Soundproof structure

Abstract

To improve soundproof performance of soundproof structures used for automotive parts and duct closing lid parts.SOLUTION: A soundproof structure 1 includes a soundproofing material 10 with an elastic sheet 200 and a support member 100 that supports the sheet 200 and divides the sheet 200 into compartments, where surface rigidity (k) of the sheet 200 and surface density (m) of the sheet 200 in the compartment satisfy a relation of the following Formula 1, and a reinforcing member 20 having a frame shape is bonded to the outer periphery of at least one surface of the soundproof material 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a soundproof structure that can be used, for example, in automobile parts, duct closing cover parts, etc. [Background technology]

[0002] A conventional soundproof structure is described in Patent Document 1. The soundproof structure described in Patent Document 1 includes an elastic sheet and a support portion that supports the sheet and divides the sheet. The support portion is a honeycomb structure in which a large number of cylindrical cells are arranged. This soundproof structure exhibits high soundproofing performance over a wide range of frequencies below 2000 Hz. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6879369 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, the conventional soundproof structure as described in Patent Document 1 has excellent soundproofing performance. On the other hand, there is a demand for further improvement in the soundproofing performance of the conventional soundproof structure.

[0005] Therefore, an object of the present invention is to provide a means for improving the soundproofing performance of a soundproof structure. [Means for solving the problem]

[0006] One aspect of the present invention provides a soundproof structure. This soundproof structure includes a soundproof material having an elastic sheet and a support member that supports the sheet and divides the sheet into partitions. The soundproof structure is characterized in that the surface stiffness (k) of the sheet in the partitions and the surface density (m) of the sheet satisfy the relationship of the following mathematical formula 1, and a reinforcing member having a frame shape is joined to the outer periphery of at least one surface of the soundproof material:

[0007]

number

[0008] According to the present invention, the soundproofing performance of a soundproof structure can be improved. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a side view showing the appearance of a soundproof structure according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view showing the appearance of a soundproofing material according to one embodiment of the present invention. [Diagram 3] FIG. 3 is a top view of a soundproofing material according to one embodiment of the present invention. [Figure 4] FIG. 4 is an enlarged cross-sectional view for illustrating the cross-sectional shape and size of a cylindrical cell constituting a soundproofing material according to one embodiment of the present invention. [Diagram 5] FIG. 5 is a cross-sectional view that shows a schematic structure in which a soundproof structure 1 according to one embodiment of the present invention is installed in an air intake duct 2 for a vehicle. [Figure 6] FIG. 6 is a graph showing the results of measuring the soundproofing performance (insertion loss) of the soundproof structures produced in Comparative Examples 1 to 3 and Example 1. [Figure 7] FIG. 7 is a graph showing the results of measuring the soundproofing performance (insertion loss) of the soundproof structures produced in Comparative Example 1, Comparative Example 3, Comparative Example 4, and Example 2. [Figure 8]FIG. 8 is a graph showing the results of calculating the increase in insertion loss per unit increase in areal density for the soundproof structures produced in Example 1 and Comparative Example 5, with Comparative Example 3 being used as the standard. [Figure 9] FIG. 9 is a graph showing the results of measuring the soundproofing performance (insertion loss) of the soundproof structures produced in Comparative Example 3, Example 1, and Comparative Example 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] One aspect of the present invention includes a soundproofing material including an elastic sheet and a support member that supports the sheet and divides the sheet into partitions, The surface stiffness (k) of the sheet in the partition portion and the surface density (m) of the sheet satisfy the relationship of the following formula 1, and A soundproof structure, comprising: a reinforcing member having a frame shape joined to an outer periphery of at least one surface of the soundproof material;

[0011]

number

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the attached drawings. Note that the following description does not limit the technical scope or meaning of terms described in the claims. Also, the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may differ from the actual ratios.

[0013] Fig. 1 is a side view showing the appearance of a soundproof structure according to one embodiment of the present invention. Fig. 2 is a perspective view showing the appearance of a soundproof material constituting the soundproof structure according to one embodiment of the present invention. Fig. 3 is a top view of the soundproof material constituting the soundproof structure according to one embodiment of the present invention. Fig. 4 is an enlarged cross-sectional view for explaining the cross-sectional shape and size of a support part of the soundproof material constituting the soundproof structure according to one embodiment of the present invention.

