KR101549045B1 - Sound insulation wall equipped with sound-absorbing body - Google Patents

Abstract

A sound absorbing body capable of increasing the sound absorbing effect and reducing the number of components and achieving miniaturization, and a soundproofing wall using the same. A plate member (1) having rigidity for generating a pressure gradient by generating a sound pressure difference by a front surface side and a back surface side in the vicinity of an edge of the plate member (1) And a sound absorbing material (2) disposed near the edge of the member.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a sound-

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a soundproof wall using a sound absorbing body that can be used indoors or outdoors to exert a sound absorbing effect with good efficiency.

As such a sound absorbing body, there are a sound absorbing material made of a fibrous material, a breathable protection material superimposed on each of both sides of the sound absorbing material, and a vibration absorbing material attached to the periphery of the air permeable protective material and the sound absorbing material, (For example, refer to Patent Document 1).

Patent Document 1: Japanese Utility Model Registration Application Laid-Open Publication 60 (1985) -75509 (see Fig. 1)

According to the structure of Patent Document 1, since the sound-absorbing material is composed of many parts such as a sound-absorbing material, two air-permeable protection materials, and a frame, it is disadvantageous both in terms of assembling work surface and cost.

Further, the sound absorbing body is configured to absorb noise by converting air energy particles into thermal energy by decelerating particles of air when particles of air having a predetermined velocity energy pass through the sound-absorbing material. In order to improve the sound absorption effect of such a sound-absorbing material to some extent, the thickness of the sound-absorbing material must be increased. As a result, there has been a problem that the entire sound absorbing body is increased in size.

SUMMARY OF THE INVENTION An object of the present invention is to provide a soundproofing wall using a sound absorbing material capable of reducing the number of parts and achieving miniaturization while improving the sound absorption effect.

In order to solve the above-mentioned problem, the sound absorbing body of the present invention is characterized in that a plate member having a rigidity for generating a sound pressure difference by a surface side and a back surface side in the vicinity of an edge to give a pressure gradient, And a sound absorbing material including a sound absorbing material disposed in the vicinity of an edge of the plate member so as to consume energy of the particle velocity of the air accelerated by the pressure gradient, wherein the sound absorbing material comprises: Wherein at least one of the area density and the flow resistance value of the sound absorbing material extends in a direction along the surface direction of the plate member so that a value outside the plane direction of the sound absorbing material is smaller Is set so as to be set.

According to the configuration of the present invention, the plate member having rigidity can generate a sound pressure difference between the front surface side and the back surface side in the vicinity of the edge, and a pressure gradient is imparted on the front surface side and the back surface side near the edge by the sound pressure difference I can do it. By this pressure gradient, particles of air are accelerated. Then, the accelerated particles pass through the sound absorbing material. When the particles pass through the sound-absorbing material, the energy of the particle velocity is consumed as heat energy, so that the sound is absorbed. Acceleration of the particles of the air in this way increases the heat energy consumed to pass through the sound-absorbing material, so that the sound-absorbing effect becomes very large. Further, the pressure gradient becomes larger as the thickness of the plate member is reduced, and the sound absorption effect can be dramatically improved. Further, since the sound absorption material can be absorbed by the sound absorption material disposed in the vicinity of the edges of the plate member and the plate member, a sound absorption body capable of realizing miniaturization with a small number of parts can be constructed. The plate member having rigidity as described herein may be any material as long as it can generate a sound pressure difference between the front surface side and the back surface side in the vicinity of the edge. For example, the plate member may be made of various metals, Or a composite paper (composite paper) in which sheets of paper are overlapped and integrated. Further, by setting at least one of the area density and the flow resistance value of the sound-absorbing material so that the area outside the surface direction is smaller than the area inside the surface direction of the sound-absorbing material, The soundproof effect (sound absorption effect) can be enhanced as compared with a constant sound absorption material in which the values of surface density and flow resistance are the same.

In the sound barrier of the present invention, the sound absorbing material may be configured to be thinner than the thickness of the plate member.

In addition, the sound barrier of the present invention may be configured such that the thickness of the sound absorbing material becomes thinner toward the upper side.

Further, in the sound barrier of the present invention, the sound-absorbing material may be formed in a plurality of step shapes having the same thickness and having a plurality of step portions in the up-down direction. In the soundproof wall of the present invention, the sound absorbing material is formed to have the same thickness in the vertical direction, the value of the area density and the flow resistance of the lower portion in the up-down direction is the largest and the value of the area density and resistance in the middle portion is the surface density And the value of the flow resistance and the value of the area density and the flow resistance of the upper portion may be the smallest.

As described above, according to the present invention, by constructing the sound absorbing body with the sound absorbing material disposed in the vicinity of the edge of the plate member and the plate member, it is possible to improve the sound absorption effect, Sound barrier can be provided. Therefore, not only is it advantageous in terms of both the assembling work surface and the cost, but it is also advantageous in terms of the carrying surface and the handling surface.

