JP2007334285A - Sound absorbing structure and rail vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound absorbing structure that improves sound absorption characteristics in a frequency range of 500 Hz to 1 kHz without making a porous material thick nor increasing an air layer. <P>SOLUTION: The sound absorbing structure 1 is constituted by arranging a multilayer structure 2 having a filmy structure 5 sandwiched between mesh structures 4 on a top-surface side of a fabric material 6 of a sound absorbing material 3 having the fabric material 6 bonded or fused on its top surface. In this sound absorbing structure 1, the multilayer structure 2 excited with acoustic incident energy behaves as a multi-mass-point system, and vibrations between the mesh structures 4 and filmy structure 5 are transduced by friction into heat energy, and further transduced into heat energy by viscous resistance based upon vibrations of fibers, friction between fibers, and air vibrations. Consequently, efficiency of transduction from the acoustic incident energy to the heat energy increases to improve the sound absorption characteristics in intermediate/low frequency ranges without varying the thickness of the sound absorbing structure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sound absorbing structure as a sound absorbing technique applicable to noise reduction and sound field control, and a rail vehicle using the same.

  Conventional sound-absorbing materials and sound-absorbing structures include porous materials, film / plate-like materials, and resonance structures. As for the film / plate-like material system and the resonance structure system, the applicable frequency band is generally a medium / low frequency and the bandwidth is relatively narrow.

  On the other hand, porous materials include inorganic fiber materials such as glass wool and rock wool, polymer fiber materials such as polyester, resin foam materials such as soft foam urethane, and metal foam materials such as aluminum. However, it is an excellent material as a sound-absorbing material for middle and high frequencies. In order to increase the sound absorption coefficient in the low range in addition to the mid / high range, measures such as increasing the thickness or providing an air layer must be taken. However, due to such measures, it is difficult to apply the sound absorption characteristics, structural design, weight, cost, etc. due to the deterioration of the sound absorption characteristics in the high frequency range and the need to secure a considerable space. A case can be seen.

Among conventional technologies, porous materials are excellent sound-absorbing materials as sound-absorbing materials for mid- and high-frequency ranges, but if the thickness cannot be reduced due to space, the sound absorption rate is insufficient in the mid- and low-frequency ranges. There is often. The frequency band that often becomes a problem with noise is 500 to 2 kHz. For example, the sound absorption characteristic (normal incidence method) of a polyester fiber system (density 35 kg / m ³ ) is 20% at 500 Hz at a thickness of 35 mm and 40 at 1 kHz. The sound absorption coefficient is only about%.

  In order to improve this, in most cases, a non-woven fabric is attached to the surface for both surface protection and adjustment of flow resistance. This also improves the sound absorption rate to about 70% at 1 kHz, but only improves the sound absorption rate to about 40% at 500 Hz. In order to achieve further improvement, the polyester fiber, which is a porous material, is thickened or an air layer is provided on the back side of the sound absorbing material. However, such measures may not be applicable when the total sound absorbing structure has a thickness of 50 mm or more and space is limited. The same situation occurs with other porous materials such as glass wool and flexible urethane foam.

  As one of the porous materials, polyester fiber-based sound absorbing material, which has been widely used recently, is that the incident energy of sound enters the material, causing the fibers to vibrate, causing friction between the fibers, or densely packed Sound absorption performance is exhibited by converting incident acoustic energy into thermal energy, for example, when viscous resistance is generated when air enters and exits the material. This sound absorption performance is closely related to the flow resistance of the sound absorber, and the sound absorption characteristics can be controlled by optimizing the flow resistance. The polyester fiber system has a sound absorption characteristic with a practical thickness by optimizing this flow resistance by applying a nonwoven fabric to the surface and combining it. However, in order to further improve the sound absorption characteristics in the middle and low frequencies, there are methods such as thickening the base material made of polyester fiber, increasing the density, and providing an air layer behind it. There are many cases where this is not possible.

  Therefore, it would be very useful to have a method and means for improving the sound absorption characteristics in the frequency range of 500 to 1 kHz without increasing the thickness of the porous material and the air layer. The present invention seeks to provide a sound absorbing structure that enables this.

  The present invention has been made to achieve the above object, and a sound absorbing structure according to the present invention has a mesh structure on the surface side of the cloth-like material of a sound-absorbing material in which the cloth-like material is bonded or fused to the surface. A multilayer structure with a film-like structure sandwiched therebetween. In addition, a multilayer structure in which a nonwoven fabric and a film-like structure are sandwiched between two mesh structures is disposed on the surface side of the cloth-like material of the sound absorbing material.

