JP7791671B2 - sound absorbing device - Google Patents

Description

The present invention relates to a sound-absorbing device.

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 has a sound-absorbing layer made of a sound-absorbing material such as nonwoven fabric, and this sound-absorbing layer is designed to absorb noise of a specified frequency.

JP 2015-13538 A

However, there are many different types of noise that vehicles emit, such as road noise caused by the vehicle's tires sliding against the road surface, and the sound of the vehicle's engine, all of which have different frequencies. For this reason, the conventional sound-absorbing devices described above can only absorb one type of noise, such as road noise or engine noise, which have different frequencies. As a result, the unabsorbed noise remains as exterior noise and interior noise.

The present invention was made in consideration of the above circumstances, and aims to provide a sound-absorbing device that can absorb multiple noises with different frequencies.

In order to solve the above-mentioned problems and achieve the objectives, 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 a sound in a different frequency band from the first noise, and a frame that supports the edges of the sound absorbing section.

The sound absorbing device according to the present invention is characterized in that it comprises a sound absorbing section and a frame that supports the edges of the sound absorbing section, and the sound absorbing section is formed from a single sheet of material of a predetermined shape or a part of multiple segments formed by dividing the sheet of material, and the sound absorbing section formed from the single sheet of material has the same predetermined shape as the single sheet of material, and the aggregate of the sound absorbing sections formed from the segments allocated across multiple sound absorbing devices from the single sheet of material has the predetermined shape of the sheet of material before it is divided.

The sound absorbing device according to the present invention is characterized in that, in the above invention, the sound absorbing section is formed from a single sheet of material of a predetermined shape or from a portion of multiple segments formed by dividing the sheet of material, and the sound absorbing section formed from the single sheet of material has the same predetermined shape as the single sheet of material, and the aggregate of sound absorbing sections formed from the segments allocated from the single sheet of material across multiple sound absorbing devices has the predetermined shape of the sheet of material before it is divided.

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 different frequency band from the first noise.

Furthermore, the sound-absorbing device according to the present invention is characterized in that, in the above invention, the frame body has an overlapping portion that overlaps the edge of the sound-absorbing portion in the thickness direction of the sound-absorbing portion.

The sound-absorbing device according to the present invention is also characterized in that the overlapping portion of the frame has a cornerless inner surface and is formed with a plurality of spaced-apart through holes.

The sound-absorbing device according to the present invention is characterized in that, in the above invention, the edge of the sound-absorbing section is a compressed section formed by compressing the sound-absorbing section in its thickness direction.

The sound-absorbing device of the present invention has the advantage of being able to absorb multiple noises with different frequencies.

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. 2 is a schematic diagram showing an example of the configuration of the opposite side of the sound absorbing device shown in FIG. 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. 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. FIG. 5 is a schematic diagram showing an example of the cross-sectional structure of the sound absorbing portion according to the first embodiment of the present invention. 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. FIG. 7 is a cross-sectional view showing a structural example of a molding die for integrally molding the sound absorbing portion and the frame body according to the first embodiment of the present invention. 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. 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. 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. 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. 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. 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.

Below, a preferred embodiment of a sound-absorbing device according to the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to this embodiment. 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. The same components are designated by the same reference numerals in each drawing.

(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 an automobile, for example, as an apron seal, which is an example of an exterior material for a vehicle, 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 .

For the sake of convenience, the present specification defines a front-to-rear direction D1, a width direction D2, and a vertical direction D3. The front-to-rear direction D1 is the front-to-rear direction of the 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-to-rear direction D1, width direction D2, and vertical direction D3, are perpendicular to each other, and this also applies to the sound-absorbing device 1 when attached to a vehicle. Furthermore, in this specification, unless otherwise specified, the term "vehicle" refers to a vehicle to which the sound-absorbing device of the present invention (sound-absorbing device 1 in this embodiment 1) is applied.

