JPH08301024A - Soundproof material - Google Patents

Abstract

PURPOSE: To provide a soundproof material which can efficiently shield and absorb its noise even if a noise of a different frequency level is generated and whose weight is not increased. CONSTITUTION: A soundproof material 1 having three sheets 2, 3 and 4 and air layers 5, 6 and 7, is installed on a surface on the engine room side of a hood panel P. Through holes 2a, 3a and 4a are respectively formed at prescribed intervlas in the respective sheets 2 to 4. Energy of a noise is attenuated and absorbed mainly by the so-called resonance effect when its wave passes through the through holes 2a to 4a and is propagated to the air layers 5 to 7 or the like. A wave of the noise strikes on the sheets 2 to 4, and its sheets 2 to 4 themselves move slowly. Its energy is converted into vibration, heat or the like, and energy possessed by the noise is attenuated. Particularly, since the plural sheets 2 to 4 and the plural air layers 5 to 7 are arranged, individual sound absorbing characteristics can be made different from each other, and resonance type sound absorption is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soundproof material attached to an adherend, for example, a hood panel for a vehicle, a roof panel, a floor panel, an engine cover of an engine, etc. The present invention relates to a soundproofing material for suppressing the propagation of heat to the outside or a vehicle interior.

[0002]

2. Description of the Related Art Conventionally, for example, a hood panel (bonnet) for a vehicle is provided with a sheet-like soundproof material on the engine room side surface in order to suppress noise generated from the engine from leaking to the outside. It is worn.

Materials such as felt and glass wool are used as this type of soundproof material. Alternatively, as shown in FIG. 5, the glass wool layer 31 is replaced with the felt layer 32.
A soundproof material 33 coated with is also used. And
As a material constituting these soundproofing materials, materials that match the frequency level of generated noise tend to be adopted. For example, the two-layer structure of the glass wool layer 31 and the felt layer 32 as described above is provided around the engine room, and the vinyl chloride leather having innumerable through holes is provided on the roof panel.
The wheel house was made of felt, and the floor panels were made of asphalt, felt and a three-layer structure of carpet.

[0004]

However, in the above-mentioned prior art, when there are many noise sources such as an engine room and the generated frequency levels are different, effective soundproofing performance may not be obtained. there were. That is,
Inside the engine room, various members such as an engine body, an intake system and a mission are arranged. Then, noise having various frequency levels was generated from these various members. On the other hand, in the conventional technique (for example, the soundproof material 33 is used as the glass wool layer 31 and the felt layer 32).
In the case of a layered structure), as shown in FIG. 6, although the noise absorption ability in a relatively high frequency range of “2 kHz” or more is excellent, a relatively low frequency of less than “2 kHz” is obtained. It was difficult to absorb the noise in the area. As a result, it may not be possible to efficiently shield and absorb low-frequency noise, which may be annoying to such a driver or an external person.

On the other hand, each layer 31, which constitutes the soundproof material 33 and the like,
It is also possible to absorb noise in the low frequency region by setting a large thickness such as 32. However,
In such a case, the thickness of the soundproof material 33 becomes large,
The weight will increase significantly. Therefore, a soundproof material in which the thickness of each layer 31, 32, etc. is simply increased has a problem in practical use.

The present invention has been made to solve the above problems, and an object thereof is to provide a large number of noise sources,
It is an object of the present invention to provide a soundproof material that can efficiently shield and absorb noise even if noise of different frequency levels is generated, and that does not cause an increase in weight.

[0007]

In order to achieve the above object, in the invention described in claim 1, the noise attached to the adherend and generated inside the adherent is transmitted to the outside. A soundproofing material for suppressing propagation, which has a plurality of sheets having a plurality of through holes and laminated with each other, and at least an air layer provided between the sheets. I am trying.

In the invention according to claim 2, the gist of the soundproofing material according to claim 1 is that at least one of the size, shape and interval of the through holes is different for each sheet. There is.