[0014] As shown in FIG. 1, a soundproof structure 1 according to an embodiment of the present invention includes a soundproofing material 10 and a reinforcing member 20. As shown in FIG. 1 and FIG. 2, the soundproofing material 10 according to an embodiment of the present invention includes a lattice structure 100 (supporting part) composed of cylindrical cells arranged continuously (regularly), and a latex rubber sheet 200 composed of elastic latex rubber. The latex rubber sheet 200 is airtightly joined to the lattice structure 100 so as to close one of the openings on both sides of the lattice structure 100, and functions as a sheet-like substrate. The thickness of the latex rubber sheet 200 in this embodiment is 0.25 mm (250 μm). Meanwhile, in this embodiment, the lattice structure 100 is composed of polyvinyl chloride resin. The lattice structure 100 has a large number of cylindrical cells 110 that are continuously (regularly) in contact with each other.

[0015] 1, in the soundproof structure 1 according to this embodiment, a rubber foam 20 having a rectangular frame shape is arranged and bonded to the lattice structure 100 on the outer periphery of the open cross section (the surface opposite to the side on which the latex rubber sheet 200 is arranged) of the lattice structure 100 (support portion) constituting the soundproofing material 10. This rubber foam 20 functions as a reinforcing member.

[0016] As shown in Fig. 2 and Fig. 3, in the soundproofing material 10 according to this embodiment, the cross-sectional shape of the cylindrical cells 110 in a cross section perpendicular to the extending direction of the lattice structure 100 (on the paper surface of Fig. 3) is a regular hexagon. That is, the lattice structure 100 has a so-called honeycomb structure. As a result, the lattice structure 100 according to this embodiment supports a latex rubber sheet 200 as a sheet-like substrate, and divides the latex rubber sheet 200 into a plurality of partitions (a large number in Figs. 2 and 3). The plurality of partitions have the same outer shape and constitute a regular array structure in which the plurality of partitions are regularly arranged.

[0017] Moreover, the cell size (distance between opposing parallel sides in a regular hexagonal cross-sectional shape; distance w shown in FIG. 4) of one cylindrical cell (110a shown in FIG. 4) constituting the honeycomb structure is 4 mm. With such a configuration, excellent sound insulation performance can be realized with a very simple configuration. Furthermore, as shown in FIG. 4, the lattice structure 100 can be considered to be composed of a large number of cylindrical cells 110 connected together, each having a wall around it. In this embodiment, the wall thickness of this cylindrical cell (distance t shown in FIG. 4) is 0.07 mm (70 μm). The height (distance h shown in FIG. 2) of the lattice structure (cylindrical cell) in the extension direction is 25 mm, and the lattice structure is composed of a single structure with a uniform height.

[0018] As described above, the soundproofing material having the structure shown in Fig. 2 and Fig. 3 can achieve excellent soundproofing performance with a very simple structure. In particular, it can exhibit the characteristic of being able to exhibit high soundproofing performance in the frequency range of 1500 to 2500 Hz, despite being lightweight and having a simple structure.

[0019] In order for such a soundproofing material to exhibit excellent soundproofing performance, it is necessary to satisfy the above formula 1. The theory behind this is described in detail in Patent Document 1. Here, in formula 1, the surface density (m) of the sheet in the partitioned portion can be expressed as in the following formula 2.

[0020]

number

[0021] In formula 2, ρ is the density of the sheet in the partition [kg / m 3 ], and h is the film thickness [m] of the sheet in the partition section.

[0022] On the other hand, in Equation 1, the surface stiffness (k) of the partition is calculated by approximating each partition of the elastic sheet with a disk of radius a with the same area, and assuming that a load p is input, the average deflection (wave ) is expressed as follows in Equation 3.

[0023]

number

[0024] In Equation 3, ν is the Poisson's ratio of the sheet in the partitioned area, E is the Young's modulus of the sheet in the partitioned area [Pa], and h is the film thickness of the sheet in the partitioned area [m]. In addition, when the partitioned area is approximated as a disk, the radius a is the radius of the circle equivalent to the area of ​​the partitioned area [m].

[0025] Then, by using the value of surface stiffness (k) calculated in this manner, the value of the resonance frequency (f0) of the soundproofing material can be expressed by the following Equation 4.

[0026]

number

[0027] Then, the value of the resonance frequency (f0) of the soundproofing material is determined by the density of the sheet in the partition (ρ; mass per unit volume; kg / m 3 ) and the thickness [m] of the sheet in the partition section, as shown in the following formula 5. This means that it is possible to control the resonant frequency (f0) of the soundproofing material by changing the size and shape of the partition section, and the material and thickness of the sheet in the partition section.

[0028]

number

[0029] In the present invention, as shown in Equation 1, it is essential that the resonance frequency (f0) calculated based on the above-mentioned approximation is greater than 900 [Hz].

