sound absorbing device

Abstract

To provide a sound absorption device that absorbs a plurality of noises of different frequencies from each other, as a whole.SOLUTION: A sound absorbing device 1 comprises a sound absorbing portion 10 with a multilayer structure and a frame 20 that supports an edge of the sound absorbing portion. The sound absorbing portion comprises a multilayer structure including a first sound-absorbing layer 11 that absorbs a first noise and a second sound-absorbing layer 12 that absorbs a second noise different from the first noise. The first noise and the second noise are sounds with different frequency bands from each other.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a sound absorbing device. [Background technology]

[0002] Conventionally, sound-absorbing devices that absorb noise generated by vehicles such as automobiles have been proposed. For example, Patent Document 1 discloses a sound-absorbing device applied to automobiles as a vehicle exterior material such as a fender protector or undercover. The sound-absorbing device (vehicle exterior material) described in Patent Document 1 includes a sound-absorbing layer made of a sound-absorbing material such as a nonwoven fabric, and the sound-absorbing layer is designed to absorb noise of a predetermined frequency. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-13538 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there are various types of noise that are generated by a vehicle, such as road noise caused by the vehicle's tires sliding against the road surface, and vehicle engine noise, and these noises have different frequencies. For this reason, the conventional sound-absorbing devices described above can only absorb one of the multiple noises with different frequencies, such as road noise and engine noise, and as a result, the noise that is not absorbed remains as exterior noise and interior noise.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide a sound absorbing device that can absorb a plurality of noises having different frequencies. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the sound absorbing device of the present invention is characterized by comprising a multi-layered sound absorbing section including a first sound absorbing layer that absorbs a first noise and a second sound absorbing layer that absorbs a second noise that is sound in a different frequency band from the first noise, and a frame that supports the edges of the sound absorbing section.

[0007] Furthermore, the sound absorbing device of the present invention is a sound absorbing device comprising a sound absorbing portion and a frame body that supports the edge of the sound absorbing portion, wherein the sound absorbing portion is constituted by a single sheet of material of a predetermined shape or a part of a plurality of divided bodies obtained by dividing the material sheet, and the sound absorbing portion constituted by the single sheet of material has the same predetermined shape as the single sheet of material, and the aggregate of the sound absorbing portions constituted by the divided bodies allocated from the single sheet of material across a plurality of the sound absorbing devices has the predetermined shape of the sheet of material before it is divided.

[0008] Furthermore, the sound absorbing device according to the present invention is characterized in that, in the above invention, the sound absorbing section is constituted by a single sheet of material of a predetermined shape or a part of a plurality of divided bodies obtained by dividing the sheet of material, and the sound absorbing section constituted by the single sheet of material has the same predetermined shape as the single sheet of material, and the aggregate of the sound absorbing sections constituted by the divided bodies allocated from the single sheet of material across a plurality of the sound absorbing devices has the predetermined shape of the sheet of material before it is divided.

[0009] Furthermore, the sound absorbing device according to the present invention is characterized in that, in the above invention, the sound absorbing section has a multi-layer structure including a first sound absorbing layer that absorbs a first noise, and a second sound absorbing layer that absorbs a second noise that is a sound in a frequency band different from the first noise.

[0010] Furthermore, in the sound absorbing device according to the present invention, in the above invention, the frame body includes an overlapping portion that overlaps an edge of the sound absorbing portion in a thickness direction of the sound absorbing portion.

[0011] In addition, the sound absorbing device according to the present invention is characterized in that, in the above invention, the overlapping portion of the frame body has an inner surface with no corners and a plurality of through holes spaced apart from each other are formed.

[0012] Furthermore, in the sound absorbing device according to the present invention, in the above invention, the edge portion of the sound absorbing portion is a compressed portion formed by compressing the sound absorbing portion in its thickness direction. [Effects of the Invention]

[0013] The sound absorbing device according to the present invention has the advantage of being able to absorb a plurality of noises having different frequencies. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram showing an example of the configuration of a sound absorbing device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing an example of the configuration of the opposite side of the sound absorbing device shown in FIG. [Figure 3] FIG. 3 is a schematic diagram showing an example of the configuration of the sound absorbing section of the sound absorbing device according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a schematic diagram showing an example of the three-dimensional structure of the sound absorbing section according to the first embodiment of the present invention. [Figure 5] FIG. 5 is a schematic diagram showing an example of the cross-sectional structure of the sound absorbing section according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram showing an example of an overlapping structure between the edge of the sound absorbing part and the frame body in the first embodiment of the present invention. [Figure 7] FIG. 7 is a cross-sectional view showing a structural example of a molding die for integrally molding the sound absorbing section and the frame body according to the first embodiment of the present invention. [Figure 8] FIG. 8 is a schematic diagram showing an example of a state in which resin flows between a plurality of pressing pins provided in a molding die. [Figure 9] FIG. 9 is a schematic diagram for explaining an example of the operation of the sound absorbing device according to the first embodiment of the present invention. [Figure 10] FIG. 10 is a schematic diagram showing an example of the configuration of a sound absorbing device according to a second embodiment of the present invention. [Figure 11] FIG. 11 is a schematic diagram showing an example of the configuration of the sound absorbing section of the sound absorbing device according to the second embodiment of the present invention. [Figure 12] FIG. 12 is a schematic diagram showing an example of the relationship between the sound absorbing portion and the material sheet of the sound absorbing device according to the second embodiment of the present invention. [Figure 13] FIG. 13 is a schematic diagram showing a modified example of the relationship between the sound absorbing portion and the material sheet of the sound absorbing device according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Preferred embodiments of the sound-absorbing device according to the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention is not limited to these embodiments. It should be noted that the drawings are schematic, and the dimensional relationships and ratios of each element may differ from those in reality. The drawings may also include parts with different dimensional relationships and ratios. In addition, the same components are designated by the same reference numerals in each drawing.

[0016] (Embodiment 1) First, the configuration of a sound absorbing device according to a first embodiment of the present invention will be described. FIG. 1 is a schematic diagram showing an example of the configuration of a sound absorbing device according to a first embodiment of the present invention. FIG. 1 shows a view (side view) of this sound absorbing device 1 as seen from one side in the width direction D2. FIG. 2 is a schematic diagram showing an example of the configuration of the opposite side of the sound absorbing device shown in FIG. 1. FIG. 2 shows a side view of the sound absorbing device 1 shown in FIG. 1 as seen from the other side in the width direction D2 (the opposite side to FIG. 1). The sound absorbing device 1 according to the first embodiment of the present invention is applied to automobiles, for example, as an apron seal, which is an example of an exterior material for vehicles, and includes a sound absorbing section 10 that absorbs noise generated by the vehicle, and a frame body 20 that supports the sound absorbing section 10, as shown in FIGS. 1 and 2.

[0017] For ease of explanation, the present specification defines a front-rear direction D1, a width direction D2, and a vertical direction D3. The front-rear direction D1 is the front-rear direction of a vehicle (automobile) to which the sound absorbing device 1 is applied. The width direction D2 is the width direction of the vehicle, and the vertical direction D3 is the vertical direction of the vehicle. These three directions, front-rear direction D1, width direction D2, and vertical direction D3, are perpendicular to one another, and this also applies to the sound absorbing device 1 when attached to a vehicle. Furthermore, in this specification, a vehicle refers to a vehicle to which the sound absorbing device according to the present invention (the sound absorbing device 1 in this embodiment 1) is applied, unless otherwise specified.