Fig. 1 (a) is a front view of the sound absorbing body of the present invention, and Fig. 1 (b) is a sectional view taken along the line AA in Fig.
2 is a rear view of the sound absorbing body of the present invention.
3 is a sectional view showing another sound absorbing body (a) to (g).
4 is an explanatory diagram for use in calculation of a sound field around the plate member.
5 is an explanatory view showing a state in which a plane wave is vertically incident on a plate member.
Fig. 6 (a) is a perspective view showing the particle velocity amplitude of the shaded region in Fig. 5, and Fig. 6 (b) is a plan view showing the particle velocity amplitude of the shaded region in Fig.
7 is a perspective view showing a sound pressure distribution in the vicinity of the edge of the plate member.
Fig. 8 shows a distribution of sound pressure amplitudes in the vicinity of the edge of the plate member. Fig. 8 (a) is a perspective view, and Fig. 8 (b) is a plan view showing contour lines.
Fig. 9 is an explanatory diagram showing the impedance of a cloth or a thin porous sound-absorbing layer.
10 is an explanatory diagram for use in the sound field calculation around the cloth.
11 is a front view of the sound absorbing body.
12 is a graph showing sound absorption power with respect to frequency.
13 is an explanatory diagram in which a soundproof wall is provided between a road and a residential area.
14 is an explanatory diagram for use in calculating an attenuation amount (attenuation amount) of a sound insulating wall formed by using a sound absorbing body.
15 is a graph showing the particle velocity distribution near the tip of the soundproof wall.
16 is a graph showing the insertion loss of the soundproof wall.
17 is a graph showing measurement results and theoretical calculation values of sound absorbing power per sound absorbing body.
18 is a graph showing the insertion loss of the calculation value and the experimental value in the case where the cloth is provided on the plate member and in the case where the cloth is not provided.
19 is a graph showing the insertion loss of a calculated value when a sound absorbing material is provided on a plate member and when a gradation sound absorbing material is provided.
20 (a) to 20 (e) are sectional views of the upper side of the soundproof wall showing various specific examples of the gradation sound absorbing material.

1 (a), 1 (b) and 2, a sound absorbing body S is shown. This sound absorbing body S is provided with a square plate member 1 and a strip shaped sound absorbing material 2 extending from the four edges of the plate member 1 in a direction away from each other in cross section have. In this embodiment, the sound absorbing member 2 is composed of four sheets, but it may be composed of one, two or three sound absorbing members. In addition to the square, the plate member 1 may be formed in a rectangular shape, a circular shape, an elliptical shape, or a triangular shape or a polygonal shape. 1 (a), the plate member 1 has a length of 0.6 m and a width of 0.6 m and a thickness of 9 mm, and the sound-absorbing material 2 has a width of 0.5 m, (Width) of 0.07 m, and the length R of a portion wrapping with the plate member 1 is 0.01 m.

The plate member 1 is made of a material having rigidity for imparting a pressure gradient by generating a sound pressure difference by the front surface side and the back surface side in the vicinity of the edge. Here, although wood is used as a material having rigidity, any material may be used as long as it is a rigid material such as a composite paper in which a variety of metals or a plurality of sheets of paper are stacked and integrated. As the metal, iron, nickel, aluminum, copper, magnesium, lead, or the like may be used as well as an alloy of two or more of these metals. From the viewpoint of sound absorption, a material having a surface density of not less than 3 kg / m ² is sufficient. However, when a soundproof wall is used, a material having a surface density of not less than 12 kg / m ² is preferable if a certain effect is expected.

The auxiliary projections 3 made of wood are arranged on the four corners of the plate member 1 in a plate shape having the same thickness as the plate member 1 extending to the side away from the corner portion. The connecting member 4 is disposed on the surface of the auxiliary protrusion 3 and the surface of the auxiliary protrusion 3 so that the plate member 1 and the auxiliary protrusion 3 are fixed by the fixing tool 5 such as a pushpin or a vis, 3 are connected and fixed via a connecting member 4.

The auxiliary projection 3 is provided with a triangular notch 3A which is fitted into the corner of the plate member 1 at one end in the longitudinal direction A projecting portion 3B having a triangular shape is provided at the other end in the longitudinal direction (the end on the side away from the plate member), and a string body (for example, (Which may be a wire or a thread) 6 is formed. The hole 3K may be formed not only on one auxiliary protrusion 3 but also on a plurality of or all auxiliary protrusions 3. 1 and 2, a sound absorbing body S is resembled by an oil body 6 passed through a hole 3K formed in one auxiliary protrusion 3 so that one corner of the square plate member 1 The sound absorbing body S is suspended in the form of a rhombic shape directed upwardly. For example, the sound absorbing body S may be formed by piercing the two auxiliary protrusions 3, 3 and using two oil- 1 may be inclined at an angle of 45 DEG in a square shape, and the posture of hanging the sound absorbing body S can be freely changed.

Each of the four sound absorbing materials 2 is mounted so as to extend between two auxiliary protrusions 3 and 3 adjacent to each other in the circumferential direction of the auxiliary protrusions 3 provided on the plate member 1. [ More specifically, each sound absorbing material 2 is a long strip in the left-right direction and is formed in a substantially inverted trapezoidal shape when seen from the front. Both ends of the two sound absorbing materials 2 in the left- And a part of the end on the side of the width direction plate member is arranged so as to cover the edge of the plate member 1. [ The sound absorbing material 2 thus arranged is fixed between the auxiliary protrusions 3 and 3 by a fixing tool 7 such as a pressing pin or a screw. The fixing tool 7 may be the same as or different from the fixing tool 5.