[0030] Here, the form of the value on the left side of the formula 1 is not particularly limited, and can be appropriately set according to the frequency range in which the soundproofing material is desired to exhibit soundproofing performance. In general, the larger the value on the left side of the formula 1, the higher the resonance frequency shifts to the high frequency side, so this should be taken into consideration when setting the value appropriately. As an example, the value on the left side of the formula 1 is preferably 1400 Hz or more, more preferably 2000 Hz or more, even more preferably 3000 Hz or more, even more preferably 4000 Hz or more, and particularly preferably 5000 Hz or more. The value on the left side of the formula 1 is, for example, 10000 Hz or more, for example 50000 Hz or more, for example 100000 Hz or more. In a soundproofing material that exhibits soundproofing performance within the scope of the technical idea of ​​the present invention, the upper limit of the value on the left side of the formula 1 is preferably 1000000 Hz or less, more preferably 800000 Hz or less, and even more preferably 600000 Hz or less.

[0031] The components of the soundproofing material 10 are described in more detail below.

[0032] (Elastic sheet) There is no particular limitation on the material of the elastic sheet (corresponding to the latex rubber sheet 200 shown in FIG. 1 and FIG. 2), and various materials can be used as long as they are elastic. In this specification, a material is "elastic" means that the material is composed of a material whose Young's modulus value is within the range of 0.001 to 70 [GPa]. The Young's modulus value for resins can be measured according to JIS K7161-1 (2014). The Young's modulus for metals can be measured according to JIS Z2241 (2011). The Young's modulus for rubber can be measured according to JIS Z6251 (2010). As the material of the elastic sheet, in addition to the latex rubber used in the above-mentioned embodiment, rubber materials such as chloroprene rubber (CR), styrene-butadiene rubber (SBR), ethylene-propylene-diene rubber (EPDM), and acrylonitrile-butadiene rubber (NBR) can be used in the same way. In addition, resin materials, metal materials, paper materials, and the like may be used as the elastic sheet. Furthermore, materials having a buffer function such as air cushions may also be used. All of these materials, including rubber materials, have high elasticity to the extent that they can exert the effect of the soundproofing material according to the present embodiment. Examples of resin materials include polyolefin resins such as polyethylene (e.g., low-density polyethylene, high-density polyethylene, etc.), polypropylene, polyvinyl chloride resin, acrylic resin, methacrylic resin, vinyl acetate resin, ethylene-vinyl acetate resin, etc. Examples of thermosetting resins include silicone resin, urethane resin, melamine resin, thermosetting acrylic resin, urea resin, phenol resin, resorcinol resin, alkyl resorcinol resin, epoxy resin, thermosetting polyester, etc. Note that resin precursors such as prepolymers, oligomers, and monomers such as urethane resin prepolymers, urea resin prepolymers (initial condensation products), phenol resin prepolymers (initial condensation products), diallyl phthalate prepolymers, acrylic oligomers, polyisocyanates, methacrylic ester monomers, and diallyl phthalate monomers that generate these resins may also be used. Examples of metal materials include copper and aluminum.The material of the elastic sheet is not limited to the above, and other materials may be used. The material of the elastic sheet is preferably a rubber material, and more preferably latex rubber or EPDM rubber. By using these rubber materials as the material of the elastic sheet, the soundproofing effect of the soundproofing material according to the present invention can be suitably exhibited. In addition, these rubber materials are particularly preferable materials because they are lightweight and contribute greatly to low fuel consumption, especially when considering application to vehicle applications. Furthermore, from the viewpoint of cost reduction, polyolefin resins such as polypropylene are also preferable as the material of the elastic sheet.

[0033] From the viewpoint of the soundproofing effect of the soundproof material, the thickness of the elastic sheet is preferably 10 to 1000 μm, and more preferably 100 to 500 μm.

[0034] (Support part (lattice structure)) The support section supports the elastic sheet and divides the sheet into (airtightly divided) compartments. There are no particular limitations on the specific configuration of the support section as long as it has a configuration that can realize such functions. Although Figures 1 to 3 show that there are many compartments, even if there is only one compartment, it falls within the scope of the present invention.

[0035] There is no particular restriction on the material of the support portion, and in addition to the polyvinyl chloride resin used in the above-mentioned embodiment, a conventionally known thermoplastic resin or thermosetting resin may be used. Metal materials and other materials may also be used as the material of the support portion. All of these materials have physical properties suitable for holding an elastic sheet and dividing it into partitions.