  According to this sound absorbing structure, the multilayer structure excited by the sound incident energy exhibits a multi-mass system behavior, and the vibration between the network structure and the film structure is converted into thermal energy by friction. Furthermore, it is converted into thermal energy by the vibration of the fibers, the friction between the fibers, and the viscous resistance due to the air vibration. Therefore, overall, the conversion efficiency from the sound incident energy to the heat energy is increased, and the sound absorption characteristics in the middle and low frequency regions can be greatly improved without changing the thickness of the sound absorption structure.

  In the sound absorbing structure, the cloth-like material can be bonded or fused to the entire surface of the sound absorbing material. The flow resistance is optimized by wrapping the entire surface of the sound absorbing material with a cloth-like material, and the most excellent sound absorbing characteristics in a wide band can be obtained by their combined effect. The cloth-like material bonded or fused to the sound absorbing material can be a non-woven fabric.

  Further, in the above sound absorbing structure, the cloth-like material bonded or fused to the sound absorbing material is raised from the sound absorbing material along the peripheral portion of the multilayer structure so as to wrap the multilayer structure, and further the multilayer structure. It is preferable that the multilayer structure and the sound-absorbing material are integrated by bending the frame around the periphery of the body and bonding or fusing to the multilayer structure. With such a structure, an integrated structure of the sound-absorbing material and the multilayer structure can be easily obtained, and stable adhesion can be ensured between the mesh structure and the film-like structure.

  In the above sound-absorbing structure, at least one of the mesh structures can be made of a metal material or a polymer material, and the film-like material can be made of a metal material or a polymer material. Examples of the metal material include aluminum and stainless steel, and examples of the polymer material include nylon material, vinyl chloride material, polyethylene material, fluorine material, and polypropylene material. One mesh structure may have a mesh size of 10 to 100 mesh and a wire diameter of 0.1 to 0.4 mmφ, and the film material may have a thickness of 10 to 100 μm.

  In the above sound absorbing structure, the mesh structure and the film-like material on the acoustic energy incident side constituting the multilayer structure are made of a metal material, and the mesh structure on the acoustic energy transmission side arranged behind is a polymer system. Can be composed of materials. Examples of metal materials include aluminum and stainless steel, and examples of polymer materials include nylon materials, vinyl chloride materials, polyethylene materials, fluorine materials, and polypropylene materials. If the mesh structure and film structure on the acoustic energy incident side are made of metal, the outer surface of the sound absorbing structure is made of metal, so that flame retardancy is ensured, and the mesh structure on the back becomes a lightweight polymer system. Therefore, the sound absorbing structure can be reduced in weight.

  Further, in the above sound absorbing structure, the sound absorbing material may be a fiber system, and the fiber direction thereof may be in a substantially vertical plane with respect to the multilayer structure. By aligning the fiber direction of the fiber-based sound absorbing material in a substantially vertical plane with respect to the multilayer structure, the structure of the fiber supports the multilayer structure in a columnar shape. Also improves. As a result, the degree of adhesion with the multilayer structure increases, and the sound absorption rate as the sound absorption structure can be improved. The fiber material as the sound absorbing material can be, for example, polyester.

  Furthermore, in the above sound absorbing structure, a surface protective material can be disposed on the acoustic energy incident side of the multilayer structure. It can be expected that the strength of the multi-layered structure against flying stones is ensured by the surface protective material. In addition, as a surface protection material, the perforated board and punching metal with an aperture ratio of 20% or more can be mentioned, for example.

  The sound-absorbing structure according to the present invention can mainly include a polyester fiber-based material as a porous sound-absorbing material, but the same as other porous sound-absorbing materials such as glass wool and foamed flexible urethane foam. The sound absorption performance can be expected to improve.

  In the case of a multilayer structure having a basic form in which a nonwoven fabric and a film-like structure are sandwiched between two network structures, friction is generated between the mesh structure, the nonwoven fabric and the membrane-like structure, resulting in vibration energy. Is effectively converted into thermal energy, and is further converted into thermal energy in a multifaceted manner by the viscous resistance caused by the vibration of the fibers, the friction between the fibers, and the vibration of the air. The mesh structure on the surface side may generate noise due to mechanical vibration or aerodynamic fluctuation, but the nonwoven fabric placed over this mesh structure can effectively suppress such noise. it can. Further, the cloth-like material bonded or melted to the sound absorbing material is raised from the sound absorbing material so as to wrap the multilayer structure along the peripheral portion of the multilayer structure, and further, the frame shape is formed on the peripheral portion of the multilayer structure. The multilayer structure is composed of two mesh structures and a non-woven fabric sandwiched between them by an integrated structure of the multilayer structure and the sound-absorbing material by bending or bonding to the multilayer structure. Stable adhesion can be ensured between the two.

