JP2000263679A - Sound-absorbing structure body - Google Patents
Sound-absorbing structure bodyInfo
- Publication number
- JP2000263679A JP2000263679A JP11076153A JP7615399A JP2000263679A JP 2000263679 A JP2000263679 A JP 2000263679A JP 11076153 A JP11076153 A JP 11076153A JP 7615399 A JP7615399 A JP 7615399A JP 2000263679 A JP2000263679 A JP 2000263679A
- Authority
- JP
- Japan
- Prior art keywords
- sound
- foam material
- absorbing structure
- foam
- sound absorbing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Building Environments (AREA)
- Laminated Bodies (AREA)
- Soundproofing, Sound Blocking, And Sound Damping (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明はフォーム材からなる
吸音構造体に関し、特に自動車用エンジンカバーに好適
に用いられる吸音構造体に関するBACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound absorbing structure made of a foam material, and more particularly to a sound absorbing structure suitably used for an engine cover of an automobile.
【０００２】[0002]
【従来の技術】連続気泡のフォーム材およびグラスウー
ルなどの連続気泡のみからなる多孔質体は、良好な吸音
特性を有することが一般的に知られている。そのため、
例えば自動車から放射される騒音低減を目的として、自
動車のエンジンカバーの内部やボンネットの内部などの
吸音処理に用いられている。しかし、これらの連続気泡
構造の多孔質体は中低音域の吸音率を高くするためには
吸音材を厚くする必要があるが、エンジンカバーやボン
ネットの内側はスペースが限られているために厚い吸音
材を設置できない場合が多く、従来の連続気泡構造の吸
音材では十分な吸音効果が得られない。2. Description of the Related Art It is generally known that a porous body composed of only open cells such as an open-cell foam material and glass wool has good sound absorbing properties. for that reason,
For example, for the purpose of reducing noise radiated from an automobile, it is used for sound absorption processing inside an engine cover or inside a hood of an automobile. However, these porous bodies with an open-cell structure require a thicker sound-absorbing material in order to increase the sound absorption coefficient in the mid-low range, but are thicker due to limited space inside the engine cover and hood. In many cases, a sound absorbing material cannot be installed, and a conventional sound absorbing material having an open-cell structure cannot provide a sufficient sound absorbing effect.
【０００３】また、連続気泡と独立気泡との混成の気泡
構造を有するフォーム材も使用されている。この混成気
泡構造を有するフォーム材は比較的低周波側に吸音のピ
ークを有するが、そのピーク値自体は十分に高いとはい
えない。また、厚いものほど低周波側に吸音ピークがシ
フトするが、そのピーク自体の周波数の幅が狭く、特定
の単一周波数もしくはその極く近傍の周波数の音源に対
しては、それらの周波数に対応した厚さの材料を用いる
ことである程度の吸音効果が得られる場合がある。しか
し、例えば、エンジンカバーの内部やボンネットの内部
などの使用部位の構造の制約上、フォーム材の厚さを自
由に変更することができない場合が多い。また、自動車
のエンジンルームの騒音は、通常ある程度の幅を持った
周波数域で大きい値を示すため、吸音率のピークの周波
数の幅が狭く、しかもこのピークを示す周波数が厚さに
依存する混成気泡構造を有するフォーム材では、十分な
吸音効果が得られない。[0003] A foam material having a mixed cell structure of open cells and closed cells has also been used. The foam material having the hybrid cell structure has a sound absorption peak on a relatively low frequency side, but the peak value itself is not sufficiently high. The sound absorption peak shifts to the lower frequency side as the thickness increases, but the width of the frequency of the peak itself is narrow, and the sound source corresponding to a specific single frequency or a frequency very close to the specific frequency corresponds to those frequencies. The use of a material having the specified thickness may provide a certain level of sound absorbing effect. However, for example, in many cases, the thickness of the foam material cannot be freely changed due to the restriction of the structure of a used portion such as the inside of an engine cover or the inside of a hood. In addition, since the noise in the engine room of an automobile usually shows a large value in a frequency range having a certain width, the peak frequency of the sound absorption coefficient is narrow, and the frequency at which this peak is present depends on the thickness. A foam material having a cellular structure cannot provide a sufficient sound absorbing effect.
【０００４】また、独立気泡のみからなる気泡構造を有
するフォーム材も使用されているが、全周波数域におい
て吸音率が低く、それ自体ほとんど吸音効果を示さな
い。Further, a foam material having a cell structure consisting of closed cells alone is also used, but has a low sound absorption coefficient over the entire frequency range and exhibits almost no sound absorption effect itself.
