Sheet-like soundproof structure

Abstract

The present invention comprises an elastic sheet and a support member that supports the sheet by being connected to the main surface of the sheet. The support member includes a plurality of openings arranged to face the sheet. The sheet includes: a connection portion connected to the support member and having a shape following the support member connection surface that is connected to the sheet; and a partition portion facing the openings and surrounded by the connection portion. The partition portion is deformed such that the central portion of the partition portion is displaced, with respect to the connection portion, in the thickness direction of the partition portion.

Description

Sheet-type soundproof structure

[0001] The present invention relates to a sheet-like soundproof structure.

[0002] WO2019 / 022245A discloses a sheet-like soundproof structure including an elastic sheet and a support member that supports the sheet and divides the sheet into compartments.

[0003] However, in the structure of WO2019 / 022245A, the frequency band that effectively blocks sound waves is fixed by the surface rigidity and surface density of the partition, making it difficult to set it according to the frequency band of the sound waves to be soundproofed.

[0004] SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a sheet-like soundproof structure capable of setting a cutoff frequency band according to the frequency band of sound waves to be soundproofed.

[0005] According to one aspect of the present invention, a device includes an elastic sheet and a support member that supports the sheet by connecting to a main surface of the sheet, the support member having a plurality of openings arranged to face the sheet, the sheet including a connecting portion that is connected to the support member and has a shape that matches the connecting surface of the support member that connects to the sheet, and a partition portion that faces the opening and is surrounded by the connecting portion, and the partition portion is deformed such that a center portion of the partition portion is displaced in the thickness direction of the partition portion relative to the connecting portion.

[0006] FIG. 1 is a top view of a sheet-like soundproof structure of the first embodiment. FIG. 2 is a bottom view of the sheet-like soundproof structure of the first embodiment. FIG. 3 is a cross-sectional view taken along line A-A in FIG. 1. FIG. 4A is a diagram showing the state before a sheet is sandwiched in a mold having a cavity for forming a support member in the manufacturing process of the sheet-like soundproof structure of the first embodiment. FIG. 4B is a diagram showing the state after the sheet is sandwiched in the mold in the manufacturing process of the sheet-like soundproof structure of the first embodiment. FIG. 4C is a diagram showing the state after molten metal containing the material of the support member is injected into the mold (cavity) in the manufacturing process of the sheet-like soundproof structure of the first embodiment. FIG. 4D is a diagram showing the state after the molten metal has solidified in the manufacturing process of the sheet-like soundproof structure of the first embodiment and the sheet-like soundproof structure has been removed from the mold. FIG. 5 is a model of a sheet-like soundproof structure for representing the transmission loss of sound waves input into the sheet-like soundproof structure. FIG. 6 shows the relationship between sound wave loss and road noise band for the model of FIG. 5 before the surface rigidity is set high, and the relationship between sound wave loss and road noise band for the model of FIG. 5 after the surface rigidity is set high. FIG. 7 shows a comparison of the insertion loss of a sheet-like soundproof structure of a comparative example in which all partitions are flat with the insertion loss of the sheet-like soundproof structure of the first embodiment in which all partitions are convex first partitions. FIG. 9 shows a vibration model (vibration mode) of peak loss for the sheet-like soundproof structure of the first embodiment. FIG. 10A shows the relationship between the ratio of the depth of the partition to the long side of the partition and the frequency of peak loss. FIG. 10B shows the state in which a sheet is sandwiched in a mold having a cavity for forming a support member in the manufacturing process of a sheet-like soundproof structure of a modified example of the first embodiment. Fig. 10C is a diagram showing the state in which the sheet-like soundproof structure has been removed from the mold after the molten metal has solidified in the manufacturing process of the sheet-like soundproof structure of a modified example of the first embodiment. Fig. 11 is a cross-sectional view of a first modified example of the partition section of the first embodiment. Fig. 12 is a cross-sectional view of a second modified example of the partition section of the first embodiment. Fig. 13 is a top view of the sheet-like soundproof structure of the second embodiment.Fig. 14 is a bottom view of the sheet-like soundproof structure of the second embodiment. Fig. 15A is a view showing the state before the sheet and spacers are sandwiched in a mold having a cavity for forming the support member in the manufacturing process of the sheet-like soundproof structure of the second embodiment. Fig. 15B is a view showing the state after the sheet and spacers are sandwiched and pressed in the mold in the manufacturing process of the sheet-like soundproof structure of the second embodiment. Fig. 15C is a view showing the state after molten metal of the material for the support member is injected into the mold (cavity) in the manufacturing process of the sheet-like soundproof structure of the second embodiment. Fig. 15D is a view showing the state after the molten metal has solidified in the manufacturing process of the sheet-like soundproof structure of the second embodiment and the sheet-like soundproof structure is removed from the mold (cross-sectional view along line A-A in Fig. 13). Fig. 16 is a view comparing the insertion loss of a comparative sheet-like soundproof structure in which all partitions are flat with the insertion loss of a sheet-like soundproof structure of the second embodiment in which a first partition with a convex cross-sectional shape and a flat second partition with a flat cross-sectional shape. Fig. 17 is a cross-sectional view of a modified sheet-like soundproof structure of the second embodiment, Fig. 18 is a top view of a modified sheet-like soundproof structure of the second embodiment, and Fig. 19 is a diagram showing a manufacturing process of a sheet that is a material for the modified sheet-like soundproof structure of the second embodiment.

