Soundproof structure

Abstract

To provide a soundproofing structure that reduces costs while exhibiting high sound absorption effects. [Solution] The soundproofing structure (1,2) of the present invention is a soundproofing structure (1,2) that reduces sound generated from a sound source (9), and comprises a reflective part (10,80) that reflects sound, and a sound-absorbing member (20) disposed between the reflective part (10,80) and the sound source (9), with a space (30,30a) provided between the reflective part (10,80) and the sound-absorbing member (20), the reflective part (10,80) having a plurality of concave curved surfaces (14,85) and / or a plurality of convex curved surfaces (15), and the space (30,30a) is formed as a single continuous space over at least two concave curved surfaces (14,85) and / or over at least two convex curved surfaces (15).

Description

Technical Field

[0001] The present invention relates to a soundproof structure for reducing sound generated from a sound source.

Background Art

[0002] For example, Japanese Patent Application Laid-Open No. 2021-131424 (Patent Document 1) describes a sound-absorbing material structure having a sound-absorbing effect. The sound-absorbing material structure of Patent Document 1 is formed by a laminate having at least a first layer disposed closer to the sound source and a second layer disposed farther from the sound source.

[0003] The first layer of this sound-absorbing material structure is thicker than the second layer along the sound propagation direction and is made of a fiber material having a relatively smaller flow resistance than the second layer. Specifically, the first layer is made of a fiber material having a flow resistance of 5000 to 8000 N·s / m 4 and a thickness of approximately 50 mm. The second layer is made of a fiber material having a flow resistance of 60000 to 170000 N·s / m 4 and a thickness of approximately 20 mm. Patent Document 1 explains that the sound-absorbing material structure composed of the above-described laminate of the first layer and the second layer can achieve a high sound-absorbing effect in a frequency band where people feel discomfort.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since the sound-absorbing material structure described in Patent Document 1 has two first layers and a second layer made of fiber materials having different flow resistances, for example, compared with a sound-absorbing structure formed by a single layer capable of absorbing sound, there is a drawback of increasing the manufacturing cost.

[0006] The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide a soundproofing structure that can reduce costs and exhibit a high sound absorption effect. [Means for solving the problem]

[0007] To achieve the above objective, the soundproofing structure provided by the present invention is a soundproofing structure that reduces sound generated from a sound source, comprising a reflective portion that reflects the sound, and a sound-absorbing member disposed between the reflective portion and the sound source, wherein a space is provided between the reflective portion and the sound-absorbing member, the reflective portion has a plurality of concave curved surfaces that curve concavely away from the sound-absorbing member, and / or a plurality of convex curved surfaces that curve convexly towards the sound-absorbing member, and the space is formed continuously and uniformly across at least two concave curved surfaces and / or at least two convex curved surfaces.

[0008] In the soundproofing structure of the present invention, the reflective portion has a mounting portion to which the sound-absorbing member is attached, a pair of retaining wall portions extending from the mounting portion in a direction away from the sound-absorbing member, and a reflective main body portion connected to the pair of retaining wall portions and disposed away from the sound-absorbing member, wherein the reflective main body portion has at least two portions that are spaced at different distances from the sound-absorbing member, and the space portion is preferably formed continuously from one of the retaining wall portions to the other.

[0009] Furthermore, it is preferable that at least a portion of the reflective surface of the reflective portion facing the sound-absorbing member has a curved shape in which the concave curved portion and the convex curved portion are formed alternately and continuously, the sound-absorbing member has a first surface disposed on the sound source side and a second surface disposed on the reflective portion side, and at least a portion of the second surface of the sound-absorbing member is formed as a flat surface. [Effects of the Invention]

[0010] The soundproofing structure of the present invention can reduce costs and exhibit a high sound absorption effect. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic cross-sectional perspective view showing a soundproofing structure according to Embodiment 1 of the present invention. [Figure 2] Figure 1 is a schematic cross-sectional view showing the reflective and sound-absorbing components of the soundproofing structure. [Figure 3] Figure 1 is a schematic cross-sectional diagram illustrating the effect of the soundproofing structure shown. [Figure 4] This is an explanatory diagram that schematically illustrates the position of sound-absorbing materials and their sound-absorbing effect. [Figure 5] This is a schematic cross-sectional perspective view showing a soundproofing structure according to Embodiment 2 of the present invention. [Modes for carrying out the invention]

[0012] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings, using examples. [Examples]

[0013] Figure 1 is a schematic cross-sectional perspective view showing the soundproofing structure 1 according to this embodiment 1. Figure 2 is a schematic cross-sectional view showing the reflective part 10 and the sound-absorbing member 20 in the soundproofing structure 1 of this embodiment 1. Figure 3 is a schematic cross-sectional explanatory diagram illustrating the effects of the soundproofing structure 1 of this embodiment 1.