【０００５】[0005]
【発明が解決しようとする課題】本発明は上記の状況に
鑑みてなされたものであり、広い周波数域において良好
な吸音特性を有し、更に目的等に応じて所望の周波数域
における吸音特性を特に高くすることが可能な吸音構造
体及び自動車用エンジンカバーを提供することを目的と
するものである。SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, has good sound absorption characteristics in a wide frequency range, and further has a desired sound absorption characteristic in a desired frequency range according to the purpose. It is an object of the present invention to provide a sound absorbing structure and an automobile engine cover that can be made particularly high.
【０００６】[0006]
【課題を解決するための手段】本発明者らは鋭意検討し
た結果、特定の気泡構造を有するフォーム材を特定の状
態で積層配置することで、広い周波数域において良好な
吸音効果を有し、また容易に所望の周波数域における吸
音特性を特に高くすることができることを見出した。さ
らに、従来のフォーム材からなる吸音材と比較して、そ
の厚さが半分以下であっても同等以上の吸音特性を示す
ことを見い出した。本発明はこのような知見に基づくも
のである。すなわち、本発明は、連続気泡と独立気泡と
の混成の気泡構造を有するフォーム材を二層以上積層し
てなることを特徴とする吸音構造体、並びに、前記吸音
構造体を用いた自動車用エンジンカバーである。Means for Solving the Problems As a result of intensive studies, the present inventors have found that a foam material having a specific cell structure is layered and arranged in a specific state, thereby having a good sound absorbing effect in a wide frequency range. It has also been found that the sound absorption characteristics in a desired frequency range can be particularly easily increased. Furthermore, it has been found that as compared with a conventional sound absorbing material made of a foam material, even if the thickness is less than half, the same sound absorbing characteristics are exhibited. The present invention is based on such findings. That is, the present invention provides a sound absorbing structure comprising two or more layers of a foam material having a mixed cell structure of open cells and closed cells, and an automobile engine using the sound absorbing structure. It is a cover.
【０００７】[0007]
【発明の実施の形態】以下、本発明に関して詳細に説明
する。一般的にフォーム材の気泡構造は連続気泡単独、
連続気泡と独立気泡との混成、独立気泡単独に大別され
る。連続気泡のみからなるフォーム材は低周波側の垂直
入射吸音率が低いため、材料を厚くする必要ある。ま
た、この連続気泡構造を有するフォーム材同士を積層し
ても吸音効果はまったく向上しない。一方、独立気泡の
みからなるフォーム材は、全周波数域において低い垂直
入射吸音率しか示さない。また、この独立気泡構造を有
するフォーム材同士を積層しても吸音効果はまったく向
上しない。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. Generally, the foam structure of the foam material is open cell only,
It is roughly classified into a mixture of open cells and closed cells, and closed cells alone. The foam material composed of only open cells has a low normal incidence sound absorption coefficient on the low frequency side, and thus the material needs to be thickened. Further, even if the foam materials having the open cell structure are laminated, the sound absorbing effect is not improved at all. On the other hand, a foam material consisting of closed cells only has a low normal incidence sound absorption coefficient in all frequency ranges. Further, even if the foam materials having the closed cell structure are laminated, the sound absorbing effect is not improved at all.
【０００８】これに対して本発明の吸音構造体は、連続
気泡と独立気泡との混成の気泡構造を有するフォーム材
を二層以上積層することにより、広い周波数域において
良好な吸音効果を有する吸音構造体となる。本発明で使
用する連続気泡と独立気泡との混成の気泡構造を有する
フォーム材料は、その主成分がゴムまたはエラストマー
であることが好ましい。これらは柔軟なフォームとな
り、セルの膜振動による吸音機構が発現するため、吸音
特性の良好な吸音構造体が得られる。ゴムまたはエラス
トマーとしては天然ゴム、ＣＲ（クロロプレンゴム）、
ＳＢＲ（スチレン・ブタジエンゴム）、ＮＢＲ（ニトリ
ル・ブタジエンゴム）、ＥＰＤＭ（エチレン・プロピレ
ン・ジエン三元共重合体）ゴム、シリコーンゴム、フッ
素ゴム、アクリルゴムなどの各種ゴム、熱可塑性エラス
トマー、軟質ウレタン等の各種エラストマーが挙げられ
るが、これらに限定されない。特にＥＰＤＭゴムを主成
分とするフォーム材は耐熱性、耐オゾン性、価格のバラ
ンスが良いため、自動車のエンジンカバー用としては好
ましい。また、このようなフォーム材として、例えば建
築用や弱電用の止水シール材として市販されているＥＰ
ＤＭやＮＢＲのフォーム材シートを使用してもよい。On the other hand, the sound-absorbing structure of the present invention has a sound-absorbing effect having a good sound-absorbing effect in a wide frequency range by laminating two or more foam materials having a mixed cell structure of open cells and closed cells. It becomes a structure. The main component of the foam material having a mixed cell structure of open cells and closed cells used in the present invention is preferably rubber or elastomer. These are flexible foams, and exhibit a sound absorbing mechanism due to cell membrane vibration, so that a sound absorbing structure having good sound absorbing characteristics can be obtained. Natural rubber, CR (chloroprene rubber),
Various rubbers such as SBR (styrene / butadiene rubber), NBR (nitrile / butadiene rubber), EPDM (ethylene / propylene / diene terpolymer) rubber, silicone rubber, fluorine rubber, acrylic rubber, thermoplastic elastomer, and soft urethane And the like, but are not limited thereto. In particular, a foam material containing EPDM rubber as a main component is preferable for use as an automobile engine cover because it has a good balance of heat resistance, ozone resistance, and price. Further, as such a foam material, for example, EP which is commercially available as a water-blocking seal material for construction or weak electricity is used.