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

[0008] [Basic configuration of sheet-like soundproof structure 1 of first embodiment] Fig. 1 is a top view of the sheet-like soundproof structure 1 of the first embodiment. Fig. 2 is a bottom view of the sheet-like soundproof structure 1 of the first embodiment. Fig. 3 is a cross-sectional view taken along line A-A in Fig. 1.

[0009] The sheet-like soundproofing structure 1 of this embodiment includes a rectangular elastic sheet 2 and a support member 3 that supports the sheet 2 and divides it into a planar shape. "Elastic" means that the Young's modulus is a value within the range of 0.001 to 70 [GPA] and that the sheet-like soundproofing structure 1 is flexible. The sheet-like soundproofing structure 1 of this embodiment is attached, for example, inside a vehicle to reduce road noise from the road surface while the vehicle is traveling.

[0010] The support member 3 is a member that supports the sheet 2 by connecting (joining) it to the main surface of the sheet 2. The support member 3 has a lattice shape in which crosspieces 32 are constructed to form a plurality of polygonal openings 31 that are arranged to face the sheet 2. As shown in Figures 1 and 2, the support member 3 has a honeycomb shape in which hexagonal openings 31 are arranged, but any shape that can form a lattice shape, such as a circle, a triangle, or a rectangle, can be used. Furthermore, the lattice shape does not need to be uniform, and may be a lattice shape that combines two or more polygons with different numbers of corners.

[0011] The support member 3 is made of resin, but any resin that can be used for injection molding, which will be described later, can be used. Examples of materials that can be used for injection molding include polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polyoxymethylene (POM), polyphthalamide (PPA), polypropylene (PP), and polybutylene terephthalate (PBT).

[0012] The sheet 2 is a flat film-like member made of rubber, including synthetic rubber, such as natural rubber, chloroprene rubber (CR), styrene-butadiene rubber (SBR), ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber (NBR), and the like.

[0013] The sheet 2 includes a connection portion 21 that is connected to the support member 3 and has a shape that conforms to the connection surface of the support member 3 (crosspiece portion 32) that connects to the sheet 2, and a partition portion 22 (first partition portion 22A) that faces the opening 31 and is surrounded by the connection portion 21.

[0014] 3, the first partition 22A is deformed such that the center of the first partition 22A is displaced in the thickness direction of the first partition 22A (sheet 2) relative to the connecting portion 21. The first partition 22A is formed, for example, in a convex shape that is convex in the direction that it enters the support member 3, but the opposite direction is also possible. The convex shape of the first partition 22A is a dome shape, and its cross section is an arc shape.

[0015] In the sheet-like soundproof structure 1 according to this embodiment, the support member 3 is made of resin, and the openings 31 make it easy to form the first partitions 22A in the sheet 2. As a result, the cross-sectional ratio of the openings 31 in the support member 3 can be increased, which contributes to reducing the overall mass. Furthermore, the sheet 2 and support member 3 can generally be mass-produced and are relatively inexpensive.

[0016] [Manufacturing Process of Sheet-Like Soundproof Structure 1 of First Embodiment] Fig. 4A is a diagram showing a state before a sheet 2 is sandwiched in a mold 4 having a cavity 411 for forming a support member 3 in a manufacturing process of the sheet-like soundproof structure 1 of the first embodiment. Fig. 4B is a diagram showing a state after the sheet 2 has been sandwiched in the mold 4 in a manufacturing process of the sheet-like soundproof structure 1 of the first embodiment. Fig. 4C is a diagram showing a state after molten metal of the material of the support member 3 has been injected into the mold 4 (cavity 411) in a manufacturing process of the sheet-like soundproof structure 1 of the first embodiment. Fig. 4D is a diagram showing a state after the molten metal has solidified in a manufacturing process of the sheet-like soundproof structure 1 of the first embodiment and the sheet-like soundproof structure 1 has been removed from the mold 4.

[0017] As shown in Figure 4A, the mold 4 for forming the support member 3 that constitutes the sheet-like soundproof structure 1 is divided into a fixed mold 41 and a movable mold 42, and a cavity 411 for forming the support member 3 is formed in the fixed mold 41, and the cavity 411 is open to the surface of the fixed mold 41 that faces the movable mold 42.

[0018] The sheet 2 has a first partition 22A formed therein by pressing or the like.

[0019] A recess 412 having a shape conforming to the convex surface of the first partition 22A of the sheet 2 is formed between the two cavities 411 of the fixed mold 41. On the other hand, a protrusion 421 having a shape conforming to the concave surface of the first partition 22A of the sheet 2 is disposed at a position facing the recess 412 of the movable mold 42.

[0020] In addition, a groove-shaped gas vent (not shown) that connects the cavity 411 to the side of the fixed mold 41 is formed on the contact surface of the fixed mold 41 with the sheet 2, and the gas (air) inside the cavity 411 can be discharged to the outside through the gas vent (not shown), allowing the molten metal to be filled into the cavity 411.

[0021] As shown in Figure 4B, when the fixed mold 41 and the movable mold 42 are fastened together with the sheet 2 sandwiched between them, the sheet 2 is pressed in the thickness direction by the fixed mold 41 and the movable mold 42 and further deforms to fit the internal space formed by the recessed portion 412 and the protruding portion 421.

