JP2024016979A - Sound absorption structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound absorption structure capable of further improving sound absorption performance.

SOLUTION: The present invention relates to a sound absorption structure that fits a cover 2, which has a porous sound absorber 3 fitted to an opposite member 1 vibrating to generate a sound and a surface member 4 covering an outer surface, not opposed to the opposite member 1, of a surface of the sound absorber 3, to the opposite member 1. The sound absorber 3 is fitted to the opposite member 1 with a fastener 7 for the opposite member 1 while partially compressed in contact with the surface of the opposite member 1, and a space part 8 is provided between a place, except a part, brought into contact with the opposite member 1, of the sound absorber 3 and the opposite member 1.

SELECTED DRAWING: Figure 4

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a sound absorbing structure that absorbs sound waves or vibrations and suppresses the sound from leaking to the outside.

An example of this type of sound absorbing structure is described in Patent Document 1. To briefly explain its structure, one of a pair of plates is provided with a plurality of protrusions such as protrusions with a rectangular cross section that protrude toward the other plate, and these protrusions form a porous structure. It is said that Furthermore, the so-called recessed portions between these protrusions are filled with a sound absorbing material. The other plate is disposed opposite to the one plate with the sound absorbing material sandwiched therebetween, and a sound absorbing space is provided between the other plate and the tip of the protrusion. According to the sound absorbing structure described in Patent Document 1, the particle velocity inside the sound absorbing space increases due to the minute vibrations of the other plate, and the vibrations are absorbed by the sound absorbing material filled between the protrusions. Furthermore, the porous structure of the protrusion itself exerts a sound-absorbing function, and these effects combine to ensure sound-absorbing performance. Note that the tip end surface of the protrusion is configured to receive the other plate when an external force is applied to the other plate.

Japanese Patent Application Publication No. 2009-40073

In the configuration described in Patent Document 1, when a sound absorbing structure consisting of one plate having a protrusion and the other plate facing it is attached to a noise source, the external force for fixing the structure is applied to each plate. It acts between. Therefore, in such a case, the protrusion and the other plate may come into contact with each other, and the above-described sound-absorbing space may substantially disappear. In that case, when the other vibrating plate comes into contact with the protrusion, the vibrations (sound waves) may propagate to one plate via the protrusion, and may even be emitted outside as noise. be. Furthermore, even if there is a sound-absorbing effect due to the sound-absorbing material filled between the protrusions, the sound-absorbing material is provided in a limited area between each protrusion, so the total amount of sound-absorbing material is limited. There is a possibility that the sound absorption effect will be reduced due to such reasons.

This invention has been made in view of the above-mentioned technical problem, and it is an object of the present invention to provide a sound absorbing structure that can further improve sound absorbing performance.

In order to achieve the above object, the present invention provides a porous sound-absorbing material that is attached to a mating member that vibrates and generates sound, and a surface that covers an outer surface of the sound-absorbing material that does not face the mating member. The sound absorbing structure includes a cover having a member attached to the mating member, wherein the sound absorbing material is attached to the mating member with a fastener to the mating member with a part of the sound absorbing material in close contact with the surface of the mating member and compressed. It is characterized in that a space is provided between a portion of the sound absorbing material other than the part that is in close contact with the mating member and the mating member.

In this invention, the sound or sound wave generated by the vibration of the mating member is absorbed by the porous sound absorbing material, so that a soundproofing effect is produced. A part of the sound-absorbing material comes into close contact with the mating member for fastening to the mating member, and absorbs sound at a frequency corresponding to the degree of compression (or density due to compression) for fastening. In addition, by providing a space between other parts of the sound-absorbing material and the mating member, direct vibration propagation from the mating member to the sound-absorbing material is blocked, and the part of the mating member corresponding to this space Sound energy is absorbed or consumed by vibrations. As a result, according to the present invention, an excellent sound absorption effect can be obtained by the sound absorption according to the density due to the compression of the sound absorbing material and the sound absorption due to the provision of the space.

FIG. 1 is a plan view of an embodiment of the invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1 and omitting the internal structure of a mating member. FIG. 2 is a cross-sectional view taken along line III-III in FIG. 1 and omitting the internal structure of the mating member. (A) is a cross-sectional view taken along the line IV--IV in FIG. 1, omitting the internal structure of the mating member, and (B) is a partially enlarged view thereof.

Next, embodiments of the present invention will be described with reference to the drawings. Note that the embodiment described below is only an example of implementing the present invention, and is not intended to limit the present invention.

FIG. 1 shows an embodiment in which the present invention is applied to a vehicle, and the left-right direction in FIG. 1 is the front-rear direction of the vehicle, and the up-down direction in FIG. 1 is the left-right direction (width direction) of the vehicle. . In FIG. 1, reference numeral "1" indicates a mating member in the embodiment of the present invention, an example of which is a cylinder head cover of an engine mounted on a vehicle. Since the cylinder head cover has a relatively thin plate-like (membrane-like) portion with no irregularities, this portion may cause so-called membrane vibration and generate noise. The NV cover 2 is attached to cover the portion where such noise is generated.