[0036] Examples of thermoplastic resins include polyvinyl chloride resins, polyethylene (e.g., low-density polyethylene, high-density polyethylene, etc.), polyolefin resins such as polypropylene, acrylic resins, methacrylic resins, acrylonitrile-butadiene-styrene resins, vinyl acetate resins, ethylene-vinyl acetate resins, styrene-butadiene resins, etc. Examples of thermosetting resins include urethane resins, melamine resins, thermosetting acrylic resins, urea resins, phenolic resins, resorcinol resins, alkylresorcinol resins, epoxy resins, and thermosetting polyesters. In addition, resin precursors such as prepolymers, oligomers, and monomers such as urethane resin prepolymers, urea resin prepolymers (initial condensates), phenolic resin prepolymers (initial condensates), diallyl phthalate prepolymers, acrylic oligomers, polyisocyanates, methacrylic ester monomers, and diallyl phthalate monomers that generate these resins may be used. Among these, thermoplastic resins are preferably used from the viewpoint of ease of molding, and vinyl chloride resins and polyolefin resins are particularly preferable due to their advantages of being lightweight, excellent in durability, and inexpensive.

[0037] As described above, the support part is preferably a lattice structure having a large number of cylindrical cells that are continuously in contact with each other. In this case, the support part divides the elastic sheet into a plurality of partitions. Furthermore, it is more preferable that at least a portion of the plurality of partitions constitute a regular array structure in which a plurality of partitions having the same outer shape are regularly arranged. With such a configuration, the product is easy to manufacture, and the presence of a large number of partitions having the same shape makes it possible to specifically exhibit soundproofing performance against sound waves in a desired frequency range.

[0038] There are no particular limitations on the size of the cylindrical cells that make up the lattice structure, so long as it satisfies the above-mentioned mathematical formula 1. In a preferred embodiment in which the lattice structure has a honeycomb structure, the size of the cylindrical cells (the distance between opposing parallel sides in a regular hexagonal cross-sectional shape) is preferably 6.0 mm or less, as shown in Figures 2 and 3. With such a size, excellent soundproofing performance can be achieved. The size of the cylindrical cells (the distance between the opposing parallel sides in the regular hexagonal cross-sectional shape) may be 5.9 mm or less, 5.8 mm or less, 5.7 mm or less, 5.6 mm or less, 5.5 mm or less, 5.4 mm or less, 5.3 mm or less, 5.2 mm or less, 5.1 mm or less, 5.0 mm or less, 4.9 mm or less, 4.8 mm or less, 4.7 mm or less, 4.6 mm or less, 4.5 mm or less, 4.4 mm or less, 4.3 mm or less, 4.2 mm or less, 4.1 mm or less, 4.0 mm or less, etc., and the narrower the numerical range, the more preferable. There is no particular limit on the lower limit of the size of the cylindrical cells, but if the size of the cylindrical cells is too small, the mass of the lattice structure (and therefore the soundproofing material) increases, so it is preferably 2.0 mm or more.

[0039] The wall thickness of the cylindrical cells (distance t shown in FIG. 4) is preferably 10 to 150 μm, and more preferably 30 to 100 μm.

[0040] As described above, the soundproofing material according to the present embodiment is preferably lightweight. From this viewpoint, the soundproofing material according to the present embodiment has an overall surface density of preferably 3.24 kg / m 2 More preferably, it is less than 2.0 kg / m 2 More preferably, it is 1.5 kg / m or less. 2 or less, and particularly preferably 1.0 kg / m 2 The following is the result.

[0041] (Reinforcing member) As described above, in the soundproof structure 1 according to this embodiment, the rubber foam 20 having a rectangular frame shape is arranged by being joined to the lattice structure 100 at the outer periphery of the opening cross section (the surface opposite to the side where the latex rubber sheet 200 is arranged) of the lattice structure 100 (supporting portion) constituting the soundproof material 10. However, the reinforcing member only needs to be joined to the outer periphery of at least one surface of the soundproof material, and may be joined to the outer periphery of the surface of the elastic sheet. In particular, from the viewpoint of exhibiting better soundproofing performance, it is preferable that the reinforcing member is joined to the outer periphery of the supporting member as shown in FIG. 1. The constituent material of the reinforcing member is not particularly limited as long as it can improve the surface rigidity of the soundproof structure, and examples thereof include rubber materials such as EPDM rubber, resin materials, and wood.