[0022] Molten metal made of the material of the support member 3 is supplied to a sleeve (not shown) attached to the fixed mold 41, and a plunger (not shown) is operated. Then, the molten metal in the sleeve (not shown) is supplied into the cavity 411 via a runner (not shown) as shown in FIG. 4C. The plunger (not shown) continues to press the molten metal, so that the molten metal that has entered the cavity 411 presses against the sheet 2 in the thickness direction and penetrates into the sheet 2 to some extent. The plunger continues to press against the molten metal until the molten metal solidifies.

[0023] After the molten metal has solidified, the operation of the plunger (not shown) is stopped and the fixed die 41 and the movable die 42 are released from the mold 4, thereby allowing the sheet-like soundproof structure 1 to be removed from the mold 4 as shown in Fig. 4D. At this time, the support member 3 (crosspiece 32) remains welded to the sheet 2 (connection portion 21).

[0024] [Model of Transmission Loss of Sheet-Like Soundproof Structure 1 and Frequency Characteristics of Loss] Fig. 5 is a model of the sheet-like soundproof structure 1 for expressing the transmission loss of sound waves input to the sheet-like soundproof structure 1. Fig. 6 is a diagram showing the relationship between sound wave loss and road noise band in the model of Fig. 5 before the surface rigidity is set high, and the relationship between sound wave loss and road noise band in the model of Fig. 5 after the surface rigidity is set high.

[0025] As described above, in the sheet-like soundproof structure 1 of this embodiment, the sheet 2 is divided into a plurality of partitions 22 by the support members 3 (crosspieces 32). Therefore, as shown in Fig. 5, 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 22 are independent of each other) in which the mass of a partition 22 is "m" and the surface rigidity of the partition 22 (resistance to deformation in response to input) is "k".

[0026] In this case, the transmission loss (TL) when a sound wave (frequency: f) passes from one main surface of the partition 22 to the other main surface can be expressed as follows:

[0027] Transmission loss (TL) resonance frequency (f ０ ) will look like this:

[0028] Here, when the area of ​​the partition 22 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 first partition 22A decreases.

[0029] Furthermore, in this embodiment, since the partition 22 (first partition 22A) has a convex shape, its surface rigidity (k) becomes larger than the surface rigidity when the partition 22 is flat, and the resonance frequency (f ０ ) can be increased.

[0030] As shown in Fig. 6, the transmission loss (TL) (and the insertion loss (IL) described later) of the sheet-like soundproof structure 1 before the surface stiffness (k) is set high (when the partition 22 is flat) has a frequency characteristic based on equation (2) (dashed line in Fig. 6). 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.

[0031] Then, after the surface rigidity (k) is set high (when the first partition portion 22A has a convex shape), the frequency characteristics of the transmission loss (TL) of the sheet-like soundproof structure 1 (solid line in FIG. 6) are shifted to the high frequency side overall compared to the transmission loss of the sheet-like soundproof structure 1 when the first partition portion 22A is flat, and the resonance frequency is "f ０ " is higher than "f ０ '".

[0032] Therefore, for example, if the object to be soundproofed is a vehicle, and the frequency band (road noise band) of road noise (road surface noise) is the resonance frequency (f ０ ), the frequency characteristics of the transmission loss (TL) of the sheet-like soundproof structure 1 having the first partition portion 22A in a convex shape as described above shifts to the high frequency side, the transmission loss (TL) in the road noise band increases, and the soundproofing performance improves.

[0033] [First Example] FIG. 7 is a diagram comparing the insertion loss of a sheet-like soundproof structure 1 of a comparative example in which all of the partitions 22 are flat with the insertion loss of the sheet-like soundproof structure 1 of the first embodiment in which all of the partitions 22 are the first partitions 22A with a convex shape.

[0034] The inventors of the present application studied the sound wave insertion loss (IL) of a sheet-like soundproof structure of a comparative example and the sheet-like soundproof structure 1 of the first embodiment. The same materials were used for the sheet 2 and the support member 3 in both the comparative example and the first embodiment. In addition, in both the comparative example and the first embodiment, the thickness of the sheet 2 was approximately 400 μm, the thickness of the support member 3 was 10 mm, and the length of the long side (diagonal line) of the opening 31 of the support member 3 was 11 mm.

[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 (A) in FIG. 7 shows the insertion loss estimated when the sheet-like soundproof structure 1 is composed only of the sheet 2 and it is assumed that the soundproofing performance is achieved in accordance with only the mass law.

[0037] The dashed line (B) in FIG. 7 shows the insertion loss estimated when it is assumed that the sheet-like soundproof structure 1, which is composed of the sheet 2 and the support member 3, exhibits soundproofing performance according to only the mass law.