Further, in the invention according to claim 3, in the soundproof material according to claim 1 or 2, the sheet is composed of two or more sheets so that a plurality of the air layers are arranged, and at least one sheet is provided. The point is that the thickness of each air layer is different in each section.

In addition, in the invention described in claim 4, the gist of the soundproofing material according to any one of claims 1 to 3 is that the sheet is made of a thermoplastic resin.

Here, any material may be used as the above-mentioned sheet, but a thermoplastic resin is particularly preferably used from the viewpoint of convenience of molding and shape retention. As the thermoplastic resin, for example, polyester such as PET and PBT (polybutylene terephthalate), polyamide such as nylon, polyolefin such as PE and PP (polypropylene), PVC and the like can be preferably used. The thickness of the sheet is preferably 0.1 mm to 1.5 mm, more preferably 0.3 mm to 0.8 mm.

[0012]

According to the invention described in claim 1, the soundproof material is attached to the adherend, and the soundproof material suppresses the propagation of the noise generated inside the adherend to the outside. Is planned.

The soundproof material has a plurality of sheets having a plurality of through holes and laminated on each other, and at least an air layer provided between the sheets, and noise energy is mainly transmitted through its wave. When passing through the holes and propagating to the air layer or the like, they can be attenuated and absorbed by the so-called resonance effect. In addition, the wave of noise hits the seat and the seat itself vibrates slightly. Then, the energy is converted into oscillating heat or the like, whereby the energy of noise can be attenuated. In particular, in the present invention, a plurality of sheets are provided,
Since the air layer is provided between them, it is possible to mutually shift the sound absorption characteristics, that is, the frequency (peak frequency) regions where the sound absorption is highest. Therefore, large sound absorption in a wider frequency range is possible.

Further, in the present invention, since the soundproof material is composed of the relatively thin sheet and the air layer, the weight of the soundproof material as a whole does not become so large. According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, at least one of the size, shape and interval of the through holes is different for each sheet. Therefore, the degree of the resonance effect when propagating through the through holes of each sheet varies depending on the sheet and the through holes. Therefore, the operation of shifting the peak frequency regions described above can be performed relatively easily and reliably.

Further, according to the invention of claim 3,
In addition to the effect of the invention described in claim 1 or 2, the sheet is composed of two or more sheets so that a plurality of air layers are arranged, and at least a part of each of the air layers has a different thickness. Therefore, similarly to the invention described in claim 2, the operation of shifting the peak frequency regions from each other can be performed relatively easily and reliably.

In addition, according to the invention described in claim 4,
In addition to the action of the invention according to any one of claims 1 to 3,
Since the sheet is composed of a thermoplastic resin,
It is easy to secure the formability and shape retention of the sheet,
The cost increase can be suppressed. Also, joining between the sheets can be easily performed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment embodying the present invention will now be described with reference to FIGS.
It will be described based on 3. In the present embodiment, the surface of the hood panel (bonnet) P as an adherend of the automobile on the engine room side (the lower side of the figure) has a soundproof structure for suppressing the noise generated from the engine from leaking to the outside. Material 1 is attached. As shown in FIG. 1, the soundproof material 1 has a sheet shape as a whole. The soundproofing material 1 includes three sheets 2, 3 and 4 and air layers 5 and 6 provided between these sheets 2 to 4. Further, the seat 4 located closest to the hood panel P is provided with irregularities, and an air layer 7 is provided between the concave portion and the hood panel P.

In this embodiment, each of the sheets 2 to 4 is
Is formed of polypropylene to a thickness of about 0.5 mm. Each sheet 2-4 has a diameter of 0.5 m
Through holes 2a, 3a, 4a of about "m" are formed at predetermined intervals. The interval is set so that, for example, the seat 4 located closest to the hood panel P side becomes smaller. That is, the distance between the through holes 2a is "8 mm".
In addition, the distance between the through holes 3a is set to "4 mm", and the distance between the through holes 4a is set to "2 mm".