[0018] 1 and 2, the sound absorbing unit 10 is a multilayer structure including a first sound absorbing layer 11 that absorbs a first noise and a second sound absorbing layer 12 that absorbs a second noise, which is sound in a different frequency band from the first noise, and is provided on the frame 20 with the surfaces of the first sound absorbing layer 11 and the second sound absorbing layer 12 exposed. For example, the sound absorbing unit 10 has the surface of the first sound absorbing layer 11 exposed on one side in the width direction D2 as shown in FIG. 1, and the surface of the second sound absorbing layer 12 exposed on the other side in the width direction D2 as shown in FIG. 2. The sound absorbing unit 10 absorbs the first noise from one side in the width direction D2 with the exposed first sound absorbing layer 11, and absorbs the second noise from the other side in the width direction D2 with the exposed second sound absorbing layer 12 on the side opposite to the first sound absorbing layer 11.

[0019] Furthermore, the edge of sound absorbing unit 10 is a region of the entire area of ​​sound absorbing unit 10 that is outside the regions that contribute to the sound absorbing performance of first sound absorbing layer 11 and second sound absorbing layer 12. As shown in Figures 1 and 2, at least a portion of the edge of sound absorbing unit 10 is joined to frame body 20 by integral molding with frame body 20 or the like. From the perspective of increasing the bonding strength between sound absorbing unit 10 and frame body 20, it is preferable that the edge of sound absorbing unit 10 be joined to frame body 20 continuously over the entire outer periphery of sound absorbing unit 10, but it may also be joined to frame body 20 discontinuously (intermittently) along the outer periphery of sound absorbing unit 10. For example, the bonding region between the edge of sound absorbing unit 10 and frame body 20 is set depending on the bonding strength between sound absorbing unit 10 and frame body 20 required for sound absorbing device 1, etc. 1 and 2, the edge of the sound absorbing part 10 is preferably a compressed part 15 formed by compressing the multi-layered sound absorbing part 10 in the thickness direction. The multi-layered structure of the sound absorbing part 10 will be described in detail later.

[0020] The first noise and the second noise absorbed by the sound absorbing section 10 described above are both noises generated by a vehicle. However, the frequency bands of the first noise and the second noise are different from each other. In the present invention, "different frequency bands" means, for example, that the maximum peak frequencies included in the frequency bands are different from each other, or that the upper and lower limit frequencies of the frequency bands are different from each other. The frequency bands of the first noise and the second noise may partially overlap, or may not overlap at all. A specific example of the first noise is road noise generated by the sliding contact between vehicle tires and the road surface. A specific example of the second noise is noise that is higher than the first noise, such as vehicle engine noise. In this specific example, the frequency band of the second noise is higher than the frequency band of the first noise. Note that the relative height of the frequency bands can be determined, for example, by the relative height of the maximum peak frequencies of the frequency bands.

[0021] The frame body 20 supports the edge of the sound absorbing unit 10. More specifically, as shown in FIGS. 1 and 2, the frame body 20 is formed by resin injection molding or the like so as to have a frame structure that corresponds to the three-dimensional structure of a vehicle exterior material (an apron seal for an automobile in this first embodiment) to which the sound absorbing device 1 is applied and the outer shape of the sound absorbing unit 10. Although not specifically shown, the frame structure of the frame body 20 is configured to have a frame edge portion that corresponds to the edge portion of the sound absorbing unit 10 described above (compression portion 15 in FIGS. 1 and 2) and an opening that penetrates the inner area surrounded by the frame edge portion. As shown in FIGS. 1 and 2, the edge of the sound absorbing unit 10 is joined to the frame edge portion of the frame body 20 in a manner that exposes the surfaces of the first sound absorbing layer 11 and the second sound absorbing layer 12 of the sound absorbing unit 10 through the opening. The frame 20 supports the edge of the sound absorbing section 10 by joining the edge of the sound absorbing section 10 to the edge of the frame so that the sound absorbing section 10 is stretched within the frame structure of the frame 20 .

[0022] 1, the frame body 20 has an overlapping portion 21 that overlaps the edge of the sound absorbing section 10 in the thickness direction of the sound absorbing section 10. For example, the overlapping portion 21 is formed by the frame edge of the frame body 20. Furthermore, as shown in FIG. 1, a plurality of through holes 22 are formed in the overlapping portion 21 of the frame body 20. The configurations of the overlapping portion 21 and the through holes 22 of the frame body 20 will be described in detail later.

[0023] 1 and 2, the upper portion 23 of the frame 20 is provided with a plurality of mounting portions 24. These mounting portions 24 are components for mounting the sound absorbing device 1 to the vehicle body, for example, as an apron seal, using fastening members such as bolts. The frame 20 also has an extension portion 25 that extends from its lower portion in the front-to-rear direction D1. The extension portion 25 is a component for mounting the sound absorbing device 1 to a vehicle body member, such as a side member, using fastening members.

[0024] (Sound absorbing part configuration) Next, the configuration of the sound absorbing section 10 in embodiment 1 of the present invention will be described. Fig. 3 is a schematic diagram showing one configuration example of the sound absorbing section of the sound absorbing device according to embodiment 1 of the present invention. Fig. 3 shows a view of this sound absorbing section 10 from one side in the width direction D2 (the same viewpoint as the sound absorbing device 1 shown in Fig. 1). Fig. 4 is a schematic diagram showing an example of the three-dimensional structure of the sound absorbing section in embodiment 1 of the present invention. Fig. 4 shows a view of this sound absorbing section 10 from diagonally above and behind. Fig. 5 is a schematic diagram showing an example of the cross-sectional structure of the sound absorbing section in embodiment 1 of the present invention. Fig. 5 shows a schematic diagram of the cross section of line AA of the sound absorbing device 1 shown in Fig. 1.

[0025] The sound absorbing section 10 is made of a sound-absorbing material sheet of a predetermined shape, and is formed into a three-dimensional structure including mountain folds, valley folds, or other folds, as shown in Figures 3 and 4, for example, by molding using a mold. The three-dimensional structure of this sound absorbing section 10 corresponds to the three-dimensional structure of the sound absorbing device 1, which is used, for example, as an apron seal. Examples of the material sheet that makes up this sound absorbing section 10 include sheets of porous material with sound absorbing properties, such as nonwoven fabrics and woven fiber fabrics. From the standpoints of sound absorption performance and cost, nonwoven fabric sheets are preferred as the material sheet. Examples of the material fiber for the material sheet include glass fiber and polyethylene terephthalate (PET) fiber.

[0026] Furthermore, from the viewpoint of improving material yield, it is preferable that the single sound absorbing section 10 is formed from a single sheet of material having a predetermined shape. In other words, it is preferable to form the sound absorbing section 10 having the three-dimensional structure by molding (shaping) a single sheet of material that has not been subjected to trimming such as cutting out of the material sheet. The sound absorbing section 10 thus formed from the single sheet of material has the same predetermined shape as the single sheet of material. For example, the pre-molded shape of the sound absorbing section 10 shown in FIG. 3 has the same predetermined shape (here, a rectangular shape) as the single sheet of material when viewed from a plane in the thickness direction. Note that examples of the predetermined shape of the single sheet of material include various shapes such as a rectangle, a trapezoid, a parallelogram, a rhombus, and a polygon.

