Sheet-like soundproof structure, method of manufacturing the same, and automobile parts and duct-closing lid parts using the same

Abstract

To provide soundproofing means which offers superior soundproofing performance and reduced manufacturing cost.SOLUTION: The above challenge is cleared by a sheet-like soundproof structure comprising an elastic sheet, and a support member provided with multiple openings partitioned by a frame and configured to support the sheet and divide the sheet into planer divided sections. A surface of the support member on a side with the sheet has asperities, and the sheet is placed on the surface of the support member such that protrusions of the asperities penetrate in a thickness direction of the sheet.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a sheet-like soundproof structure that can be used, for example, in automobile parts and duct closing cover parts, and a method for producing the same. [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, the conventional soundproof structure has a problem that it is relatively expensive and difficult to reduce the manufacturing cost.

[0005] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a soundproofing means that has excellent soundproofing performance and is capable of realizing reduction in manufacturing costs. [Means for solving the problem]

[0006] One aspect of the present invention provides a sheet-like soundproof structure. This sheet-like soundproof structure includes an elastic sheet, and a support member having a plurality of openings defined by crosspieces, supporting the sheet and defining the sheet into planar partitions. The sheet-like soundproof structure is characterized in that the surface of the support member on which the sheet is disposed has projections and recesses, and the sheet is disposed on the surface of the support member such that the projections of the projections and recesses penetrate the sheet in the thickness direction. Effect of the Invention

[0007] The sheet-like soundproof structure according to one embodiment of the present invention has the above-mentioned configuration, and thus has excellent soundproofing performance and can achieve reduced manufacturing costs. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a plan view of a sheet-like soundproof structure according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a bottom view of the sheet-like soundproof structure according to one embodiment of the present invention. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III shown in FIG. [Figure 4] FIG. 4 is an enlarged view of one opening 3C of the expanded metal 3 shown in FIG. [Diagram 5] FIG. 5 is a cross-sectional view taken along line VV shown in FIG. [Figure 6] FIG. 6 is an explanatory diagram showing a schematic structure of the drafter. [Figure 7] FIG. 7 is a graph showing the results of measuring the soundproofing performance (insertion loss) of the sheet-like soundproofing structures produced in Comparative Example 1, Comparative Example 2, and Example 1. [Figure 8] FIG. 8 is a graph showing the results of measuring the soundproofing performance (insertion loss) of the sheet-like soundproofing structures produced in Examples 2 and 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] One form of the present invention is a sheet-like soundproofing structure comprising an elastic sheet and a support member having a plurality of openings defined by crosspieces, supporting the sheet and defining the sheet into planar partitions, wherein the surface of the support member on the side on which the sheet is disposed has projections and recesses, and the sheet is disposed on the surface of the support member such that the projections of the projections penetrate in the thickness direction of the sheet.

[0010] 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.

[0011] Fig. 1 is a plan view of a sheet-like soundproof structure according to one embodiment of the present invention, Fig. 2 is a bottom view of the sheet-like soundproof structure according to one embodiment of the present invention, and Fig. 3 is a cross-sectional view taken along line III-III shown in Fig. 1.

[0012] The sheet-like soundproof structure 1 shown in Figures 1 to 3 comprises an elastic sheet 2 and an expanded metal 3 serving as a support member that supports the sheet 2 and divides the sheet 2 into planar partitions 2A. The expanded metal 3 serving as a support member has projections and recesses on both sides, and more specifically has projections 3B at the intersections of numerous diamond-shaped crosspieces 3A. As a result, the surface of the expanded metal 3 on which the sheet 2 is placed also has numerous projections 3B, and these projections 3B penetrate the sheet 2 in its thickness direction to form protrusions.

[0013] 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 2A. Examples of such support members include expanded metal or expanded metal-like mesh members, or wire mesh or wire mesh-like mesh members. In the sheet-like soundproof structure 1 according to this embodiment, the support members are formed using such materials, and the partitions 2A can be easily formed in the sheet 2 through the openings 3C. As a result, the cross-sectional ratio of the openings in the support member can be increased, which contributes to reducing the overall mass. In addition, the above-mentioned sheets and support members can generally be mass-produced and are relatively inexpensive.

