opening, silencer system according to claim 18, the depth L _d of the sound absorbing material is different.   20. The noise reduction system according to claim 18, wherein the acoustic characteristics of the sound absorbing material are different for each position of the opening. A muffling system in which a muffling device is arranged on a tubular member provided through a wall separating two spaces,
The silencer includes a sound absorbing material and a high resistance member having a higher acoustic characteristic impedance than the sound absorbing material,
A part of the surface of the sound absorbing material is an opening connected to a first resonance sound field space of the tubular member in the sound deadening system,
At least another portion of the surface of the sound absorbing material is covered with the high-resistance member, and is isolated from the sound field space.
Wherein S ₁ the area of the opening of the sound absorbing material, when the surface area of the inner wall of the sound absorbing material to S _d, the ratio S ₁ / S _d of the area S ₁ to the area S _{d is, 0 <S 1 / S d} <40 %The filling,
When the ratio of the acoustic characteristic impedance of the high resistance member to the absolute value of the acoustic characteristic impedance of the sound absorbing material is Zr, and the thickness of the high resistance member is t (mm),
log (t × Zr ^2.5 )> 1.99
A silencing system that satisfies. In the axial direction of the tubular member, the sound absorbing material is disposed between the wall and a decorative plate disposed apart from the wall, with a part being inserted through a through hole formed in the decorative plate. Has been
The noise reduction system according to any one of claims 1 to 21, further comprising a boundary cover that covers a boundary between the decorative plate and the through hole when viewed from an axial direction of the tubular member. In the axial direction of the tubular member, the sound absorbing material is disposed at one end of the tubular member,
23. The sound deadening system according to any one of claims 1 to 22, further comprising a soundproof member disposed in the tubular member. In the axial direction of the tubular member, the sound absorbing material is disposed at one end of the tubular member,
The noise reduction system according to any one of claims 1 to 23, further comprising a soundproof member disposed at the other end of the tubular member.