As the sound absorbing material 2, for example, a woven fabric or a knitted fabric having a surface density of 0.66 kg / m ² and a flow resistance of 924 Ns / m ³ is used, it may be a nonwoven fabric, a porous body made of inorganic fibers such as glass wool or rock wool, or a porous body made of various kinds of metal fibers.

When the sound absorbing body S constituted as described above is disposed in, for example, a space in which sound is generated, the plate member 1 having rigidity is provided on the front surface side and the back surface side near the edge of the plate member 1 A sound pressure difference can be generated. That is, when the pressure on the sound source side is generated on the surface side of the plate member 1, the pressure amplitude on the back side, on which the sound opposite to the sound source is generated, becomes smaller than the pressure amplitude on the surface side, 1, and a pressure gradient can be imparted on the front surface side and the back surface side in the vicinity of the edge. By this pressure gradient, the particles of air that propagate the sound are accelerated near the edge of the plate member 1, the accelerated particles pass through the sound absorbing member 2 provided at the edge of the plate member 1, The velocity energy is consumed as thermal energy, and sound absorption occurs. As the particles of the air are accelerated in this way, the heat energy consumed to pass through the sound-absorbing material 2 becomes large, so that the sound-absorbing effect becomes very large. Therefore, it is not necessary to increase the thickness of the sound absorbing material 2. Further, the pressure gradient becomes larger as the thickness of the plate member 1 is reduced, and the sound absorption effect can be dramatically improved. In addition, since the sound absorbing material 2 disposed near the edge of the plate member 1 can absorb sound, a sound absorbing body S capable of realizing miniaturization with a small number of parts can be constructed .

로 표시하고, 판 부재(1)의 도면 중의 표면 측(법선을 향해 있는 쪽)의 값을

, 이면 측의 값을

라고 하면, 판 부재(1)의 표면 상에서는 법선 방향의 공기의 입자 속도는 0이므로, 단위 법선 벡터를

으로 표시하면,Next, the sound field around the plate member 1 and the sound field around the sound-absorbing material 2 will be described. First, the sound field around the plate member 1, which is a thin steel plate, will be described. A calculation method of the sound field around the plate member which is thinner than the wavelength as shown in Fig. 4 will be described. Speed potential

And the value of the surface side (toward the normal) of the plate member 1 in the drawing is represented by

, And the value on the back side

, The particle velocity of the air in the normal direction is zero on the surface of the plate member 1,

Quot;

식 (1)

Equation (1)

. Considering equation (1), the velocity potency at the receiving point P from the integral of Helmholtz-Kirchhoff is given by the following equation.

식 (2)

Equation (2)

는, 판 부재(1)의 양면에서의 포텐셜 차, 또한

는 P점에서의 직접음(直接音),

,

는 파수,

는 각 주파수,

는 음속을 나타낸다. 여기서, 시간항

는 생략되어 있다.only,

A potential difference on both sides of the plate member 1,

Is a direct sound (direct sound) at point P,

,

Wave number,

Respectively,

Represents the sound velocity. Here,

Are omitted.

방향으로 미분하여 얻어지는 식은On the other hand, in Expression (2), at point P in space,

The equation obtained by differentiating in the direction

식 (3)이다. 그리고, 속도 포텐셜

와 음압

및 입자 속도

사이에는

를 공기의 밀도라고 하면, 이하의 관계

(3). Then,

And sound pressure

And particle velocity

Between

Is the density of air, the following relationship

식 (4)가 있고,

방향의 입자 속도는

이다. 공간의 점 P에서의 속도 포텐셜

또는

방향의 입자 속도 성분

를 식 (2), (3)으로부터 구하기 위해서는, 미지 함수인 판 부재(1)의 양면에서의 포텐셜 차

를 알 필요가 있다. 이를 위해, 식 (3)에 있어서, 점 P를 판 부재(1)의 면에 수렴(한없이 접근시킨 극한)시키면,

There is equation (4)

The particle velocity in the direction

to be. The velocity potential at point P in space

or

Direction particle velocity component

(2) and (3), the potential difference on both surfaces of the plate member 1, which is an unknown function,

. To this end, in the equation (3), when the point P is converged on the surface of the plate member 1 (infinitely close to the surface of the plate member 1)

식 (5)를 얻는다. 여기서,

는 점 P에서의 면의 법선을 나타낸다. 판 부재(1)는 강판이므로 좌변은 0이 되고, 판 부재(1)의 양면(兩面) 위의 속도 포텐셜 차

를 미지 함수로 하는 제1종 적분 방정식 (6)이 된다.

(5) is obtained. here,

Represents the normal of the plane at the point P. Since the plate member 1 is a steel plate, the left side becomes 0, and the velocity potential difference on both surfaces of the plate member 1

(6), which is an unknown function.

식(6)

Equation (6)

This integral equation (6) has a highly specific nucleus (super-specific nucleus) as follows.

식 (7)

Equation (7)

(Sound pressure and particle velocity) around the plate member 1 can be obtained by numerically solving the integral equation (6) numerically by the boundary element method (BEM) and substituting it into the equation (2) .