[0038] As shown in FIG. 7, in the comparative example, the resonant frequency (f ０ ) (1600 [Hz]), a peak with an insertion loss higher than that indicated by the dashed line (B) occurs. Peak loss (C) is a vibration mode in which vibration occurs at a wavelength sufficiently longer than the long side (diagonal) of the partition 22, and peak loss (D) is a vibration mode in which the partition 22 and the connection portion 21 vibrate in opposite phases, as described below. In these two vibration modes, the phases of the sound waves generated from one main surface of the sheet-like soundproof structure 1 and the sound waves generated from the other main surface of the sheet-like soundproof structure 1 are opposite in phase, so the sound waves cancel each other out, resulting in a high peak loss. However, in the comparative example, the insertion loss is low in the frequency band from the resonance frequency (1600 [Hz]) to, for example, 3200 [Hz], making it difficult to effectively block road noise in this frequency band.

[0039] On the other hand, in this embodiment, the first partition 22A has a convex shape, so that the surface rigidity (k) of the first partition 22A is higher than that of the comparative example. ０ ') moves to the high frequency side (4400 [Hz]), and the resonant frequency (f ０ The insertion loss in the frequency band (1300 [Hz] - 3800 [Hz]) lower than that of the comparative example is higher.

[0040] The peak loss (F) (2820 [Hz]) is the peak loss (D) shifted to the higher frequency side, but it is the maximum value of the insertion loss in the measurement range. The peak loss (E) is in the same vibration mode as the peak loss (C), but no change in the peak value or frequency was observed.

[0041] [Relationship between Peak Loss Model and Depth / Long Side of First Partition 22A] Fig. 8 is a diagram showing a vibration model (vibration mode) of peak loss of the sheet-like soundproof structure 1 of the first embodiment. Fig. 9 is a diagram showing the relationship between the ratio of the depth of the first partition 22A to the long side of the first partition 22A and the frequency of peak loss.

[0042] The peak loss (D) and peak loss (F) shown in FIG. 7 are vibrations caused by a circular motion around an axis that is the direction in which the first partitions 22A are arranged (or linear vibrations with the thickness direction of the first partitions 22A as the amplitude direction), and are caused by a vibration mode in which the first partitions 22A and the connecting portions 21 (support member 3) have the same period and are in opposite phase to each other.

[0043] In this vibration mode, the sound waves generated in the first partition 22A by vibration caused by the externally input sound waves and the sound waves generated in the connection portion 21 by vibration caused by the externally input sound waves have the same frequency but opposite phases, so they cancel each other out, resulting in large insertion losses such as peak losses (D) and (F). In this embodiment, the resonant frequencies (f ０ ) is higher than 1473 [Hz], the peak loss associated with the vibration mode (FIG. 8) is likely to appear.

[0044] As shown in Fig. 9, the inventors of the present invention investigated the relationship between the ratio of the depth of the first partition 22A to the long side of the first partition 22A and the peak frequency of the vibration mode. They found that the peak frequency monotonically increases as the ratio increases. Furthermore, it is considered that the peak frequency monotonically increases up to a ratio of 0.20.

[0045] [Manufacturing process of a modified example of the first embodiment] Fig. 10A is a diagram showing a state in which a sheet 2 is sandwiched in a mold 4 having a cavity 411 for forming the support member 3 in a manufacturing process of a sheet-like soundproof structure 1 of a modified example of the first embodiment. Fig. 10B is a diagram showing a state in which molten metal of the material of the support member 3 is injected into the mold 4 (cavity 411) in a manufacturing process of a sheet-like soundproof structure 1 of a modified example of the first embodiment. Fig. 10C is a diagram showing a state in which the sheet-like soundproof structure 1 is removed from the mold 4 after the molten metal has solidified in a manufacturing process of a sheet-like soundproof structure 1 of a modified example of the first embodiment.

[0046] 10A , unlike the basic form, the modified example does not have the recessed portion 412 of the fixed mold 41 and the protruding portion 421 of the movable mold 42, and the portion between the cavities 411 of the fixed mold 41 and the movable mold 42 is flat. Furthermore, the sheet 2 is sandwiched between the fixed mold 41 and the movable mold 42 in a flat state.

[0047] Molten metal made of the material of the support member 3 is supplied to a sleeve (not shown) attached to the fixed mold 41, and a plunger (not shown) is operated. The molten metal in the sleeve (not shown) is then supplied via a runner (not shown) into the cavity 411 as shown in FIG. 10B . The plunger (not shown) continues to press the molten metal, so that the molten metal that has entered the cavity 411 presses against the sheet 2 in its thickness direction and penetrates into the sheet 2 to some extent. As a result, the sheet 2 is pushed to the periphery by the pressure from the molten metal (support member 3 after solidification), and as a result, the sheet 2 is subjected to stress such that the portion of the sheet 2 that will become the first partition 22A becomes convex in the direction away from the molten metal (support member 3 after solidification).

[0048] After the molten metal has solidified, the operation of the plunger (not shown) is stopped and the fixed die 41 and the movable die 42 are released from the mold 4, thereby allowing the sheet-like soundproof structure 1 to be removed from the mold 4 as shown in Fig. 10C. At this time, the stress causes the first partition 22A of the sheet 2 to deform into a convex shape that is convex in the thickness direction of the sheet 2 and in the direction away from the support member 3.

[0049] [Modifications of the first partition section 22A] Fig. 11 is a cross-sectional view of a first modification of the first partition section 22A of the first embodiment. Fig. 12 is a cross-sectional view of a second modification of the first partition section 22A of the first embodiment.

[0050] In the first modified example, the first partition 22A has a conical shape with a triangular cross section. In the second modified example, the first partition 22A has a mortar shape with a trapezoidal cross section. Either shape can be formed by press molding, and the surface rigidity (k) can be increased.