[0042] According to the study by the present inventors, it was found that the arrangement of such a reinforcing member further improves the soundproofing performance compared to the case where the reinforcing member is not arranged. It was also confirmed that the arrangement of such a reinforcing member in a soundproofing material other than the soundproofing structure including the elastic sheet and the support member according to the present embodiment does not improve the soundproofing performance. The mechanism by which the soundproofing structure according to the present embodiment exerts the above-mentioned action and effect is not completely clear, and the present invention is not bound by any theory, but the following mechanism is presumed. That is, in a soundproofing structure including an elastic sheet and a support member, it is considered that when the overall surface rigidity is increased, surface vibration occurs in multiple modes, resulting in improved soundproofing performance. Therefore, it is presumed that the arrangement of the reinforcing member improves the surface rigidity of the soundproofing structure, which induces resonant vibration of the soundproofing structure, thereby improving the soundproofing performance.

[0043] In this embodiment, the reinforcing member made of the rubber foam 20 has a rectangular frame shape when viewed in a plan view. In this specification, the term "frame shape" means that the outermost periphery of the reinforcing member is topologically doughnut-shaped when viewed in a plan view. Examples of such frame shapes include the above-mentioned square shape (rectangular frame shape), as well as doughnut shapes (circular frame shapes), triangular frame shapes, pentagonal frame shapes, and hexagonal frame shapes. Among them, the rectangular frame shape or circular frame shape is preferable as the frame shape from the viewpoint of suppressing the occurrence of gaps and sound leakage from the gaps when the soundproof structure is installed relative to other components. Note that, as in the examples described later, two or more types of reinforcing members may be used in combination, such as using a reinforcing member whose outermost periphery is a rectangular frame shape and a reinforcing member whose outermost periphery is a circular frame shape disposed inside the rectangular frame shape. Furthermore, a reinforcing member that divides the outermost periphery of the frame shape into two or more regions may be further disposed, for example, to form a square shape or a square shape.

[0044] In this embodiment, the cross-sectional shape of the reinforcing member made of the rubber foam 20 is rectangular. The cross-sectional shape of the reinforcing member having a frame shape is not limited to rectangular, but is preferably substantially uniform along the longitudinal direction of the frame shape. This configuration can uniformly increase the surface rigidity of the soundproof structure, which can effectively contribute to improving the soundproofing performance. Examples of such cross-sectional shapes include rectangular, trapezoidal, convex, concave, etc. Among them, from the viewpoint of ease of manufacturing and cost reduction, it is more preferable that the cross-sectional shape is rectangular or trapezoidal, and particularly preferable that it is rectangular.

[0045] In this embodiment, the reinforcing member made of rubber foam 20 is arranged by being joined to the lattice structure 100, which is a support member. By joining the reinforcing member to the surface of the lattice structure 100 (support member) side rather than the surface of the latex rubber sheet 200 side in this way, the vibration of the sheet that contributes to the exhibiting of soundproofing performance is not inhibited, and the vibration area of ​​the sheet is increased, so that the soundproofing performance can be exhibited more effectively. However, in some cases, the reinforcing member may be arranged on the surface of the sheet side as necessary.

[0046] The configuration of the soundproofing structure according to one aspect of the present invention is not limited to the above embodiment, and can be modified as appropriate without departing from the gist of the present invention. In addition, the soundproofing structure according to the embodiment has a structure in which a support member is arranged on one side of the sheet, but it is also possible to arrange support members on both sides of the sheet, or to arrange support members with openings of different sizes and positions on both sides of the sheet. In addition, the "periphery" where the reinforcing members are arranged is not limited to the outermost periphery, and may be located outside the center to an extent that the surface rigidity of the soundproofing structure can be improved.

[0047] The soundproof structure according to this embodiment can be applied to automobile parts, duct blocking lid parts, and the like. That is, according to another embodiment of the present invention, an automobile part or duct blocking lid part is provided that includes the soundproof structure according to one embodiment of the present invention. The automobile part or duct blocking lid part can be a passageway for noise generated at a sound source. By applying the soundproof structure according to this embodiment to the automobile part or duct blocking lid part, it is possible to more effectively block the emission of noise from such parts to the outside and the intrusion of noise from the outside. Examples of ducts as automobile parts to which the soundproof structure according to this embodiment can be applied include intake ducts and air conditioning ducts.

[0048] In the following, an application example of the soundproof structure according to this embodiment will be described, taking as an example a case where the soundproof structure is applied to a flap of an air intake duct for a vehicle, as an automobile part that is also a duct closing cover part.

[0049] 5 is a cross-sectional view showing a schematic structure in which a soundproofing structure 1 according to one embodiment of the present invention is installed in a vehicle air intake duct 2. The vehicle air intake duct 2 has a tubular shape with openings on both ends, and the cross-sectional shape of the ends matches the frame shape of a reinforcing member 20 arranged in the soundproofing structure 1.