As shown in Fig. 5, an example in which the distribution of the particle velocity amplitude | v | in the shaded region is calculated when a planar wave having a velocity of 1 and a amplitude of 1 is vertically incident on a flat plate of 1 m 占 1 m in rigidity, (a) and (b). 6 (a) and 6 (b), it can be seen that there is a region in which the particle velocity amplitude is extremely large near the edge of the steel sheet (plate member 1). The phenomenon that a large particle velocity amplitude is generated in the vicinity of an edge is called an edge effect here. The reason why the particle velocity amplitude is extremely large in the vicinity of the edge is that the sound pressure distribution | p | of the dot portion shown in Fig. 7 is calculated and displayed as shown in Figs. 8A and 8B, The reason is that the sound pressure gradient is very large. When a sound absorbing material such as a cloth or a thin porous material is placed in such a region having a very large particle velocity amplitude (a region where air particles vibrate very heavily) The energy is converted into thermal energy, and a large sound absorption performance can be obtained. And the particle velocity is proportional to the sound pressure gradient.

In addition, it is thought that the soundproofing performance can be improved by using the same idea even for a soundproofing wall which is widely used for sounding road noise or railroad noise. It is believed that since the sound absorbing material such as cloth or porous material is provided in the vicinity of the edge, the particle velocity can be made weaker, so that a further sound effect is obtained. In the case of a semi-infinite planar steel wall, the velocity potential of the diffraction region behind the sound barrier can be expressed as an integrated value of the particle velocity distribution in the region above the edge.

, 천 양면의 음압을 각각

라고 하고, 천을 통과하는 입자의 속도를

라고 하면,Subsequently, considering a sound field around a sound-absorbing material such as a cloth or a thin porous sound-absorbing layer, a breathable cloth or a thin porous sound-absorbing layer (hereinafter referred to as the latter cloth) can be considered as shown in Fig. Flow resistance

, The sound pressure on both sides of the cloth

And the velocity of the particles passing through the fabric

In other words,

식 (8)

Equation (8)

에 의해 여진(勵振)되게 된다.

를 천의 면밀도,

을 천의 진동 속도라고 하고, 시간 항을

라고 가정하면 다음 식을 얻는다.. In addition, the cloth itself can be used as a pressure-

As shown in FIG.

The surface density of the cloth,

Is referred to as the vibration speed of the cloth,

The following equation is obtained.

식 (9)

Equation (9)

는

및

, 양자의 입자 속도의 합으로 표시되고,Thus, the particle velocity of air in the fabric

The

And

, Expressed by the sum of both particle velocities,

식 (10)

Equation (10)

로 두면,.

If you leave it as,

식(11)

Equation (11)

Lt; / RTI &

식 (12)

Equation (12)

Is obtained.

(2) and (3) can be obtained by the velocity potential difference distributed directly on both sides of the cloth as in the case of the plate member 1, considering the sound field when the cloth is present in the space as shown in Fig. . However, in the case of cloth,

식 (13)

Equation (13)

The boundary integral equation becomes the following equation.

식 (14)

Equation (14)

를 구하여, 식 (2), (3)에 대입하면 음압이나 입자 속도를 구할 수 있다.Solve equation (14)

(2) and (3), the sound pressure and particle velocity can be obtained.

및 이면을 통과하는 에너지

의 차에 의해 산출된다.

는 이하의 식The energy per unit area absorbed by the cloth (sound absorbing material) is the energy passing through the surface of the cloth (sound absorbing material)

And the energy passing through the back surface

. ≪ / RTI >

Is expressed by the following equation

식 (15)

Equation (15)

식 (16)

Equation (16)

는 각각 천(흡음재)의 표면과 이면의 음압,

는 입자 속도, *는 복소공액(complex conjugate)을 의미하고 있다. 천(흡음재)의 면 전체에서는, 그것을 적분하여Lt; / RTI >

The sound pressure on the front and back surfaces of the cloth (sound absorbing material)

Is the particle velocity, and * is the complex conjugate. On the entire surface of the cloth (sound absorbing material), it is integrated

식 (17)

Equation (17)

이다.. only,

to be.

The sound absorbing body S of the present invention will be described on the basis of the sound field around the plate member 1 and the sound field around the sound absorbing member 2 as described above. ) In the vicinity of the edge, the particles firstly oscillated very strongly. When a sound absorbing material such as a cloth or a thin porous sound absorbing material that does not disturb the particle velocity distribution in such a region is placed, the negative energy is converted into heat energy by friction between the air particles and the fibers of the sound absorbing material, and a large sound absorbing effect is expected . The friction resistance is considered to be proportional to the particle velocity. 11 is an example of a sound absorbing body S applying such a principle.

Fig. 12 shows the result of obtaining the random incidence sound absorbing power in the case where the sound absorbing body S shown in Fig. 11 is installed in a space, by combining the equations (6) and (14). It can be seen that a relatively large sound absorbing force is obtained even though only the vicinity of the edge is absorbed. The flow resistance r _S is calculated for two types, 415 Ns / m ³ and 830 Ns / m ³ . The sound absorption ratio x area is also referred to as an equivalent sound absorption area. The sound absorbing body S is constituted by the sound absorbing material 2 composed of the plate member 1 and cloth as described above. The plate member 1 has a square of 0.9 m x 0.9 m and an annular cloth 2 having a width of 0.1 m is arranged on the outer peripheral edge of the plate member.