[0051] [Effects of First Embodiment] The sheet-like soundproof structure 1 of the first embodiment includes an elastic sheet 2 and a support member 3 that supports the sheet 2 by connecting to a main surface of the sheet 2, the support member 3 including a plurality of openings 31 arranged to face the sheet 2, the sheet 2 including a connection portion 21 that is connected to the support member 3 and has a shape that follows the connection surface of the support member 3 that connects to the sheet 2, and a partition portion 22 (first partition portion 22A) that faces the opening 31 and is surrounded by the connection portion 21, and the partition portion 22 (first partition portion 22A) is deformed such that a central portion of the partition portion 22 (first partition portion 22A) is displaced in the thickness direction of the partition portion 22 (first partition portion 22A) relative to the connection portion 21.

[0052] With the above configuration, the frequency band with high sound wave insertion loss can be shifted to a higher position than the frequency band when the partition 22 (first partition 22A) is flat, resulting in a sheet-like soundproofing structure 1 in which the cutoff frequency band can be set according to the frequency band of the sound waves to be soundproofed.

[0053] In this embodiment, the surface rigidity (k) of the first partition portion 22A and the surface density (m) of the first partition portion 22A satisfy the formula (4). The above configuration makes it easier for a high peak loss to occur due to the vibration mode (FIG. 8).

[0054] In this embodiment, the cross-sectional shape of the first partition portion 22A is an arc shape, a triangle shape, or a trapezoid shape.

[0055] With the above configuration, the design of the first partition 22A can be created to meet the user's requirements.

[0056] In this embodiment, the first partition 22A has a mortar shape or a cone shape.

[0057] With the above configuration, the design of the first partition 22A can be created to meet the user's requirements.

[0058] In this embodiment, the ratio of the displacement in the thickness direction from the connection portion 21 at the center of the first partition portion 22A to the long side (diagonal line) of the first partition portion 22A is set to be higher than 0 and equal to or less than 0.2.

[0059] With the above configuration, the high peak loss of the insertion loss due to the vibration mode (FIG. 8) can be set in the desired frequency band.

[0060] In this embodiment, the support member 3 (the crosspiece 32 ) is welded to the connection portion 21 .

[0061] With the above-described configuration, the support member 3 can be firmly connected to the sheet 2, and the vibration mode components due to the connection portion 21 and the first partition portion 22A can be enhanced.

[0062] In this embodiment, the first partition 22A has a shape that is convex in the direction that enters the opening 31.

[0063] With the above-described configuration, the overall thickness of the sheet-like soundproof structure 1 can be reduced, and interference with the object to which it is attached can be reduced.

[0064] In this embodiment, the first partition portion 22A and the connecting portion 21 vibrate due to sound waves and have a vibration mode (Figure 8) in which the first partition portion 22A and the connecting portion 21 vibrate in opposite phases to each other, and the resonant frequency of the vibration mode (Figure 8) can be adjusted by changing the ratio.

[0065] In the above configuration, a vibration mode (FIG. 8) is generated in which the first partitions 22A and the connecting portions 21 (support member 3) vibrate in a circular motion around the axis along which the first partitions 22A are aligned (or in a linear motion with the thickness direction of the first partitions 22A as the amplitude direction), and the first partitions 22A and the connecting portions 21 vibrate at the same period and are out of phase with each other. In this vibration mode (FIG. 8), the sound waves generated in the first partitions 22A due to vibration from an externally input sound wave and the sound waves generated in the connecting portions 21 due to vibration from an externally input sound wave have the same frequency but are out of phase with each other, so they cancel each other out, resulting in a large insertion loss (such as peak loss (D) and peak loss (F)). Therefore, with the above configuration, a high peak loss due to the vibration mode (FIG. 8) can be set in a desired frequency band.

[0066] [Basic Configuration of Sheet-like Soundproof Structure 1 of Second Embodiment] Fig. 13 is a top view of the sheet-like soundproof structure 1 of the second embodiment. Fig. 14 is a bottom view of the sheet-like soundproof structure 1 of the second embodiment.

[0067] The sheet-like soundproofing structure 1 of the second embodiment is similar to the first embodiment in that it comprises an elastic rectangular sheet 2 and a support member 3 that supports the sheet 2 and divides the sheet 2 into a planar shape, but in addition to the first dividing portion 22A, a second dividing portion 22B is formed.

[0068] The second partition 22B is flat and undergoes almost no deformation in the thickness direction (see FIG. 15D).

[0069] 13 and 14 , among the partitions 22 defined by the support member 3, the second partitions 22B are, for example, biased toward one short side of the sheet 2 (support member 3), and the first partitions 22A are located in a position in the partition 22 other than the position where the second partitions 22B are located. However, the arrangement pattern of the first partitions 22A and the second partitions 22B can be set arbitrarily. Furthermore, the ratio of the number of first partitions 22A (N1) to the number of second partitions 22B (N2) can also be set arbitrarily. For example, N1:N2 = 1:1 can be used, and the ratio N2 / (N1 + N2) can also be set arbitrarily between 0.2 and 0.8. In addition, since the sheet-like soundproof structure 1 forms a single vibration system as a whole, if the ratio of the number of first partitions 22A (N1) to the number of second partitions 22B (N2) is constant, it is thought that the frequency characteristics of the insertion loss (IL) will hardly change even if the arrangement pattern of the first partitions 22A and second partitions 22B is changed.