[0014] For convenience, in the following explanation, the direction along the direction from the sound-absorbing member 20 toward the reflective body portion 13 of the reflective portion 10 will be referred to as the vertical direction. In this case, the vertical direction can also be said to be the direction perpendicular to the first surface (outer surface) and second surface (inner surface) of the sound-absorbing member 20 in this embodiment 1, the thickness direction of the soundproofing structure 1, or the thickness direction of the sound-absorbing member 20 (see Figure 1).

[0015] As shown in FIG. 1, the vertical direction is orthogonal to the horizontal direction, and the front-rear direction is defined as the direction in which the concave curved surface portion 14 and the convex curved surface portion 15, which will be described later, of the reflection main body portion 13 extend in a fixed shape. In this case, the front-rear direction can also be referred to as the length direction of the sound insulation structure 1 or the length direction of the sound absorption member 20. Furthermore, the left-right direction is defined as the direction along the direction from one of the pair of attachment portions 11, which will be described later, of the reflection portion 10 to the other. In this case, the left-right direction can also be referred to as the width direction of the sound insulation structure 1 or the width direction of the sound absorption member 20.

[0016] The sound insulation structure (sound absorption structure) 1 of the first embodiment is integrally provided on an under cover, which is an automotive exterior part. For example, it covers and protects at least a part of the engine as the sound source 9, and can absorb and reduce noise such as engine noise generated from the engine. The sound insulation structure 1 has a reflection portion 10 that reflects sound (noise) and a single sound absorption member 20 disposed between the reflection portion 10 and the sound source 9. Also, a space portion 30 is provided between the reflection portion 10 and the sound absorption member 20.

[0017] The reflection portion 10 is formed of a hard synthetic resin or a metal such as steel that does not deform or is difficult to deform even when an external force is applied, and has higher rigidity than the sound absorption member 20. Also, the reflection portion 10 of the first embodiment has a portion where the cross-section (transverse cross-section) orthogonal to the front-rear direction is formed in a fixed shape. Note that the reflection portion 10 may include a portion where the cross-section orthogonal to the front-rear direction changes.

[0018] The reflection portion 10 of the first embodiment has a pair of left and right attachment portions 11 to which the sound absorption member 20 is attached, a pair of left and right holding wall portions 12 extending in the vertical direction from the left and right attachment portions 11, a reflection main body portion 13 connected to the left and right holding wall portions 12, and a front wall portion (not shown) and a rear wall portion (not shown) provided at the front-rear ends of the reflection portion 10. Also, the left and right attachment portions 11, the left and right holding wall portions 12, the reflection main body portion 13, the front wall portion, and the rear wall portion are integrally formed.

[0019] The left and right attachment portions 11 are each formed in a shape with an L-shaped cross section orthogonal to the front-rear direction. By installing the left and right attachment portions 11, the sound absorption member 20 can be accommodated and fixed inside the attachment portions 11, so that the sound absorption member 20 can be easily and stably attached to a predetermined position of the reflection portion 10. In the present invention, the method and means for fixing the sound absorption member 20 to the reflection portion 10 are not particularly limited.

[0020] The left and right holding wall portions 12 each extend straight from the attachment portion 11 in a direction away from the sound absorption member 20, and hold the reflection main body portion 13 at a position away from the sound absorption member 20. In the first embodiment, the left and right holding wall portions 12 are provided along a direction orthogonal to the left-right direction and are arranged parallel to each other.

[0021] Each holding wall portion 12 has a wall base end portion connected to the inner end portion of the attachment portion 11 and a wall tip end portion connected to the outer end portion of the reflection main body portion 13. By installing the left and right holding wall portions 12 on the reflection portion 10, a space portion 30 can be stably provided between the reflection main body portion 13 of the reflection portion 10 and the sound absorption member 20 attached to the attachment portion 11.