The sound absorbing body S shown in Figs. 1 (a) and 1 (b) and Fig. 2 may be constructed as shown in Figs. 3 (a) to 3 (g). That is, the sound absorbing material 2 of the sound absorbing body S shown in Figs. 1 (a) and 1 (b) and Fig. 2 is configured to be thinner than the plate member 1, 3B shows a case where the thickness of the sound absorbing material 2 is equal to the thickness of the member 1 and the thickness of the sound absorbing material 2 is equal to the thickness of the plate member 1, 2 are projected on both sides of the plate member 1 in the thickness direction. 3 (c) shows a case where the thickness of the sound absorbing material 2 is thinner than the thickness of the plate member 1, and in FIG. 3 (d) And has a tapered portion 1T having a tapered end. 3 (e), the plate member 1 is constituted by a curved surface which is gently convex to the left in the drawing, and in FIG. 3 (f), the end surface 1A of the plate member 1 And a curved surface that is convex upward. 3 (g), the plate member 1 is provided with a narrow width portion 1W having a thin thickness on the end face side.

Further, a soundproof wall W constructed using the sound absorbing body S is shown in Fig. This soundproof wall W absorbs the sound from the road side, thereby making it possible to suppress invasion of traveling sound of the vehicle C, engine sound, etc. from the road to the house as much as possible. This soundproof wall W is provided with a plate member 10 having a rigidity for giving a tilt by giving a sound pressure difference in the vicinity of the edge and the upper surface of the road surface 10B A difference in the sound pressure is generated on the back surface side opposite to the front surface side. On the lower surface of the road surface 10B of the plate member 10, a sound-absorbing treatment layer 10A is formed. The surface (back surface) of the soundproof wall W on the house side may be formed as a rigid surface or by performing a sound absorption process. A porous sound absorbing layer (a porous body made of inorganic fibers or a porous body made of various metal fibers, which may be made of cloth) 11 as a sound absorbing material extending upward is disposed on the upper face of the plate member 10 The surface side and the back surface side of the sound-absorbing layer 11 are protected by a protection material 12 such as a wire mesh or a punching metal and a cap 13 for non-removal is provided on the top of the protection material 12, And forms an acoustic barrier W.

Therefore, by constructing the sound barrier wall W as described above, it is effective in reducing the road traffic noise (which can also be used for railway noise). That is, it is possible to reduce the sound pressure of the region on the diffraction side by reducing the particle velocity by converting negative acceleration energy into heat energy by the sound absorbing layer 11 at an accelerated large particle velocity appearing in the region near the edge. This can be understood as an example of attempting to calculate a diffraction sound field by providing a cloth at the tip portion of a soundproof wall (thin semi-infinite steel plate) as shown in Fig. In a semi-infinite soundproof wall or the like, the sound pressure in the diffraction-side area can be obtained by integrating the particle velocity distribution on the surface extended to the top of the soundproof wall. Thus, by reducing the large particle velocities in these areas, particularly near the edges, the diffraction sound can be reduced.

Fig. 15 shows the distribution of the particle velocity amplitude above the soundproof wall when there is no transition when a spherical wave is generated from the sound source position shown in Fig. 14 by calculation. In the figure, the horizontal axis represents the distance from the top of the sound barrier wall to the upper side. It can be seen that the particle velocity amplitude is very large at the upper side of the sound barrier wall and in the vicinity of the edge. The sound source is calculated as the intensity at which the amplitude of the velocity potential becomes 1 at a position 1 m away.

Fig. 16 is a result of calculation of the level attenuation (also referred to as insertion loss) due to the provision of the sound insulating wall at the sound receiving position on the diffraction side shown in Fig. (B) shows a case where a cloth having a width of 50 cm is provided on the upper end of the soundproof wall, and (c) shows a case where the height of the soundproof wall is matched with the cloth top without a cloth. As a result of calculation at 125 Hz, the flow resistance of the fabric is 830 Ns / m ³ . From these results, it can be said that the effect of the cloth that is installed is more than the imagination.

17 is a graph showing the measured values and the theoretical calculation values of the sound absorbing power per sound absorbing body. The measured values are measured by hanging the sound absorbing body S of Figs. 1 (a) and 1 (b) and the sound absorbing body S in the room, and the theoretical calculation value and the measured value are the same value. Further, the higher the frequency, the larger the sound absorption power is, and especially the higher frequency is effective.

In recent years, there have been proposed various types of noise reduction walls of the tip improvement type, but it is considered that there are many ineffective ones compared with the high cost. Also, it is not possible to use the edge effect as shown here. The present invention is very simple and compact, but it is expected that it can be widely applied in terms of performance, ease of manufacture, and ease of construction. Further, as the area of the plate member 1 constituting the sound absorbing body S is increased, sound of a lower frequency can be absorbed, and the area (size) of the plate member 1 can be changed in accordance with the frequency of sound absorption have.