[0070] [Manufacturing Process of Sheet-Like Soundproof Structure 1 of Second Embodiment] Fig. 15A is a diagram showing a state before the sheet 2 and spacers 5 are sandwiched in a mold 4 having a cavity 411 for forming the support member 3 in the manufacturing process of the sheet-like soundproof structure 1 of the second embodiment. Fig. 15B is a diagram showing a state after the sheet 2 and spacers 5 are sandwiched and pressed in the mold 4 in the manufacturing process of the sheet-like soundproof structure 1 of the second embodiment. Fig. 15C is a diagram showing a state after molten metal of the material of the support member 3 is injected into the mold 4 (cavity 411) in the manufacturing process of the sheet-like soundproof structure 1 of the second embodiment. Fig. 15D is a diagram showing a state after the molten metal has solidified in the manufacturing process of the sheet-like soundproof structure 1 of the second embodiment and the sheet-like soundproof structure 1 is removed from the mold 4 (cross-sectional view along line A-A in Fig. 13 ).

[0071] As shown in Figure 15A, the shape of the mold 4 (fixed mold 41, movable mold 42) for forming the support member 3 that constitutes the sheet-like soundproof structure 1 is the same as the shape in the modified example of the first embodiment (Figure 10A).

[0072] The spacer 5 is disposed so as to overlap the sheet 2, and its outer shape is formed following the shape of the region of the sheet 2 that forms the second partition 22B. The spacer 5 is disposed so that the outer shape of the spacer 5 and the outer shape of the region overlap in a plan view. Therefore, in the second embodiment, the first partition 22A and the second partition 22B are formed simultaneously.

[0073] 15B, the sheet 2 and the spacer 5 are overlapped and sandwiched between the mold 4 (fixed mold 41, movable mold 42) with the sheet 2 facing the cavity 411. At this time, the portion of the sheet 2 overlapping the spacer 5 is compressed in the thickness direction by the spacer 5, and the overlapping portion facing the cavity 411 is pushed to a predetermined depth within the cavity 411. On the other hand, the portion of the sheet 2 not overlapping the spacer 5 is arranged as shown in FIG. 10A as described above.

[0074] A molten metal made of the material of the support member 3 is supplied to a sleeve (not shown) attached to the fixed mold 41, and a plunger (not shown) is operated. Then, the molten metal in the sleeve (not shown) is supplied into the cavity 411 via a runner (not shown) as shown in FIG. 15C, and the plunger (not shown) continues to press the molten metal.

[0075] At this time, the molten metal that has entered the cavity 411 facing the portion of the cavity 411 where the sheet 2 and the spacer 5 overlap pushes the outer periphery of the portion of the sheet 2 that has entered the cavity 411 toward the spacer 5, but the portion inside the outer periphery remains in the cavity 411. Furthermore, the molten metal hardly leaks out of the cavity 411. On the other hand, the molten metal that has entered the cavity 411 facing the portion of the sheet 2 that does not overlap the spacer 5 is pressed in the thickness direction as described above and enters the main body of the sheet 2 to some extent. The plunger continues to press against the molten metal until the molten metal solidifies.

[0076] After the molten metal has solidified, the operation of the plunger (not shown) is stopped and the fixed die 41 and the movable die 42 are released from the mold 4, thereby allowing the sheet-like soundproof structure 1 to be removed from the mold 4 as shown in Fig. 15D. At this time, the support member 3 (crosspiece 32) remains welded to the sheet 2 (connection portion 21).

[0077] The portion of the sheet-like soundproof structure 1 (sheet 2) removed from the mold 4 that overlaps with the spacer 5 becomes the second partition 22B, and the portion that is not overlapped with the spacer 5 becomes the first partition 22A. At this time, the thickness of the second partition 22B is approximately the same as the thickness of the first partition 22A.

[0078] As described above, the support members 3 (cross-sections 32) that define the second partition 22B in the sheet 2 hardly penetrate into the main body of the sheet 2, and therefore the support members 3 (cross-sections 32) generate almost no residual stress on the sheet 2. Therefore, the second partition 22B has a flat plate shape (a rectangular cross section).

[0079] Meanwhile, the support member 3 (crosspiece 32) that defines the first partition 22A in the sheet 2 is embedded in the main body of the sheet 2, generating residual stress in the support member 3 (crosspiece 32) against the sheet 2. As a result, the first partition 22A is deformed such that the center of the first partition 22A is displaced in the thickness direction (the direction in which the center of the first partition 22A moves away from the support member 3 (opening 31) becomes convex) relative to the connection portion 21 of the first partition 22A (the peripheral portion of the first partition 22A supported by the support member 3).

[0080] [Second Example] FIG. 16 is a diagram comparing the insertion loss of a sheet-like soundproofing structure of a comparative example in which all of the partitions 22 are flat with the insertion loss of the sheet-like soundproofing structure 1 of the second embodiment, which includes a first partition 22A with a convex cross-sectional shape and a second partition 22B with a flat plate-like cross-sectional shape.