[0027] Prior patent documents, such as JP 2020-82707 A, disclose conventional sound-absorbing devices, such as vehicle exterior materials (composite vehicle components) including undercovers that are provided with sound-absorbing properties. In such conventional sound-absorbing devices, a porous sheet material, such as a sound-absorbing nonwoven fabric, is stretched within a resin frame of the vehicle exterior material, thereby imparting sound-absorbing properties to the vehicle exterior material. However, in conventional sound-absorbing devices, in order to form a sound-absorbing layer by providing the porous sheet material within the resin frame of the vehicle exterior material, the porous sheet material must be trimmed according to the internal shape and dimensions of the resin frame, thereby removing portions of the porous sheet material, such as its four corners. The portions removed from the porous sheet material result in material loss when constructing the sound-absorbing layer from the porous sheet material, resulting in reduced material yield when constructing the sound-absorbing layer. Furthermore, if the portions removed from the porous sheet material are discarded as material loss, they are disposed of by incineration or other disposal processes, which may be harmful to the environment.

[0028] In contrast, in the sound absorbing device 1 according to the first embodiment of the present invention, a single sound absorbing section 10 is formed from a single sheet of material of a predetermined shape, and the single sound absorbing section 10 has the same predetermined shape as the single sheet of material. As a result, there is no need to trim the material sheet when forming the sound absorbing section 10 from it, and therefore it is possible to reduce material loss when forming the sound absorbing section 10, thereby improving the material yield when forming the sound absorbing section 10 and suppressing the adverse impact on the environment caused by the disposal of the material sheet.

[0029] 3 and 4, the sound absorbing part 10 has a multi-layer structure including a first sound absorbing layer 11 and a second sound absorbing layer 12 which have different sound absorbing performances. In detail, as shown in Fig. 5, the multi-layer structure of the sound absorbing part 10 is made up of the above-mentioned first sound absorbing layer 11 and second sound absorbing layer 12, and an intermediate layer 13 interposed between these two layers.

[0030] The first sound-absorbing layer 11 is made of a sheet of sound-absorbing material such as nonwoven fabric, and as shown in FIG. 5, is provided on the opposite side of the sound-absorbing section 10 in the thickness direction (width direction D2 in FIG. 5) from the second sound-absorbing layer 12. That is, the first sound-absorbing layer 11 is provided on one end surface of the intermediate layer 13 so that the first sound-absorbing surface 11a is exposed on one side in the width direction D2 (negative side in FIG. 5). The first sound-absorbing surface 11a is the exposed surface of the first sound-absorbing layer 11 in the multilayer structure of the sound-absorbing section 10, and more specifically, as shown in FIG. 5, it is the surface of both end surfaces of the first sound-absorbing layer 11 in the thickness direction that is opposite the intermediate layer 13. The first sound-absorbing layer 11 receives first noise, such as road noise, from the first sound-absorbing surface 11a and vibrates to absorb the first noise.

[0031] The sound absorbing performance of the first sound absorbing layer 11 can be set to be suitable for absorbing the first noise by adjusting the basis weight of the first sound absorbing layer 11. The basis weight of the first sound absorbing layer 11 is determined by the mass per unit area (g / m 2 ) and can be adjusted by controlling the content and type of the constituent material of the first sound absorbing layer 11. For example, if the constituent material of the first sound absorbing layer 11 is a nonwoven fabric, the sound absorbing performance of the first sound absorbing layer 11 can be set as described above by controlling the content and type of fibers that make up the nonwoven fabric and the content and type of resin that binds the fibers together in the nonwoven fabric.

[0032] Furthermore, when the sound absorbing performance of the first sound absorbing layer 11 is set to be suitable for absorbing noise in a lower frequency band, the basis weight of the first sound absorbing layer 11 is adjusted to be greater. When the sound absorbing performance of the first sound absorbing layer 11 is set to be suitable for absorbing noise in a higher frequency band, the basis weight of the first sound absorbing layer 11 is adjusted to be smaller. For example, when the first noise to be absorbed by the first sound absorbing layer 11 is road noise, the road noise is noise in a lower frequency band than the second noise, such as engine noise, to be absorbed by the second sound absorbing layer 12, and so the basis weight of the first sound absorbing layer 11 is adjusted to be greater than that of the second sound absorbing layer 12.

[0033] The second sound absorbing layer 12 is made of a sheet of sound-absorbing material such as nonwoven fabric, and as shown in Fig. 5, is provided on the opposite side of the first sound absorbing layer 11 in the thickness direction of the sound absorbing unit 10. That is, the second sound absorbing layer 12 is provided on the other end surface of the intermediate layer 13 so that the second sound absorbing surface 12a is exposed on the other side in the width direction D2 (the forward side in Fig. 5). The second sound absorbing surface 12a is the exposed surface of the second sound absorbing layer 12 in the multilayer structure of the sound absorbing unit 10, and more specifically, as shown in Fig. 5, it is the surface of both end surfaces of the second sound absorbing layer 12 in the thickness direction that is opposite to the intermediate layer 13. The second sound absorbing layer 12 receives second noise, such as engine noise, from the second sound absorbing surface 12a and vibrates, thereby absorbing the second noise.

[0034] The sound absorbing performance of the second sound absorbing layer 12 can be set to a level suitable for absorbing the second noise by adjusting the basis weight of the second sound absorbing layer 12. The basis weight of the second sound absorbing layer 12 is the mass per unit area (g / m 2 ), the adjustment of the basis weight of the second sound absorbing layer 12 and the setting of the sound absorption performance can be performed in the same manner as in the above-mentioned first sound absorbing layer 11. For example, if the second noise to be absorbed by the second sound absorbing layer 12 is engine noise, the engine noise is in a higher frequency band than the first noise, such as road noise, to be absorbed by the first sound absorbing layer 11, and so the basis weight of the second sound absorbing layer 12 is adjusted to be less than that of the first sound absorbing layer 11.

[0035] The intermediate layer 13 supports the first sound absorbing layer 11 and the second sound absorbing layer 12 so that they can vibrate. More specifically, the intermediate layer 13 is made of the same material sheet as the first sound absorbing layer 11 and the second sound absorbing layer 12, and is interposed between the first sound absorbing layer 11 and the second sound absorbing layer 12, as shown in Fig. 5. The first sound absorbing layer 11, the second sound absorbing layer 12, and the intermediate layer 13 form a multilayer structure in which the first sound absorbing layer 11 and the second sound absorbing layer 12 are stacked in the thickness direction of the sound absorbing part 10, with the intermediate layer 13 sandwiched between them. The intermediate layer 13, together with the first sound absorbing layer 11 and the second sound absorbing layer 12, is formed into the three-dimensional structure of the sound absorbing part 10.