FIG. 18 shows graphs of experimental results and calculated values of soundproofing (sound absorption) of soundproof walls. More specifically, a model with the soundproof wall shown in Fig. 14 is produced, and the result of the insertion loss and the calculated value (the value calculated by using the above-described equation (14)) at a position a predetermined distance from the soundproof wall are calculated , And is shown in the graph of Fig. As the model, a wall made of wooden plate having a thickness of 9 mm and a length of 90 cm x width of 180 cm and a soundproof wall provided with a cloth (5 cm in length x 180 cm in width) I prepared the wall. In the graph of FIG. 18, the insertion loss is measured using the soundproof wall, the measured value is plotted and connected by a straight line, a line K1, and a plate member of the soundproof wall is regarded as a half- 14, a line K2 drawn by connecting the calculated values calculated by the insertion loss and connected in a straight line, and a line K2 having a height equal to the upper end of the cloth provided on the plate member of the soundproof wall, Considering the infinite barrier, calculate the insertion loss by calculating the insertion loss in Eq. (14), plotting the straight line K10 connecting the straight line, and calculating the insertion loss in Eq. (14) The line K11 is plotted by plotting the values and the line K12 is plotted by measuring the insertion loss using the wall and plotting the measured values. The fabric has a surface density of 0.6 kg / m ² and a flow resistance of 789 Ns / m ³ . In addition, the frequency of the measured value is plotted as a value obtained by dividing the frequency measured by the model by 1/10.

In the graph of FIG. 18, the value of the broken line K2 is higher than the value of the straight line K10. From this, it can be seen that the insertion loss (sound insulation effect) calculated by the equation (14) is higher than the insertion loss (sound insulation effect) of the wall at the same height as the upper end of the soundproof wall by considering the plate member of the soundproof wall as a half- Able to know. On the contrary, the value of the broken line K11 is lower than the value of the straight line K10. From this, it can be seen that the insertion loss (sound insulation effect) calculated by Eq. (14), considering the wall as a semi-infinite barrier, is smaller than the insertion loss (sound insulation effect) As shown in FIG. In addition, the value of the line K1 and the value of the line K2 are very close to each other. From this, it is clear that the calculated value (the value of the broken line K2) obtained by calculating the insertion loss in Equation (14) by considering the plate member of the soundproof wall as a semi-infinite barrier is a highly reliable value. In addition, the value of the line K11 and the value of the line K12 are very close to each other. From this, it is clear that the calculated value (the value of the broken line K11) calculated by the equation (14), which regards the non-fabricated wall as a semi-infinite barrier, is a highly reliable value. Some of the soundproofing effect also includes a sound absorbing effect.

That is, it is apparent from the graph of FIG. 18 that insertion loss (sound insulation effect) is increased when a sound absorbing material (cloth in FIG. 18) is provided at the upper end of the plate member in the sound barrier. In addition, the value of the insertion loss obtained by calculation is approximately equal to the measured value with high reliability.

18 shows a case in which a cloth having a surface density of 0.6 kg / m ² and a flow resistance of 789 Ns / m ³ is provided at the upper end of the plate member constituting the soundproof wall, Respectively. On the other hand, FIG. 19 shows a sound absorbing material (a sound absorbing material and a sound absorbing material) having a surface density and a flow resistance which are constant from the lower portion to the upper portion, (Hereinafter referred to as "gradient sound absorbing material") is more effective for soundproofing. The graph of Fig. 19 shows the insertion loss with respect to the noise level (A-type sound pressure level) in the automobile, and is based on the calculation value of the insertion loss with high reliability as described above. The term " a sound absorbing material " means that the surface density and the flow resistance are the same.

In the graph of FIG. 19, a line H connecting the calculation values obtained by calculating the insertion loss by considering the plate member having the same height as the soundproof wall provided with the cloth at the upper end of the plate member as a semi-infinite barrier, The plate member of the soundproofing wall provided with a certain sound absorbing material at the upper end is regarded as a half-wall, the calculated value of the insertion loss is plotted, and the five lines U1 to U5 connected by a straight line and the gradient sound absorbing material Five bent lines G1 to G5 are drawn by plotting calculated values of insertion loss by considering the plate member of a soundproof wall as a semi-infinite barrier and connecting them by a straight line. Table 1 below shows the calculation value (dB) of the insertion loss with respect to the distance (m) from the wall. The calculated value is a value calculated by using the above-described equation (14).

[Table 1]

The constant sound absorbing material of the strand U1 has a surface density of 192 kg / m ² and a flow resistance of 6400 Ns / m ³ . The constant sound absorbing material of the strand U2 has a surface density of 96 kg / m ² and a flow resistance of 3200 Ns / m ³ . The constant sound absorbing material of the strand U3 has a surface density of 12 kg / m ² and a flow resistance of 400 Ns / m ³ . The constant sound absorbing material of the strand U4 has a surface density of 48 kg / m ² and a flow resistance of 1600 Ns / m ³ . The constant sound absorbing material of the strand U5 has a surface density of 24 kg / m ² and a flow resistance of 800 Ns / m ³ .

