Sheet-shaped soundproof structure and installation method for sheet-shaped soundproof structure

Abstract

According to the present invention, a sheet-shaped soundproof structure that is to be installed on an object to be soundproofed includes an elastic sheet and a support member that has a plurality of openings that are formed by crosspiece parts, supports the sheet, and divides the sheet into planar divisions. The surface of the support member on the side on which the sheet is provided is uneven, the sheet is provided on the surface of the support member such that protrusions on the uneven surface penetrate the sheet in the thickness direction, and the support member is installed on the object to be soundproofed in a stretched state such that tensile stress is applied to the support member and the sheet from the object to be soundproofed.

Description

Sheet-like soundproof structure and installation method for sheet-like soundproof structure

[0001] The present invention relates to a sheet-like soundproof structure and a method for attaching the sheet-like soundproof structure.

[0002] Soundproof structures in which a support member such as an expanded metal is attached to an elastic sheet have been known for some time. However, the support member has an uneven structure, which creates gaps between the sheet and the support member, hindering the soundproofing effect.

[0003] JP2016-59585 discloses a technique for coating the support member with resin, but since the thickness of the resin is constant, the uneven structure is maintained and it is difficult to eliminate gaps between the sheets.

[0004] Therefore, an object of the present invention is to provide a sheet-like soundproof structure that has excellent soundproofing performance by eliminating the gap between the support member and the sheet, and also achieves reduced manufacturing costs.

[0005] According to one aspect of the present invention, there is provided a sheet-like soundproof structure to be attached to an object to be soundproofed, the sheet having elasticity, and a support member having a plurality of openings partitioned by crosspieces, supporting the sheet and partitioning the sheet into planar partitions. The surface of the support member on which the sheet is placed has an uneven shape, and the sheet is placed on the surface of the support member so that the convex portions of the uneven shape penetrate the sheet in the thickness direction. Furthermore, the support member is attached to the object to be soundproofed in a tensioned state, so that tensile stress is applied from the object to the support member and the sheet.

[0006] FIG. 1 is a plan view of a sheet constituting a sheet-like soundproof structure of this embodiment. FIG. 2 is a plan view of an expanded metal constituting the sheet-like soundproof structure. FIG. 3 is a diagram illustrating the uneven shape of the surface of the expanded metal supporting the sheet. FIG. 4 is a cross-sectional view showing the state before the convex portions of the expanded metal are inserted into the sheet. FIG. 5 is a cross-sectional view showing the state after the convex portions of the expanded metal are inserted into the sheet. FIG. 6 is a diagram for comparing a sheet-like soundproof structure with an object to be soundproofed. FIG. 7 is a diagram showing the state after the sheet-like soundproof structure is attached to the object to be soundproofed. FIG. 8 is a cross-sectional view of the sheet-like soundproof structure and the object to be soundproofed before the sheet-like soundproof structure is attached to the object to be soundproofed. FIG. 9 is a cross-sectional view of the sheet-like soundproof structure and the object to be soundproofed after the sheet-like soundproof structure is attached to the object to be soundproofed. FIG. 10 is a model of a sheet-like soundproof structure for representing the loss of sound waves input to the sheet-like soundproof structure. FIG. 11 shows the relationship between sound wave loss and road noise band before applying tensile stress to the model of FIG. 10 , and the relationship between sound wave loss and road noise band after applying tensile stress to the sheet-like soundproof structure model. FIG. 12 shows the change in insertion loss when the tensile stress applied in the short-side direction of the expanded metal is changed. FIG. 13 shows the change in insertion loss when the tensile stress applied in the long-side direction of the expanded metal is changed. FIG. 14 shows a first example of an object to which a sheet-like soundproof structure is to be attached, in the form of a floor mat on the floor of a driver's seat, showing the state before (top) and the state after (bottom) the sheet-like soundproof structure is attached to the floor. FIG. 15 shows an example of a driver's seat floor mat. FIG. 16 shows a second example of an object to which a sheet-like soundproof structure is to be attached. FIG. 17 shows a third example of an object to which a sheet-like soundproof structure is to be attached.

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0008] [Basic configuration of sheet-like soundproof structure] Fig. 1 is a plan view of a sheet 2 that constitutes a sheet-like soundproof structure 1 of this embodiment. Fig. 2 is a plan view of an expanded metal 3 that constitutes the sheet-like soundproof structure 1. Fig. 3 is a diagram for explaining the uneven shape of the surface of the expanded metal 3 that supports the sheet 2. Fig. 4 is a cross-sectional view showing the state before the convex portions 33 of the expanded metal 3 are inserted into the sheet 2. Fig. 5 is a cross-sectional view showing the state after the convex portions 33 of the expanded metal 3 have been inserted into the sheet 2.