  In the case of a sound absorbing structure having a basic form including a nonwoven fabric in a multilayer structure, the mesh structure disposed on the acoustic energy incident side is a metal material, and the mesh structure on the acoustic energy transmission side disposed behind is It is composed of a polymer material, and a nonwoven fabric sandwiched between these network structures can be arranged on the acoustic energy incident side, and a film-like material can be arranged on the acoustic energy transmission side to constitute a polymer material. . Here, regarding the network structure, the metal system is 30 to 200 mesh and the wire diameter is 0.1 to 0.4 mmφ, and the polymer system is 10 to 30 mesh and the aperture ratio is 10 to 50%. be able to. Moreover, as a polymeric material which comprises a film-form material, it can be set as the thing of 10-100 micrometers in thickness.

  Furthermore, in the case of a sound absorbing structure having a basic form including a nonwoven fabric in a multilayer structure, for example, aluminum or stainless steel is used as a metal material constituting the network structure disposed on the acoustic energy incident side, and superimposed on it. The non-woven fabric to be arranged is polyester-based, and the polymer material constituting the film-like material is, for example, polyolefin-based, polyester-based, nylon-based, vinyl chloride-based, polyethylene-based, fluorine-based, polypropylene-based material, Examples of the polymer material constituting the network structure on the acoustic energy transmission side include nylon, vinyl chloride, polyethylene, fluorine, and polypropylene materials. If the mesh structure on the acoustic energy incident side is made of a metal system and the non-woven fabric to be arranged next is subjected to super flame retardant treatment, a high flame retardancy, for example, a flame retardant standard for vehicles can ensure a non-flammable level. it can. In addition, since the film-like material and the mesh structure on the back surface thereof are made of a lightweight polymer, the sound absorbing structure can be reduced in weight. Even when a large air fluctuation or external vibration acts as an external force other than acoustic energy on the sound absorbing structure, it is possible to eliminate the possibility of chattering.

Furthermore, in the case of a sound-absorbing structure having a basic form including a nonwoven fabric in a multilayer structure, the nonwoven fabric is a spunbond nonwoven fabric, the sound-absorbing material is a fiber system such as polyester, and each is a powdered hot-melt resin, and its ventilation resistance Can be combined to be optimal. Usually, since the fiber-based sound absorbing material is formed by stacking planar laminated surfaces by spraying, the fibers are mainly arranged randomly in the laminated surface. By aligning the laminated surface of the fiber-based sound absorbing material in a substantially vertical plane with respect to the multilayer structure, the bonded fibers support the multilayer structure in the form of ribs. As the rigidity increases, the smoothness also improves. As a result, the degree of adhesion with the multilayer structure is increased, and the adsorption rate as the composite sound absorbing structure can be improved.
Furthermore, by adopting such a structure, the incident acoustic energy is effectively converted into thermal energy by the composite sound absorbing structure, and at the same time, the acoustic energy transmitted through the multilayer structure is further converted into the nonwoven fabric. The air-flow resistance of the polyester fiber type sound absorbing material roughly aligned in the vertical direction is optimally adjusted, and a composite sound absorbing structure in which the sound absorbing characteristics in the mid-low range are drastically improved is obtained.

  Furthermore, in the sound absorbing structure having the basic form including the nonwoven fabric in the multilayer structure, a surface protective material that transmits sound waves can be disposed on the acoustic energy incident side of the multilayer structure. It is expected that the strength of the multi-layered structure against flying stones is ensured by the surface protective material. Examples of the surface protective material include a perforated plate and a punching metal.

  The composite sound-absorbing structure according to the present invention can mainly include a polyester-based material as a porous sound-absorbing material, but other porous sound-absorbing materials such as glass wool, foamed flexible urethane foam, etc. In the same way, the sound absorption performance is expected to improve.