A foam material sheet such as DM or NBR may be used.
【０００９】本発明で使用されるフォーム材は連続気泡
と独立気泡との混成気泡構造であるから、連続気泡の割
合が多くなると連続気泡単独のフォーム材の欠点が現れ
るようになり、独立気泡の割合が多くなると、独立気泡
単独のフォーム材の欠点が現れるようになる。一般的
に、連続気泡構造のフォーム材は吸水率が大きく、独立
気泡構造のフォーム材は吸水率が小さく、連続気泡と独
立気泡の混成気泡構造のフォーム材はその中間である。
従って、この吸水率を特定することにより、連続気泡と
独立気泡との割合を規定することができるようになる。
吸水率はJIS K6767のB法によって測定され、本発明で使
用するフォーム材の吸水率は好ましくは0.01 g/cm3以上
で0.2g/cm3以下、より好ましくは0.02g/cm3以上で0.15g
/cm3以下、さらに好ましくは0.04g/cm3以上で0.1g/m3以
下とするのが良い。Since the foam material used in the present invention has a mixed cell structure of open cells and closed cells, when the proportion of open cells increases, the disadvantage of the open cell alone foam material appears, As the proportion increases, the disadvantage of the foam material consisting of closed cells alone appears. Generally, a foam material having an open-cell structure has a high water absorption, a foam material having a closed-cell structure has a low water absorption, and a foam material having a mixed-cell structure of open cells and closed cells is intermediate.
Therefore, by specifying the water absorption, the ratio of open cells to closed cells can be defined.
The water absorption is measured by the method B of JIS K6767, the water absorption of the foam material used in the present invention is preferably 0.01 g / cm 3 or more and 0.2 g / cm 3 or less, more preferably 0.02 g / cm 3 or more and 0.15 or more. g
/ cm 3 or less, more preferably 0.04 g / cm 3 or more and 0.1 g / m 3 or less.
【００１０】密度の低いフォーム材は低周波側の垂直入
射吸音率が低いため、材料を厚くすの必要がある。ま
た、密度の低いフォーム材同士を積層しても吸音効果は
ほとんど向上しない。密度の高いフォーム材は全周波数
域において低い垂直入射吸音率しか示さない。また、密
度の高いフォーム材同士を積層しても吸音効果はほとん
ど向上しない。よって、本発明で使用するフォーム材は
ある特定の範囲の密度を持つことが好ましい。本発明で
使用するフォーム材の密度は好ましくは20kg/m3 以上で
400kg/m3以下、より好ましくは30kg/m3 以上で300kg/m3
以下、さらに好ましくは50kg/m3 以上で200kg/m3以下と
するのが良い。A low-density foam material has a low normal incidence sound absorption coefficient on the low frequency side, so that it is necessary to make the material thicker. Further, even if foam materials having low density are laminated, the sound absorbing effect is hardly improved. Dense foam materials show low normal incidence sound absorption over the entire frequency range. Further, even if high-density foam materials are laminated, the sound absorbing effect is hardly improved. Therefore, it is preferable that the foam material used in the present invention has a certain specific range of density. Density of the foam material used in the present invention is preferably 20 kg / m 3 or more
400 kg / m 3 or less, more preferably 30 kg / m 3 or more and 300 kg / m 3
Hereinafter, it is more preferable that the pressure be 50 kg / m 3 or more and 200 kg / m 3 or less.