As shown in Figures 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. The sound absorbing unit 10 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, as shown in Figure 1, the sound absorbing unit 10 has the surface of the first sound absorbing layer 11 exposed on one side in the width direction D2, and as shown in Figure 2, the surface of the second sound absorbing layer 12 exposed on the other side in the width direction D2. 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 opposite side from the first sound absorbing layer 11.

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

The first and second noises absorbed by the sound-absorbing section 10 described above are both noises generated by a vehicle. However, the frequency bands of the first and second noises 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 frequency limits of the frequency bands are different from each other. The frequency bands of the first and second noises may partially overlap, or may not overlap at all. An example of the first noise is road noise generated by the sliding contact between the vehicle tires and the road surface. An example of the second noise is noise that is louder than the first noise, such as the sound of a vehicle engine. In this 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.

The frame body 20 supports the edges of the sound-absorbing section 10. Specifically, as shown in FIGS. 1 and 2, the frame body 20 is formed by resin injection molding or the like to have a frame structure that corresponds to the three-dimensional structure of the vehicle exterior material (an automobile apron seal in this embodiment) to which the sound-absorbing device 1 is applied and the outer shape of the sound-absorbing section 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 section 10 described above (compression section 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 edges of the sound-absorbing section 10 are 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 section 10 through the opening. The frame body 20 supports the edge of the sound absorbing unit 10 by joining the edge of the sound absorbing unit 10 to the frame edge, so that the sound absorbing unit 10 is stretched within the frame structure of the frame body 20.

As shown in FIG. 1, the frame body 20 also 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 portion of the frame body 20. As shown in FIG. 1, the overlapping portion 21 of the frame body 20 also has a plurality of through holes 22 formed therein. Details of the configurations of the overlapping portion 21 and through holes 22 of the frame body 20 will be described later.

As shown in Figures 1 and 2, the upper part 23 of the frame 20 is provided with a plurality of mounting portions 24. These mounting portions 24 are components for attaching 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 part in the fore-and-aft direction D1. The extension portion 25 is a component for attaching the sound absorbing device 1 to a vehicle body member, such as a side member, using fastening members.

(Configuration of sound absorbing part)
Next, the configuration of the sound absorbing section 10 according to the first embodiment of the present invention will be described. 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. FIG. 3 shows the sound absorbing section 10 as viewed 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 according to the first embodiment of the present invention. FIG. 4 shows the sound absorbing section 10 as viewed from diagonally above and behind. 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. FIG. 5 shows a schematic diagram of the cross section of the sound absorbing device 1 shown in FIG. 1 taken along line A-A.

The sound-absorbing section 10 is composed 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 constitutes this sound-absorbing section 10 include sheets of porous material with sound-absorbing properties, such as nonwoven fabric and woven fiber fabric. From the standpoints of sound-absorbing performance and cost, nonwoven fabric sheets are preferred as the material sheet. Furthermore, examples of the material fiber for the material sheet include glass fiber and polyethylene terephthalate (PET) fiber.

Furthermore, from the perspective of improving material yield, it is preferable that a single sound absorbing section 10 be constructed from a single sheet of material of a predetermined shape. In other words, it is preferable to form the sound absorbing section 10 with the above three-dimensional structure by molding (shaping) a single sheet of material that has not been subjected to trimming processes such as cutting out the material sheet. The sound absorbing section 10 constructed from the single sheet of material in this manner has the same predetermined shape as the single sheet of material. For example, the pre-molding shape of the sound absorbing section 10 shown in Figure 3 has the same predetermined shape (here, a rectangular shape) as the single sheet of material when viewed in a plan view from the thickness direction. Note that examples of the predetermined shape of the single sheet of material include rectangles, trapezoids, parallelograms, rhombus, polygons, etc.