  As is clear from the above, according to the sound absorbing structure of the present invention, excellent sound absorption in the mid- and low-frequency ranges that cannot be realized with a polyester fiber sound absorbing material in which a nonwoven fabric is pasted on the surface on which the sound wave that has been optimized is conventionally incident. Performance can be demonstrated. The sound absorbing structure of the present invention not only exhibits excellent sound absorbing performance, but also protects against various factors such as weather resistance, durability, waterproofness, chemical resistance, etc. It is also a great advantage that it is effective for improving the flammability (more enhanced if it is made of a metal-based multilayer structure), and there is a great practical advantage. In addition, when applied to a part with an air flow such as a duct, a part of the fiber is not carried away, and it is safe in terms of air purification. In particular, in the case of a sound-absorbing structure having a basic form including a nonwoven fabric in a multilayer structure, the mesh structure on the surface side may cause chatter noise that may be caused by mechanical vibration or aerodynamic pulsation. Such a noise can be effectively suppressed by the nonwoven fabric, and a quiet sound absorbing structure can be obtained.

  Hereinafter, an exemplary configuration of a sound absorbing structure according to the present invention will be described based on a cross-sectional view and a three-dimensional view. Further, in the following examples, the effect of the present invention will be described by an experimental example using a reverberation chamber.

  FIG. 1 shows a basic structure of a sound absorbing structure according to the present invention. FIG. 1A is a cross-sectional view taken along the line A-A in FIG. 1B, and FIG. A sound absorbing structure 1 shown in FIG. 1 includes a multilayer structure 2 and a sound absorbing material 3. The multilayer structure 2 includes at least two mesh structures 4a and 4b that transmit sound waves (generally referred to as the case). , And a film-like material 5 sandwiched between the mesh structures 4a and 4b in close contact with each other. A cloth-like material 6 is bonded or fused to the surface of the sound absorbing material 3. The multilayer structure 2 is arranged so as to overlap the cloth-like material 6 side of the sound absorbing material 3.

  In the sound absorbing structure 1, at least one of the mesh structures 4 is made of a metal material such as aluminum or stainless steel, or a polymer material such as nylon, vinyl chloride, polyethylene, fluorine, or polypropylene. The mesh structure is 10 to 100 mesh and the wire diameter is 0.1 to 0.4 mmφ. The film material 5 is made of a metal material such as aluminum or stainless steel, or a polymer material such as nylon, vinyl chloride, polyethylene, fluorine, or polypropylene, and has a thickness of 10 to 100 μm. Is. On the other hand, the sound absorbing material 3 is made of a fiber-based material such as polyester, and the fiber direction thereof is in a substantially vertical plane with respect to the surface of the multilayer structure 2. The cloth-like material 6 can be a non-woven fabric.

  The mesh structure 4a and the film-like material 5 on the acoustic energy incident side are made of metal materials such as aluminum and stainless steel, and the mesh structure 4b on the acoustic energy transmission side is made of nylon, vinyl chloride, polyethylene, fluorine, It can be composed of a polymer material such as polypropylene. By making the mesh structure 4a and the film structure 5 made of metal, the outer surface of the sound absorbing structure 1 is made of metal, so that flame retardancy is ensured. Moreover, the weight of the sound absorbing structure 1 can be reduced by making the mesh structure 4b on the back surface a lightweight polymer.

  The vibration between the mesh structures 4a, 4b and the film-like material 5 is converted into thermal energy by friction, and further, due to vibration of fibers in individual structures or materials, friction between fibers, and viscous resistance due to air vibration, Converted to thermal energy. Therefore, overall, the sound incident energy is efficiently converted into heat energy, and the sound absorption characteristics in the middle and low frequency regions can be greatly improved without increasing the thickness of the sound absorbing structure.

  FIG. 2 is a view showing another embodiment of the sound absorbing structure according to the present invention. FIG. 2A is a cross-sectional view taken along the line BB in FIG. 2B, and FIG. In the sound absorbing structure 10 shown in FIG. 2, the cloth-like material 16 is bonded or fused to the entire surface of the sound absorbing material 3. The other points are the same as those of the sound absorbing structure 1 shown in FIG. 1, and thus the same reference numerals are given to the same elements and the detailed description thereof is omitted. By enclosing the entire surface of the sound absorbing material 3 with the cloth-like material 16, the flow resistance is optimized, and the best sound absorbing characteristics in a wide band can be obtained by the combined effect thereof.