【００１１】また、一般的に柔軟なフォーム材ほどセル
の膜振動による吸音機構が発現するため、吸音特性の良
好な構造体が得られる。逆に硬いフォーム材はセルの膜
振動による吸音機構が発現しないため、全周波数域にお
いて低い垂直入射吸音率しか示さない。このような硬い
フォーム材同士を積層しても吸音効果はほとんど向上し
ない。従って、本発明で使用するフォーム材はある特定
の範囲の圧縮硬さを持つことが好ましい。具体的には、
25％圧縮硬さにおいて、好ましくは0.5N/cm2以下、より
好ましくは0.3N/cm2以下、さらに好ましくは0.1N/cm2以
下とするのが良い。この範囲の25％圧縮硬さを有する連
続気泡と独立気泡との混成の気泡構造を有するフォーム
材は、特に接着せずに積層したときの吸音特性の向上効
果が大きい。尚、この25％圧縮硬さはJIS K6767によっ
て測定される。In general, a flexible foam material exhibits a sound absorbing mechanism due to membrane vibration of a cell, so that a structure having good sound absorbing characteristics can be obtained. Conversely, a rigid foam material does not exhibit a sound absorption mechanism due to cell membrane vibration, and thus exhibits only a low normal incidence sound absorption coefficient over the entire frequency range. Even if such hard foam materials are laminated, the sound absorbing effect is hardly improved. Therefore, the foam material used in the present invention preferably has a specific range of compression hardness. In particular,
At 25% compression hardness, it is preferably 0.5 N / cm 2 or less, more preferably 0.3 N / cm 2 or less, and still more preferably 0.1 N / cm 2 or less. Foam materials having a mixed cell structure of open cells and closed cells having a compression hardness of 25% in this range have a great effect of improving the sound absorbing properties particularly when laminated without bonding. The 25% compression hardness is measured according to JIS K6767.
【００１２】本発明の吸音構造体は、上記のフォーム材
を２層以上積層して構成される。この時、フォーム材同
士は、その少なくとも１つの界面において、他方のフォ
ーム材と非固着状態、即ちフォーム材同士がその界面に
おいて自由に動くことができる状態で積層されても良い
し、他方のフォーム材と部分的に固着した状態で積層さ
れてもよい。非固着状態で積層する場合は、全体をメッ
シュ等で包囲して積層状態を維持する必要がある。他
方、部分的に固着する場合は、その固着方法は制限され
るのではなく、例えば両面テープや接着材を用いて接着
しても良いし、フォーム材同士を縫製やピン止めによっ
て接合しても良い。また、これらの方法を併用すること
も可能である。The sound absorbing structure of the present invention is formed by laminating two or more layers of the above foam material. At this time, the foam materials may be laminated at at least one interface in a non-adhered state with the other foam material, that is, in a state where the foam materials can freely move at the interface, or the other foam material may be laminated. It may be laminated in a state of being partially fixed to the material. When laminating in a non-adhered state, it is necessary to maintain the laminated state by surrounding the whole with a mesh or the like. On the other hand, in the case of partially fixing, the fixing method is not limited. For example, the fixing may be performed using a double-sided tape or an adhesive, or the foam materials may be joined by sewing or pinning. good. Also, these methods can be used in combination.
【００１３】また、フォーム材同士を部分的に固定する
場合は、固着されている面積の合計（以下、全固着面積
と呼ぶ）が、界面の全面積に占める割合が大きすぎと十
分に高い吸音特性を示さなくなる。本発明においては、
この全固着面積の割合がある特定の範囲の値を持つこと
が好ましく、好ましくは、50％以下、より好ましくは30
％以下、さらに好ましくは10％以下とするのが良い。全
固着面積の割合がこの範囲にある吸音構造体は、吸音特
性の向上効果が大きい。また、フォーム材同士の界面の
全面を固着した場合は、積層しない場合よりもむしろ吸
音特性は低下する。本発明において、フォーム材同士を
積層することにより、吸音特性が向上する理由は定かで
はないが、入射した音響波がフォーム材界面においてフ
ォーム材を振動させて、音響波自身が減衰することによ
るものと推察される。従って、フォーム材同士を全面的
に固着すると、この効果が発現せず、吸音特性の向上が
得られなくなる。When the foam materials are partially fixed to each other, the sum of the fixed areas (hereinafter referred to as the total fixed area) is sufficiently high if the proportion of the total area of the interface is too large. No longer shows its properties. In the present invention,
It is preferable that the ratio of the total fixing area has a value in a specific range, preferably 50% or less, more preferably 30% or less.
%, More preferably 10% or less. The sound absorbing structure having the ratio of the total fixing area in this range has a large effect of improving the sound absorbing characteristics. Further, when the entire surface of the interface between the foam materials is fixed, the sound absorption characteristics are deteriorated rather than when the layers are not laminated. In the present invention, the reason why sound absorption characteristics are improved by laminating foam materials is not clear, but the incident acoustic wave vibrates the foam material at the foam material interface, and the acoustic wave itself is attenuated. It is inferred. Therefore, if the foam materials are entirely fixed to each other, this effect is not exhibited, and the improvement of the sound absorbing characteristics cannot be obtained.