The peripheral portions of the sheets 2 to 4 are heat-sealed or adhered to each other to form 1
A sheet of soundproofing material 1 is constructed. Next, the operation and effect of the soundproofing material 1 in this embodiment will be described.

In the present embodiment, the soundproofing material 1 attached to the hood panel P can suppress the noise generated in the engine room with the hood panel P as a boundary from being propagated to the outside. That is, the soundproof material 1 has a plurality of through holes 2a to 4a, and a plurality of sheets 2 to 4 which are laminated with each other,
With the air layers 5 to 7, the energy of noise can be attenuated and absorbed by the so-called resonance effect mainly when the wave thereof propagates through the through holes 2a to 4a to the air layers 5 to 7 and the like. Also, noise waves hit sheets 2-4,
The sheets 2 to 4 vibrate slightly. Then, the energy is converted into oscillating heat or the like, whereby the energy of noise can be attenuated.

In particular, in this embodiment, a plurality of sheets 2 to
4 is provided and a plurality of air layers 5 to 7 are provided, so that the individual sound absorption characteristics, that is, the frequency (peak frequency) region where the sound absorption coefficient is highest, as shown in FIG. Can be shifted from each other. For example, in the figure, the sheet 2 on the noise source side mainly absorbs sound having a peak frequency on the low frequency side, and the sheet 4 on the hood panel P side mainly absorbs sound having a peak frequency on the high frequency side. Therefore, as shown in FIG. 2B, it is possible to superimpose a so-called resonance-type sound absorption in which each curve of FIG. It is possible to reliably absorb noise in the frequency domain.

Further, according to this embodiment, in particular, each through hole 2
The intervals a to 4a are set to be different for each of the sheets 2 to 4. Therefore, the through holes 2 of each of the sheets 2 to 4
The degree of the resonance effect when passing through the sheets a to 4a differs depending on the sheets 2 to 4. Therefore, the action of shifting the peak frequency regions described above can be performed relatively easily and reliably.

Further, according to the present embodiment, the soundproof material 1 is composed of the relatively thin sheets 2 to 4 and the air layers 5 to 7, so that the weight of the soundproof material 1 as a whole becomes large. There is no. Therefore, it is possible to achieve excellent noise prevention performance in a wide frequency range, and at the same time, significantly reduce the weight.

Here, the following experiment was conducted in order to confirm the action and effect of the above sound absorption. That is,
A sample of the soundproof material 1 was prepared, and the sound absorption coefficient was actually measured by changing the frequency of the sample. The result is shown in Figure 3.
Shown in

As shown in the figure, it can be seen that the sample of the soundproofing material 1 of the present embodiment has a high noise absorbing effect as a whole as compared with the prior art. In particular, it can be seen that the noise in the relatively low frequency region where the frequency is less than “2 kHz” can be reliably absorbed. Therefore, according to the soundproofing material 1 of the present embodiment, it can be said that it is possible to efficiently absorb the noise at the low frequency level, which may be annoying to the driver or those outside, and to exhibit excellent soundproofing performance. .

The present invention is not limited to the above embodiment, but may be configured as follows, for example. (1) In the above embodiment, the three sheets 2 to 4 are:
Although each of the sheets has a substantially flat shape, for example, as shown in FIG. 4, the sheets 12, 13, 1 having the legs 12b, 13b, 14b together with the through holes 12a, 13a, 14a.
4 may be adopted. With such a configuration, the leg portions 12b to 14b come into contact with the adjacent sheets, so that the interval between the sheets 12 to 14 can be kept constant and the shape retention can be improved.

(2) In the above embodiment, the intervals of the through holes 2a to 4a are set to be different for each sheet 2 to 4, but
The sizes, shapes, etc. of the through holes 2a to 4a may be changed, and these changes may be appropriately combined.

(3) In the above embodiment, the intervals between the sheets 2 to 4 are made substantially constant and the widths (thicknesses) of the air layers 5 to 7 are made substantially constant, but these widths are changed. You may do it. Even with such a configuration, peak frequency regions can be shifted from each other, and excellent noise prevention performance in a wide frequency region can be easily exerted.