  FIG. 3 is a view showing still another embodiment of the sound absorbing structure according to the present invention. 3A is a cross-sectional view taken along the line CC of FIG. 3B, and FIG. 3B is a three-dimensional view with a part broken away. The sound absorbing structure 20 shown in FIG. 3 is such that the cloth-like material 26 wraps the multilayer structure 2 along the peripheral portion 2a of the multilayer structure 2 from the sound absorbing material 3 side in the sound absorbing structure shown in FIG. The cloth-like material 26 that has been raised and raised is further bent into a frame shape around the peripheral edge portion 2 a of the multilayer structure 2. The frame-like portions 26a and 26b around the cloth-like material 26 are bonded or fused to the multilayer structure 2 so that the multilayer structure 2 and the sound absorbing material 3 are integrated by the cloth-like material 26, thereby forming a mesh structure. Stable adhesion is ensured between the bodies 4 and 4 and the film structure (film material 5). The other points are the same as those of the sound absorbing structure 1 shown in FIG. 1, and thus the same reference numerals are given to the same elements and the detailed description thereof is omitted.

  FIG. 4 is a view showing still another embodiment of the sound absorbing structure according to the present invention. 4A is a cross-sectional view taken along the line DD of FIG. 4B, and FIG. 4B is a three-dimensional view with a part broken away. The sound absorbing structure 30 shown in FIG. 4 is a hole having an aperture ratio of 20% or more on the acoustic energy incident side (left side in FIG. 4A) of the multilayer structure 2 in the sound absorbing structure 20 shown in FIG. It is a structure in which a surface protection material 37 such as a board, punching metal, or expanded metal is disposed. For example, when applied to a floor structure of a railway vehicle, the surface protective member 37 can ensure the strength of the multilayer structure 2 against a stepping stone or the like. The other points are the same as those of the sound absorbing structure 1 shown in FIGS. 1 and 3, and therefore, the same elements are denoted by the same reference numerals, and detailed description thereof is omitted.

FIG. 5 is a graph showing an example of the frequency characteristic of the sound absorption coefficient for the product of the present invention and the conventional product. As a product of the present invention, the sound absorbing material 3 is a polyester fiber-based sound absorbing material (density 35 kg / m ³ , thickness 35 mm), and the surface (sonic wave incident side) is a non-woven cloth material 6 with a basis weight (weight per m ² ). ) A heat-absorbing structure in which 100gr of spunbond is heat-sealed, and the multilayer structure 2 (SUS40 mesh network structure / SUS thin film 40μ / SUS40 mesh network structure) is arranged on the upper surface is used. It was. FIG. 5 shows a comparison of sound absorption characteristics according to the reverberation chamber method between this sound absorbing structure and a conventional product. It can be seen that the combination of the multilayer structure 2 and the sound-absorbing material 3 of the present invention (superimposing) greatly improves the middle / low frequency range.

FIG. 6 is a graph showing an example of the frequency characteristic of the sound absorption rate for another product of the present invention and a conventional product. As the product of the present invention, the sound absorbing material 3 is a polyester fiber-based sound absorbing material (density 35 kg / m ³ , thickness 35 mm), the surface (sound incident side) is a cloth-like material 6 and a non-woven fabric with a basis weight of 100 gr is matured. The other five surfaces are heat-bonded with a spunbond having a weight of 50 gr, and a multilayer structure having the same structure as that of the first embodiment on the sound incident side surface of the sound absorber 3 in which the entire surface is wrapped with spunbond. A sound absorbing structure in which the body 2 is closely attached was used (corresponding to the sound absorbing structure 10 shown in FIG. 2). FIG. 6 shows a comparison of sound absorption characteristics according to the reverberation chamber method between this sound absorbing structure and a conventional product. From the result of FIG. 6, the sound absorption structure which is the product of the present invention is a result that is further improved from the result of FIG. 5, and proves the effect of the present invention. The sound absorbing structure fixed by the frame system is more stable.

  FIG. 7 shows another basic structure of the sound absorbing structure according to the present invention. FIG. 7A is a cross-sectional view taken along line EE in FIG. 7B, and FIG. The sound absorbing structure 40 shown in FIG. 7 is composed of a multilayer structure 42 and a sound absorbing material 3, and the multilayer structure 42 has at least two components that transmit sound waves, as in the embodiment shown in FIG. 1. It consists of a mesh structure 4a, 4b (when the generic name is used, reference numeral 4), a film-like material 5 and a nonwoven fabric 7 sandwiched between the mesh structures 4a, 4b. The sound absorbing structure 40 is not different from the sound absorbing structure 1 shown in FIG. 1 except that the multilayer structure 42 includes the nonwoven fabric 7. A cloth-like material 6 made of a nonwoven fabric is bonded or fused to the surface of the sound absorbing material 3 while ensuring an optimum ventilation resistance. The multilayer structure 42 is arranged so as to overlap the cloth-like material 6 side of the sound absorbing material 3.