[0036] As shown in FIG. 5 , one of the thickness-wise end faces of the intermediate layer 13 (the end face on the negative side in the width direction D2 in FIG. 5 ) is surface-bonded to the back surface of the first sound-absorbing layer 11. The back surface of the first sound-absorbing layer 11 is the surface of the thickness-wise end faces of the first sound-absorbing layer 11 opposite the first sound-absorbing surface 11a. The intermediate layer 13 supports the first sound-absorbing layer 11 surface-bonded in this manner, while allowing the first sound-absorbing layer 11 to vibrate during sound absorption. In this way, the intermediate layer 13 supports the first sound-absorbing layer 11 so that it can vibrate. Furthermore, the intermediate layer 13 vibrates together with the first sound-absorbing layer 11 when absorbing the first noise, thereby assisting the sound absorption of the first sound-absorbing layer 11. At this time, the intermediate layer 13 further absorbs and attenuates the first noise that has been attenuated by the sound-absorbing effect of the first sound-absorbing layer 11, for example. Alternatively, the intermediate layer 13 absorbs and attenuates noise that the first sound absorbing layer 11 was not able to absorb.

[0037] As shown in FIG. 5 , the other of the two thickness-wise end faces of the intermediate layer 13 (the end face on the positive side in the width direction D2 in FIG. 5 ) is surface-bonded to the back surface of the second sound-absorbing layer 12. The back surface of the second sound-absorbing layer 12 is the surface of the two thickness-wise end faces of the second sound-absorbing layer 12 opposite the second sound-absorbing surface 12a. The intermediate layer 13 supports the second sound-absorbing layer 12 to which it is surface-bonded, while allowing the second sound-absorbing layer 12 to vibrate during sound absorption. In this way, the intermediate layer 13 supports the second sound-absorbing layer 12 so that it can vibrate. Furthermore, the intermediate layer 13 vibrates together with the second sound-absorbing layer 12 when absorbing the second noise, thereby assisting the sound absorption of the second sound-absorbing layer 12. At this time, the intermediate layer 13 further absorbs and attenuates the second noise that has already been attenuated by the sound-absorbing effect of the second sound-absorbing layer 12, for example. Alternatively, the intermediate layer 13 absorbs and attenuates noise that the second sound absorbing layer 12 has not been able to absorb.

[0038] The thickness of the intermediate layer 13 as described above is set based on the sound absorption performance of each of the first sound absorbing layer 11 and the second sound absorbing layer 12 required for the sound absorbing section 10, the cost required for the intermediate layer 13, and the allowable mass of the intermediate layer 13.

[0039] Specifically, to improve the sound absorption performance of the first sound absorbing layer 11 and the second sound absorbing layer 12 as required, it is necessary to increase the thickness of the intermediate layer 13 so that the end faces of the intermediate layer 13, which are surface-bonded to the first sound absorbing layer 11 and the second sound absorbing layer 12, respectively, can vibrate more easily. In order to increase the thickness of the intermediate layer 13, it is necessary to increase the basis weight of the intermediate layer 13. The basis weight of the intermediate layer 13 can be adjusted using the same method as for the first sound absorbing layer 11 and the second sound absorbing layer 12 described above. However, increasing the basis weight of the intermediate layer 13 increases the fiber content of the material that makes up the intermediate layer 13, which results in increased cost and mass of the intermediate layer 13. In other words, improving the sound absorption performance of the first sound absorbing layer 11 and the second sound absorbing layer 12 increases the cost and mass of the intermediate layer 13, which is a trade-off with reducing the cost and mass of the intermediate layer 13. Therefore, the thickness of the intermediate layer 13 is set taking into account the degree of increase in sound absorption performance required for each of the first sound-absorbing layer 11 and the second sound-absorbing layer 12, as well as the degree of increase in cost and mass that is acceptable for the intermediate layer 13.

[0040] 3 and 4, sound absorbing unit 10 includes compressed portions 15 supported by frame 20 (see FIGS. 1 and 2). Compressed portions 15 are edge portions of sound absorbing unit 10, and are formed by compressing multi-layered sound absorbing unit 10 in the thickness direction. For example, as shown in FIG. 3, compressed portions 15 are preferably formed continuously over the entire outer periphery of sound absorbing unit 10, but may also be formed discontinuously (intermittently) along the outer periphery of sound absorbing unit 10.

[0041] More specifically, as shown in FIG. 5 , the compressed section 15 is formed by compressing the first sound absorbing layer 11, the second sound absorbing layer 12, and the intermediate layer 13 at the edge of the sound absorbing section 10 in their thickness direction. In the first sound absorbing layer 11, the second sound absorbing layer 12, and the intermediate layer 13 in the compressed section 15, the spacing between the fibers in each of these layers is narrower than in the uncompressed layers. In addition, the density of each layer in the compressed section 15 is greater than the density of the uncompressed layers. Therefore, the compressed section 15 is less susceptible to the inflow of fluids such as resin from its edge 14 (i.e., the outer peripheral edge of the edge of the sound absorbing section 10), and is more rigid than the uncompressed layers. The compressed section 15, which has such high rigidity, can suppress unintended bending or sagging of the sound absorbing section 10.

[0042] The "uncompressed layers" mentioned above refer to the first sound absorbing layer 11, second sound absorbing layer 12, and intermediate layer 13 of the inner multilayer structure of sound absorbing section 10 that are surrounded by compressed section 15. These inner first sound absorbing layer 11, second sound absorbing layer 12, and intermediate layer 13 contribute to the sound absorbing performance of sound absorbing section 10. On the other hand, compressed section 15 has first sound absorbing layer 11, second sound absorbing layer 12, etc. as described above, but does not absorb the first noise or second noise that is the target for sound absorption. In other words, in the present invention, first sound absorbing layer 11, second sound absorbing layer 12, and intermediate layer 13 refer to the inner layers surrounded by compressed section 15, unless otherwise specified.

[0043] (Overlapping structure of sound absorbing part and frame) Next, the overlapping structure between the sound absorbing section 10 and the frame 20 in the first embodiment of the present invention will be described. As shown in FIG. 1 above, the frame 20 has an overlapping section 21 that overlaps with the edge of the sound absorbing section 10. FIG. 6 is a schematic diagram showing an example of the overlapping structure between the edge of the sound absorbing section and the frame in the first embodiment of the present invention. FIG. 6 shows an enlarged view of the area surrounded by the dashed line in the sound absorbing device 1 shown in FIG. 1. An example of the cross-sectional structure of this overlapping section 21 is shown in FIG. 5 above.

[0044] 5 and 6 , the overlapping portion 21 is a region of the frame 20 that overlaps in the thickness direction with the compressed portion 15 that forms the edge of the sound absorbing portion 10, and is formed along the outer periphery of the sound absorbing portion 10. From the viewpoint of increasing the bonding strength between the sound absorbing portion 10 and the frame 20, the overlapping portion 21 is preferably bonded to the compressed portion 15 of the sound absorbing portion 10 over the entire outer periphery of the sound absorbing portion 10 and overlaps with the compressed portion 15. In this case, the overlapping portion 21 may overlap one end face of the compressed portion 15 in the thickness direction, as shown in FIG. 5 , or may overlap both end faces of the compressed portion 15 in the thickness direction, although this is not specifically shown. Note that the overlapping portion 21 may overlap the compressed portion 15 intermittently along the outer periphery of the sound absorbing portion 10, as long as suitable bonding strength between the sound absorbing portion 10 and the frame 20 is ensured. For example, the overlap width between the compressed portion 15 of the sound absorbing portion 10 and the overlapping portion 21 of the frame body 20 is the distance between the outer peripheral end of the sound absorbing portion 10 (edge ​​end 14 shown in Figure 5) and the inner peripheral end of the overlapping portion 21, and is preferably 10 mm or more and 20 mm or less.