Prior patent documents such as JP 2020-82707 A disclose conventional sound-absorbing devices, such as vehicle exterior materials (composite vehicle components) such as undercovers that have been given sound-absorbing properties. In such conventional sound-absorbing devices, a porous sheet material, such as a sound-absorbing nonwoven fabric, is stretched within the 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, which requires the removal of portions such as the four corners of the porous sheet material. The portions removed from the porous sheet material result in material loss when the sound-absorbing layer is constructed from the porous sheet material, resulting in a decrease in 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.

In contrast, in the sound absorbing device 1 according to embodiment 1 of the present invention, a single sound absorbing section 10 is constructed 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 constructing the sound absorbing section 10 from it, which reduces material loss when constructing the sound absorbing section 10. As a result, material yield when constructing the sound absorbing section 10 can be improved, and the negative impact on the environment caused by the disposal of the material sheet can be suppressed.

As shown in Figures 3 and 4, the sound absorbing section 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 more detail, as shown in Figure 5, the multi-layer structure of the sound absorbing section 10 is composed of the first sound absorbing layer 11 and second sound absorbing layer 12 described above, and an intermediate layer 13 interposed between these two layers.

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 multi-layer structure of the sound-absorbing section 10, and 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 absorbs first noise, such as road noise, by receiving the first noise from the first sound-absorbing surface 11a and vibrating.

The sound absorption 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 the mass per unit area (g/ ^m2 ) of the first sound absorbing layer 11, and can be adjusted by controlling the content and type of material constituting the first sound absorbing layer 11. For example, if the material constituting the first sound absorbing layer 11 is a nonwoven fabric, the sound absorption performance of the first sound absorbing layer 11 can be set as described above by controlling the content and type of fiber constituting the nonwoven fabric and the content and type of resin that bonds the fibers in the nonwoven fabric.

Furthermore, when the sound absorption 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 a greater basis weight. When the sound absorption 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 a lesser basis weight. For example, if 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 therefore the basis weight of the first sound absorbing layer 11 is adjusted to a greater basis weight than the second sound absorbing layer 12.

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 multi-layer structure of the sound-absorbing unit 10, and 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 the intermediate layer 13. The second sound-absorbing layer 12 absorbs second noise, such as engine noise, by receiving the second noise from the second sound-absorbing surface 12a and vibrating.

The sound absorption 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. Because the basis weight of the second sound absorbing layer 12 is the mass per unit area (g/ ^m2 ) of the second sound absorbing layer 12, the adjustment of the basis weight and the setting of the sound absorption performance of the second sound absorbing layer 12 can be performed using the same method as for the 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 a lower basis weight than that of the first sound absorbing layer 11.

The intermediate layer 13 supports the first sound absorbing layer 11 and 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 second sound absorbing layer 12, and is interposed between the first sound absorbing layer 11 and second sound absorbing layer 12, as shown in FIG. 5. The first sound absorbing layer 11, second sound absorbing layer 12, and intermediate layer 13 form a multilayer structure in which the first sound absorbing layer 11 and second sound absorbing layer 12 are stacked in the thickness direction of the sound absorbing section 10, with the intermediate layer 13 sandwiched between them. The intermediate layer 13, together with the first sound absorbing layer 11 and second sound absorbing layer 12, is molded into the three-dimensional structure of the sound absorbing section 10.

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, which is 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 unable to absorb.

As shown in FIG. 5 , the other of the 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 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, which is surface-bonded in this manner, 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 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 was unable to absorb.

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

Specifically, to improve the sound absorption performance of the first and second sound absorbing layers 11 and 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 and second sound absorbing layers 11 and 12, respectively, can vibrate more easily. Increasing the thickness of the intermediate layer 13 also requires increasing the basis weight of the intermediate layer 13. Adjusting the basis weight of the intermediate layer 13 can be done using the same techniques as those for the first and second sound absorbing layers 11 and 12 described above. On the other hand, increasing the basis weight of the intermediate layer 13 increases the fiber content of the material that makes up the intermediate layer 13, resulting in increased cost and mass of the intermediate layer 13. In other words, improving the sound absorption performance of the first and second sound absorbing layers 11 and 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 allowable increase in cost and mass for the intermediate layer 13.