[0022] The reflection main body portion 13 is provided between the left and right holding wall portions 12. The reflection main body portion 13 is continuously formed from the left holding wall portion 12 to the right holding wall portion 12 and is formed with a constant thickness except for the left and right side edge portions.

[0023] The reflection main body portion 13 has a plurality of concave curved surface portions 14 having a shape curved in a concave shape so as to be away from the sound absorption member 20 and a plurality of convex curved surface portions 15 having a shape curved in a convex shape so as to approach the sound absorption member 20. Each of the concave curved surface portions 14 and each of the convex curved surface portions 15 of the reflection main body portion 13 are continuously provided along the front-rear direction.

[0024] The reflective body portion 13 has concave curved surfaces 14 and convex curved surfaces 15 arranged alternately and continuously in the left-right direction. As a result, when a cross-section perpendicular to the front-rear direction of the reflective body portion 13 is viewed, the reflective body portion 13 has a wave shape that curves regularly and smoothly at regular intervals. By providing the reflective body portion 13 with multiple concave curved surfaces 14 and multiple convex curved surfaces 15, the rigidity of the reflective body portion 13 can be increased, and as a result, the thickness of the reflective body portion 13 can be reduced, thereby reducing the weight and cost of the soundproofing structure 1.

[0025] The reflective body portion 13 has a reflective surface 13a that is positioned opposite the sound-absorbing member 20 and reflects sound that has passed through the sound-absorbing member 20, and an outer surface 13b positioned on the opposite side of the reflective surface 13a. The reflective surface 13a of the reflective body portion 13 has a concave and convex curved surface shape 16 that displaces in a wave-like manner up and down with respect to the left and right direction, for example, because the concave curved surface portion 14 and convex curved surface portion 15 described above are provided alternately and continuously along the left and right direction.

[0026] In particular, in this embodiment 1, the continuous uneven curved surface shape 16 on the reflective surface 13a of the reflective body portion 13 is provided over the entire left-right direction of the reflective body portion 13. As a result, the reflective body portion 13 and the reflective surface 13a of this embodiment 1 have at least two portions with different separation distances from the second surface of the sound-absorbing member 20 (in other words, the thickness 31 between the reflective body portion 13 and the sound-absorbing member 20 in the space portion 30) (see Figure 1). Furthermore, the uneven curved surface shape 16 of this embodiment 1 does not have any planes parallel to the left-right direction.

[0027] In this invention, the uneven curved surface shape 16 on the reflective surface 13a of the reflective body portion 13 may be provided only in a portion of the left-right direction of the reflective body portion 13. Also, in this invention, the shape of the outer surface 13b of the reflective body portion 13 is not particularly limited.

[0028] The sound-absorbing member 20 is formed in a thin, plate-like or rectangular shape. The sound-absorbing member 20 has a first surface that faces the sound source 9 and a second surface that faces the reflective body 13. The first surface of the sound-absorbing member 20 facing the sound source 9 and the second surface facing the reflective body 10 are not curved or uneven surfaces like the reflective body 13, but are formed as planes that are at least parallel in the left-right direction macroscopically. Furthermore, in this embodiment 1, the first and second surfaces of the sound-absorbing member 20 are also formed as planes that are parallel in the front-back direction.

[0029] The sound-absorbing member 20 is made of a soft, porous material. The sound-absorbing member 20 has a structure in which multiple fine holes (pores) are formed inside. When sound enters the sound-absorbing member 20 and propagates through it, a portion of the sound energy is consumed as thermal energy in the pores within the sound-absorbing member 20 due to friction and viscous resistance between air molecules and the material, vibration of the porous material, etc., thereby exhibiting a sound-absorbing (porous sound-absorbing) effect.

[0030] In this embodiment 1, the porous material used to form the sound-absorbing member 20 can be, for example, a nonwoven fabric made using polyester fibers, nylon fibers, glass wool, etc., or a foamed resin such as polyurethane or polyolefin.

[0031] The thickness (vertical dimension) of the sound-absorbing member 20 from the first surface to the second surface is preferably 5 mm or more and 100 mm or less. A thickness of 5 mm or more ensures adequate strength of the sound-absorbing member 20. Furthermore, it expands the frequency range of sound that can be absorbed within the sound-absorbing member 20.