[0014] The expanded metal 3, which is the support member of this embodiment, has a bending rigidity larger than that of the sheet 2. As a result, resonance occurs on the surface of the support member due to acoustic waves, and surface resonance vibration also occurs in the sheet in contact with the support member. As a result, there is an advantage that the sound insulation performance is improved near the resonance frequency. However, in some cases, the bending rigidity of the support member may be smaller than that of the sheet. In addition, examples of materials constituting the support member having a bending rigidity larger than that of the sheet include metal materials such as stainless steel, iron, and aluminum. Although these materials are lightweight, by using them as the constituent materials of the support member according to this embodiment, sound insulation performance that greatly exceeds the mass law can be achieved. In addition, the material is not limited to metal, and may be, for example, plastic that can be manufactured by an expansion method involving heating.

[0015] Fig. 4 is an enlarged view of one opening 3C of the expanded metal 3 shown in Fig. 1. Fig. 5 is a cross-sectional view taken along line VV shown in Fig. 4. The expanded metal 3 and the like, which are the constituent materials of the support member in this embodiment, may have unavoidable unevenness on their surfaces due to their structure, as shown in Fig. 5. For this reason, if a support member such as the expanded metal 3 is directly fixed to a flat sheet 2, the unevenness may cause non-contact portions between the crosspiece 3A and the sheet 2, and the entire circumference of the partition portion 2A may not be covered by the crosspiece 3A, resulting in partial gaps that may impair soundproofing performance.

[0016] As described above, in the sheet-like soundproofing structure 1 of this embodiment, the convex portion 3B on the surface of the expanded metal 3 on which the sheet 2 is arranged is configured to penetrate the sheet 2 in its thickness direction.

[0017] According to the study by the inventors, it was found that the soundproofing performance is further improved by the projection 3B penetrating the sheet 2 in this way, compared with the case where the projection 3B does not even penetrate the sheet 2. The mechanism by which the sheet-like soundproofing structure according to this embodiment exhibits the above-mentioned action and effect is not completely clear, and the following mechanism is presumed, although the present invention is not bound by any theory. That is, according to the above-mentioned configuration, the entire circumference of the partition 2A is easily covered by the crosspiece 3A. As a result, it is possible to ensure that the surface rigidity of the sheet 2 in the partition 2A and the resonance frequency of the soundproofing structure 1 are within a preferable range, and it is considered that the soundproofing performance is improved. More specifically, when a uniformly distributed pressure is applied in the thickness direction of the sheet 2, the sheet-like soundproofing structure 1 can maintain the planar partition 2A as the surface rigidity of the sheet 2 is ensured. As a result, it is presumed that the position of maximum deflection of the planar partition 2A is present within the opening 3C of the expanded metal 3, and high soundproofing performance can be realized.

[0018] Furthermore, the sheet-like soundproof structure 1 according to this embodiment does not have any essential components other than the sheet and the support members. Therefore, the sheet-like soundproof structure 1 can obtain excellent soundproofing performance while using relatively inexpensive materials for the support members and reinforcing members, and can realize reduction in manufacturing costs.

[0019] Furthermore, in the sheet-like soundproof structure 1 according to this embodiment, as described above, by making the bending rigidity of the support member greater than the bending rigidity of the sheet 2, the soundproofing performance is improved in the vicinity of the resonance frequency.

[0020] The sheet-like soundproof structure according to one embodiment of the present invention is not limited to the above embodiment in its configuration, and can be appropriately modified within the scope of the present invention. For example, in the sheet-like soundproof structure according to the above embodiment, the convex portion 3B present on the surface of the expanded metal 3 on the side where the sheet 2 is arranged penetrates the sheet 2 in the thickness direction to form a protrusion. However, the present invention is not limited to this configuration, and the convex portion 3B may penetrate into the sheet 2 without penetrating the sheet 2. Even with this configuration, the entire periphery of the partition portion 2A is easily covered by the crosspiece portion 3A as described above, and the planar partition portion 2A can be maintained with the surface rigidity of the sheet 2 ensured. As a result, high soundproof performance can be achieved. Here, if the sheet 2 is arranged on the surface of the expanded metal 3 (support member) so that the convex portion 3B penetrates the sheet 2 in the thickness direction, it is preferable from the viewpoint of covering the entire periphery of the partition portion 2A with the crosspiece portion 3A. On the other hand, when considering long-term use, there is a possibility that the sheet may deteriorate at the penetration portion, and therefore, from the standpoint of long-term durability, it is preferable that the sheet 2 is arranged on the surface of the expanded metal 3 (support member) so that the convex portion 3B penetrates the sheet 2 without penetrating it in the thickness direction.