【００１４】本発明において、フォーム材の積層枚数は
制限されるものではなく、例えば３層、４層を積層する
ことも可能である。全厚が同じであれば、フォーム材の
積層枚数が多いほど、高周波側の吸音率が向上する。逆
に、積層枚数が少ないほど低周波側の吸音率が向上す
る。このように、本発明によれば、フォーム材の積層枚
数を適宜変更することにより、所望の周波数の吸音率を
高めることが可能となる。In the present invention, the number of foam materials to be laminated is not limited, and for example, three or four layers can be laminated. If the total thickness is the same, the higher the number of laminated foam materials, the higher the sound absorption coefficient on the high frequency side. Conversely, the smaller the number of layers, the higher the sound absorption coefficient on the low frequency side. As described above, according to the present invention, it is possible to increase the sound absorption coefficient at a desired frequency by appropriately changing the number of laminated foam materials.
【００１５】また、本発明においては、各層でフォーム
材の種類が異なっても良い。例えば、密度の異なるフォ
ーム材同士を積層しても良いし、エラストマーやゴムの
種類の異なるフォーム材同士（例えば、ＥＰＤＭとＮＢ
Ｒ）を積層しても良く、その他にも種々の積層形態とす
ることができる。In the present invention, the type of the foam material may be different for each layer. For example, foam materials having different densities may be laminated, or foam materials having different types of elastomer or rubber (for example, EPDM and NB)
R) may be laminated, and various other laminated forms may be adopted.
【００１６】上記の如く構成される吸音構造体を自動車
用エンジンカバーに適用するには、例えばピン止め、網
掛け、縫製等の手段によりカバー本体に固定する。これ
らの手段は複数を併用することもできる。In order to apply the sound absorbing structure constructed as described above to an automobile engine cover, the sound absorbing structure is fixed to the cover body by means of, for example, pinning, shading, sewing or the like. A plurality of these means can be used in combination.
【００１７】[0017]
【実施例】以下、本発明を実施例にてさらに詳しく説明
するが、本発明は以下の実施例に限定されるものではな
い。 （実施例１）EPDM製で厚さ15mm、密度100kg/m3、吸水率
0.071 g/cm3、25%圧縮硬さ0.040N/cm2のフォーム材２枚
を接着せずに積層して吸音構造体を作製した。EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples. (Example 1) EPDM, thickness 15 mm, density 100 kg / m 3 , water absorption
Two foam materials of 0.071 g / cm 3 and 25% compression hardness of 0.040 N / cm 2 were laminated without bonding to form a sound absorbing structure.
【００１８】（実施例２）EPDM製で厚さ10mm、密度100k
g/m3、吸水率0.071 g/cm3、25%圧縮硬さ0.040N/cm2のフ
ォーム材３枚を接着せずに積層して吸音構造体を作製し
た。(Embodiment 2) EPDM, thickness 10 mm, density 100 k
Three foam materials having a g / m 3 , a water absorption of 0.071 g / cm 3 , and a 25% compression hardness of 0.040 N / cm 2 were laminated without bonding to produce a sound absorbing structure.
【００１９】（実施例３）EPDM製で厚さ7.5mm、密度100
kg/m3、吸水率0.071 g/cm3、25%圧縮硬さ0.040N/cm2の
フォーム材４枚を接着せずに積層して吸音構造体を作製
した。(Embodiment 3) EPDM, thickness 7.5 mm, density 100
Four foam materials having kg / m 3 , a water absorption of 0.071 g / cm 3 and a 25% compression hardness of 0.040 N / cm 2 were laminated without bonding to produce a sound absorbing structure.
【００２０】（実施例４）EPDM製で厚さ10mm、密度100k
g/m3、吸水率0.071 g/cm3、25%圧縮硬さ0.040N/cm2の第
１のフォーム材と、EPDM製で厚さ20mm、密度100kg/m3、
吸水率0.071 g/cm 3、25%圧縮硬さ0.040N/cm2の第２のフ
ォーム材とを接着せずに積層して吸音構造体を作製し
た。尚、垂直入射吸音率は第２のフォーム材側が剛壁に
なるように吸音構造体を設置して測定した。(Embodiment 4) EPDM, thickness 10 mm, density 100 k
g / mThree, Water absorption 0.071 g / cmThree, 25% compression hardness 0.040N / cmTwoNo.
1 foam material, made of EPDM, thickness 20mm, density 100kg / mThree,
Water absorption 0.071 g / cm Three, 25% compression hardness 0.040N / cmTwoThe second file
To form a sound-absorbing structure
Was. In addition, the normal incidence sound absorption coefficient is such that the second foam material side has a rigid wall.
The sound absorption structure was installed so as to be as follows.
【００２１】（実施例５）NBR製で厚さ15mm、密度120kg
/m3、吸水率0.058 g/cm3、25%圧縮硬さ0.070N/cm 2のフ
ォーム材２枚を接着せずに積層して吸音構造体を作製し
た。(Example 5) Made of NBR, thickness 15 mm, density 120 kg
/ mThree, Water absorption 0.058 g / cmThree, 25% compression hardness 0.070N / cm TwoNo
A sound-absorbing structure is made by laminating two foam materials without bonding
Was.