[0045] The sound absorbing section 10 is made of a sound-absorbing material such as a nonwoven fabric, and therefore has many fine holes on its surface. In contrast, the frame 20 is formed by injection molding of resin or the like, and therefore has a smoother, more attractive surface with fewer irregularities than the sound absorbing section 10. Therefore, from the perspective of improving the appearance of the sound absorbing device 1, it is preferable that the overlapping section 21 overlaps the compression section 15 so as to cover the entire outer periphery of the sound absorbing section 10, regardless of whether the overlapping section 21 is joined to the compression section 15. It is also preferable that the overlapping section 21 overlaps the compression section 15 so as to cover the edge of the end face of the sound absorbing section 10 in the thickness direction that is exposed to the outside of the vehicle in which the sound absorbing device 1 is installed. For example, when the sound absorbing device 1 is attached to a vehicle in such a manner that the first sound absorbing layer 11 of the sound absorbing section 10 is exposed to the outside of the vehicle, it is preferable that the overlapping section 21 overlaps with the compression section 15 from the side of the first sound absorbing layer 11, as shown in Figures 5 and 6.

[0046] 6, a plurality of through holes 22 are formed in the overlapping portion 21 of the frame body 20. Each of the plurality of through holes 22 has an inner surface with a cornerless shape (circular in FIG. 6), and is spaced apart from one another. Examples of cornerless shapes include a circle, an ellipse, an oval, a polygon with rounded corners, and other rounded shapes.

[0047] Each of the plurality of through holes 22 is formed to follow the outline of a pressing pin in a mold when the sound absorbing unit 10 and the frame 20 are integrally molded by resin injection molding. FIG. 7 is a cross-sectional schematic diagram showing an example of the configuration of a molding die for integrally molding the sound absorbing unit and the frame according to the first embodiment of the present invention. As shown in FIG. 7, the molding die 50 includes, for example, a first mold 51 and a second mold 55. The first mold 51 has a cavity surface 51a to be filled with resin, a cavity surface 51b for molding the first sound absorbing layer 11 of the sound absorbing unit 10, and a plurality of pressing pins 52. The plurality of pressing pins 52 are provided on the cavity surface 51a of the first mold 51 to be filled with resin. The second mold 55 has a cavity surface 55a opposite the cavity surface 51a of the first mold 51, and a cavity surface 55b for molding the second sound absorbing layer 12 of the sound absorbing unit 10.

[0048] In the integral molding of the sound absorbing section 10 and the frame 20, the molding die 50 sandwiches the sound absorbing section 10 between a first mold 51 and a second mold 55, as shown in FIG. 7, thereby molding the first sound absorbing layer 11, the second sound absorbing layer 12, and the intermediate layer 13 to form the intended three-dimensional structure of the sound absorbing section 10. At the same time, the first mold 51 uses multiple pressing pins 52 to press the compressed section 15 of the sound absorbing section 10 against the cavity surface 55a of the second mold 55. Then, resin 30 is injected into the space between the cavity surface 51a of the first mold 51 and the cavity surface 55a of the second mold 55. The resin 30 flows into the space by injection pressure and fills the interior of the molding die 50, as shown in FIG. 7. At this time, the resin 30 flows between the plurality of pressing pins 52 and fills the space between the cavity surface 51 a of the first mold 51 and the compression portion 15 .

[0049] FIG. 8 is a schematic diagram showing an example of resin flow between multiple pressure pins provided in a molding die. As shown in FIG. 8, each of the multiple pressure pins 52 has a cornerless cross-sectional shape (circular in FIG. 8). That is, each of the multiple pressure pins 52 does not have corners that could obstruct the flow of resin 30. Resin 30 flows smoothly between the pressure pins 52. As a result, resin 30 is uniformly and evenly filled between the cavity surface 51a of the first mold 51 and the compression section 15 of the sound absorbing section, from the upstream side of the injection to the boundary 51c between the cavity surfaces 51a and 51b of the first mold 51 (see FIGS. 7 and 8). The resin 30 thus filled is integrally molded (e.g., insert molded) with the compression section 15 of the sound absorbing section 10 and forms the overlapping section 21 of the frame 20 described above. As a result of the resin 30 smoothly flowing between the pressing pins 52 as described above, a plurality of through holes 22 (see FIG. 6) corresponding to the outer shapes of the pressing pins 52 are formed in the overlapping portion 21. The center-to-center distance of each of the plurality of through holes 22 corresponds to the pitch of each of the pressing pins 52, and may be uniform between the through holes 22 or may vary to the extent that the flow of the resin 30 is not obstructed.

[0050] Furthermore, as described above, the compressed section 15 of the sound absorbing section 10 has a high rigidity and narrows the spacing between the constituent materials (the spacing between the fibers contained therein) to make it difficult for fluid to flow in. Therefore, even when the resin 30 is injected into the molding die 50 to integrally mold the sound absorbing section 10 and the frame 20, the compressed section 15 resists the injection pressure of the resin 30 and maintains a state in which the boundary section 51c between the cavity surfaces 51a, 51b of the first mold 51 is closed and a state in which the compressed section 15 is in surface contact with the cavity surface 55a of the second mold 55. This makes it possible to prevent the resin 30 from unintentionally flowing between the compressed section 15 and the cavity surface 51b of the first mold 51, or between the compressed section 15 and the cavity surfaces 55a, 55b of the second mold 55. Furthermore, the compression portion 15 can prevent the resin 30 from unintentionally flowing in from the edge portion 14 of the sound absorbing portion 10 .

[0051] (Sound absorbing device effect) Next, the operation of the sound absorbing device 1 according to the first embodiment of the present invention will be described. Fig. 9 is a schematic diagram for explaining an example of the operation of the sound absorbing device according to the first embodiment of the present invention. As shown in Fig. 9, the sound absorbing device 1 is applied to a vehicle 100 as an apron seal, which is an example of an exterior material for a vehicle.

[0052] Specifically, as shown in FIG. 9 , vehicle 100 includes vehicle exterior materials such as fender liners 101, an apron 102, an apron seal (sound-absorbing device 1), an undercover 105, and a side member 106 that form the wheel well and vehicle body. Vehicle 100 also includes tires 103 mounted on wheels 104 within the wheel well, and a power source 107 such as an engine within the vehicle's power compartment. For example, sound-absorbing device 1 as an apron seal is attached to side member 106 and undercover 105 so that first sound-absorbing layer 11 of sound-absorbing section 10 is exposed to the outside (vehicle exterior) of vehicle 100 and second sound-absorbing layer 12 of sound-absorbing section 10 is exposed to the inside (vehicle interior) of vehicle 100. Power source 107 is a device that generates power for vehicle 100, and may be, for example, an internal combustion engine such as a gasoline engine or a diesel engine, an electric motor (motor) driven by electricity, or a hybrid engine that combines an internal combustion engine and an electric motor.