As shown in Figures 3 and 4, the sound absorbing unit 10 also includes a compression section 15 supported by the frame 20 (see Figures 1 and 2) described above. The compression section 15 is an edge of the sound absorbing unit 10, and is formed by compressing the multi-layered sound absorbing unit 10 in its thickness direction. For example, as shown in Figure 3, the compression section 15 is preferably formed continuously around the entire outer periphery of the sound absorbing unit 10, but may also be formed discontinuously (intermittently) along the outer periphery of the sound absorbing unit 10.

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 this 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. A compressed section 15 with such high rigidity can suppress unintended bending or sagging of the sound absorbing section 10.

The above "uncompressed layers" refers to the first sound absorbing layer 11, second sound absorbing layer 12, and intermediate layer 13 of the inner multi-layer structure of the sound absorbing section 10, which are surrounded by the 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 the sound absorbing section 10. On the other hand, although the compressed section 15 has the above-mentioned first sound absorbing layer 11 and second sound absorbing layer 12, they do not absorb the first noise or second noise that are the target of sound absorption. In other words, in this invention, the first sound absorbing layer 11, second sound absorbing layer 12, and intermediate layer 13 refer to the inner layers surrounded by the compressed section 15, unless otherwise specified.

(Overlapping structure of sound absorbing part and frame body)
Next, the overlapping structure between the sound absorbing section 10 and the frame body 20 in the first embodiment of the present invention will be described. As shown in Fig. 1 above, the frame body 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 body 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 also shown in Fig. 5 above.

As shown in Figures 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 perspective of increasing the bonding strength between the sound absorbing portion 10 and the frame 20, it is preferable that the overlapping portion 21 be bonded to the compressed portion 15 of the sound absorbing portion 10 over the entire outer periphery of the sound absorbing portion 10 and overlap 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 Figure 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 section 15 of the sound absorbing section 10 and the overlapping section 21 of the frame body 20 is the distance between the outer peripheral edge of the sound absorbing section 10 (edge edge 14 shown in Figure 5) and the inner peripheral edge of the overlapping section 21, and is preferably 10 mm or more and 20 mm or less.

The sound-absorbing section 10 is made of a sound-absorbing material such as nonwoven fabric, and therefore has many fine holes on its surface. In contrast, the frame 20 is formed by resin injection molding 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 with the compression section 15 so as to cover the entire outer periphery of the sound-absorbing section 10, regardless of whether it is joined to the compression section 15. Furthermore, it is preferable that the overlapping section 21 overlaps with 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 a manner that exposes the first sound absorbing layer 11 of the sound absorbing section 10 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.

Furthermore, as shown in Figure 6, a plurality of through holes 22 are formed in the overlapping portion 21 of the frame body 20. Each of these plurality of through holes 22 is a through hole having an inner surface with a cornerless shape (circular in Figure 6) and is spaced apart from one another. Examples of cornerless shapes include a circle, an ellipse, an oval, a rounded polygon, and other rounded shapes with no corners.

Each of these multiple through holes 22 is formed to follow the outline of a pressure pin inside the mold when the sound absorbing unit 10 and the frame 20 are integrally molded by resin injection molding. Figure 7 is a cross-sectional schematic diagram showing an example configuration of a molding mold for integrally molding the sound absorbing unit and the frame in embodiment 1 of the present invention. As shown in Figure 7, this molding mold 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 multiple pressure pins 52. These multiple pressure 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.

When integrally molding the sound absorbing section 10 and frame 20, the molding die 50 sandwiches the sound absorbing section 10 between the first mold 51 and the 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 desired three-dimensional structure of the sound absorbing section 10. At the same time, the first mold 51 uses multiple pressure pins 52 to press the compression section 15 of the sound absorbing section 10 against the cavity surface 55a of the second mold 55. Resin 30 is then 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 this space due to the injection pressure, filling the interior of the molding die 50 as shown in FIG. 7. At this time, the resin 30 flows between the multiple pressing pins 52 and fills the space between the cavity surface 51a of the first mold 51 and the compression section 15.