[0050] 1 is disposed at an opening of vehicle air intake duct 2 on the vehicle exterior side (upper side in Fig. 5). Specifically, soundproofing structure 1 is disposed so that reinforcing member 20 constituting soundproofing structure 1 covers the entire periphery of the end of the wall of the opening of vehicle air intake duct 2.

[0051] With this configuration, the reinforcing member 20 airtightly closes the end of the wall of the opening of the vehicle intake duct 2. As a result, it is possible to effectively prevent noise generated inside the vehicle from leaking to the outside of the vehicle. Even with this configuration, the effect of the present invention can be fully achieved, in that the surface rigidity of the soundproof structure is improved by the placement of the reinforcing member, thereby inducing resonant vibration of the soundproof structure, and as a result, soundproofing performance is improved.

[0052] The following embodiments are also included within the scope of the present invention: a soundproof structure as defined in claim 1 having the features of claim 2; a soundproof structure as defined in claim 1 or 2 having the features of claim 3; a soundproof structure as defined in any one of claims 1 to 3 having the features of claim 4; a soundproof structure as defined in any one of claims 1 to 4 having the features of claim 5; a soundproof structure as defined in any one of claims 1 to 5 having the features of claim 6; a soundproof structure as defined in any one of claims 1 to 6 having the features of claim 7; an automobile part comprising a soundproof structure as defined in any one of claims 1 to 7; and a duct closing cover part comprising a soundproof structure as defined in any one of claims 1 to 7. EXAMPLES

[0053] The present invention will be described in more detail below with reference to examples, although the technical scope of the present invention is not limited to the following examples.

[0054] <Evaluation of soundproofing performance of soundproofing structures> The soundproofing performance against sound waves of each frequency was measured for the soundproofing structures produced in the examples and comparative examples described later. Specifically, a speaker (sound source) was placed inside a soundproofing box made of an iron pot, and a 200 mm x 200 mm sample (soundproofing structure) was placed at the opening (170 mm x 170 mm square) of the soundproofing box so that their centers and directions were aligned. In addition, in order to prevent the sample (soundproofing structure) from bending at the opening of the soundproofing box, the sample (soundproofing structure) was fixed to the opening using double-sided tape. Then, sound was generated from the speaker (sound source) installed inside the soundproofing box, and the insertion loss [unit: dB] was measured relative to the case where the sample (soundproofing structure) was not placed (control), to evaluate the soundproofing performance. The larger the insertion loss value at a certain frequency, the better the soundproofing performance against sound waves of that frequency. The sound source generation conditions were as follows: Spectrum level: White noise (100~8192Hz) F max :8192Hz ·Δf (frequency resolution): 1Hz Average value: 300 arithmetic average (300 measurements were taken at slightly different times for each measurement, and the arithmetic average was used as the measured value) Overlap: 75%.

[0055] <<Creating a soundproof structure>> [Comparative Example 1] The silicone rubber sheet (200 mm×200 mm, thickness 1 mm) was used as it is as the soundproof structure of this comparative example.

[0056] [Comparative Example 2] A frame-shaped reinforcing member was bonded (joined) to the outer periphery of one side of the silicone rubber sheet (200 mm × 200 mm, thickness 1 mm) used in Comparative Example 1 using an adhesive, as shown in Fig. 1, to form a soundproof structure of this Comparative Example. Note that Eptsealer (manufactured by Nitto L Materials Corporation, width 25 mm, thickness 10 mm) was used as the reinforcing member.

[0057] [Comparative Example 3] The soundproofing material described in Example 1 of Patent Document 1 was used as it is for the soundproofing structure of this comparative example. This soundproofing structure has a configuration in which the open cross section of a honeycomb structure (honeycomb support having a large number of regular hexagonal cross sections (the distance between opposing parallel sides in the regular hexagonal cross section is 4 mm), support thickness 25 mm) made of polyvinyl chloride (PVC) is airtightly adhered to one side of a sheet (film thickness 0.25 mm) made of latex rubber. The size of this soundproofing structure is 200 mm x 200 mm. The surface density of the soundproofing structure of this comparative example is 0.48 kg / m 2 It was.

[0058] [Example 1] A frame-shaped reinforcing member was bonded (joined) to the outer periphery of the other open cross section of the honeycomb structure of the soundproof structure of Comparative Example 3 using an adhesive in the same manner as in Comparative Example 2 to obtain the soundproof structure of this example. The surface density of the soundproof structure of this example was 1.10 kg / m 2 It was.