[0032] By keeping the thickness of the sound-absorbing member 20 to 100 mm or less, the increase in manufacturing costs can be suppressed. In this invention, the shape, thickness, material, etc. of the sound-absorbing member 20 are not particularly limited, as long as it is formed to absorb sound propagating within the sound-absorbing member 20.

[0033] The space 30 of the soundproof structure 1 is provided so as to be sandwiched between the reflective body portion 13 of the reflective portion 10 and the sound-absorbing member 20 in a cross-sectional view of the soundproof structure 1 (Figure 2). The space 30 is sealed by being surrounded by the sound-absorbing member 20 and the left and right retaining walls 12, the reflective body portion 13, the front wall portion (not shown), and the rear wall portion (not shown) of the reflective portion 10.

[0034] Here, the vertical dimension between the reflective surface 13a of the reflective body portion 13 and the second surface of the sound-absorbing member 20 in the space portion 30 is defined as the thickness 31 of the space portion 30. Furthermore, the thickness 31 of the space portion 30 can be said to be the shortest distance from the second surface of the sound-absorbing member 20 to the reflective surface 13a of the reflective body portion 13 in each part of the sound-absorbing member 20, and can also be said to be the distance between the reflective surface 13a of the reflective body portion 13 and the sound-absorbing member 20.

[0035] In this case, as described above, in this embodiment 1, the reflective surface 13a of the reflective body portion 13 is formed in a curved shape 16 that is wavy in the left-right direction, and the second surface of the sound-absorbing member 20 is formed in a plane parallel to the left-right direction. Therefore, the space portion 30 formed between the reflective surface 13a of the reflective body portion 13 and the second surface of the sound-absorbing member 20 has a portion in which the thickness 31 of the space portion 30 is uneven in the left-right direction.

[0036] In particular, in this embodiment 1, the thickness 31 of the space 30 is formed to be non-uniform over the entire left-right direction of the space 30 (i.e., over a continuous range from the left retaining wall 12 to the right retaining wall 12). Note that "the part where the thickness 31 of the space 30 is non-uniform" can be rephrased as "the part where the thickness 31 of the space 30 is not continuous and constant, or the part where adjacent parts have different thicknesses."

[0037] In this invention, the space 30 only needs to be formed continuously and uniformly over a range where at least two concave curved surfaces 14 are formed and / or over a range where at least two convex curved surfaces 15 are formed, for example, in the left-right direction. In this embodiment 1, in order to enhance the sound absorption effect of the sound-absorbing member 20, it is preferable that the portion where the thickness 31 of the space 30 is uneven (in other words, the portion where a continuous concave-convex curved shape 16 of the reflective main body 13 is formed) is provided over 50% or more of the space 30 in the left-right direction, more preferably over 70% or more of the space 30, and especially over the entire range (a continuous range from the left retaining wall 12 to the right retaining wall 12).

[0038] In the soundproofing structure 1 of this embodiment 1, the reflective surface 13a of the reflective body portion 13 is formed in an uneven curved shape 16, and the thickness 31 of the space portion 30 is set to be non-uniform throughout the entire left-right direction of the space portion 30. As a result, as will be described later, sound that has passed through the sound-absorbing member 20 can be reflected by the reflective body portion 13 at various angles. Furthermore, the angle of incidence at which the sound reflected by the reflective body portion 13 enters the sound-absorbing member 20, and the distance at which the reflected sound enters the sound-absorbing member 20, can be easily varied.

[0039] Next, we will explain the mechanism by which the soundproofing structure 1 of this embodiment 1 reduces sound (noise) generated from the sound source 9. Sound (sound waves) are waves (elastic waves) that propagate through a medium such as air. Sound waves are longitudinal waves that propagate as compressional waves in gases and liquids, and when represented as transverse waves, they can be shown as sine waves as shown in Figure 4. It is also known that the frequency range that humans can hear (audible range) is approximately 20 Hz to 20,000 Hz. The wavelength λ of a sound wave changes with frequency, and the wavelength λ of low frequencies 41 is longer than the wavelength λ of high frequencies 42.

[0040] In the sound wave shown in Figure 4, the part (position) where the amplitude of the waveform is maximum is where the velocity of the particles in the medium (air molecules) is maximum, and the sound energy is maximum. For example, the sound reflected by the reflective body 13 of the soundproofing structure 1 (reflected sound) has maximum sound energy at a position where the distance from the reflective body 13 is 1 / 4 the length of the wavelength λ of the sound.