[0009] The sheet-like soundproof structure 1 of this embodiment includes a rectangular elastic sheet 2 and a rectangular expanded metal 3 as a support member that supports the sheet 2 and divides the sheet 2 into a planar shape.

[0010] The sheet 2 is a flat, membrane-like member made of rubber, for example, synthetic rubber. The expanded metal 3 functions as a support member that supports the sheet 2 and divides the sheet 2 into planar partitions 21 ( FIG. 3 ). Examples of such a support member include expanded metal 3 or an expanded metal-like mesh member, or a wire mesh or a wire mesh-like mesh member. In the sheet-like soundproof structure 1 according to this embodiment, by using such a material to form the support member, the partitions 21 ( FIG. 3 ) can be easily formed in the sheet 2 through the openings. As a result, the cross-sectional ratio of the openings in the support member can be increased, contributing to a reduction in the overall mass. Furthermore, the above-described sheet 2 and support member are generally mass-producible and relatively inexpensive.

[0011] A first engagement portion 22 in the shape of a through hole (ring) is arranged near the corner of the sheet 2, and a second engagement portion 32 in the shape of a through hole (ring) is arranged at a position opposite (communicating with) the first engagement portion 22 of the expanded metal 3.

[0012] In the sheet-like soundproof structure 1 of this embodiment, the sheet 2 is attached to the expanded metal 3 with the first engaging portion 22 and the second engaging portion 32 in communication (overlapping in plan view).

[0013] The expanded metal 3 has a diamond-shaped or tortoiseshell-shaped mesh structure formed by cutting staggered cuts in a metal plate and expanding the metal plate in the surface direction, that is, the longitudinal direction of the cuts, and has uneven shapes (broken lines in Figure 3) on both main surfaces. More specifically, as shown in Figures 3 and 4, it has protrusions 33 whose vertices are the intersections of numerous crosspieces 31 that form a diamond-shaped lattice.

[0014] 5, the convex portions 33 on the main surface of the expanded metal 3 facing the sheet 2 (for example, the sheet 2 is spread out and placed on a flat floor or workbench larger than the sheet 2) penetrate into the main surface of the sheet 2 in the thickness direction, so that the entire main surface of the expanded metal 3 facing the sheet 2 comes into contact with the sheet 2. This divides the sheet 2 into a large number of diamond-shaped compartments 21 (FIG. 3).

[0015] The expanded metal 3, which is the support member of this embodiment, has a bending rigidity greater than that of the sheet 2. This causes resonance on the surface of the support member due to acoustic waves, which also generates surface resonance vibration in the sheet 2 (compartment 21 ( FIG. 3 )) that is in contact with the support member. This has the advantage of improving sound insulation performance near the resonance frequency. However, in some cases, the bending rigidity of the support member may be smaller than that of the sheet 2. Metal materials such as stainless steel, iron, or aluminum are suitable as materials for the support member, which have a bending rigidity greater than that of the sheet 2. Despite their light weight, these materials, when used as the support member of this embodiment, can provide sound insulation performance that significantly exceeds the mass law. Furthermore, the material is not limited to metal, and may be, for example, plastic, which can be manufactured using an expansion method involving heating.

[0016] [Sheet-like soundproof structure 1 and object to be soundproofed 4] Fig. 6 is a diagram for comparing the sheet-like soundproof structure 1 with the object to be soundproofed 4. Fig. 7 is a diagram showing the sheet-like soundproof structure 1 attached to the object to be soundproofed 4. Fig. 8 is a cross-sectional view of the sheet-like soundproof structure 1 and the object to be soundproofed 4 before the sheet-like soundproof structure 1 is attached to the object to be soundproofed 4. Fig. 9 is a cross-sectional view of the sheet-like soundproof structure 1 and the object to be soundproofed 4 after the sheet-like soundproof structure 1 has been attached to the object to be soundproofed 4.

[0017] 6 and 8, a convex engaged portion 41 is disposed on the soundproofing object 4 (vehicle body) to which the sheet-like soundproofing structure 1 is attached. The engaged portion 41 is disposed at a position substantially opposite each of the engaging portions (first engaging portion 22, second engaging portion 32) of the sheet-like soundproofing structure 1.

[0018] The sheet-like soundproof structure 1 is attached to the object to be soundproofed 4 in such a manner that the engaging portions (first engaging portion 22, second engaging portion 32) of the sheet-like soundproof structure 1 are inserted into the engaged portions 41 (the engaging portions are engaged with the engaged portions 41).

[0019] If the distance between the engaging portions (first engaging portion 22, second engaging portion 32) arranged in the long side direction of the sheet-like soundproof structure 1 is L1, and the distance between the engaged portions 41 arranged in the long side direction of the soundproofing object 4 (long side direction of the sheet-like soundproof structure 1) is L2, then the relationship L1 < L2 holds.