[0021] The method for manufacturing the sheet-like soundproof structure according to this embodiment is not particularly limited, but an example is a method of pressing an elastic sheet and a support member in a laminated state in the lamination direction. That is, according to another embodiment of the present invention, a method for manufacturing a sheet-like soundproof structure is also provided, which includes pressing a laminate of an elastic sheet and a support member having a plurality of openings partitioned by a crosspiece and having an uneven surface on the sheet side in the lamination direction of the laminate, and arranging the sheet on the surface of the support member so that the convex parts of the unevenness penetrate the sheet in the thickness direction. According to this manufacturing method, a soundproof structure having excellent soundproof performance can be obtained at a low cost. In addition, when forming a laminate of an elastic sheet and a support member, by applying an adhesive between them, the entire outer periphery of the partition part can be more reliably adhered to the crosspiece of the support member. However, the use of an adhesive is not essential. In addition, by adjusting the thickness of the sheet and the pressing conditions, it is possible to control whether the convex parts penetrate the sheet or penetrate into the sheet without penetrating it. For example, when the pressing pressure in the lamination direction of the laminate is about 0.1 MPa, the convex parts do not penetrate the sheet. For this reason, the pressing pressure in the stacking direction of the laminate is preferably 0.3 MPa or more, more preferably 0.5 MPa or more, even more preferably 0.8 MPa or more, even more preferably 1.0 MPa or more, particularly preferably 1.5 MPa or more, and most preferably 2.0 MPa or more. There is no particular limit to the upper limit of the pressing pressure, but it is usually sufficient if it is 5.0 MPa or less. By pressing the laminate with such a pressing pressure, it is possible to flatten the expanded metal 3 etc. shown in FIG. 5 as a whole, while allowing the protrusions 3B to penetrate into the sheet 2.

[0022] The sheet-like soundproofing structure according to this embodiment can be applied to automobile parts, duct closing lid parts, and the like. That is, according to another embodiment of the present invention, an automobile part or duct closing lid part is provided that includes the sheet-like soundproofing structure according to one embodiment of the present invention. Automobile parts and duct closing lid parts can be intrusion paths for noise generated at a sound source. By applying the sheet-like soundproofing structure according to this embodiment to automobile parts or duct closing lid parts, it is possible to more effectively block the intrusion of noise from such parts.

[0023] Below, an example of the application of the sheet-like soundproofing structure of this embodiment will be described, taking as an example a case where it is applied to the flap of a drafter installed in the air exhaust section of a vehicle ventilation system, as an automotive part that is also a duct blocking lid part.

[0024] Conventionally, vehicles are equipped with a vehicle ventilation device that takes in air from outside the vehicle cabin to ventilate the air inside the vehicle cabin even when the windows are closed. This vehicle ventilation device is configured, for example, to have an air intake section at the front of the vehicle and an air exhaust section at the rear of the vehicle, and ventilates the air inside the vehicle cabin by utilizing the pressure difference between the ram pressure acting on the air intake section and the negative pressure acting on the air exhaust section when the vehicle is running. In this type of ventilation device, a drafter is provided at the air exhaust section so that the air inside the vehicle cabin is not constantly exhausted outside the vehicle, and this drafter has an openable flap that restricts or allows the exhaust of air. The flap switches the opening and closing state of the opening of the drafter body to adjust the exhaust state of air outside the vehicle.

[0025] 6 is an explanatory diagram showing a schematic structure of the drafter 10. The drafter 10 is mainly composed of a pair of openings 11 formed in a housing, which is the drafter main body, and a pair of flaps 12. The drafter main body has an opening on the surface opposite to the surface on which the openings 11 are provided (the back side in the figure).

[0026] The individual openings 11 are formed at predetermined intervals in the height direction of the drafter body and have a rectangular shape. These openings 11 communicate the internal space between the trim and the inner panel with the internal space between the bumper fascia and the inner panel.

[0027] In the embodiment shown in Fig. 6, each flap 12 is composed of the sheet-like soundproof structure 1 according to the embodiment shown in Figs. 1 to 3, and has a size equal to or slightly larger than the opening 11. In this embodiment, the sheet-like soundproof structure 1 is arranged so that the side on which the expanded metal 3 (support member) is arranged faces the inside of the drafter. However, the arrangement direction of the sheet-like soundproof structure 1 is not particularly limited.