As shown in FIGS. 2 to 4, the NV cover 2 is configured to cover a part of the surface of the mating member 1, and includes a highly elastic and porous sound absorbing material 3 such as urethane, and a sound absorbing material 3 made of the sound absorbing material 3. It is constituted by a thin synthetic resin surface member 4 that covers the outer surface (the surface not facing the mating member 1). The sound absorbing material 3 has a thickness that provides the required sound absorbing performance, and has a shape that approximately follows the shape of the surface of the mating member 1. In particular, the inner surface 3a has substantially the same shape as the surface of the mating member 1 where the NV cover 2 is to be attached.

More specifically, the NV cover 2 is attached to the mating member 1 by bringing a part of its inner surface 3a into close contact with the surface of the mating member 1. (A) and (B) of FIG. 4 show the close contact area, and the part of the mating member 1 that faces in the vertical direction (vertical direction in FIG. 4) is the so-called seat surface 5. A lower surface portion 6 facing the seat surface 5 is formed as a part of the inner surface 3a of the sound absorbing material 3. The NV cover 2 is attached to the mating member 1 with its lower surface 6 placed on the seat surface 5 and brought into close contact. That is, in the vicinity of the lower surface portion 6 and the seat surface 5, there is provided a fastener 7 such as a bolt that passes through the NV cover 2 in the vertical direction and screws its tip into the mating member 1. By tightening the fasteners 7, the NV cover 2 is attached to the mating member 1 with the required strength.
Note that, as shown in FIG. 1, the fasteners 7 are arranged at both ends of the NV cover 2 in the longitudinal direction (the longitudinal direction of the vehicle). Therefore, in this state, a part of the sound absorbing material 3 is sandwiched between the surface member 4 and the seat surface 5 and is compressed. The degree of compression or the density due to compression is related to the sound absorption characteristics of the sound absorbing material 3, so the fastener should be 7 determines the degree of compression or density of the sound absorbing material 3.

Although the sound absorbing material 3 is in contact with the mating member 1 in the vertical direction, it is not in contact with the mating member 1 in the front-rear direction or the left-right direction (width direction) at other predetermined locations, and the sound absorbing material 3 is in contact with the mating member 1 in the vertical direction. A space 8 is provided between them.

The mating member 1 vibrates slightly as the engine rotates, for example, and thus becomes a source of noise. Since the above-mentioned NV cover 2 is attached to the surface side of the part of the mating member 1 that tends to generate sound, most of the vibrations (sound waves or sounds) propagated from the mating member 1 to the NV cover 2 are absorbed by the sound absorbing material. Absorbed by 3. As described above, the sound absorbing material 3 is attached to the mating member 1 with the lower surface portion 6 in close contact with the seat surface 5. Therefore, sound (vibration) is transmitted to the sound absorbing material 3 through these mutually contacting parts. ) is propagated. However, the sound absorbing material 3 is not compressed to the extent that its porous structure is completely collapsed, but is compressed to the extent that predetermined pores are formed and maintains a predetermined density. Of the vibrations propagated to the sound absorbing material 3, vibrations at a predetermined frequency are absorbed by the sound absorbing material 3, and leakage of sound at that frequency to the outside as noise is avoided or suppressed.

On the other hand, since the mating member 1 vibrates slightly at the location where the space 8 is provided, sound energy is absorbed or consumed by the vibration, and noise to the outside is suppressed accordingly. Furthermore, in addition to the fact that the minute vibrations of the mating member 1 are not directly propagated to the sound absorbing material 3 , the sound propagated to the sound absorbing material 3 via the air inside the space 8 is absorbed by the sound absorbing material 3 . Accordingly, noise to the outside is suppressed. Furthermore, in the above-described sound-absorbing structure, the sound-absorbing material 3 and the mating member 1 are opposed to each other with the space 8 in between, without being in contact with each other in many places, except for the close contact in some parts for fastening. Therefore, the area of the sound absorbing material 3 that absorbs sound propagating through the air inside the space 8 becomes wider, and the sound absorbing performance improves accordingly. Overall, in the embodiment of the present invention described above, the sound absorption effect can be improved more than ever before, and the generation of noise from the mating member 1 to the outside can be suppressed.

1 Mating member 2 NV cover 3 Sound absorbing material 3a Inner surface 4 Surface member 5 Seat surface 6 Lower surface portion 7 Fastener 8 Space portion

Claims (1)

A sound absorbing device in which a cover is attached to the mating member, the cover having a porous sound-absorbing material attached to a mating member that vibrates and generates sound, and a surface member covering an outer surface of the sound-absorbing material that does not face the mating member. The structure is
The sound absorbing material is attached to the mating member with a fastener for the mating member in a compressed state with a part of the sound absorbing material in close contact with the surface of the mating member,
A sound-absorbing structure characterized in that a space is provided between a portion of the sound-absorbing material excluding the part that is in close contact with the mating member and the mating member.

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