[0059] [Soundproofing performance evaluation results] The soundproofing structures produced in the above Comparative Examples 1 to 3 and Example 1 were measured for soundproofing performance (insertion loss) by the above-mentioned method. Then, the difference between the insertion loss of Comparative Example 2 and that of Comparative Example 1 in the frequency range of 400 to 1600 Hz was calculated (a positive value indicates the effect of improving the soundproofing performance by further arranging a reinforcing member when a silicone rubber sheet is used as the main body of the soundproofing structure). Similarly, the difference between the insertion loss of Example 1 and that of Comparative Example 3 at each frequency was calculated (a positive value indicates the effect of improving the soundproofing performance by further arranging a reinforcing member when the main body of the soundproofing structure is composed of an elastic sheet and a honeycomb structure). These results are shown in FIG. 6.

[0060] As shown in Fig. 6, a comparison between Comparative Example 1 and Comparative Example 2, in which a silicone rubber sheet was used as the main body of the soundproof structure, shows that in this case, the arrangement of the frame-shaped reinforcing member did not particularly improve the soundproofing performance (insertion loss). In contrast, a comparison between Comparative Example 3, in which the main body of the soundproof structure is composed of an elastic sheet and a honeycomb structure, and Example 1 shows that the arrangement of the frame-shaped reinforcing member improved the soundproofing performance (insertion loss) (up to 4 dB in the range of 500 to 1200 Hz).

[0061] [Comparative Example 4] In the soundproofing structure produced in Comparative Example 2, a circular frame-shaped (outer diameter 120 mm, inner diameter 70 mm) reinforcing member made of the same material was further bonded (joined) using an adhesive to the inside of the frame-shaped reinforcing member arranged on the outermost periphery to form the soundproofing structure of this comparative example.

[0062] [Example 2] In the soundproofing structure produced in Example 1, a circular frame-shaped (outer diameter 120 mm, inner diameter 70 mm) reinforcing member made of the same material was further bonded (joined) using an adhesive to the inside of the frame-shaped reinforcing member arranged on the outermost periphery to form the soundproofing structure of this comparative example.

[0063] [Soundproofing performance evaluation results] The soundproofing structures produced in the above Comparative Example 1, Comparative Example 3, Comparative Example 4 and Example 2 were measured for soundproofing performance (insertion loss) by the above-mentioned method. Then, the difference between the insertion loss of Comparative Example 4 and that of Comparative Example 1 in the frequency range of 400 to 1600 Hz (positive values ​​indicate the effect of improving the soundproofing performance by further arranging two types of reinforcing members when a silicone rubber sheet is used as the main body of the soundproofing structure) was calculated. Similarly, the difference between the insertion loss of Example 2 and that of Comparative Example 3 at each frequency (positive values ​​indicate the effect of improving the soundproofing performance by further arranging two types of reinforcing members when the main body of the soundproofing structure is composed of an elastic sheet and a honeycomb structure) was calculated. These results are shown in FIG. 7.

[0064] As shown in Fig. 7, a comparison between Comparative Example 1 and Comparative Example 4, in which a silicone rubber sheet was used as the main body of the soundproof structure, shows that in this case, even if a circular frame-shaped reinforcing member was added to the inside, no particular improvement in soundproofing performance (insertion loss) was confirmed by the arrangement of the frame-shaped reinforcing member. In contrast, a comparison between Comparative Example 3, in which the main body of the soundproof structure is composed of an elastic sheet and a honeycomb structure, and Example 2, shows that an improvement in soundproofing performance (insertion loss) was confirmed (maximum 6 dB in the range of 500 to 1200 Hz) by the arrangement of the frame-shaped reinforcing member.

[0065] [Comparative Example 5] The soundproof structure of this comparative example was produced in the same manner as in Example 1, except that a reinforcing member (EPTSealer) was bonded to the entire surface of the open cross section of the honeycomb structure using an adhesive. The surface density of the soundproof structure of this example was 1.85 kg / m 2 It was.

[0066] [Soundproofing performance evaluation results] The soundproofing structures produced in Example 1 and Comparative Example 5 were measured for soundproofing performance (insertion loss) by the above-mentioned method. Then, the difference between the insertion loss of each of Example 1 and Comparative Example 5 and the insertion loss of Comparative Example 3 in the frequency range of 600 to 3000 Hz was calculated (a positive value indicates an improvement in soundproofing performance due to the further placement of a reinforcing member when the main body of the soundproofing structure is composed of an elastic sheet and a honeycomb structure). Next, the difference calculated in this way for each frequency of 600 to 3000 Hz was used as the increase in surface density due to the placement of a reinforcing member in Example 1 or Comparative Example 5 ((1.10-0.48=) 0.62 kg / m in Example 1). 2 , and in Comparative Example 5, (1.85-0.48=) 1.37 kg / m 2 The increase in insertion loss per unit increase in areal density was calculated by dividing the increase in areal density by the square root of the square root of the areal density. The results are shown in Figure 8.