[0053] When vehicle 100 is traveling, first noise 110 such as road noise caused by tires 103 sliding against the road surface is generated on the vehicle exterior side, and second noise 120 as noise generated from power source 107 is generated on the vehicle interior side. Examples of noise generated from power source 107 include engine noise generated from an internal combustion engine, motor noise generated from an electric motor, and composite noise (a combination of engine noise and motor noise) generated from a hybrid engine. First noise 110 and second noise 120 are noises in different frequency bands. Specifically, first noise 110 on the vehicle exterior side is noise in a lower frequency band than second noise 120 on the vehicle interior side.

[0054] As shown in Fig. 9, the sound absorbing device 1 receives a first noise 110 with a first sound absorbing layer 11 facing the exterior of the vehicle and absorbs the first noise 110 through the vibration of the first sound absorbing layer 11. As a result, the first sound absorbing layer 11 suppresses the reflection (reverberation) of the first noise 110 within the wheelhouse and the propagation of the first noise 110 toward the interior of the vehicle. In parallel with this, the sound absorbing device 1 receives a second noise 120 with a second sound absorbing layer 12 facing the interior of the vehicle and absorbs the second noise 120 through the vibration of the second sound absorbing layer 12. As a result, the second sound absorbing layer 12 suppresses the reflection (reverberation) of the second noise 120 within the power compartment and the propagation of the second noise 120 toward the exterior of the vehicle.

[0055] Furthermore, even when vehicle 100 is stopped, as long as power source 107 is operating, second noise 120 is generated from power source 107. In this case, sound absorbing device 1 also absorbs second noise 120 using second sound absorbing layer 12 in the same manner as described above, thereby suppressing reflection of second noise 120 inside the vehicle and propagation of second noise 120 to the outside of the vehicle.

[0056] As described above, the sound absorbing device 1 according to the first embodiment of the present invention comprises a multi-layered sound absorbing section 10 and a frame body 20 that supports the edges of the sound absorbing section 10, and the sound absorbing section 10 has a multi-layered structure that includes a first sound absorbing layer 11 that absorbs a first noise and a second sound absorbing layer 12 that absorbs a second noise that is a sound in a different frequency band from the first noise.

[0057] With the above configuration, the first sound-absorbing layer 11 absorbs the first noise from one thickness-wise side of the sound-absorbing section 10, and the second sound-absorbing layer 12 absorbs the second noise from the other thickness-wise side of the sound-absorbing section 10. This allows, for example, external noise, such as road noise, generated on the vehicle exterior, and internal noise, such as engine noise, generated on the vehicle interior and having a higher frequency band than the external noise, to be absorbed without reflection. This allows for the absorption of multiple noises in different frequency bands, and suppresses the reverberation and propagation of these multiple noises. This provides a sound-absorbing device that is particularly suitable for vehicle exterior materials that are exposed to external noise, such as road noise, from the vehicle exterior, and internal noise, such as engine noise, from the vehicle interior.

[0058] Furthermore, in the sound absorbing device 1 according to the first embodiment of the present invention, the sound absorbing section 10 is formed from a single sheet of material having a predetermined shape (e.g., a rectangular shape) that has sound absorbing properties, and the sound absorbing section 10 formed from the single sheet of material has the same predetermined shape as the single sheet of material. As a result, there is no need to trim the material sheet when forming the sound absorbing section 10, and material loss during the formation of the sound absorbing section 10 can be reduced. As a result, the material yield during the formation of the sound absorbing section 10 can be improved, and the amount of material sheet waste can be reduced, contributing to environmental conservation and improvement.

[0059] Furthermore, in the sound absorbing device 1 according to the first embodiment of the present invention, the frame 20 has overlapping portions 21 that overlap the edges of the sound absorbing portion 10 in the thickness direction of the sound absorbing portion 10. This makes it possible to strengthen the joint strength between the edges of the sound absorbing portion 10 and the frame 20 in accordance with the width of the overlapping portions 21 (the overlap width between the edges of the sound absorbing portion 10 and the frame 20). Furthermore, the edges of the sound absorbing portion 10, which have many fine irregularities, can be covered by the frame 20, which has a smooth surface with few irregularities, thereby improving the appearance of the sound absorbing device 1.

[0060] Furthermore, in the sound absorbing device 1 according to the first embodiment of the present invention, a plurality of spaced-apart through holes 22 having cornerless inner surfaces are formed in the overlapping portion 21 of the frame body 20. That is, in the molding die 50 used to integrally mold the sound absorbing section 10 and the frame body 20 by resin injection molding, a plurality of pressure pins 52 that press the edge of the sound absorbing section 10 against the cavity surface of the molding die 50 are configured to have the same cornerless outer shape as the through holes 22. This allows the resin injected into the cavity of the molding die 50 to flow smoothly between the plurality of pressure pins 52, thereby filling the cavity of the molding die 50 with the required amount of resin and forming the overlapping portion 21 of the frame body 20 evenly.

[0061] Furthermore, in the sound absorbing device 1 according to the first embodiment of the present invention, the edges of the sound absorbing section 10 are formed as compressed sections 15, which are formed by compressing the sound absorbing section 10 in its thickness direction. This reduces the spacing between the constituent materials at the edges of the sound absorbing section 10 (for example, the spacing between the fibers contained therein) and increases the rigidity of the edges. Therefore, even when resin is injected into the molding die 50 to integrally mold the sound absorbing section 10 and the frame 20, the compressed sections 15, which are the edges of the sound absorbing section 10, are not deformed by the injection pressure of the resin and can maintain the appropriate molded shape corresponding to the molding die 50. This prevents resin from unintentionally flowing between the cavity surface of the molding die 50 and the compressed sections 15, and as a result, prevents resin from unintentionally adhering to at least one of the sound absorbing surfaces of the first sound absorbing layer 11 and the second sound absorbing layer 12 of the sound absorbing section 10. Furthermore, it is possible to prevent resin from unintentionally flowing in from the outer peripheral end of the compression section 15 (edge ​​end 14 of the sound absorbing section 10), thereby avoiding a situation in which resin flows into the inside of the sound absorbing section 10 and the sound absorbing performance of the sound absorbing section 10 is reduced.

[0062] (Embodiment 2) Next, a sound absorbing device according to a second embodiment of the present invention will be described. Fig. 10 is a schematic diagram showing an example of the configuration of a sound absorbing device according to the second embodiment of the present invention. Like Fig. 1 described above, Fig. 10 shows a side view of this sound absorbing device 1A as seen from one side in the width direction D2. As shown in Fig. 10, this sound absorbing device 1A has a sound absorbing section 10A instead of the sound absorbing section 10 of the sound absorbing device 1 according to the first embodiment described above, and a frame body 20A instead of the frame body 20. The frame body 20A has an overlapping section 21A that corresponds to the shape of the edge of the sound absorbing section 10A instead of the overlapping section 21 of the frame body 20 in the first embodiment. The other configuration is the same as that of the first embodiment, and the same components are designated by the same reference numerals.

[0063] Fig. 11 is a schematic diagram showing one configuration example of a sound absorbing section of a sound absorbing device according to embodiment 2 of the present invention. Like Fig. 3 described above, Fig. 11 shows sound absorbing section 10A as seen from one side in width direction D2. In embodiment 2, sound absorbing section 10A is made up of some of multiple divisions (a single division in Fig. 11) obtained by dividing a material sheet of a predetermined shape. The material constituting this material sheet is the same as that of sound absorbing section 10 in embodiment 1 described above.