[0020] Therefore, when attaching the sheet-like soundproof structure 1 to the object to be soundproofed 4, a tensile stress is applied to the sheet-like soundproof structure 1 in the long side direction to stretch it until the distance between the engaging portions (first engaging portion 22, second engaging portion 32) becomes L2, and then the engaged portion 41 is inserted into the engaging portion. At this time, the short side direction of the sheet-like soundproof structure 1 contracts in accordance with the stretching in the long side direction.

[0021] Correspondingly, if the spacing between the engaging portions (first engaging portions 22, second engaging portions 32) aligned in the short side direction of the sheet-like soundproof structure 1 is W1 and the spacing between the engaged portions 41 aligned in the short side direction of the object to be soundproofed 4 (the short side direction of the sheet-like soundproof structure 1) is W2, then there is a relationship of W1 > W2. The spacing W2 between the engaged portions 41 in the short side direction of the object to be soundproofed 4 is set so as to match the spacing between the engaging portions aligned in the short side direction when the sheet-like soundproof structure 1 is extended in the long side direction and the spacing between the engaging portions aligned in the long side direction becomes L2.

[0022] When the sheet-like soundproofing structure 1 is attached to the object to be soundproofed 4 as described above, a tensile stress is constantly applied to the sheet-like soundproofing structure 1 (sheet 2, expanded metal 3) in a direction that widens the distance between the two engaging portions (first engaging portion 22, second engaging portion 32) aligned in the long side direction.

[0023] [Model of Sheet-like Soundproof Structure 1 and Frequency Characteristics of Loss] Fig. 10 is a model of the sheet-like soundproof structure 1 for expressing the loss of sound waves input to the sheet-like soundproof structure 1. Fig. 11 is a diagram showing the relationship between the sound wave loss and the road noise band before applying tensile stress to the model of Fig. 10 and the relationship between the sound wave loss and the road noise band after applying tensile stress to the model of the sheet-like soundproof structure 1.

[0024] As described above, in the sheet-like soundproof structure 1 of this embodiment, the sheet 2 is divided into a plurality of partitions 21 by the expanded metal 3. Therefore, as shown in Fig. 10, the sheet-like soundproof structure 1 can be considered as a model of a spring vibration system (two vibration systems formed by two adjacent partitions 21 are independent of each other) in which the mass of a partition 21 is "m" and the surface rigidity of the partition 21 (difficulty in deformation in response to input) is "k".

[0025] In this case, the transmission loss (TL) when a sound wave (frequency: f) passes from one main surface of the partition 21 to the other main surface can be expressed as follows:

[0026] Transmission loss (TL) resonance frequency (f ０ ) will look like this:

[0027] Here, when the area of ​​the partition 21 is reduced, the mass (m) is reduced and the surface rigidity (k) is increased, so the value of (k / m) is increased. ０ ) increases as the area of ​​the partition 21 decreases.

[0028] As described above, the partitions 21 (FIG. 3) are formed by penetrating the convex portions 33 of the expanded metal 3 into the sheet 2, so the mass (m) of the partitions 21 does not change much even when tensile stress is applied to the sheet-like soundproof structure 1. On the other hand, when the partitions 21 are subjected to tensile stress, the partitions 21 become hard and the surface rigidity (k) increases. Therefore, the resonance frequency (f ０ ) increases when tensile stress is applied to the sheet-like soundproof structure 1, and the greater the tensile stress, the greater the resonant frequency (f ０ ) also becomes larger.

[0029] As shown in Fig. 11, the transmission loss (TL) (as well as the insertion loss (IL)) of the sheet-like soundproof structure 1 before the application of the tensile stress has a frequency characteristic based on the formula (1) (dotted line in Fig. 11). The transmission loss (TL) is proportional to the resonant frequency (f ０ The minimum value is at the resonant frequency (f ０ In the frequency band below the resonant frequency (f), the transmission loss (TL) increases monotonically as the frequency decreases. ０ ) the transmission loss (TL) increases monotonically with increasing frequency.

[0030] After the tensile stress is applied, the frequency characteristics of the transmission loss (TL) of the sheet-like soundproof structure 1 (solid line in FIG. 11) are shifted to the high frequency side as a whole, and the resonance frequency is "f ０ " is higher than "f ０ '".

[0031] Therefore, for example, if the object 4 to be soundproofed is a vehicle, the frequency band (road noise band) of road noise (road surface noise) is a resonance frequency (f ０), when a tensile stress is applied to the sheet-like soundproof structure 1 as described above, the frequency characteristics of the transmission loss (TL) shift to the high frequency side, the transmission loss (TL) in the road noise band increases, and the soundproofing performance is improved.