[0067] As shown in Figure 8, by comparing Example 1 in which a frame-shaped reinforcing member was arranged on the outer periphery of the main body of a soundproof structure consisting of an elastic sheet and a honeycomb structure, with Comparative Example 5 in which a reinforcing member was arranged on the entire surface of the main body, it was confirmed that by arranging a frame-shaped reinforcing member, a greater insertion loss was achieved per unit increase in areal density.

[0068] [Comparative Example 6] The soundproof structure of this comparative example was produced in the same manner as in Example 1, except that no adhesive was used when arranging the frame-shaped reinforcing member on the outer periphery of the open cross section of the honeycomb structure.

[0069] [Soundproofing performance evaluation results] The soundproofing structures produced in the above Comparative Example 3, Example 1, and Comparative Example 6 were measured for soundproofing performance (insertion loss) by the above-mentioned method. Then, the difference between the insertion loss of Comparative Example 3 and that of Example 1 in the frequency range of 300 to 3000 Hz (positive values ​​indicate the effect of improving the soundproofing performance by bonding (joining) the frame-shaped reinforcing member with an adhesive when the main body of the soundproofing structure is composed of an elastic sheet and a honeycomb structure) was calculated. Similarly, the difference between the insertion loss of Comparative Example 3 and that of Comparative Example 6 at each frequency (positive values ​​indicate the effect of improving the soundproofing performance by arranging the frame-shaped reinforcing member without using an adhesive when the main body of the soundproofing structure is composed of an elastic sheet and a honeycomb structure) was calculated. These results are shown in FIG. 9.

[0070] As shown in Figure 9, by comparing Example 1 in which a frame-shaped reinforcing member was bonded (joined) using an adhesive to the outer periphery of the main body of a soundproofing structure consisting of an elastic sheet and a honeycomb structure, with Comparative Example 6 in which a frame-shaped reinforcing member was bonded to the outer periphery of the main body without using an adhesive, it was confirmed that the adhesive placement of the frame-shaped reinforcing member on the outer periphery of the main body improved the soundproofing performance (insertion loss) (up to 6 dB in the range of 300 to 3000 Hz).

[0071] From the above, it has been shown that the present invention makes it possible to improve the soundproofing performance of a soundproofing structure. It has also been shown that in order to achieve such an improved soundproofing performance, it is necessary to provide a frame-shaped reinforcing member on the outer periphery of at least one of the main bodies of the soundproofing structure, rather than on the entire surface of the main body, and that when the reinforcing member is provided on the outer periphery of the main body, it is necessary to provide it by bonding (joining). [Explanation of symbols]

[0072] 1. Soundproofing structure, 2 Vehicle intake duct, 10 Soundproofing materials, 20 Rubber foam (reinforcement material), 100 Grid structure (support part), 110, 110a cylindrical cell; 200 Latex rubber sheet (elastic sheet), h Height of the support (cylindrical cell) in the extension direction, w is the size of the cylindrical cell (the distance between the opposing parallel sides of the regular hexagonal cross-sectional shape), t is the thickness of the inner wall (lattice wall) of the cylindrical cell.

Claims

1. The soundproofing material includes an elastic sheet and a support member that supports the sheet and divides the sheet into partitions, The surface stiffness (k) of the sheet in the partition portion and the surface density (m) of the sheet satisfy the relationship of the following mathematical formula 1, and A soundproof structure, in which a reinforcing member having a frame shape is joined to the outer periphery of at least one surface of the soundproof material. [0010]

2. 2. The soundproof structure according to claim 1, wherein the frame shape is a rectangular frame shape or a circular frame shape.

3. 3. The soundproof structure according to claim 1, wherein the cross-sectional shape of the reinforcing member is substantially uniform along the longitudinal direction of the frame shape.

4. 3. The soundproof structure according to claim 1, wherein the reinforcing member is joined to the supporting member.

5. 3. The soundproof structure according to claim 1, wherein the support member is a lattice structure having a large number of cylindrical cells that are continuously adjacent to each other.

6. The surface density of the soundproofing material is 3.24 kg / m ２ 3. The soundproof structure according to claim 1 or 2, wherein the soundproof structure has a thickness of less than 100 nm.

7. An automobile part comprising the soundproof structure according to claim 1 or 2.

8. A duct closing cover part comprising the soundproof structure according to claim 1 or 2.

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