[0064] More specifically, as shown in FIG. 11, sound absorbing section 10A is formed into a three-dimensional structure corresponding to sound absorbing device 1A by molding (shaping) a single divided body assigned to sound absorbing device 1A (see FIG. 10) from a single sheet of the above-mentioned material without trimming. The shape of such sound absorbing section 10A before molding is the same as the shape of the single divided body. Note that sound absorbing section 10A is configured similarly to sound absorbing section 10 in the above-mentioned first embodiment, except for its different external shape. For example, as shown in FIG. 11, sound absorbing section 10A has a multilayer structure including first sound absorbing layer 11 and second sound absorbing layer 12, similar to the above-mentioned first embodiment. Furthermore, the edge of sound absorbing section 10A is a compressed section 15, similar to the above-mentioned first embodiment.

[0065] In the second embodiment of the present invention, sound absorbing section 10A is formed from a portion of a plurality of divided bodies obtained by dividing a material sheet of a predetermined shape. The aggregate of sound absorbing sections 10A formed by dividing the single material sheet into a plurality of sound absorbing devices 1A has the predetermined shape of the material sheet before division. FIG. 12 is a schematic diagram showing an example of the relationship between the sound absorbing sections and the material sheet of a sound absorbing device according to the second embodiment of the present invention. In FIG. 12, material sheet 200 is an example of a material sheet of a predetermined shape according to the second embodiment of the present invention, and is a sheet made of a porous material with sound absorption properties, such as a nonwoven fabric or a woven fiber fabric. For example, in FIG. 12, material sheet 200 has a rectangular shape. Furthermore, two sound absorbing devices 1A-1 and 1A-2 are examples of a plurality of sound absorbing devices 1A that are manufactured sequentially, and each has a configuration similar to that of sound absorbing device 1A shown in FIG. 10, for example.

[0066] In manufacturing multiple sound absorbing devices 1A, a single sheet of material 200 is used for each of two sound absorbing devices 1A-1 and 1A-2. For example, as shown in FIG. 12 , the single sheet of material 200 is divided into two divided bodies 200a and 200b, and these two divided bodies 200a and 200b are assigned to the two sound absorbing devices 1A-1 and 1A-2, respectively, without being trimmed. Specifically, one divided body 200a is molded into the desired three-dimensional structure to form sound absorbing section 10A-1, and is integrally molded with frame body 20A-1 by resin injection molding. In this manner, one sound absorbing device 1A-1 is manufactured. Similarly, the other divided body 200b is molded into the desired three-dimensional structure to form sound absorbing section 10A-2, and is integrally molded with frame body 20A-2 by resin injection molding. In this manner, another sound absorbing device 1A-2 is manufactured.

[0067] Here, two divided bodies 200a, 200b obtained from a single sheet of material 200 constitute sound absorbing sections 10A-1, 10A-2 of two sound absorbing devices 1A-1, 1A-2, respectively, without being trimmed. That is, the pre-molding outer shape of one sound absorbing section 10A-1 is the same as the outer shape of one divided body 200a, and the pre-molding outer shape of the other sound absorbing section 10A-2 is the same as the outer shape of the other divided body 200b. Therefore, the aggregate of sound absorbing sections 10A-1, 10A-2 formed by divided bodies 200a, 200b allocated across two sound absorbing devices 1A-1, 1A-2 from a single sheet of material 200 has the predetermined shape of the pre-molding sheet of material 200 (rectangular in FIG. 12 ). Therefore, it is possible to reduce material waste when constructing two sound absorbing sections 10A-1, 10A-2 from a single material sheet 200, thereby improving material yield during the manufacture of the two sound absorbing devices 1A-1, 1A-2 and suppressing the adverse impact on the environment caused by the disposal of the material sheet 200.

[0068] In the second embodiment described above, one sound absorbing section 10A-1 is formed by dividing a single sheet of material 200 into two divided bodies 200a and 200b, and one divided body 200a is formed by dividing the single sheet of material 200, and the other sound absorbing section 10A-2 is formed by dividing the other divided body 200b. However, the present invention is not limited to this. For example, a single sheet of material 200 may be divided into three or more divided bodies, and these three or more divided bodies may be allocated across multiple sound absorbing devices to form the sound absorbing sections of the multiple sound absorbing devices.

[0069] Fig. 13 is a schematic diagram showing a modified example of the relationship between the sound absorbing portion and the material sheet of the sound absorbing device according to the second embodiment of the present invention. In Fig. 13, the material sheet 200 is divided into four divisions 200c-1, 200c-2, 200d-1, and 200d-2, which is an example of three or more divisions. For example, the divisions 200c-1 and 200c-2 have the same outer shape, and the divisions 200d-1 and 200d-2 have the same outer shape. The divisions 200c-1 and 200c-2 and the divisions 200d-1 and 200d-2 have different outer shapes.

[0070] As shown in FIG. 13, four divided bodies 200c-1, 200c-2, 200d-1, and 200d-2 obtained by dividing a single material sheet 200 are assigned to two sound absorbing devices 1A-1 and 1A-2 in a predetermined combination without any trimming process. Specifically, one set of divided bodies 200c-1 and 200d-1 is molded into the desired three-dimensional structure to form sound absorbing section 10A-1, and is integrally molded with frame body 20A-1 by resin injection molding. In this way, one sound absorbing device 1A-1 is manufactured. Similarly, the other set of divided bodies 200c-2 and 200d-2 is molded into the desired three-dimensional structure to form sound absorbing section 10A-2, and is integrally molded with frame body 20A-2 by resin injection molding. In this way, another sound absorbing device 1A-2 is manufactured.

[0071] Here, the four divided bodies 200c-1, 200c-2, 200d-1, and 200d-2 obtained from the single material sheet 200 are separated into the two sets described above without being trimmed, and form the sound absorbing sections 10A-1 and 10A-2 of the two sound absorbing devices 1A-1 and 1A-2, respectively. That is, the pre-molding outer shape of one sound absorbing section 10A-1 is the same as the outer shape of the combination of one set of divided bodies 200c-1 and 200d-1. The pre-molding outer shape of the other sound absorbing section 10A-2 is the same as the outer shape of the combination of the other set of divided bodies 200c-2 and 200d-2. Therefore, the aggregate of sound absorbing sections 10A-1, 10A-2 formed by divisions 200c-1, 200c-2, 200d-1, and 200d-2 allocated across two sound absorbing devices 1A-1, 1A-2 from a single sheet of material 200 has the predetermined shape of the sheet of material 200 before division (rectangular in FIG. 13 ). Therefore, even when one sound absorbing section is formed from two divisions, it is possible to reduce material waste when forming two sound absorbing sections 10A-1, 10A-2 from a single sheet of material 200. As a result, it is possible to improve material yield during the manufacture of the two sound absorbing devices 1A-1, 1A-2 and to reduce adverse environmental impacts resulting from the disposal of sheet of material 200.