[0041] Therefore, as shown in Figure 4, the sound-absorbing member 20 of the soundproof structure 1 is installed so as to cover a position 43 (or a position corresponding to a position greater than or equal to the wavelength λ and 1 / 4 or 3 / 4 of the wavelength λ) that is separated from the reflective body 13 by a length of 1 / 4 (or 3 / 4) of the wavelength λ via the space 30, thereby effectively absorbing the reflected sound 47 reflected by the reflective body 13 within the sound-absorbing member 20, and thus increasing the sound absorption rate of the reflected sound 47. Furthermore, by interposing the space 30, even if the thickness of the sound-absorbing member 20 is reduced to, for example, 100 mm or less as described above, it becomes possible to stably install the sound-absorbing member 20 so as to cover the above-mentioned position.

[0042] Furthermore, the sound-absorbing member 20 of the soundproofing structure 1 can expand the frequency range in which it can absorb reflected sound 47 from the reflective main body 13 as its thickness increases. For this reason, in this embodiment 1, it is preferable that the sound-absorbing member 20 is formed to have a thickness of 5 mm or more, as described above.

[0043] In this embodiment 1 of soundproofing structure 1, the sound generated from the sound source 9 (engine) first enters the sound-absorbing member 20 of the soundproofing structure 1 and propagates within the sound-absorbing member 20. As described above, the sound-absorbing member 20 absorbs a portion of the sound generated from the sound source 9 by consuming a portion of the sound energy. The sound that is not absorbed by the sound-absorbing member 20 passes through the sound-absorbing member 20 and propagates as transmitted sound 46 from the second surface of the sound-absorbing member 20 to the space 30.

[0044] Subsequently, when the transmitted sound 46 strikes the reflective body 13, the reflective body 13 vibrates due to resonance, and the sound energy can be consumed by the internal friction of the vibrating reflective body 13. In this way, a portion of the transmitted sound 46 (especially low-frequency sounds) can be absorbed.

[0045] Furthermore, the reflective body portion 13 can reflect at least a portion of the sound that was not absorbed by the reflective body portion 13 off its reflective surface 13a, allowing it to propagate to the space portion 30 as reflected sound 47. In this embodiment 1, the reflective surface 13a of the reflective body portion 13 is formed into a continuous concave-convex curved surface shape 16 by alternating concave curved surface portions 14 and convex curved surface portions 15 as described above, and the thickness 31 of the space portion 30 is uneven, allowing the distance from the reflective surface 13a of the reflective body portion 13 to the sound-absorbing member 20 to be varied between the left retaining wall portion 12 and the right retaining wall portion 12.

[0046] As a result, in this embodiment 1, the reflected sound 47 reflected by the reflective body 13 is reflected (diffusely reflected) in various directions in a complex manner, and then incident on the sound-absorbing member 20 again via the space 30. Furthermore, because the thickness 31 of the space 30 is non-uniform throughout the left-right direction, the length from when the reflected sound 47 is diffusely reflected in a complex manner by the reflective surface 13a of the reflective body 13 until it is incident on the sound-absorbing member 20 can be varied in various ways depending on the position and direction in which the sound hits the reflective surface 13a, the angle of the reflective surface 13a with respect to the left-right direction, etc. As a result, the frequency band of the reflected sound 47 that can be absorbed by the sound-absorbing member 20 can be further expanded, so that sound absorption in a wide frequency band can be achieved, and the sound absorption rate of the reflected sound 47 by the sound-absorbing member 20 can be further increased.

[0047] As described above, in the soundproofing structure 1 of this embodiment 1, the sound generated from the sound source 9 and the reflected sound 47 reflected by the reflective body 13 can be absorbed by propagating them within a single thin sound-absorbing member 20. Furthermore, when the reflective body 13 reflects sound, it is also possible to absorb sound by the reflective body 13 by utilizing the resonance of the reflective body 13. Moreover, in the soundproofing structure 1 of this embodiment 1, the reflective surface 13a of the reflective body 13 is formed in an uneven curved shape 16, and the space 30 is formed with an uneven thickness, so the frequency range of the reflected sound 47 that can be absorbed by the sound-absorbing member 20 can be expanded. Therefore, the soundproofing structure 1 of this embodiment 1 has high sound absorption performance because it can effectively absorb and reduce sound generated from the sound source 9 across a wide frequency range.