[0032] If there are multiple resonant frequencies of the sheet-like soundproof structure 1 before the application of tensile stress, applying the tensile stress to the sheet-like soundproof structure 1 in a frequency band slightly lower than each resonant frequency increases the transmission loss (TL) and improves soundproofing performance.

[0033] [Example] Fig. 12 is a diagram showing a change in loss when the tensile stress applied in the short side direction of the expanded metal 3 is changed. Fig. 13 is a diagram showing a change in loss when the tensile stress applied in the long side direction of the expanded metal 3 is changed.

[0034] The inventors of the present application investigated the insertion loss (IL) of sound waves when a tensile stress was applied to the sheet-like soundproof structure 1 of this embodiment. The expanded metal 3 was made of aluminum and had a length of 270 mm and a width of 200 mm. The sheet 2 had a length of 240 mm and a width of 200 mm. The sheet 2 was made of N03C and EV250 manufactured by Mitsui Dow Polychemicals, and had a three-layer structure of N03C / EV250 / N035C with a thickness ratio of 1:5:1 and an overall thickness of 150 μm. The sheet-like soundproof structure 1 was then fabricated by pressing the expanded metal 3 (protrusions 33) against the sheet 2 at a pressure of 2 MPa at an ambient temperature of 90°C with their centers and orientations aligned.

[0035] Then, sound waves were generated from a speaker (sound source) set inside the soundproof box, and the insertion loss [dB] was measured when the sheet-like soundproof structure 1 was installed and when it was not installed, to evaluate the soundproofing performance. A larger insertion loss value at a certain frequency means better soundproofing performance against sound waves of that frequency.

[0036] The dashed line graphs in FIGS. 12 and 13 show the insertion loss estimated from the surface density of the sheet-like soundproof structure 1 when it is assumed that the soundproofing performance is achieved in accordance with only the mass law.

[0037] FIG. 12 compares cases in which tensile stress is applied in the short side direction of the expanded metal 3, that is, along the shorter of a pair of diagonals of the diamond-shaped opening of the expanded metal 3. Comparative Example 1 shows the case in which the strain (ε=(L2−L1) / L1) ( FIG. 6 ) is zero, Example 1 shows the case in which the expanded metal 3 is stretched by 2 mm in the short side direction (strain (ε) is 0.01), and Example 2 shows the case in which the expanded metal 3 is stretched by 10 mm in the short side direction (strain (ε) is 0.05).

[0038] FIG. 13 compares cases in which tensile stress is applied in the long side direction of the expanded metal 3, that is, along the longer of a pair of diagonals of the diamond-shaped opening of the expanded metal 3. Comparative Example 2 shows the case in which the strain (ε=(L2−L1) / L1) is zero, Example 3 shows the case in which the expanded metal 3 is stretched by 2 mm in the long side direction (strain (ε) is 0.01), and Example 4 shows the case in which the expanded metal 3 is stretched by 7 mm in the long side direction (strain (ε) is 0.035).

[0039] As shown in FIGS. 12 and 13 , in both Comparative Example 1-2 and Example 1-4, the partition portions 21 are formed in the sheet 2 by penetrating the convex portions 33 of the expanded metal 3 into the sheet 2, and the frequency band has a value higher than the insertion loss (dashed line) estimated by the mass law.

[0040] As shown in Fig. 12, the peak (A) of the insertion loss (IL) that appears near 500 [Hz] in Comparative Example 1 is due to the behavior of the sheet 2 and the expanded metal 3 in response to sound waves. The peak (A) shifts to near 530 [Hz] in Example 1 and to near 650 [Hz] in Example 2. Furthermore, the peak value is higher in Example 1 than in Comparative Example 1, and further higher in Example 2 than in Example 1. Furthermore, comparing Comparative Example 1 and Example 2, the insertion loss at 650 [Hz] is improved by approximately 6 [dB].

[0041] 13, the peak (B) of the insertion loss (IL) that appears near 420 [Hz] in Comparative Example 2 shifts to near 530 [Hz] in Example 1 and to near 650 [Hz] in Example 2. Furthermore, the peak value is higher in Example 3 than in Comparative Example 2, and further higher in Example 4 than in Example 3. Furthermore, the insertion loss at 650 [Hz] is improved by approximately 10 [dB] when comparing Comparative Example 2 and Example 4.

[0042] This is thought to be because a resonance frequency exists at a slightly higher frequency (e.g., 800 Hz) near the frequency at which peak (A) of Comparative Example 1 and peak (B) of Comparative Example 2 appear, and this frequency shifts to the higher frequency side due to tensile stress, causing peaks (A) and (B) to also shift to the higher frequency side and increasing their peak values.