[0072] In the above-described modified example of the second embodiment, one set of the divided bodies 200c-1, 200c-2, 200d-1, and 200d-2 formed by dividing a single sheet of material 200 constitutes one sound absorbing section 10A-1, and the other set of the divided bodies 200c-2 and 200d-2 constitutes the other sound absorbing section 10A-2. However, the present invention is not limited to this. For example, two or four divided bodies, or three or more divided bodies, may be obtained from a single sheet of material 200. Furthermore, the divided bodies divided from a single sheet of material 200 may all have the same or different external shapes, or may be a combination of those with the same external shapes and those with different external shapes. Furthermore, the number of divided bodies that constitute the sound absorbing section from a single sheet of material 200 may be two or three or more.

[0073] As described above, in the second and modified embodiments of the present invention, in a sound absorbing device including a sound absorbing portion and a frame that supports the edges of the sound absorbing portion, the sound absorbing portion is formed from a portion of multiple segments obtained by dividing a sheet of material of a predetermined shape, and the aggregate of the sound absorbing portions formed by dividing the segments from the single sheet of material across the multiple sound absorbing devices has the predetermined shape of the sheet of material before division, with the remainder being configured similarly to the first embodiment. Therefore, while achieving the same effects as the first embodiment described above, when forming each of the sound absorbing portions of the multiple sound absorbing devices from the single sheet of material, there is no need to trim the sheet of material, thereby reducing material waste during the formation of each sound absorbing portion. As a result, material yield can be improved during the manufacture of multiple sound absorbing devices, and the amount of material sheet waste can be reduced, contributing to environmental conservation and improvement.

[0074] In the above-described first and second embodiments and the modified example, an apron seal is used as an example of a vehicle exterior material to which the sound-absorbing device is applied, but the present invention is not limited to this. For example, the sound-absorbing device according to the present invention may be a vehicle exterior material other than an apron seal, such as a fender liner or an undercover (such as a part for constituting a vehicle's whole house or underfloor structure).

[0075] Furthermore, in the above-described first and second embodiments and the modified example, a multi-layered sound absorbing section is illustrated, which is composed of three layers: a first sound absorbing layer that absorbs a first noise, a second sound absorbing layer that absorbs a second noise, and an intermediate layer interposed therebetween. However, the present invention is not limited to this. For example, the first sound absorbing layer, the second sound absorbing layer, and the intermediate layer may each independently have a single-layer structure or a multi-layer structure. In other words, the sound absorbing section of the sound absorbing device according to the present invention may have a multi-layered structure of three or more layers, which is composed of one or more first sound absorbing layers, one or more second sound absorbing layers, and one or more intermediate layers.

[0076] Furthermore, in the above-described first and second embodiments and modifications, road noise is exemplified as the first noise absorbed by the first sound absorbing layer, and noise such as engine noise generated by the vehicle's power source (noise originating from the power source) is exemplified as the second noise absorbed by the second sound absorbing layer, but the present invention is not limited to this. In the present invention, these first noise and second noise may be the above-described road noise or noise originating from the power source, or may be other noises, such as collision noise generated by a collision between the vehicle and an object outside the vehicle (earth, sand, pebbles, water, etc.). Furthermore, the first noise is not limited to noise having a lower frequency band than the second noise, and may be noise having a higher frequency band than the second noise.

[0077] In the first, second, and modified embodiments described above, the sound absorbing section is formed from a single or divided piece of a material sheet having a predetermined shape, but the present invention is not limited to this. For example, in the first embodiment described above, the sound absorbing section may be formed from a single piece of material sheet having a predetermined shape that is cut into multiple pieces. In the second and modified embodiments described above, the number of divided pieces allocated from a single sheet of material across multiple sound absorbing devices may be one, two, or three or more for each sound absorbing device.

[0078] Furthermore, the present invention is not limited to the above-described first and second embodiments and modifications, and also includes configurations in which the above-described components are appropriately combined. In addition, other embodiments, examples, operational techniques, etc., made by those skilled in the art based on the above-described first and second embodiments and modifications are all included in the scope of the present invention. [Explanation of symbols]

[0079] 1, 1A, 1A-1, 1A-2 Sound absorption device 10, 10A, 10A-1, 10A-2 sound absorbing section 11 First sound-absorbing layer 11a 1st sound absorption surface 12 Second sound-absorbing layer 12a 2nd sound absorption surface 13 Middle class 14 Edge 15 Compression section 20, 20A, 20A-1, 20A-2 frame 21, 21A overlapping part 22 Through hole 23 Upper 24 Mounting part 25 Extension 30 Resin 50 molding die 51 First mold 51a, 51b cavity surface 51c Boundary 52 Pressing pin 55 Second mold 55a, 55b cavity surface 100 vehicles 101 Fender liner 102 Apron 103 Tires 104 Wheels 105 Undercover 106 Side member 107 Power source 110 No. 1 Noise 120 Second Noise 200 material sheets 200a, 200b, 200c-1, 200c-2, 200d-1, 200d-2 split body D1 Anteroposterior direction D2 width direction D3 Up and down direction

Claims

1. a multi-layered sound absorbing section including a first sound absorbing layer that absorbs a first noise and a second sound absorbing layer that absorbs a second noise that is a sound in a frequency band different from the first noise; a frame body that supports an edge portion of the sound absorbing portion; Equipped with the edge portion of the sound absorbing portion is a compressed portion formed by compressing the sound absorbing portion in its thickness direction, the compression portion is a region of the sound absorbing portion that is integrally molded with the frame body using resin, the frame includes an overlapping portion that overlaps an edge of the sound absorbing portion in a thickness direction of the sound absorbing portion, The overlapping portion of the frame body has a cornerless inner surface and a plurality of through holes spaced apart from each other. A sound absorbing device characterized by:

2. A sound absorbing device comprising a sound absorbing part and a frame body supporting an edge of the sound absorbing part, the edge portion of the sound absorbing portion is a compressed portion formed by compressing the sound absorbing portion in its thickness direction, the compression portion is a region of the sound absorbing portion that is integrally molded with the frame body using resin, the frame includes an overlapping portion that overlaps an edge of the sound absorbing portion in a thickness direction of the sound absorbing portion, The overlapping portion of the frame body has a plurality of through holes that have a cornerless inner surface and are spaced apart from each other, the sound absorbing portion is formed by a single material sheet having a predetermined shape or by a part of a plurality of divided bodies obtained by dividing the material sheet; the sound absorbing portion formed by the single material sheet has the same predetermined shape as the single material sheet, the assembly of the sound absorbing parts formed by the divided bodies allocated across the plurality of sound absorbing devices from the single material sheet has a predetermined shape of the material sheet before division, A sound absorbing device characterized by:

3. the sound absorbing portion is formed by a single material sheet having a predetermined shape or by a part of a plurality of divided bodies obtained by dividing the material sheet; the sound absorbing portion formed by the single material sheet has the same predetermined shape as the single material sheet, the assembly of the sound absorbing parts formed by the divided bodies allocated across the plurality of sound absorbing devices from the single material sheet has a predetermined shape of the material sheet before division, 2. The sound absorbing device according to claim 1.

4. The sound absorbing part is a first sound absorbing layer that absorbs the first noise; a second sound absorbing layer that absorbs a second noise that is a sound in a frequency band different from the first noise; and having a multilayer structure comprising 3. The sound absorbing device according to claim 2.

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