[0028] The flap 12, which is made of a sheet-like soundproof structure, has one upper side rotatably attached to the upper part of the opening 11 in the drafter body. Therefore, the opening 11 is switched between open and closed depending on the rotation state of the flap 12. Specifically, for example, when the flap 12 is rotated upward due to an increase in internal pressure in the vehicle cabin when the door is closed, the opening 11 is opened (drafter open). In this case, ventilation of the air in the vehicle cabin is possible. On the other hand, when the flap 12 is rotated downward to cover the opening 11, the opening 11 is closed (drafter closed). In this case, ventilation of the air in the vehicle cabin is suppressed.

[0029] The following embodiments are also included within the scope of the present invention: a sheet-like soundproof structure as defined in any one of claims 1 to 3 having the features of claim 4; a sheet-like soundproof structure as defined in any one of claims 1 to 4 having the features of claim 5; a sheet-like soundproof structure as defined in any one of claims 1 to 5 having the features of claim 6; an automobile part comprising a sheet-like soundproof structure as defined in any one of claims 1 to 6; a duct closing cover part comprising a sheet-like soundproof structure as defined in any one of claims 1 to 6; and a manufacturing method as defined in claim 9 having the features of claim 10. EXAMPLES

[0030] 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.

[0031] <Evaluation of soundproofing performance of sheet-type soundproofing structures> The soundproofing performance against sound waves of each frequency was measured for the sheet-like 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 more excellent the soundproofing performance against sound waves of that frequency. The generation conditions of the sound source 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%.

[0032] <<Production of sheet-like soundproof structure>> [Comparative Example 1] An ethylene propylene (EPDM) rubber sheet (thickness: 150 μm) was used as the sheet-like soundproof structure of this comparative example.

[0033] [Comparative Example 2] As an elastic sheet, a sheet (thickness 150 μm) made of thermoplastic polyester elastomer (Hytrel (registered trademark) 3046, manufactured by Toray Celanese Co., Ltd.) was prepared. An adhesive-coated aluminum expand metal (support member) was laminated on one side of this sheet to obtain a laminate. Next, this laminate was pressed using a flat press. The pressing pressure was 0.1 MPa, the pressing plate temperature was 150° C., and the pressing time was 2 minutes. The laminate thus obtained was used as the sheet-like soundproof structure of this comparative example. It was confirmed that in the sheet-like soundproof structure of this comparative example, the convex portion of the support member did not penetrate into the sheet, and a gap existed between the outer periphery of the partition portion of the sheet and the crosspiece of the support member.

[0034] [Example 1] A laminate was produced in the same manner as in Comparative Example 2, except that the pressing pressure when pressing the laminate was changed to 2.0 MPa, to produce a sheet-like soundproof structure of this example. It was confirmed that in the sheet-like soundproof structure of this example, the convex parts of the support member penetrate the sheet, and no gap exists between the outer periphery of the partition part of the sheet and the crosspiece part of the support member.

[0035] [Soundproofing performance evaluation results (1)] The soundproofing performance (insertion loss) of the sheet-like soundproofing structures produced in Comparative Example 1, Comparative Example 2, and Example 1 was measured by the above-mentioned method. The results in the frequency range of 700 to 1400 Hz are shown in FIG. 7. The solid line graph in FIG. 7 shows the above-mentioned measurement results. The dashed line graph in FIG. 7 shows the insertion loss estimated from the areal density value of the sheet-like soundproofing structures produced in each experimental example, assuming that the soundproofing performance is exhibited according to only the mass law.

[0036] As shown in Fig. 7, in Comparative Example 1, in which only the sheet was used, the insertion loss measured was almost in accordance with the mass law. In Comparative Example 2, in which the convex portion of the support member did not penetrate the sheet, the insertion loss value was below the mass law in most frequency ranges. In contrast, in Example 1, in which the convex portion of the support member penetrated the sheet, insertion loss peaks were observed at approximately 800 Hz and approximately 1000 Hz, which are in the road noise range. This means that the sheet-like soundproofing structure of Example 1 exhibits excellent soundproofing performance against sounds in these frequency bands.

[0037] [Example 2] As an elastic sheet (thermal adhesive film), a sheet (thickness 300 μm) made of ethylene-methacrylic acid-isobutylene acrylate terpolymer (manufactured by Mitsui Dow Polychemicals, Nucrell (registered trademark) N035C) was prepared. An adhesive-coated aluminum expand metal (support member) was laminated on one side of this sheet to obtain a laminate. Next, this laminate was pressed using a flat press. The pressing pressure was 10 MPa, the pressing plate temperature was 90° C., and the pressing time was 4 minutes. The laminate thus obtained was used as the sheet-like soundproof structure of this example. It was confirmed that in the sheet-like soundproof structure of this example, the convex portion of the support member penetrates the sheet, and no gap exists between the outer periphery of the partition portion of the sheet and the crosspiece portion of the support member.