Figure 8 is a schematic diagram showing an example of resin flow between multiple pressure pins arranged in a molding die. As shown in Figure 8, each of the multiple pressure pins 52 has a cornerless cross-sectional shape (circular in Figure 8). That is, each of the multiple pressure pins 52 has no corners that would obstruct the flow of resin 30. Resin 30 flows smoothly between the pressure pins 52. As a result, resin 30 is evenly and uniformly 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 all the way to the boundary 51c between the cavity surfaces 51a and 51b of the first mold 51 (see Figures 7 and 8). The resin 30 filled in this way 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 body 20 described above. As a result of the resin 30 smoothly flowing between the pressure pins 52 as described above, a plurality of through holes 22 (see FIG. 6) corresponding to the outer shapes of the pressure pins 52 are formed in the overlapping portion 21. The center-to-center distance between the plurality of through holes 22 corresponds to the pitch of the pressure pins 52, and may be equal between the through holes 22 or may vary to the extent that the flow of the resin 30 is not impeded.

Furthermore, as described above, the compressed section 15 of the sound-absorbing section 10 has narrow spacing between the constituent materials (spacing between the fibers contained therein) to make it difficult for fluids to flow in, and has high rigidity. Therefore, even when resin 30 is injected into the molding die 50 to integrally mold the sound-absorbing section 10 and the frame body 20, the compressed section 15 resists the injection pressure of the resin 30, maintaining a closed state for the boundary section 51c between the cavity surfaces 51a, 51b of the first mold 51 and a state of surface contact with the cavity surface 55a of the second mold 55. This prevents 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 section 15 can prevent the resin 30 from unintentionally flowing in through the edge 14 of the sound absorbing section 10.

(Action of sound absorbing device)
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.

Specifically, as shown in FIG. 9 , vehicle 100 includes exterior vehicle components such as fender liners 101, aprons 102, apron seals (sound-absorbing devices 1), undercovers 105, and side members 106 that make up the wheel wells and body. Vehicle 100 also includes tires 103 mounted on wheels 104 within the wheel wells, and a power source 107, such as an engine, within the vehicle's power compartment. For example, sound-absorbing device 1 serving as an apron seal is attached to side members 106 and undercovers 105 so that the first sound-absorbing layer 11 of sound-absorbing section 10 is exposed to the outside (vehicle exterior) of vehicle 100 and the 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.

When the vehicle 100 is traveling, a first noise 110 such as road noise caused by the tires 103 sliding against the road surface is generated on the outside of the vehicle, and a second noise 120 is generated on the inside of the vehicle as noise generated from the power source 107. Examples of noise generated from the 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. The first noise 110 and second noise 120 are noises in different frequency bands. Specifically, the first noise 110 on the outside of the vehicle is noise in a lower frequency band than the second noise 120 on the inside of the vehicle.

As shown in FIG. 9 , the sound absorbing device 1 receives a first noise 110 with the 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 the 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.

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

As explained above, the sound absorbing device 1 according to embodiment 1 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. 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.

With the above configuration, the first sound-absorbing layer 11 absorbs the first noise from one thickness side of the sound-absorbing section 10, while the second sound-absorbing layer 12 absorbs the second noise from the other thickness side of the sound-absorbing section 10. This makes it possible to absorb, without reflecting, both exterior noise, such as road noise, generated on the vehicle exterior, and interior noise, such as engine noise, generated on the vehicle interior and having a higher frequency band than the exterior noise. This makes it possible to absorb multiple noises in different frequency bands, and suppress the reverberation and propagation of these multiple noises. This makes it possible to realize a sound-absorbing device that is particularly suitable for vehicle exterior materials that are exposed to exterior noise, such as road noise, from the vehicle exterior, and interior noise, such as engine noise, from the vehicle interior.