[0048] Furthermore, the sound-absorbing member 20 provided in the soundproofing structure 1 of this embodiment 1 is formed from a single member made of a porous material and is formed in a thin, plate-like shape. In addition, by providing a plurality of concave curved surfaces 14 and a plurality of convex curved surfaces 15 on the reflective body 13, the thickness of the reflective body 13 can be reduced as described above. This makes it possible to reduce the manufacturing cost of the soundproofing structure 1 and to make the soundproofing structure 1 lighter and thinner. [Examples]

[0049] Figure 5 is a schematic perspective view showing the soundproofing structure 2 according to this embodiment 2. Although the shape of the reflective body portion 83 and the space portion 30a of this embodiment 2 differs from that of the soundproofing structure 1 of embodiment 1 described above, the parts other than the reflective body portion 83 and the space portion 30a are formed substantially the same as those of the soundproofing structure 1 of embodiment 1. Therefore, in this embodiment 2, in order to avoid redundancy, the explanation will mainly focus on the reflective part and the space portion of the soundproofing structure, and the same reference numerals will be used to represent substantially the same members and parts as those of the soundproofing structure 1 of embodiment 1, and their detailed explanations will be omitted.

[0050] The soundproofing structure 2 of this embodiment 2 includes a reflective section 80 that reflects sound, and a sound-absorbing member 20 that is placed between the reflective section 80 and the sound source. A space 30a is provided between the reflective section 80 and the sound-absorbing member 20.

[0051] The reflective portion 80 of this embodiment 2 includes a pair of left and right mounting portions 81, a pair of left and right retaining wall portions 82, a reflective body portion 83 connected to the left and right retaining wall portions 82, and a front wall portion (not shown) and a rear wall portion (not shown) provided at the front and rear ends of the reflective portion 80. The mounting portions 81, retaining wall portions 82, front wall portion, and rear wall portion of this embodiment 2 are formed substantially the same as those of the reflective portion 10 of embodiment 1.

[0052] The reflective body portion 83 has a thin plate-shaped body base portion 84 and a plurality of concave curved surfaces 85 that are conically recessed in the body base portion 84 in a direction away from the sound-absorbing member 20. The plurality of concave curved surfaces 85 are integrally formed with the body base portion 84 and are regularly arranged in the front-to-back and left-to-right directions. The plurality of concave curved surfaces 85 are formed to be the same shape and size as each other.

[0053] The reflective body portion 83 has a reflective surface 83a positioned opposite the sound-absorbing member 20, and an outer surface 83b positioned on the opposite side of the reflective surface 83a. The reflective surface 83a of the reflective body portion 83 has a non-flat, uneven shape formed by a plurality of concave curved surfaces 85.

[0054] In this embodiment 2, the space 30a is provided so as to be sandwiched between the reflective body portion 83 of the reflective portion 80 and the sound-absorbing member 20 in a cross-sectional view of the soundproofing structure 2, and is sealed by the sound-absorbing member 20 and the reflective portion 80. This space 30a is formed uniformly and continuously over a range in which a plurality of concave curved surfaces 85 are formed, for example in the left-right direction and the front-back direction. In this space 30a, there are portions in which the thickness of the space 30a is uneven due to the plurality of concave curved surfaces 85 provided on the reflective body portion 83.

[0055] In this soundproofing structure 2 of this embodiment 2, by directing the transmitted sound that has passed through the sound-absorbing member 20 to the reflective main body 83, a portion of the transmitted sound can be absorbed, and at least a portion of the sound that was not absorbed can be reflected back into the sound-absorbing member 20.

[0056] In particular, in this embodiment 2, since the reflective body portion 83 is provided with a plurality of conical concave curved surfaces 85, the transmitted sound that hits the reflective body portion 83 can be reflected (diffusely reflected) in a more complex manner than, for example, the soundproofing structure 1 of embodiment 1 described above. As a result, the frequency range of reflected sound that can be absorbed by the sound-absorbing member 20 can be expanded, and sound absorption over a wide frequency range can be performed stably.