(4) In the above-described embodiment, the soundproof material 1 and the like are attached to the hood panel P in the engine room. However, the roof panel, the wheel house, the floor panel, the engine cover of the engine, etc. In addition to the various objects to be attached in the above item, it may be attached to other places for suppressing noise.

(5) In the above embodiments, polypropylene was adopted as the material for forming the sheets 2 to 4, but polyesters such as PET and PBT (polybutylene terephthalate), polyamides such as nylon, PE and PP were used.
It may be made of any material including polyolefins such as (polypropylene) and various thermoplastic resins such as PVC.

(6) In the above embodiment, the three sheets 2 to
Although the soundproofing material 1 is configured by 4, the soundproofing material 1 may be configured by any number as long as it is at least two or more. (7) In the above embodiment, the distance between the through holes 2a is "8 mm".
In the above, the distance between the through holes 3a is set to "4 mm" and the distance between the through holes 4a is set to "2 mm". However, the values are not limited to these values. The interval between 2a may be smaller than the interval between the through holes 4a.

The technical idea which is not described in each claim of the claims and which can be grasped from the above-mentioned embodiment will be described below together with its effect. (A) The soundproof material according to any one of claims 1 to 4, wherein the sheet is provided with a leg portion that can be brought into contact with an adjacent sheet. With such a configuration, the distance between the sheets can be kept constant and the shape retention can be improved.

[0033]

As described above in detail, according to the soundproof material of the present invention, even if there are many noise sources and noises of different frequency levels are generated, the noises can be effectively shielded and absorbed. It has an excellent effect that it is possible to achieve a significant weight reduction.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a soundproof material according to an embodiment.

FIG. 2A and FIG. 2B are graphs showing the relationship of the normal incident sound absorption coefficient with respect to the frequency for explaining the action of the soundproofing material of the embodiment.

FIG. 3 is an actual measurement graph for explaining the function and effect of the soundproofing material according to the embodiment.

FIG. 4 is a cross-sectional view schematically showing a main part of a soundproof material in another example.

FIG. 5 is a cross-sectional view schematically showing a soundproofing material in a conventional technique.

FIG. 6 is a graph showing the relationship between the normal incident sound absorption coefficient and the frequency of a conventional soundproofing material.

[Explanation of symbols]

1 ... Soundproofing material, 2, 3, 4, 12, 13, 14 ... Sheet,
2a, 3a, 4a, 12a, 13a, 14a ... through hole,
5, 6, 7 ... Air layer, P ... Hood panel as an adherend.

Front Page Continuation (72) Inventor Yutaka Ogasawara 1st Nagahata, Ochiai, Nishikasugai-gun, Aichi Prefecture Toyoda Gosei Co., Ltd. In the company

Claims (4)

[Claims] 1. A soundproofing material (1) attached to an adherend (P) for suppressing the propagation of noise generated inside the adherend (P) to the outside. A plurality of through holes (2a, 3a, 4a, 12a, 13a, 14
a), a plurality of sheets (2, 3, 4, 12, 13, 14) laminated on each other, and at least the sheets (2, 3, 4, 12, 13, 1)
4) A soundproof material comprising an air layer (5, 6, 7) provided between them. 2. The through holes (2a, 3a, 4a, 12a,
13a, 14a) has at least one of the size, shape and interval of each of the sheets (2, 3, 4, 12, 13,
14) different according to 14).
Soundproofing material described in. 3. The seats (2, 3, 4, 12, 13, 14) so that a plurality of the air layers (5, 6, 7) are arranged.
The soundproof material according to claim 1 or 2, characterized in that the air layer (5, 6, 7) is composed of two or more sheets, and the air layers (5, 6, 7) have different thicknesses in at least a part thereof. 4. The sheet (2, 3, 4, 12, 13,
The soundproof material according to any one of claims 1 to 3, wherein 14) is made of a thermoplastic resin.