[0043] 12, no particular peak appears in the frequency band of 3600 [Hz] in Comparative Example 1, but a peak (C) appears in Example 1, and the peak (C) is larger in Example 2 compared to Example 1. Comparing Comparative Example 1 and Example 2, the insertion loss at 3600 [Hz] is improved by approximately 10 [dB].

[0044] 13, with regard to the insertion loss (IL) at frequencies from 3200 [Hz] to 4000 [Hz], the insertion loss (background) is higher in Examples 1 and 2 than in Comparative Example 2. Furthermore, the insertion loss at 3600 [Hz] is improved by approximately 4 [dB] when comparing Comparative Example 2 with Example 4.

[0045] This is thought to be because a resonance frequency exists at a frequency as high as 4000 [Hz] (for example, 5000 [Hz]), and this is shifted to the higher frequency side by the tensile stress, resulting in an increase in insertion loss (background).

[0046] The frequency band generally referred to as road noise is 100-1000 Hz, and as described above, the frequency of the insertion loss peaks ((A) and (B)) can be adjusted by changing the area of ​​the diamond-shaped openings in the expanded metal 3. That is, the larger the area of ​​the openings, the lower the frequency of the insertion loss peaks, and the smaller the area of ​​the openings, the higher the frequency of the insertion loss peaks. Therefore, by appropriately setting the size of the openings, it is possible to effectively reduce noise of the frequency that is to be insulated (for example, near 1000 Hz). On the other hand, the weight of the expanded metal 3 increases as the area of ​​the openings in the expanded metal 3 decreases.

[0047] In the sheet-like soundproof structure 1 of this embodiment, the peak of insertion loss is shifted to the high-frequency side by applying tensile stress (strain). Therefore, even if the area of ​​the opening of the expanded metal 3 (the area of ​​the partition 21) is larger than the predetermined area that gives rise to the peak at the desired frequency to be insulated in terms of insertion loss, the desired peak frequency in terms of insertion loss can be achieved by applying tensile stress to the sheet-like soundproof structure 1, thereby controlling the frequency range to be insulated. Furthermore, the expanded metal 3 of this embodiment can be made lighter than expanded metal 3 having an opening area (the area of ​​the partition 21) that is the predetermined area.

[0048] Furthermore, by adjusting the tensile stress (strain), the peak of the insertion loss of the sheet-like soundproof structure 1 can be set to a desired frequency. Therefore, the peak of the insertion loss can be set to any of a predetermined frequency band with one expanded metal 3, so there is no need to prepare expanded metal 3 with different opening areas (structures and materials of the support members) for each frequency, thereby reducing costs.

[0049] [Installation Example 1] Fig. 14 shows a first example of an installation target of the sheet-like soundproof structure 1, in which the sheet-like soundproof structure 1 is installed as a floor mat on the floor surface of a driver's seat, showing the state before (upper figure) and the state after (lower figure) the sheet-like soundproof structure 1 is installed on the floor surface. Fig. 15 shows an example of a floor mat for the driver's seat.

[0050] In a first example shown in Fig. 14, the sheet-like soundproof structure 1 is used as a floor mat (see Fig. 15) to be placed on the floor surface of the driver's seat. The sheet-like soundproof structure 1 in the first example is formed into the shape (shape of the floor surface) of the floor mat (nonwoven fabric 5 and sheet-like soundproof structure 1), and has a plurality of (e.g., five) engaging portions (first engaging portion 22, second engaging portion 32) arranged therein (upper diagram in Fig. 14).

[0051] On the other hand, the soundproofing object 4 is the floor surface of the driver's seat, and engaged portions 41 are arranged on the floor surface in the same number (five locations) as the engaging portions (first engaging portions 22, second engaging portions 32). Here, the multiple engaged portions 41 are arranged so that a first polygon (a pentagon in FIG. 14 ) formed with the positions of the multiple engaged portions 41 as its corners is approximately similar in shape to, and larger than, a second polygon formed with the positions of the multiple engaging portions (first engaging portions 22, second engaging portions 32) as its corners.

[0052] Then, with the expanded metal 3 and sheet 2 pulled in the direction that expands the second polygon, each of the multiple engaging portions (first engaging portions 22, second engaging portions 32) engages with a different engaged portion 41. As a result, the expanded metal 3 and sheet 2 are attached to the floor surface while being subjected to a tensile stress in the direction that expands the second polygon, i.e., a tensile stress that spreads in the planar direction (all directions) from the center of the expanded metal 3 and sheet 2. Note that the first polygon may be substantially similar to the second polygon but elongated in one direction, and the expanded metal 3 and sheet 2 may be attached to the floor surface while being subjected to a tensile stress that stretches them in that one direction.