[0057] Therefore, the soundproofing structure 2 of this embodiment 2 exhibits excellent sound absorption effects and can reduce the sound (noise) generated from the sound source (engine). Furthermore, in this embodiment 2, the sound-absorbing member 20 is formed from a single member made of a porous material and is formed in a thin, plate-like shape, which reduces the manufacturing cost of the soundproofing structure 2, makes the soundproofing structure 2 lighter, and makes the soundproofing structure 2 thinner.

[0058] In this invention, the shape and size of the plurality of concave curved surfaces 85 provided on the reflective main body portion 83 of the soundproofing structure 2 are not particularly limited. In addition, in this invention, the reflective main body portion 83 of the soundproofing structure 2 may be provided with a plurality of convex curved surfaces that curve to protrude in a conical shape in the direction approaching the sound-absorbing member 20, instead of the concave curved surfaces 85.

[0059] In this embodiment 2, the multiple concave curved surfaces 85 are formed with the same shape and size as each other. However, in the present invention, the multiple concave curved surfaces 85 may be formed with two or more different shapes and / or two or more different sizes. Furthermore, in this embodiment 2, the multiple concave curved surfaces 85 are arranged regularly in the front-to-back and left-to-right directions. However, in the present invention, the multiple concave curved surfaces 85 may be arranged randomly.

[0060] For example, by having multiple concave curved surfaces 85 have two or more different shapes and / or two or more different sizes, and by having multiple concave curved surfaces 85 arranged randomly, it becomes possible to reflect (diffusely reflect) the transmitted sound that hits the reflective body 83 in a more complex manner.

[0061] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible within the scope of having a configuration substantially identical to that described in the claims of the present invention and achieving similar effects.

[0062] For example, the soundproofing structure 1 of Example 1 is integrally provided with the underbody cover of the automobile, as described above. However, in the present invention, the soundproofing structure may be manufactured separately from the underbody cover, and then the manufactured soundproofing structure may be attached to the underbody cover afterward.

[0063] Examples 1 and 2 describe the case where the soundproofing structure is applied to the underbody of an automobile. However, the soundproofing structure of the present invention can also be applied to automobile exterior parts other than underbody covers, such as fender protectors and engine head covers, as well as other automobile parts. [Explanation of Symbols]

[0064] 1,2 Soundproofing structure (sound-absorbing structure) 9 Sound Sources 10 Reflector 11 Mounting part 12 Retaining wall 13 Reflector body 13a Reflective surface 13b External surface 14 Concave curved part 15 Convex curved part 16 Uneven curved shape 20 Sound-absorbing material 30,30a Space part 31 Thickness of the space 41 Low frequency 42 High frequency 43. Position 1 / 4 of the sound wavelength from the main reflective surface. 46 Transmitted sound 47 Reflected sound 80 Reflector 81 Mounting part 82 Retaining wall 83 Reflector body 83a Reflective surface 83b External surface 84 Main base 85 Concave curved surface part λ wavelength

Claims

1. A soundproofing structure that reduces the sound generated from a sound source, The system comprises a reflective section that reflects the aforementioned sound, and a sound-absorbing member disposed between the reflective section and the sound source. A space is provided between the reflective portion and the sound-absorbing member. The reflective portion has a plurality of concave curved surfaces that curve concavely away from the sound-absorbing member, and / or a plurality of convex curved surfaces that curve convexly towards the sound-absorbing member. The space is formed continuously and uniformly across at least two concave curved surfaces and / or at least two convex curved surfaces. A soundproofing structure characterized by the following features.

2. The reflective portion includes a mounting portion to which the sound-absorbing member is attached, a pair of retaining wall portions extending from the mounting portion in a direction away from the sound-absorbing member, and a reflective body portion connected to the pair of retaining wall portions and positioned away from the sound-absorbing member. The reflective body portion has at least two parts that are spaced at different distances from the sound-absorbing member. The space is formed continuously from one of the retaining walls to the other. The soundproofing structure according to claim 1.

3. At least a portion of the reflective surface of the reflective part facing the sound-absorbing member has a curved shape in which the concave curved surface and the convex curved surface are formed alternately and continuously. The sound-absorbing member has a first surface disposed on the sound source side and a second surface disposed on the reflecting part side. At least a portion of the second surface of the sound-absorbing member is formed in a flat plane. The soundproofing structure according to claim 1.

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