【００２２】（実施例６）EPDM製で厚さ10mm、密度100k
g/m3、吸水率0.071 g/cm3、25%圧縮硬さ0.040N/cm2の第
１のフォーム材と、NBR製で厚さ15mm、密度120kg/m3、
吸水率0.058 g/cm3、25%圧縮硬さ0.070N/cm2の第２のフ
ォーム材とを接着せずに積層して吸音構造体を作製し
た。尚、垂直入射吸音率はNBR製のフォーム材側が剛壁
になるように吸音構造体を設置して測定した。(Embodiment 6) EPDM, thickness 10 mm, density 100 k
g / m 3 , water absorption 0.071 g / cm 3 , 25% compression hardness 0.040 N / cm 2 First foam material, made of NBR, thickness 15 mm, density 120 kg / m 3 ,
A sound absorbing structure was produced by laminating a second foam material having a water absorption of 0.058 g / cm 3 and a 25% compression hardness of 0.070 N / cm 2 without bonding. The normal incidence sound absorption coefficient was measured by installing a sound absorbing structure such that the NBR foam material side became a rigid wall.
【００２３】（実施例７）EPDM製で厚さ15mm、密度100k
g/m3、吸水率0.071 g/cm3、25%圧縮硬さ0.040N/cm2のフ
ォーム材２枚を用い、それぞれの表面の中心部分のみを
接着して吸音構造体を作製した。尚、接着部分の形状は
円形とし、接着部分の面積は界面の全面積の10%になる
ようにした。(Embodiment 7) EPDM, thickness 15 mm, density 100 k
Using two foam materials having g / m 3 , a water absorption of 0.071 g / cm 3 , and a 25% compression hardness of 0.040 N / cm 2 , only the center part of each surface was bonded to produce a sound absorbing structure. The shape of the bonding portion was circular, and the area of the bonding portion was 10% of the total area of the interface.
【００２４】（実施例８）EPDM製で厚さ15mm、密度100k
g/m3、吸水率0.071 g/cm3、25%圧縮硬さ0.040N/cm2のフ
ォーム材２枚を用い、それぞれの中心部分のみをピンで
留めて吸音構造体を作製した。(Embodiment 8) EPDM, thickness 15 mm, density 100 k
Using two foam materials having g / m 3 , a water absorption of 0.071 g / cm 3 , and a 25% compression hardness of 0.040 N / cm 2 , a sound absorbing structure was produced by pinning only the center of each of the foam materials.
【００２５】（比較例１）EPDM製で厚15mm、密度100kg/
m3、吸水率0.071 g/cm3、25%圧縮硬さ0.040N/cm2のフォ
ーム材２枚を用い、界面全面を両面テープで接着して吸
音構造体を作製した。(Comparative Example 1) EPDM, thickness 15 mm, density 100 kg /
Using two foam materials having m 3 , a water absorption of 0.071 g / cm 3 and a 25% compression hardness of 0.040 N / cm 2 , the entire surface of the interface was adhered with a double-sided tape to produce a sound absorbing structure.
【００２６】（比較例２）EPDM製で厚さ30mm、密度100k
g/m3、吸水率0.071 g/cm3、25%圧縮硬さ0.040N/cm2のフ
ォーム材１枚を吸音構造体とした。(Comparative Example 2) Made of EPDM, thickness 30 mm, density 100 k
One foam material having g / m 3 , a water absorption of 0.071 g / cm 3 , and a 25% compression hardness of 0.040 N / cm 2 was used as a sound absorbing structure.
【００２７】（比較例３）EPDM製で厚さ15mm、密度460k
g/m3、吸水率0.0028 g/cm3、25%圧縮硬さ1.05N/cm2のフ
ォーム材２枚を接着せずに積層して吸音構造体を作製し
た。(Comparative Example 3) EPDM, thickness 15 mm, density 460 k
Two foam materials having a g / m 3 , a water absorption of 0.0028 g / cm 3 and a 25% compression hardness of 1.05 N / cm 2 were laminated without bonding to form a sound absorbing structure.
【００２８】（比較例４）軟質ウレタン製で厚さ15mm、
密度25kg/m3、吸水率0.76 g/cm3、25%圧縮硬さ0.065N/c
m2のフォーム材２枚を接着せずに積層して吸音構造体を
作製した。(Comparative Example 4) Made of soft urethane and having a thickness of 15 mm
Density 25 kg / m 3 , water absorption 0.76 g / cm 3 , 25% compression hardness 0.065 N / c
Two m2 foam materials were laminated without bonding to produce a sound absorbing structure.