In the composite sound absorbing structure 40, the acoustic energy incident side, that is, the network structure 4a that is initially arranged with respect to the acoustic incident energy is made of a metallic material such as aluminum or stainless steel, and is arranged rearward. The network structure 4b is made of a polymer material such as nylon, vinyl chloride, polyethylene, fluorine, or polypropylene. In the case of the metallic network structure 4a, the mesh structure is 30 to 200 mesh and the wire diameter is 0.1 to 0.4 mmφ. In the case of the resin-based network structure 4b, it is configured with 10 to 30 mesh and an aperture ratio of 10 to 50%. The nonwoven fabric 7 sandwiched between the two network structures 4a and 4b is a nonwoven fabric impregnated with a resin and has a surface weight of 35 to 100 g / m ² . The membranous material 5 is made of a polymer material such as polyolefin, nylon, vinyl chloride, polyethylene, fluorine, polypropylene, Teflon (registered trademark), and a nonwoven fabric having a thickness of 10 to 100 μm. A film-like material is adhered and stacked. On the other hand, the sound absorbing material 3 is made of a fiber-based material such as polyester, the fiber direction thereof is in a substantially vertical plane with respect to the multilayer structure 42, and the surface is a non-woven fabric as the cloth-like material 6. A spunbonded nonwoven fabric having a weight of 20 to 100 g / m ² is fused or bonded with a powdered hot melt or the like so as not to impair air permeability.

  The mesh structure 4a on the acoustic energy incident side is made of a metal material such as aluminum or stainless steel, and the mesh structure 4b on the acoustic energy transmission side is made of nylon, vinyl chloride, polyethylene, fluorine, polypropylene, or the like. It can be composed of a polymer material. By making the mesh structure 4a a metal mesh having a relatively fine mesh and enhancing the flame retardancy of the nonwoven fabric 7 which is the next layer, the flame retardance of the sound absorbing structure 40 is ensured. Moreover, the weight of the sound absorbing structure 40 can be reduced by making the film-like material 5 and the mesh structure 4b on the back surface of the film-like material 5 a lightweight polymer.

  When the sound absorbing structure 40 is subjected to acoustic excitation, the acoustic energy is generated due to friction generated between the mesh structures 4a and 4b and the membrane material and the nonwoven fabric 7 due to the behavior of a complicated multi-mass system. It is efficiently converted into thermal energy, and further converted into thermal energy by vibration of fibers in individual structures or materials, friction between fibers, and viscous resistance due to air vibration. Therefore, overall, the sound incident energy is efficiently converted into heat energy, and the sound absorption characteristics in the middle and low frequency regions can be greatly improved without increasing the thickness of the sound absorbing structure.

  FIG. 8 is a view showing still another embodiment of the sound absorbing structure according to the present invention. FIG. 8A is a cross-sectional view taken along the line F-F in FIG. 8B, and FIG. In the sound absorbing structure 50 shown in FIG. 8, the cloth-like material 56 made of a nonwoven fabric is bonded or fused to the entire surface of the sound absorbing material 3. Since the other points are the same as those of the sound absorbing structure 40 that is the basic form shown in FIG. 7, the same reference numerals as those in the sound absorbing structure 40 are used for the common structures, and the description thereof is omitted. By wrapping the entire surface of the sound absorbing material 3 with the cloth-like material 56 which is a non-woven fabric, the flow resistance is optimized, and the best sound absorbing characteristics in a wide band can be obtained by their combined effect.

  FIG. 9 is a view showing still another embodiment of the sound absorbing structure according to the present invention. 9A is a cross-sectional view taken along line GG in FIG. 9B, and FIG. 9B is a three-dimensional view with a part broken away. In the sound absorbing structure 60 shown in FIG. 9, the multilayer structure 62 has an aperture ratio of 20 on the acoustic energy incident side (left side in FIG. 9A) of the multilayer structure 42 of the sound absorbing structure 50 shown in FIG. % Or more perforated plates, punched metal, expanded metal and other surface protective materials 67 are disposed. For example, when applied to the floor structure of a railway vehicle, the surface protective material 67 can ensure the strength of the multilayer structure 62 against a stepping stone or the like.