In addition, in the sound-absorbing device 1 according to embodiment 1 of the present invention, the sound-absorbing section 10 is constructed from a single sheet of material having sound-absorbing properties and a predetermined shape (e.g., rectangular), and the sound-absorbing section 10 constructed 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 constructing the sound-absorbing section 10, and material loss during construction of the sound-absorbing section 10 can be reduced. As a result, material yield during construction 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.

In addition, in the sound absorbing device 1 according to embodiment 1 of the present invention, the frame body 20 has an overlapping portion 21 that overlaps the edge of the sound absorbing portion 10 in the thickness direction of the sound absorbing portion 10. This makes it possible to strengthen the bond between the edge of the sound absorbing portion 10 and the frame body 20 in accordance with the width of the overlapping portion 21 (the overlap width between the edge of the sound absorbing portion 10 and the frame body 20). Furthermore, the edge of the sound absorbing portion 10, which has many fine irregularities, can be covered by the frame body 20, which has a smooth surface with few irregularities, thereby improving the appearance of the sound absorbing device 1.

In addition, in the sound absorbing device 1 according to embodiment 1 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 evenly forming the overlapping portion 21 of the frame body 20.

Furthermore, in the sound-absorbing device 1 according to embodiment 1 of the present invention, the edge of the sound-absorbing section 10 is formed as a compressed section 15, which is formed by compressing the sound-absorbing section 10 in its thickness direction. This narrows the spacing between the constituent materials (e.g., the spacing between the fibers) at the edge of the sound-absorbing section 10 and increases the rigidity of the edge. 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 section 15, which is the edge of the sound-absorbing section 10, is 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 section 15, thereby preventing 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 edge of the compression section 15 (edge 14 of the sound absorbing section 10), thereby avoiding a situation in which resin flows into the interior of the sound absorbing section 10 and the sound absorbing performance of the sound absorbing section 10 is reduced.

(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 edge shape 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.

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

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

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

In the manufacture of multiple sound absorbing devices 1A, a single sheet of material 200 is used for each of the 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 segments 200a and 200b, and these segments 200a and 200b are assigned to the two sound absorbing devices 1A-1 and 1A-2, respectively, without being trimmed. Specifically, one segment 200a is molded into the desired three-dimensional structure to form the sound absorbing section 10A-1, and is integrally molded with the frame body 20A-1 by resin injection molding. In this way, one sound absorbing device 1A-1 is manufactured. Similarly, the other segment 200b is molded into the desired three-dimensional structure to form the sound absorbing section 10A-2, and is integrally molded with the frame body 20A-2 by resin injection molding. In this way, another sound absorbing device 1A-2 is manufactured.

Here, two divided bodies 200a, 200b obtained from a single sheet of material 200 constitute the sound absorbing sections 10A-1, 10A-2 of the two sound absorbing devices 1A-1, 1A-2, respectively, without any trimming process. 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 from a single sheet of material 200 across the two sound absorbing devices 1A-1, 1A-2, has the predetermined shape of the sheet of material 200 before division (rectangular in Figure 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 environmental impact caused by the disposal of the material sheet 200.

In the above-described second embodiment, one sound absorbing section 10A-1 is formed using one of the two divided sections 200a, 200b obtained by dividing a single sheet of material 200, and the other sound absorbing section 10A-2 is formed using the other divided section 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 sections, and these three or more divided sections may be allocated across multiple sound absorbing devices to form the sound absorbing sections of these multiple sound absorbing devices.

Figure 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 embodiment 2 of the present invention. In Figure 13, the material sheet 200 is divided into four divisions 200c-1, 200c-2, 200d-1, and 200d-2, as an example of three or more divisions. For example, divisions 200c-1 and 200c-2 have the same external shape, and divisions 200d-1 and 200d-2 have the same external shape. Divisions 200c-1 and 200c-2 and divisions 200d-1 and 200d-2 have different external shapes.