[0081] The sheet-like soundproof structure 1 of the comparative example and the second embodiment according to the second example was manufactured in the same manner as the first example. In addition, the ratio (N1:N2) of the number of first partitions 22A (N1) to the number of second partitions 22B (N2) in the sheet-like soundproof structure 1 was 1:1.

[0082] The dashed line (B) shown in Fig. 16 is the same as the dashed line (B) shown in the first embodiment (Fig. 7), and the peak loss (C)-(F) shown in Fig. 16 has the same vibration mode as the peak loss (C)-(F) shown in the first embodiment (Fig. 7). Descriptions of characteristics common to the first embodiment and the second embodiment will be omitted unless necessary.

[0083] In the sheet-like soundproof structure 1 of the second embodiment, the partition 22 has a first partition 22A and a second partition 22B, and the surface rigidity (k) of the entire sheet 2 is higher than that of the comparative example. ０ ) (1700 [Hz]), the resonance frequency (f ０ ') moves to the high frequency side (4000 [Hz]), and the resonant frequency (f ０ The insertion loss in the frequency band (1350 [Hz] - 4000 [Hz]) lower than that of the comparative example is higher than that of the comparative example. Therefore, like the first embodiment, the second embodiment also has the effect of efficiently reducing noise in a wide frequency band.

[0084] Furthermore, the insertion loss (IL) of the sheet-like soundproofing structure 1 of the second embodiment includes a peak loss (D) (approximately 1200 Hz) due to the primary resonance of the second partition portion 22B and a peak loss (F) (approximately 3350 Hz) due to the primary resonance of the first partition portion 22A, and the peak loss (F) is shifted to the high frequency side, as in the first embodiment.

[0085] Furthermore, as described above, the sheet-like soundproof structure 1 of the second embodiment forms a single vibration system by including the first partition 22A and the second partition 22B, and therefore, as shown in FIG. 16, the peak loss (D) and peak loss (F) show values ​​higher than the dashed line (B).

[0086] Therefore, noise in a frequency band centered on the peak loss (D) (for example, road noise) and noise in a frequency band centered on the peak loss (F) (for example, operating noise of an air conditioner) can be efficiently reduced simultaneously.

[0087] [Modification of Second Embodiment] Fig. 17 is a cross-sectional view of a modification of the sheet-like soundproof structure 1 of the second embodiment. Fig. 18 is a top view of the modification of the sheet-like soundproof structure 1 of the second embodiment.

[0088] In a modification of the second embodiment, an uneven pattern (protrusions 23 that become grain) is formed on the opposite side of the main surface of the sheet 2 to which the support member 3 is joined. The protrusions 23 are circular (cylindrical), for example, as shown in Figures 17 and 18, and are uniformly arranged in the surface direction of the sheet 2. The shape of the protrusions 23 in a plan view is not limited to a circle, and various shapes such as a triangle, a rectangle, a polygon, an ellipse, or a star can be used.

[0089] In addition, the uneven pattern (protrusions 23) may be formed only in the area where the second partition 22B of the sheet 2 is formed, or may be formed in the area where the first partition 22A of the sheet 2 is formed and the area where the second partition 22B is formed (i.e., the entire surface).

[0090] In this way, by forming the uneven pattern (protrusions 23) in at least the area of ​​the sheet 2 where the second partition 22B is formed, the rigidity of the second partition 22B is increased, and the peak of the insertion loss of the second partition 22B (for example, the peak loss (D) in Figure 16) can be shifted to the high frequency side, thereby efficiently reducing noise at the desired frequency.

[0091] [Manufacturing Process of Sheet 2] FIG. 19 is a diagram showing a manufacturing process of the sheet 2 that is the material of the modified sheet-like soundproof structure 1 of the second embodiment.

[0092] As shown in FIG. 19, the manufacturing apparatus for sheet 2 includes a release sheet 201, a molten resin supply section 202 that stores molten resin 203, a rolling roller 204 consisting of two rollers, and a winding section 205.

[0093] The release sheet 201 is a sheet having an uneven shape on one main surface, and is wound into a roll so that the surface having the uneven shape (protrusions 23) faces inward. The length of the release sheet 201 in the width direction is approximately the same as the short side of the sheet-like soundproof structure 1.

[0094] The molten resin supply unit 202 stores molten resin 203 and supplies the resin 203 from a slit (opening) in the lower part toward the rolling rollers 204, and the length of the slit is approximately the same as the width of the release sheet 201. The molten resin supply unit 202 supplies the resin toward the other main surface of the release sheet 201 that does not have an uneven shape (protrusions 23), which is sandwiched between the rolling rollers 204.

[0095] The release sheet 201 unwound from the roll is inserted between two rollers of the rolling rollers 204 and taken up by the take-up unit 205. Furthermore, molten resin 203 is applied to the release sheet 201 at a position immediately before it is sandwiched between the rolling rollers 204. The resin 203 is pressed together with the release sheet 201 by the rolling rollers 204, so that it spreads to cover the release sheet 201, and solidifies due to a drop in temperature, bonding to the release sheet 201. Therefore, the release sheet 201 downstream of the rolling rollers 204 has a laminate structure (sheet 2) of the release sheet 201 and the resin 203, and is taken up by the take-up unit 205 in this laminate structure.