【００２９】（比較例５）軟質ウレタン製で厚さ30mm、
密度25kg/m3、吸水率0.76 g/cm3、25%圧縮硬さ0.065N/c
m2のフォーム材１枚を吸音構造体とした。(Comparative Example 5) Made of soft urethane and having a thickness of 30 mm
Density 25 kg / m 3 , water absorption 0.76 g / cm 3 , 25% compression hardness 0.065 N / c
Form one material m 2 was sound absorbing structure.
【００３０】上記各吸音構造体に関して、所定の周波数
ごとに垂直入射吸音率を測定した。測定はJIS A1405に
従って、剛壁密着の条件で測定した。結果を表１および
表２に示す。For each of the above sound absorbing structures, the normal incidence sound absorption coefficient was measured for each predetermined frequency. The measurement was carried out in accordance with JIS A1405 under the condition of rigid wall contact. The results are shown in Tables 1 and 2.
【００３１】[0031]
【表１】 [Table 1]
【００３２】[0032]
【表２】 [Table 2]
【００３３】表１の結果から、本発明による吸音構造体
が広い周波数域において優れた吸音特性を有することは
明らかである。よって、自動車のエンジンカバー等に好
適な吸音構造体を提供することができる。From the results in Table 1, it is clear that the sound absorbing structure according to the present invention has excellent sound absorbing characteristics in a wide frequency range. Therefore, it is possible to provide a sound-absorbing structure suitable for an engine cover or the like of an automobile.
【００３４】これに対して、比較例１の吸音構造体は連
続気泡と独立気泡との混成の気泡構造を有するフォーム
材が２枚、界面全体が接着された状態で積層されてお
り、低い吸音特性しか示さなかった。比較例２の吸音構
造体は連続気泡と独立気泡との混成の気泡構造を有する
フォーム材が一層のみで構成されているもので、低い吸
音特性しか示さなかった。比較例３の吸音構造体は独立
気泡の気泡構造を有し、25%圧縮硬さおよび密度が本発
明の範囲よりも大きいフォーム材が２枚接着せずに積層
されたもので、低い吸音特性しか示さなかった。比較例
４の吸音構造体は連続気泡の気泡構造を有するフォーム
材が２枚接着せずに積層されており、比較例５の吸音構
造体は連続気泡の気泡構造を有するフォーム材が一層の
みで構成されている。比較例４の吸音構造体と５の吸音
構造体とは同等の吸音特性であり、また、ともに中低音
域では低い吸音特性しか示さなかった。連続気泡のみの
気泡構造を有するフォーム同士を積層しても吸音特性は
向上しないことが確認された。On the other hand, in the sound absorbing structure of Comparative Example 1, two foam materials having a mixed cell structure of open cells and closed cells are laminated in a state where the entire interface is bonded, and low sound absorption is obtained. It showed only characteristics. The sound absorbing structure of Comparative Example 2 was composed of only one foam material having a mixed cell structure of open cells and closed cells, and showed only low sound absorbing characteristics. The sound-absorbing structure of Comparative Example 3 has a closed-cell cell structure, in which two foam materials having a 25% compression hardness and a density higher than the range of the present invention are laminated without bonding, and have low sound-absorbing properties. Only showed. In the sound absorbing structure of Comparative Example 4, two foam materials having an open-celled cell structure are laminated without bonding, and in the sound absorbing structure of Comparative Example 5, only one foam material having an open-celled cell structure is provided. It is configured. The sound absorbing structures of Comparative Example 4 and 5 had the same sound absorbing characteristics, and both exhibited only low sound absorbing characteristics in the middle and low range. It was confirmed that the sound absorption characteristics were not improved even when the foams having the cell structure of only open cells were laminated.
【００３５】[0035]
【発明の効果】以上説明したように、本発明によれば、
広い周波数に周波数域において良好な吸音特性を有し、
更に目的等に応じて所望の周波数域における吸音特性を
高くすることが可能で、自動車用エンジンカバー等に好
適な吸音構造体を提供することができる。As described above, according to the present invention,
Has good sound absorption characteristics in the frequency range over a wide frequency range,
Further, it is possible to increase the sound absorption characteristics in a desired frequency range according to the purpose and the like, and it is possible to provide a sound absorption structure suitable for an automobile engine cover or the like.
フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ テーマコート゛(参考） Ｇ１０Ｋ 11/16 Ｇ１０Ｋ 11/16 Ａ // Ｅ０４Ｂ 1/86 Ｇ (72)発明者 丹羽 隆弘 東京都大田区久が原５−34−３−406 Ｆターム(参考） 2E001 DF04 FA00 GA12 GA32 GA76 GA82 HE02 LA00 LA04 LA11 4F100 AK75 BA02 BA03 BA04 BA05 BA10A BA10B BA14 BA32 DJ02A DJ02B DJ03A DJ03B EC08 EC13 GB32 JA13A JA13B JD15A JD15B JH01 JK05A JK05B YY00 YY00A YY00B 5D061 AA04 AA26 BB01 BB24 CC15Continued on the front page (51) Int.Cl. 7 Identification symbol FI Theme coat II (reference) G10K 11/16 G10K 11/16 A // E04B 1/86 G (72) Inventor Takahiro Niwa 5-Kugahara, Ota-ku, Tokyo 34-3-406 F-term (reference) 2E001 DF04 FA00 GA12 GA32 GA76 GA82 HE02 LA00 LA04 LA11 4F100 AK75 BA02 BA03 BA04 BA05 BA10A BA10B BA14 BA32 DJ02A DJ02B DJ03A DJ03B EC08 EC13 GB32 JA13A JA13B JD15A JD15BJH00Y05Y06A05 AA26 BB01 BB24 CC15
Claims (10)
を有するフォーム材を二層以上積層してなることを特徴
とする吸音構造体。1. A sound-absorbing structure comprising two or more layers of a foam material having a mixed cell structure of open cells and closed cells.
において他方のフォーム材と非固着状態で積層されてい
ることを特徴とする請求項１記載の吸音構造体。2. The sound-absorbing structure according to claim 1, wherein the foam members are laminated on at least one interface in a non-fixed state with the other foam member.
において他方のフォーム材と部分的に固着した状態で積
層されていることを特徴とする請求項１記載の吸音構造
体。3. The sound-absorbing structure according to claim 1, wherein the foam materials are laminated on at least one interface while being partially fixed to the other foam material.
の面積に対して50％以下であることを特徴とする請求項
３記載の吸音構造体。4. The sound-absorbing structure according to claim 3, wherein the total fixing area of the foam materials is not more than 50% of the area of the interface.
は縫製によって固定されていることを特徴とする請求項
３または請求項４に記載の吸音構造体。5. The sound absorbing structure according to claim 3, wherein the foam members are fixed to each other by pinning and / or sewing.
0.2g/cm3以下であることを特徴とする請求項１〜５のい
ずれか一項に記載の吸音構造体。6. The foam material having a water absorption of 0.01 g / cm 3 or more.
Sound absorbing structure according to any one of claims 1 to 5, characterized in that 0.2 g / cm 3 or less.
g/ m3 以下であることを特徴とする請求項１〜６のいず
れかの一項に記載の吸音構造体。7. 400 k when the density of the foam material is 20 kg / m 3 or more.
The sound absorbing structure according to claim 1, wherein the sound absorbing structure is not more than g / m 3 .
下であることを特徴とする請求項１〜７のいずれかの一
項に記載の吸音構造体。8. The sound-absorbing structure according to claim 1, wherein a 25% compression hardness of the foam material is 0.5 N / cm 2 or less.
音構造体を用いたことを特徴とする自動車用エンジンカ
バー。9. An automobile engine cover using the sound absorbing structure according to claim 1. Description:
とも１つの手段により吸収音構造体をカバー本体に固定
したことを特徴とする請求項９記載の自動車用エンジン
カバー。10. The automobile engine cover according to claim 9, wherein the sound absorbing structure is fixed to the cover body by at least one of pinning, shading and sewing.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07615399A JP3322845B2 (en) | 1999-03-19 | 1999-03-19 | Sound absorbing structure |
| EP00100679.0A EP1020846B1 (en) | 1999-01-14 | 2000-01-13 | Sound absorbing structure |
| US09/482,731 US6720069B1 (en) | 1999-01-14 | 2000-01-14 | Sound absorbing structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07615399A JP3322845B2 (en) | 1999-03-19 | 1999-03-19 | Sound absorbing structure |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000263679A true JP2000263679A (en) | 2000-09-26 |
| JP3322845B2 JP3322845B2 (en) | 2002-09-09 |
Family
ID=13597095
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP07615399A Expired - Lifetime JP3322845B2 (en) | 1999-01-14 | 1999-03-19 | Sound absorbing structure |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3322845B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1215381A2 (en) * | 2000-12-12 | 2002-06-19 | Nichias Corporation | Soundproof cover for automobile |
| JP2012504256A (en) * | 2008-09-29 | 2012-02-16 | ダウ グローバル テクノロジーズ エルエルシー | Laminated perforated sound absorbing foam |
-
1999
- 1999-03-19 JP JP07615399A patent/JP3322845B2/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1215381A2 (en) * | 2000-12-12 | 2002-06-19 | Nichias Corporation | Soundproof cover for automobile |
| EP1215381A3 (en) * | 2000-12-12 | 2003-04-23 | Nichias Corporation | Soundproof cover for automobile |
| JP2012504256A (en) * | 2008-09-29 | 2012-02-16 | ダウ グローバル テクノロジーズ エルエルシー | Laminated perforated sound absorbing foam |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3322845B2 (en) | 2002-09-09 |
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