As shown in Figure 13, four divided bodies 200c-1, 200c-2, 200d-1, and 200d-2 separated from a single sheet of material 200 are assigned to two sound absorbing devices 1A-1 and 1A-2 in a predetermined combination without any trimming. 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.

Here, the four divided bodies 200c-1, 200c-2, 200d-1, and 200d-2 obtained from a single sheet of material 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. In other words, the pre-molding external shape of one sound absorbing section 10A-1 is the same as the external shape of the combination of one set of divided bodies 200c-1 and 200d-1. The pre-molding external shape of the other sound absorbing section 10A-2 is the same as the external 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, which are formed from segments 200c-1, 200c-2, 200d-1, and 200d-2 allocated across the two sound absorbing devices 1A-1, 1A-2 from a single sheet of material 200, has the predetermined shape of the material sheet 200 before it is divided (a rectangular shape in FIG. 13). Therefore, even if one sound absorbing section is formed from two segments, it is possible to reduce material waste when forming the 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 reduce the negative impact on the environment caused by the disposal of the material sheet 200.

In the modified example of the second embodiment described above, one set of 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 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 as described above may be obtained from a single sheet of material 200, or three or more divided bodies may be obtained. Furthermore, the multiple 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 bodies with the same and different external shapes. Furthermore, the number of sound absorbing devices to which divided bodies forming sound absorbing sections from a single sheet of material 200 are assigned may be two as described above, or may be three or more.

As explained above, in the second embodiment and its variant of the present invention, in a sound absorbing device comprising a sound absorbing section and a frame supporting the edges of the sound absorbing section, the sound absorbing section is formed from a portion of a plurality of segments obtained by dividing a material sheet of a predetermined shape, and the aggregate of the sound absorbing sections formed from the segments allocated across the plurality of sound absorbing devices from the single material sheet has the predetermined shape of the material sheet before division, with the remainder being configured in the same manner as in the first embodiment. Therefore, in addition to enjoying the same effects as in the first embodiment described above, when constructing each sound absorbing section of the plurality of sound absorbing devices from the single material sheet, there is no need to trim the material sheet, thereby reducing material waste during construction of each sound absorbing section. As a result, material yield can be improved during the manufacture of the plurality of sound absorbing devices, and the amount of material sheet waste can be reduced, contributing to environmental conservation and improvement.

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

Furthermore, in the above-mentioned first and second embodiments and variants, a sound absorbing section with a multi-layer structure has been exemplified, 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, second sound absorbing layer, and 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-layer 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.

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 engine noise and other noises generated by the vehicle's power source (power source-derived noise) are 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 and second noises may be the above-described road noise and power source-derived noise, or may be other noises, such as collision noises generated by the vehicle colliding with an object outside the vehicle (earth, sand, pebbles, water, etc.). Furthermore, the first noise is not limited to noises with a lower frequency band than the second noise, and may also be noises with a higher frequency band than the second noise.

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

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

1, 1A, 1A-1, 1A-2 Sound absorbing device 10, 10A, 10A-1, 10A-2 Sound absorbing part 11 First sound absorbing layer 11a First sound absorbing surface 12 Second sound absorbing layer 12a Second sound absorbing surface 13 Intermediate layer 14 Edge portion 15 Compressed portion 20, 20A, 20A-1, 20A-2 Frame 21, 21A Overlapping portion 22 Through hole 23 Upper portion 24 Mounting portion 25 Extension portion 30 Resin 50 Molding mold 51 First mold 51a, 51b Cavity surface 51c Boundary portion 52 Pressing pin 55 Second mold 55a, 55b Cavity surface 100 Vehicle 101 Fender liner 102 Apron 103 Tire 104 Wheel 105 Undercover 106 Side member 107 Power source 110 First noise 120 Second noise 200 Material sheet 200a, 200b, 200c-1, 200c-2, 200d-1, 200d-2 Divided body D1 Front-rear direction D2 Width direction D3 Up-down direction

Claims (4)

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: 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: 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. 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.