FIG. 10 is a graph showing an example of frequency characteristics of the normal incidence method sound absorption coefficient in comparison with the product of the present invention and the conventional product. As the sound-absorbing structure 70 according to the present invention, the sound-absorbing material 3 is a polyester fiber-based sound-absorbing material (density 44 kg / m ³ , thickness 40 mm, fiber longitudinal orientation), and a nonwoven fabric as a cloth-like material 6 on the surface (sound wave incident side). As a result, a spunbonded nonwoven fabric having a basis weight (weight per m ² ) of 100 g is heat-fused with a powdered hot melt resin, and a multilayer structure 72 (SUS100 mesh / resin as the network structure 4a is further formed on the upper surface thereof. using nonwoven fabric impregnated -75g ^/ m 2 / film-like material olefin thickness 50μ as 5 resin film / network structure resin net 14 mesh) sound absorbing structure configured by disposing as 4b. In the figure, the sound-absorbing structure 70 of the present invention and the conventional product (100 g / m ² spunbond nonwoven fabric are heated to a polyester fiber-based sound absorbing material (density 44 kg / m ³ , thickness 40 mm, fiber lateral orientation) by powder hot melt. The sound absorption characteristics by the normal incidence method with those of the fused ones were compared (FIG. 10 (c)). Further, FIG. 11 shows a comparison between the sound absorbing structure 70 according to the present invention (shown in FIG. 10) and a structure in which the orientation of the polyester fiber sound absorbing material as the sound absorbing material in the sound absorbing structure 70 is set in the horizontal direction. Is going. From FIG. 10 and FIG. 11, the sound absorbing structure according to the present invention has a large middle and low frequency range due to the combination (overlap) of the multilayer structure 72 and the sound absorbing material 3 fused with the nonwoven fabric (cloth-like material 6). It can be seen that it has been improved.

  As described above, it has been generally shown that the longitudinal orientation is superior to the lateral orientation in terms of sound absorption characteristics. However, in practice, the sound absorbing structure according to the present invention has the conventional ventilation even in the horizontal orientation and random orientation. Needless to say, it exhibits superior sound absorption characteristics as compared with typical glass wool, rock wool and flexible urethane foam as a porous material with controlled resistance.

  FIG. 12 is a schematic view showing a range in which the sound absorbing structure according to the present invention can be applied to a railway vehicle. The region where the sound absorbing structure is attached by means such as pasting is the range indicated by the arrows along the vehicle body of the railway vehicle 100, that is, the inner and outer surfaces 103a and 103b of the skirt 103 extending from the side structure, and the lower surface of the floor 104 of the vehicle body. 104a. That is, from the carriage 101 including the wheels 102 and 102, there is noise when the wheels 102 and 102 roll on the rail and noise generated by the mounted motor. These noises may be transmitted directly to the floor 104 by being reflected by the skirt 103 and entering the passenger compartment or the cabin interior 105. In addition, noise that has come out of the vehicle is remarkable in the case of tunnels and sound insulation walls, but may be reflected by structures outside the vehicle and enter the vehicle again. Therefore, noise is absorbed by sticking the sound absorbing structure according to the present invention to the inner surface 103a and outer surface 103b of the skirt 103 and the lower surface 104a of the floor 104, and the noise is prevented from entering the passenger compartment or the cabin interior 105. be able to.

  The object of application of the composite sound absorbing structure according to the present invention is a sound insulation wall or excavation in the railway and road fields, a sound absorbing structure part used to suppress multiple reflections inside the tunnel, noise reduction and sound field control in the building field. Therefore, the present invention can be applied to a wide range of sound absorbing structure parts used for noise reduction, such as around the engine of a railway vehicle, automobile, construction machine, agricultural machine, vehicle compartment, and cabin interior noise reduction.

It is a figure which shows the basic structure of the sound-absorbing structure by this invention. It is a figure which shows another Example of the sound-absorbing structure by this invention. It is a figure which shows another Example of the sound-absorbing structure by this invention. It is a figure which shows another Example of the sound-absorbing structure by this invention. It is a graph which compares and shows an example of the frequency characteristic of a sound absorption coefficient about this invention product and a conventional product. It is a graph which contrasts and shows an example of the frequency characteristic of a sound absorption rate about another this invention product and a conventional product. It is a figure which shows another basic structure of the sound-absorbing structure by this invention. It is a figure which shows another Example of the sound-absorbing structure by this invention. It is a figure which shows another Example of the sound-absorbing structure by this invention. It is a graph which compares and shows an example of the frequency characteristic of a sound absorption coefficient about this invention product and a conventional product. It is a graph which contrasts and shows an example of the frequency characteristic of a sound absorption rate about another this invention product and a conventional product. It is the figure which showed the range where the sound-absorbing structure by this invention is applied in a railway vehicle.