The gradation sound absorbing material of the curve G1 has a surface density of 192 kg / m ² at the lower end portion of the sound absorbing material and a flow resistance of 6400 Ns / m ³ , and these values become smaller as it goes to the upper end. . The gradation sound absorbing material of the curve G2 has a surface density of 96 kg / m ² at the lower end portion of the sound absorbing material and a flow resistance of 3200 Ns / m ³ , and these values become smaller toward the upper end. . The gradation sound absorbing material of the curve G3 has a surface density of 12 kg / m ² at the lower end portion of the sound absorbing material and a flow resistance of 400 Ns / m ³ , and these values become smaller toward the upper end. . The gradation sound absorbing material of the curve G4 has a surface density of 48 kg / m ² at the lower end portion of the sound absorbing material and a flow resistance of 1600 Ns / m ³ , and these values become smaller as it goes to the upper end. . The gradient sound-absorbing material of the curve G5 has a surface density of 24 kg / m ² at the lower end portion of the sound-absorbing material and a flow resistance of 800 Ns / m ^{3. As} these values become smaller toward the upper end, Respectively.

19, it can be seen that the values of the broken lines U1 to U5 and the values of the broken lines G1 to G5 are higher than the value of the broken line H, respectively. From this, it can be seen that the soundproof wall provided with the cloth as the sound absorbing material at the upper end of the plate member is superior in soundproofing effect to the wall not using the sound absorbing material. The insertion loss (sound insulation effect) of the broken lines G1, G2, G4 and G5 except for the broken line G3 is larger than the insertion loss (sound insulation effect) of the broken lines U1 to U5 Is higher than the line U5 having the highest insertion loss (sound insulation effect). In addition, the insertion loss (sound insulation effect) of the broken line G3 is higher than the insertion loss (sound insulation effect) of the broken line U1 having the lowest insertion loss (sound absorption effect) in the graph.

That is to say, it is clear from the graph of FIG. 19 that insertion loss (soundproof effect) is increased by providing a sound absorbing material at the upper end of the plate member in the sound barrier wall. It is apparent from the graph of FIG. 19 that the provision of a gradation sound absorbing material at the upper end of the plate member results in an increase in insertion loss (sound insulating effect) as compared with the provision of a constant sound absorbing material. In addition, in Figure 19, but shows the case of five kinds of gradient sound-absorbing material, the area density in the range of 12kg / m ² ~192kg / m and an arbitrary area density in the range of ^2, the flow resistance is 400Ns / m ³ ~6400Ns / m ³ It is possible to presume that the insertion loss (soundproof effect) becomes higher.

Various specific examples of the sound barrier wall will be described with reference to Figs. 20 (a) to 20 (e). The soundproof wall W includes a plate member 10 having a rigidity for imparting a pressure gradient in the vicinity of the edge to give a pressure gradient and a plate member 10 provided at the upper end thereof for energizing the particle velocity of air accelerated by the pressure gradient And a gradient sound-absorbing material 14 for consumption. 20A, the gradation sound-absorbing material 14 is composed of three types of sound-absorbing materials 14A, 14B, and 14C having a thicker thickness at the lower side. That is, three sound absorbing materials 14A, 14B and 14C having different thicknesses are arranged in the vertical direction so that the thickness of the gradient sound absorbing material 14 is made thinner so that the gradation sound absorbing material 14 is divided into a plurality of And is formed in a stepped shape. The value of the area density and the flow resistance of the lower sound absorbing material 14A is larger than the value of the area density and flow resistance of the sound absorbing material 14B in the middle. The value of the area density and the flow resistance of the uppermost sound absorbing material 14C is smaller than the value of the area density and the flow resistance of the sound absorbing material 14B therebelow. 20 (b), the gradient sound-absorbing material 14 is formed in a substantially triangular shape having an inclined surface of a straight line (which may be curved) such that the thickness becomes thinner toward the upper side. The value of the area density and the flow resistance of the gradation sound-absorbing material 14 becomes gradually smaller toward the upper side and becomes a value close to zero or zero at the upper end. With this configuration, the surface density of the gradation sound-absorbing material 14 and the value of the flow resistance change linearly (continuously) along the up-down direction, so that the deterioration of sound insulation effect in the non-linear portion , It is possible to sound effectively. 20C, the gradation sound-absorbing material 14 is composed of six sound-absorbing materials 14A having the same thickness and the same size and having the same values of surface density and flow resistance. That is, the three sound-absorbing materials 14A are arranged in the thickness direction in the upper end of the plate member 10 and the two sound-absorbing materials 14A and 14A are superimposed on the upper ends of the three sound-absorbing materials 14A, 14A and 14A And one sound absorbing material 14A is disposed at the upper ends of the two sound absorbing materials 14A and 14A. In this case as well, the gradient sound-absorbing material 14 is formed in a plurality of stepped shapes having a plurality of stepped portions in the vertical direction. By arranging the sound-absorbing material as described above, the surface density and the flow resistance value of the three sound-absorbing materials 14A positioned at the lowermost end become the greatest value, and the surface density and the flow resistance of one sound-absorbing material 14A located at the uppermost end become the smallest value . 20D, the gradation sound-absorbing material 14 is composed of five sound-absorbing materials 14A, 14B, and 14C having the same thickness and different height (vertical dimension). That is, a second sound absorbing material 14B whose height is smaller than that of the first sound absorbing material 14C having the largest key is disposed on both sides in the thickness direction of the first sound absorbing material 14C, and on the outer surfaces of the second sound absorbing materials 14B, 14B, And a sound absorbing material 14A is disposed. In this case as well, the gradient sound-absorbing material 14 is formed in a plurality of stepped shapes having a plurality of stepped portions in the vertical direction. By arranging the sound-absorbing material as described above, the thickness of the gradation sound-absorbing material 14 can be reduced from the bottom by two sheets of the third sound-absorbing material 14A, two sheets of the second sound-absorbing material 14B, one sheet of the first sound-absorbing material 14C, Two sound-absorbing materials 14B, three sheets of the first sound-absorbing material 14C, and one sheet of the first sound-absorbing material 14C are sequentially thinned. Therefore, the value of the area density and the flow resistance of the gradation sound-absorbing material 14 becomes smaller in order from the bottom. 20 (e), the gradation sound-absorbing material 14 is formed to have the same thickness in the vertical direction, but the surface area and the flow resistance value of the lower portion 14a are the largest in the vertical direction, The value of the area density and the flow resistance of the upper portion 14c is smaller than the value of the area density and flow resistance of the lower portion 14a and the value of the area density and flow resistance of the upper portion 14c is the smallest. For example, the gradient sound-absorbing material 14 of FIG. 20 (e) is constituted by a sponge, a foam, and the like, and the holes formed in the lower portion 14a are formed to be the most compact, The shape and size of the hole are determined so that the flow resistance of the hole becomes the largest. On the other hand, the shape and size of the hole are determined so that the hole formed in the upper portion 14c is formed most severely and the value of the flow resistance of the hole becomes the smallest.