[0038] [Example 3] A laminate was produced using the same method as in Example 2 described above, except that the pressing pressure when pressing the laminate was changed to 1.0 MPa, the pressing time was changed to 2 minutes, and the platen temperature of the press machine was changed to 55°C on the heat-sealing film side and 90°C on the support member side, to produce a sheet-like soundproof structure of this example. In the sheet-like soundproof structure of this example, it was confirmed that the convex parts of the support member penetrate into the sheet without penetrating it, and that there was no gap between the outer periphery of the partition part of the sheet and the battens of the support member. In addition, the fact that the convex parts of the support member penetrate into the sheet without penetrating it was also confirmed by connecting terminals to the contact parts between the expanded metal battens of the sample and the expanded metal convex parts of the film using a digital multimeter (manufactured by Yokogawa Instruments Works, Ltd., model number: 7541) and finding that the electrical resistance value was over-range (overload (OL; no current flowing).

[0039] [Soundproofing performance evaluation results (2)] The soundproofing performance (insertion loss) of the sheet-like soundproofing structures produced in Examples 2 and 3 was measured by the method described above. The results in the frequency range of 400 to 8000 Hz are shown in Fig. 8. The solid line graph in Fig. 8 shows the measurement results. The dashed line graph in Fig. 8 shows the insertion loss estimated from the areal density values ​​of the sheet-like soundproofing structures produced in each Example, assuming that the soundproofing performance is exhibited according to only the mass law.

[0040] 8, in Example 2 in which the protrusions of the support member penetrate the sheet, and in Example 3 in which the protrusions penetrate the sheet without penetrating the sheet, almost the same insertion loss profile was observed, and in both Examples, insertion loss peaks exceeding the dashed line graph were observed in the frequency ranges of about 400 to 800 Hz, 1200 to 1800 Hz, and 2000 to 2400 Hz. Among these, the insertion loss peaks in the road noise range of about 400 Hz to about 800 Hz mean that the sheet-like soundproofing structures of Examples 2 and 3 exhibit excellent soundproofing performance against sounds in these frequency bands.

[0041] As described above, the sheet-like soundproof structure according to the present invention has excellent soundproofing performance and can reduce manufacturing costs. [Explanation of symbols]

[0042] 1. Sheet-like soundproof structure, 2. Elastic sheet; 2A compartment, 3 Expanded metal (support member), 3A cross section, 3B Convex part, 3C opening, 10 Drafter, 11 aperture, 12 Flaps.

Claims

1. An elastic sheet; a support member having a plurality of openings defined by crosspieces, supporting the sheet and defining the sheet into planar partitions; Equipped with A sheet-like soundproofing structure, wherein the surface of the support member on which the sheet is placed has projections and recesses, and the sheet is placed on the surface of the support member so that the projections of the projections penetrate in the thickness direction of the sheet.

2. 2. The sheet-like soundproof structure according to claim 1, wherein the sheet is disposed on the surface of the support member such that the protrusions penetrate the sheet in a thickness direction.

3. 2. The sheet-like soundproof structure according to claim 1, wherein the sheet is disposed on the surface of the support member so that the protrusions do not penetrate the sheet in the thickness direction.

4. 3. 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.

5. 3. The sheet-like soundproof structure according to claim 1, wherein the supporting member is made of a material selected from the group consisting of stainless steel, iron and aluminum.

6. 3. The sheet-like soundproof structure according to claim 1, wherein the bending rigidity of the support member is greater than the bending rigidity of the sheet.

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

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

9. An elastic sheet; A method for manufacturing a sheet-like soundproofing structure includes pressing a laminate of a support member having a plurality of openings partitioned by crosspieces and having an uneven surface on the sheet side in a stacking direction of the laminate, thereby placing the sheet on the surface of the support member so that the convex portions of the uneven surface penetrate in the thickness direction of the sheet.

10. 10. The method for producing a sheet-like soundproof structure according to claim 9, wherein a pressing pressure in a lamination direction of the laminate during the pressing is 0.3 MPa or more.

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