[0096] [Effects of the Second Embodiment] The sheet-like soundproof structure 1 of the second embodiment includes an elastic sheet 2 and a support member 3 that supports the sheet 2 by connecting to a main surface of the sheet 2, the support member 3 including a plurality of openings 31 arranged to face the sheet 2, the sheet 2 including a connection portion 21 that is connected to the support member 3 and has a shape that follows the connection surface of the support member 3 that connects to the sheet 2, and a plurality of partitions 22 that face the openings 31 and are surrounded by the connection portion 21, the plurality of partitions 22 being a first partition portion 22A and a second partition portion 22B arranged at a different position from the first partition portion 22A, the first partition portion 22A being deformed such that the central portion of the first partition portion 22A is displaced relative to the connection portion 21 in the thickness direction of the first partition portion 22A (the direction in which the central portion of the first partition portion 22A moves away from the support member 3 (opening 31) is convex), and the second partition portion 22B is flat (the central portion of the second partition portion 22B and the connection portion 21 of the second partition portion 22B are located at approximately the same position in the thickness direction).

[0097] With the above configuration, the frequency band with high sound wave insertion loss (peak loss) can be shifted to a higher position than the frequency band when the partition portion 22 is flat, resulting in a sheet-like soundproofing structure 1 in which the cutoff frequency band can be set according to the frequency band of the sound waves to be soundproofed. Furthermore, since the partitions 22 are arranged by combining flat partitions (second partitions 22B) with partitions (first partitions 22A) having a cross-sectional shape that is arc-shaped, triangular, or trapezoidal, with respect to the insertion loss of the vibration system consisting of the sheet 2 and the support member 3, a peak loss (D) caused by the primary resonance of the second partitions 22B and a peak loss (F) caused by the primary resonance of the first partitions 22A, the peak loss (F) being shifted to the higher frequency side than the peak loss (D), appear simultaneously ( FIG. 16 ). Furthermore, it is possible to realize a state in which the peak losses (D) and (F) are higher than the insertion loss (dashed line (B)) estimated when it is assumed that the sheet-like soundproof structure 1 consisting of the sheet 2 and the support member 3 exhibits soundproofing performance in accordance with only the mass law ( FIG. 16 ), thereby enabling noise in the desired frequency band to be efficiently reduced. Furthermore, since the insertion loss in the frequency band lower than the resonant frequency (f0') can be made higher than when all of the partitions 22 are flat (FIG. 16), a high insertion loss can be realized over a wide frequency band, and noise can be efficiently reduced. Note that the configuration may be such that the central portions of some of the partitions 22 (first partitions 22A, and the remaining partitions 22 excluding these some partitions 22 are second partitions 22B) among the plurality of partitions 22, or the central portions of all of the plurality of partitions 22 (first partitions 22A) among the plurality of partitions 22 deform so as to be displaced relative to the connecting portion 21 in the thickness direction of the partitions 22 (the direction in which the central portions of the first partitions 22A move away from the support member 3 (opening 31) is convex).

[0098] In this embodiment, an uneven pattern is arranged on the surface of the flat partition 22 (second partition 22B) opposite to the surface that is joined to the support member 3.

[0099] With the above configuration, the stiffness of the second partition 22B (similarly to the first partition 22A) is increased, and the resonant frequency (f ０ ) becomes higher, the desired frequency band (resonant frequency (f ０') and below) can be effectively reduced.

[0100] 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 soundproofing structure comprising: an elastic sheet; and a support member that supports the sheet by connecting to a main surface of the sheet, wherein the support member has a plurality of openings arranged to face the sheet; the sheet comprises a connection portion that is connected to the support member and has a shape that follows the connection surface of the support member that connects to the sheet; and a partition portion that faces the opening and is surrounded by the connection portion, wherein the partition portion is deformed so that a center portion of the partition portion is displaced in the thickness direction of the partition portion relative to the connection portion.

2. A sheet-like soundproof structure according to claim 1, wherein the surface rigidity (k) of the partitions and the surface density (m) of the partitions satisfy the formula (1).

3. A sheet-like soundproof structure according to claim 1, wherein the cross-sectional shape of the partition is arc-shaped, triangular, or trapezoidal.

4. A sheet-like soundproof structure according to claim 1, wherein the partition has a mortar or cone shape.

5. The sheet-like soundproof structure according to claim 1, wherein the partitions are arranged in a combination of flat plate-shaped sections and sections having an arc-shaped, triangular, or trapezoidal cross section.

6. A sheet-like soundproof structure according to claim 5, wherein a concave-convex pattern is arranged on the surface of said flat partition portion opposite to the surface that is joined to said support member.

7. A sheet-like soundproof structure according to claim 1, wherein the ratio of the displacement in the thickness direction from the connecting portion of the central portion to the long side of the partition portion is set to be higher than 0 and not higher than 0.

2.

8. The sheet-like soundproof structure according to claim 1, wherein the support member is welded to the connecting portion.

9. A sheet-like soundproof structure according to claim 1, wherein the partition has a shape that is convex in the direction that it enters the opening.

10. A sheet-like soundproof structure as described in claim 7, wherein the partitions and the connecting parts vibrate in response to sound waves and have a vibration mode in which the partitions and the connecting parts vibrate in opposite phases to each other, and the resonant frequency of the vibration mode can be adjusted by changing the ratio.

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