20A, the gradation sound-absorbing material 14 is composed of the three sound-absorbing materials 14A, 14B, and 14C, but the gradation sound-absorbing material 14 may be formed of one sound-absorbing material. 20 (a), 20 (c), 20 (d) and 20 (e) show the case where the value of the area density and the flow resistance of the sound absorbing material are changed in three stages in the vertical direction, The value of the surface density and the flow resistance in the vertical direction can be changed to a state close to a linear shape. Even in a configuration in which the value of the area density and the flow resistance of the gradient sound-absorbing material change in two levels in the vertical direction, that is, the value of the area density and the flow resistance of the gradation sound-absorbing material are set so that the upper portion is smaller than the lower portion of the gradation sound- do. It is preferable that the value of the area density and the value of the flow resistance of the gradient sound-absorbing material are set so that the upper portion of the gradation sound-absorbing material is smaller than the lower portion of the gradation sound-absorbing material. However, Of the gradation sound absorbing material may be set so that the upper portion is smaller than the lower portion of the gradation sound absorbing material.

The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present invention.

In the above embodiment, the sound absorbing material 2 is provided over almost the entire edge of the plate member 1, but it may be provided only in a part thereof. The sound absorbing material 2 may be disposed so as to partially cover the edge of the plate member 1, but the sound absorbing material 2 may be disposed so as not to cover the edge of the plate member 1 at all.

In addition, in the above embodiment, the sound absorbing body S may be suspended and fixed to a floor or the like to be used in a partition (partition material) or the like.

Further, in the above embodiment, the sound absorbing material is disposed at the upper end of the plate member, but the sound absorbing material may be disposed at the lateral side end of the plate member. In other words, the mounting position of the sound-absorbing material is not particularly limited as long as the sound-absorbing material is disposed so as to extend outward along the surface direction of the plate member from the edge of the plate member.

1: plate member, 1A: section, 1W: narrow width portion, 2: sound absorbing material, 3: auxiliary projection, 3A: cutout portion, 3B: projection portion, 3K: hole, 4: connecting member, 5: 7: Vis, 10: Plate member, 10: Sound absorbing treatment layer, 11: Sound absorbing layer, 12: Protection material, 13: Cap, 14: Gradient sound absorbing material, S: Sound absorbing material, W:

Claims (5)

A plate member having a rigidity for generating a pressure gradient by generating a sound pressure difference by a front surface side and a back surface side in the vicinity of an edge of the plate member and an edge of the plate member for consuming energy of a particle velocity of air accelerated by the pressure gradient, A sound insulating wall comprising a sound absorbing body including a sound absorbing material disposed in the vicinity thereof,
Wherein the sound absorbing material extends outward along the surface direction of the plate member at an edge of the plate member and at least one value of a surface density and a flow resistance value of the sound absorbing material Is set to be a small value,
Sound barrier. The method according to claim 1,
Wherein the sound absorbing material is configured to be thinner than the thickness of the plate member. 3. The method according to claim 1 or 2,
Wherein the sound absorbing material is configured such that its thickness becomes thinner toward the upper side. 3. The method according to claim 1 or 2,
Wherein the sound absorbing material is formed in a plurality of stepped shapes having the same thickness and having a plurality of stepped portions in the vertical direction. 3. The method according to claim 1 or 2,
The sound absorbing material is made of the same thickness in the vertical direction, and the surface density and the flow resistance value of the lower portion in the up-and-down direction are the largest and the value of the surface density and resistance of the intermediate portion is smaller than the value of the surface density and flow resistance of the lower portion , The surface density of the upper portion and the value of the flow resistance are minimized.

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