[0053] The sheet-like soundproof structure 1 is placed so that the main surface on the sheet 2 side faces the floor. In addition, a nonwoven fabric 5 is placed so as to cover the main surface on the expanded metal 3 side of the sheet-like soundproof structure 1 (FIG. 14 (lower diagram) and FIG. 15).

[0054] [Installation Example 2 and Installation Example 3] Fig. 16 is a diagram showing a second example of an object to which the sheet-like soundproof structure 1 is attached. Fig. 17 is a diagram showing a third example of an object to which the sheet-like soundproof structure 1 is attached.

[0055] In the second example shown in Fig. 16, the sheet-like soundproof structure 1 is attached to the interior trim of a vehicle. The interior trim is provided with a large number of protrusions 6 as shown in Fig. 17.

[0056] Therefore, a plurality of engaging portions (first engaging portions 22, second engaging portions 32) (not shown) are arranged on the sheet-like soundproof structure 1 so as to form corners of a polygon that is approximately similar to the polygon whose corners are the positions of the plurality of protrusions 6 and that is slightly smaller than the polygon formed by the protrusions 6. Then, by engaging each engaging portion with a different protrusion 6 (engaged portion) while the sheet-like soundproof structure 1 is spread out approximately uniformly in the planar direction, the sheet-like soundproof structure 1 is attached to the interior trim while being subjected to tensile stress in the planar direction.

[0057] In a third example shown in Fig. 17, a sheet-like soundproof structure 1 is attached to the inside of the body metal (front or rear) of a vehicle. As shown in Fig. 17, the body metal has a plurality of holes 7 (or protrusions).

[0058] Therefore, in the third example, a plurality of holes 7 arranged in the body metal are used as the engaged portions. Meanwhile, for example, a plurality of protrusions (pins) are arranged as second engaging portions 32 (not shown) of the expanded metal 3. In this case, the plurality of protrusions are arranged on the expanded metal 3 so that the polygon having corners where the plurality of protrusions are arranged is approximately similar in shape to the polygon having corners where the plurality of holes 7 are arranged, but is slightly smaller than the polygon formed by the plurality of holes 7. The first engaging portions 22 (not shown) of the sheet 2 are arranged in the same manner as the second engaging portions 32 (protrusions), and the sheet-like soundproof structure 1 is formed by inserting the second engaging portions 32 (not shown) into the first engaging portions 22 (not shown).

[0059] Then, with the sheet-like soundproofing structure 1 spread out approximately uniformly in the planar direction, each second engaging portion 32 (not shown) is engaged with a different hole 7 (engaged portion), and the sheet-like soundproofing structure 1 is attached to the body metal while being subjected to tensile stress in the planar direction.

[0060] The engaging portion and engaged portion in this embodiment can be any component that can be attached to the soundproofing object 4 while applying tensile stress to the sheet-like soundproofing structure 1, such as a hook, clip, sewing, bolt fastening, adhesive, sealing material, tape, welding, etc.

[0061] Effect of this embodiment The sheet-like soundproof structure 1 of this embodiment is a sheet-like soundproof structure 1 that is attached to an object to be soundproofed 4, and includes an elastic sheet 2, and a support member (expanded metal 3) that has a plurality of openings defined by crosspieces 31, supports the sheet 2, and defines the sheet 2 into planar partitions 21, the surface of the support member (expanded metal 3) on which the sheet 2 is placed has an uneven shape, the sheet 2 is placed on the surface of the support member (expanded metal 3) so that the convex portions 33 of the uneven shape penetrate the sheet 2 in the thickness direction, and the support member (expanded metal 3) is attached to the object to be soundproofed 4 in a pulled state, so that tensile stress is applied from the object to be soundproofed 4 to the support member (expanded metal 3) and the sheet 2.

[0062] With the above configuration, the peak of insertion loss is shifted to the higher frequency side by applying tensile stress (strain) to the sheet-like soundproof structure 1. Therefore, even if the area of ​​the opening of the expanded metal 3 (the area of ​​the partition 21) is larger than the predetermined area that gives rise to the peak at the desired frequency to be insulated in terms of insertion loss, the desired peak frequency in terms of insertion loss can be achieved by applying tensile stress to the sheet-like soundproof structure 1, thereby controlling the frequency range to be insulated. Furthermore, the support member (expanded metal 3) of this embodiment can be made lighter than a support member (expanded metal 3) whose opening area (the area of ​​the partition 21) is the predetermined area.

[0063] Furthermore, by adjusting the tensile stress (strain), the peak of the insertion loss of the sheet-like soundproof structure 1 can be set to a desired frequency. Therefore, the peak of the insertion loss can be set to any of a predetermined frequency band with a single support member (expanded metal 3), so there is no need to prepare support members (expanded metal 3) with different opening areas for different frequencies, thereby reducing costs.