Explanation of symbols

1, 10, 20, 30, 40, 50, 60, 70 Sound absorbing structure 2 Multi-layer structure 2a Peripheral portion 3 Sound absorbing material 4, 4a, 4b Network structure 5 Film-like material 6, 16, 26, 56 Cloth-like Material 7 Non-woven fabric 26a Frame-shaped part 37, 67 Surface protective material 42, 62, 72 Multi-layer structure

Claims (17)

A multilayer structure composed of at least two mesh structures that transmit sound waves and a film-like material sandwiched between the mesh structures in close contact with each other;
A sound-absorbing material having a cloth-like material bonded or fused to the surface;
The multilayer structure is arranged to overlap the cloth-like material side of the sound absorbing material;
A sound-absorbing structure. The sound absorbing structure according to claim 1,
The cloth-like material is bonded or fused to the entire surface of the sound absorbing material;
A sound-absorbing structure. The sound absorbing structure according to claim 1,
The cloth-like material is raised from the sound-absorbing material so as to wrap the multilayer structure, and is further bent into a frame shape at the periphery of the multilayer structure, and adhered or fused to the multilayer structure. The multilayer structure and the sound absorbing material are integrated,
A sound-absorbing structure. The sound absorbing structure according to claim 1,
At least one of the network structures is made of a metal material or a polymer material,
The film material is composed of a metal material or a polymer material,
A sound-absorbing structure. The sound absorbing structure according to claim 1,
The mesh structure and the film-like material on the acoustic energy incident side are made of a metal-based material,
The network structure on the acoustic energy transmission side is made of a polymer material;
A sound-absorbing structure. The sound absorbing structure according to claim 1,
The sound absorbing material is made of a fiber-based material, and the fiber direction is in a substantially vertical plane with respect to the multilayer structure,
A sound-absorbing structure. In the sound-absorbing structure according to claim 1,
A surface protective material is disposed on the acoustic energy incident side of the multilayer structure,
A sound-absorbing structure. The sound absorbing structure according to any one of claims 1 to 7 is applied to an inner surface or an outer surface of a skirt that extends downward from a lower surface of a vehicle body floor or a side structure,
Rail vehicle characterized by. A multilayer structure composed of at least two network structures that transmit sound waves and a nonwoven fabric and a film-like material sandwiched between the network structures in close contact with each other;
A sound-absorbing material having a cloth-like material bonded or fused to the surface;
The multilayer structure is arranged to overlap the cloth-like material side of the sound absorbing material;
A sound-absorbing structure. The sound absorbing structure according to claim 9, wherein
The cloth-like material is bonded or fused to the entire surface of the sound absorbing material;
A sound-absorbing structure. The sound absorbing structure according to claim 9, wherein
The cloth-like material is a non-woven fabric;
A sound-absorbing structure. The sound absorbing structure according to claim 9, wherein
The network structure on the acoustic energy incident side is made of a metal-based material,
The network structure on the acoustic energy transmission side is made of a polymer material,
The nonwoven fabric is a nonwoven fabric disposed on the acoustic energy incident side,
The membrane material is a polymer material disposed on the acoustic energy transmission side;
A sound-absorbing structure. The sound absorbing structure according to claim 10, wherein
The metal material constituting the mesh structure on the acoustic energy incident side and the polymer material constituting the mesh structure on the acoustic energy transmission side are both mesh materials,
A sound-absorbing structure. The sound absorbing structure according to claim 9, wherein
The network structure on the acoustic energy incident side is made of a metal-based material,
The network structure on the acoustic energy transmission side is made of a polymer material,
The nonwoven fabric is a polymer material sandwiched between the mesh structures on the acoustic energy incident side and the acoustic energy transmission side,
The film material is made of a resin material;
A sound-absorbing structure. The sound absorbing structure according to claim 9, wherein
The sound-absorbing material is composed of a nonwoven fabric and a fiber-based material, and the fiber direction is in a substantially vertical plane with respect to the surface of the multilayer structure,
The nonwoven fabric and the fiber material are fused or bonded so as not to impair air permeability,
A sound-absorbing structure. In the sound-absorbing structure according to any one of claims 9 to 11,
A surface protective material is disposed on the acoustic energy incident side of the multilayer structure,
A sound-absorbing structure. The sound absorbing structure according to any one of claims 9 to 16 is applied to an inner surface or an outer surface of a skirt that extends downward from a lower surface of a vehicle body floor or a side structure,
Rail vehicle characterized by.

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