[0064] In this embodiment, the support member (expanded metal 3) is an expanded metal 3 or an expanded metal-like mesh member, or a wire mesh or a wire mesh-like mesh member.

[0065] With the above-described configuration, the support member (expanded metal 3) can be realized with a simple configuration.

[0066] In this embodiment, a pair of engaging portions (second engaging portions 32) are attached to the support member (expanded metal 3), a pair of engaged portions 41 are attached to the object to be soundproofed 4, and the engaging portions (second engaging portions 32) engage with the engaged portions 41, thereby enabling the support member (expanded metal 3) and the sheet 2 to be attached to the object to be soundproofed 4. The spacing between the pair of engaged portions 41 is set longer than the spacing between the pair of engaging portions (second engaging portions 32). When the support member (expanded metal 3) and the sheet 2 are pulled in a direction widening the spacing between the pair of engaging portions (second engaging portions 32), one of the pair of engaging portions (second engaging portions 32) engages with one of the pair of engaged portions 41 and the other of the pair of engaging portions (second engaging portions 32) engages with the other of the pair of engaged portions 41, and the support member (expanded metal 3) and the sheet 2 are attached to the object to be soundproofed 4 while being subjected to tensile stress in a direction widening the spacing between the pair of engaging portions (second engaging portions 32).

[0067] With the above-described configuration, the support member (expanded metal 3) and the sheet 2 can be attached to the object to be soundproofed 4 with a simple configuration while a tensile stress is applied to them.

[0068] In this embodiment, the support member (expanded metal 3) has a diamond lattice shape in which multiple diamond-shaped openings are arranged by the crosspieces 31, and the direction in which the spacing between a pair of engaging portions (second engaging portions 32) is widened is set parallel to the shorter of the pair of diagonals formed by the diamond.

[0069] With the above-described configuration, tensile stress can be applied to the support member (expanded metal 3) while reducing the burden on the support member (expanded metal 3).

[0070] In this embodiment, the support member (expanded metal 3) has a diamond lattice shape in which multiple diamond-shaped openings are arranged by the crosspieces 31, and the direction in which the spacing between a pair of engaging portions (second engaging portions 32) is widened is set parallel to the longer of the pair of diagonals formed by the diamond.

[0071] With the above-described configuration, tensile stress can be applied to the support member (expanded metal 3) while reducing the burden on the support member (expanded metal 3).

[0072] In this embodiment, the tensile stress is set so that the strain on the sheet 2 in the direction widening the gap between the pair of engaging portions is 0.01 or more.

[0073] With the above configuration, the peak of the insertion loss resulting from the behavior of the sheet 2 and the support member (expanded metal 3) with respect to sound waves can be efficiently shifted to the high frequency side.

[0074] In this embodiment, a plurality of engaging portions (second engaging portions 32) are attached to the peripheral portion of the support member (expanded metal 3) so as to surround the peripheral portion, and the same number of engaged portions 41 as the plurality of engaging portions (second engaging portions 32) are attached to the soundproofing object 4, and the plurality of engaged portions 41 are arranged so that a first polygon formed with the positions of the plurality of engaged portions 41 as its corners is approximately similar in shape to but larger than a second polygon formed with the positions of the plurality of engaging portions (second engaging portions 32) as its corners, and when the support member (expanded metal 3) and sheet 2 are pulled in the direction expanding the second polygon, each of the plurality of engaging portions (second engaging portions 32) engages with a mutually different engaged portion 41, so that the support member (expanded metal 3) and sheet 2 are attached to the soundproofing object 4 while being subjected to tensile stress in the direction expanding the second polygon.

[0075] With the above-described configuration, tensile stress can be applied to the support member (expanded metal 3) and the sheet 2 substantially uniformly.

[0076] In this embodiment, the object to be soundproofed 4 is the body of an automobile.

[0077] The above configuration makes it possible to efficiently insulate road noise generated while the automobile is traveling.

[0078] The method for attaching a sheet-like soundproof structure 1 of this embodiment is a method for attaching a sheet-like soundproof structure 1 to an object to be soundproofed 4, the sheet-like soundproof structure 1 including an elastic sheet 2 and a support member (expanded metal 3) having a plurality of openings defined by crosspieces 31, supporting the sheet 2 and dividing the sheet 2 into planar partitions 21, in which the surface of the support member (expanded metal 3) on which the sheet 2 is placed has an uneven shape, and the sheet 2 is placed on the surface of the support member (expanded metal 3) so that protruding portions 33 of the uneven shape penetrate the sheet 2 in the thickness direction, and the support member (expanded metal 3) and the sheet 2 are attached to the object to be soundproofed 4 in a pulled state, thereby applying tensile stress from the object to be soundproofed 4 to the support member (expanded metal 3) and the sheet 2.

[0079] By using the above method, the insertion loss peak is shifted to the higher frequency side by applying tensile stress (strain) to the sheet-like soundproof structure 1. Therefore, even if the area of ​​the opening (area of ​​the partition 21) of the expanded metal 3 is larger than the predetermined area that gives rise to the peak at the desired frequency to be insulated in terms of insertion loss, the desired peak frequency in terms of insertion loss can be achieved by applying tensile stress to the sheet-like soundproof structure 1, thereby controlling the frequency range to be insulated. Furthermore, the support member (expanded metal 3) of this embodiment can be made lighter than a support member (expanded metal 3) having an opening area (area of ​​the partition 21) that is the predetermined area.

[0080] Furthermore, by adjusting the tensile stress (strain), the peak of the insertion loss of the sheet-like soundproof structure 1 can be set to a desired frequency. Therefore, the peak of the insertion loss can be set to any of a predetermined frequency band with a single support member (expanded metal 3), so there is no need to prepare support members (expanded metal 3) with different opening areas for different frequencies, thereby reducing costs.

[0081] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

Claims

1. A sheet-like soundproof structure to be attached to an object to be soundproofed, comprising: an elastic sheet; and a support member having a plurality of openings partitioned by crosspieces, supporting the sheet and partitioning the sheet into planar partitions, wherein the surface of the support member on which the sheet is placed has an uneven shape, the sheet is placed on the surface of the support member so that the convex parts of the uneven shape penetrate the sheet in the thickness direction, and the support member is attached to the object to be soundproofed in a pulled state, so that tensile stress is applied from the object to the support member and the sheet.

2. The sheet-like soundproofing structure according to claim 1, wherein the support member is an expanded metal or an expanded metal-like mesh member, or a wire mesh or a wire mesh-like mesh member.

3. A sheet-like soundproof structure as claimed in claim 1, wherein a pair of engaging portions is attached to the support member, a pair of engaged portions is attached to the object to be soundproofed, the engaging portions engage with the engaged portions, thereby enabling the support member and the sheet to be attached to the object to be soundproofed, the distance between the pair of engaged portions is set longer than the distance between the pair of engaging portions, and the support member and the sheet are attached to the object to be soundproofed while being subjected to the tensile stress in the direction widening the distance between the pair of engaging portions, by having one of the pair of engaging portions engage with one of the pair of engaged portions and the other of the pair of engaging portions engage with the other of the pair of engaged portions when the support member and the sheet are pulled in a direction widening the distance between the pair of engaging portions.

4. A sheet-like soundproofing structure as described in claim 3, wherein the support member has a diamond lattice shape in which a plurality of diamond-shaped openings are arranged by the crosspieces, and the direction in which the spacing between the pair of engaging portions is widened is set parallel to the shorter of the pair of diagonals formed by the diamonds.

5. A sheet-like soundproofing structure as described in claim 3, wherein the support member has a diamond lattice shape in which a plurality of diamond-shaped openings are arranged by the crosspieces, and the direction in which the spacing between the pair of engaging portions is widened is set parallel to the longer of the pair of diagonals formed by the diamonds.

6. A sheet-like soundproofing structure according to claim 3, wherein the tensile stress is set so that the strain on the sheet in the direction widening the gap between the pair of engaging portions is 0.01 or more.

7. A sheet-like soundproof structure as claimed in claim 1, wherein a plurality of engaging portions are attached to the peripheral edge of the support member so as to go around the peripheral edge, and the object to be soundproofed has the same number of engaged portions as the plurality of engaging portions attached to the object to be soundproofed, and the plurality of engaged portions are arranged so that a first polygon formed with corners at the positions of the plurality of engaged portions is substantially similar to a second polygon formed with corners at the positions of the plurality of engaging portions and is larger than the second polygon, and the support member and the sheet are attached to the object to be soundproofed in a state where they are subjected to the tensile stress in the direction of widening the second polygon, with each of the plurality of engaging portions engaging with the engaged portions which are different from one another when the support member and the sheet are pulled in a direction widening the second polygon.

8. The sheet-like soundproof structure according to claim 1, wherein the object to be soundproofed is the body of an automobile.

9. A method for attaching a sheet-like soundproof structure to an object to be soundproofed, the method comprising: attaching a sheet-like soundproof structure to the object to be soundproofed, the sheet-like soundproof structure including: an elastic sheet; and a support member having a plurality of openings defined by crosspieces, the support member supporting the sheet and defining the sheet into planar partitions; the surface of the support member on which the sheet is placed has an uneven shape; the sheet is placed on the surface of the support member so that the convex parts of the uneven shape penetrate the sheet in the thickness direction; and attaching the support member and the sheet to the object to be soundproofed in a pulled state, thereby applying tensile stress from the object to the support member and the sheet.

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