JP2004156555A

JP2004156555A - Silencer for fuel cell vehicle and sound absorbing material of the silencer

Info

Publication number: JP2004156555A
Application number: JP2002324130A
Authority: JP
Inventors: Tetsuo Goto; 鐵雄後藤; Kazuo Kodera; 和男小寺
Original assignee: NIHON GLASSFIBER INDUSTRIAL CO Ltd
Current assignee: NIHON GLASSFIBER INDUSTRIAL CO Ltd
Priority date: 2002-11-07
Filing date: 2002-11-07
Publication date: 2004-06-03
Anticipated expiration: 2022-11-07
Also published as: JP3776080B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lightweight and recyclable silencer and sound absorbing material thereof having a good drainage under the condition where the exhaust gas is in the form of vapor while maintaining a good sound absorbing performance for a long period. <P>SOLUTION: The sound absorbing material 3 with a bulk density adjusted at 20 to 200 kg/m<SP>3</SP>using mainly the organic fiber is filled in at least a part of the internal space of a silencer casing 4 arranged in an exhaust pipe 1 of a fuel cell vehicle. The organic fiber preferably may be the organic fiber having the crimp or the fiber of which surface is treated with a water repelling agent. Plate-shaped, rod-shaped, and block-shaped elements of the felted organic fiber are preferably formed in a cylindrical shape by connecting them so that at least a part of the element connecting surface is directed from the inner circumference to the outer circumference direction. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、燃料電池を用いた燃料電池車の排気管に設けられる消音器及びその吸音材に関するものである。
【０００２】
【従来の技術】
従来の自動車用消音器は、排気管の一部に多数の通気孔を貫設し、該排気管の一部の外周に吸音材としてのグラスウールを配設し、その外周に金属よりなる外管を被せてなるものが一般的である。また、排気管とグラスウールとの間に金属繊維よりなる飛散防止層を設け、グラスウールの熱劣化及び飛散を防止したものもある。また、吸音材としてのグラスウール自体をステンレス鋼繊維等の金属繊維で置き換えることも検討されている。これらは、勿論、内燃機関からの排気管に設けるものとして開発されてきた。
【０００３】
ところで、内燃機関式自動車の代替技術の一つとして、燃料電池からの電流によりモータを作動させて車輪を駆動する、いわゆる燃料電池車の実用化が近付いている。燃料電池は水の電気分解の逆反応を利用した発電デバイスであり、二つの電極にそれぞれ水素と酸素とを供給して電気化学反応（前記逆反応）を起こさせ、同電極から外部に電流を取り出すが、同反応により生ずる水蒸気が排気ガスとして排出される。前述した吸音材としてグラスウール又はステンレス鋼繊維を用いた消音器は、この燃料電池からの排気管に設けることもできるが、その際に新たに留意すべき点は前記水蒸気による吸音材の含水である。消音器筐体内の底部には前記水蒸気の結露により水が溜まるため、この底部に溜まった水が毛細管現象により吸い上げられ、吸音材全体に含水状態となりやすい。吸音材が含水すると、吸音材の繊維間の空隙（空気層）が無くなるため、吸音性能が低下する。
【０００４】
しかるところ、最近、消音器筐体の内部空間を連通孔を有する仕切板により上側の室と下側の室とに区画し、上側の室にグラスウールを充填することによりグラスウールの含水を防止するようにした燃料電池車の消音器が公開された（特開２００２−２０６４１３公報）。
【０００５】
【特許文献１】
特開２００２−２０６４１３公報
【０００６】
【発明が解決しようとする課題】
燃料電池車の消音器及びその吸音材には、次の課題がある。
（１）自動車のリサイクル率の向上のため、吸音材もリサイクル可能なものとする。
（２）自動車の燃費向上のため、吸音材の重量当たりの吸音性（重量効率）を高くして、吸音材を軽量化する。
（３）前記のとおり、吸音材の含水を防止する必要がある。
前記グラスウールを用いた消音器は、軽量性は良いが、リサイクル性が悪い。また、水はけが悪いため、燃料電池車に用いると、含水して吸音性能が低下しやすい。そこで、前記公開公報の公知例のように消音器筐体の内部空間を区画する等して対策する必要があるが、そうすると、消音器の構造が複雑になり、コストアップとなってしまう。また、前記ステンレス鋼繊維を用いた消音器は、リサイクル性は良いが、軽量性が良くない。
【０００７】
本発明の目的は、排気ガスが水蒸気である環境下で、水はけが良く、長期にわたり良好な吸音性能を維持することができ、かつ軽量でリサイクルが可能な燃料電池車の消音器及びその吸音材を提供することにある。
【０００８】
【課題を解決するための手段】
燃料電池には色々な種類があり、反応温度で分類すると、反応温度が３００℃以下の低温形とそれ以上の高温型とに分類できる。主に有機繊維を用いる本発明を適用できるのは、その耐熱性の点で、反応温度が３００℃以下の低温形燃料電池を用いた燃料電池車である。かかる低温形燃料電池としては、現時点では、固体高分子型（ＰＥＦＣ）、アルカリ形（ＡＦＣ）、リン酸形（ＰＡＦＣ）の各燃料電池を例示できる。
【０００９】
（１）第１の発明は、主に有機繊維を用いて嵩密度２０〜２００ｋｇ／ｍ^３に調整した燃料電池車の消音器用吸音材である。同嵩密度の調整値は、消音器筐体の内部空間への充填時における値である。
「有機繊維」の種類は、特に限定されない。「主に有機繊維」とは、繊維に有機又は無機のバインダーを混合し、保型性を高めることで充填しやすくさせる場合も含む意味である。この場合、バインダー量が多いと、繊維の接着点の数が増して強度は上がるが、吸音性能は低下するため、出来るだけ少なくするのが望ましい。
嵩密度２０ｋｇ／ｍ^３未満では、グラスウール並みの吸音性能を付与することができない。嵩密度２００ｋｇ／ｍ^３を越えた場合は、毛細管現象による含水が著しく生じ、水はけが悪く、吸音性能が低下する。嵩密度はさらに好ましくは３５〜５０ｋｇ／ｍ^３である。
【００１０】
（２）第２の発明は、有機繊維が、ポリプロピレン（ＰＰ）、ポリエチレン（ＰＥ）、ポリエチレンテレフタレート（ＰＥＴ）、レーヨン、ビニロン、ナイロン、ポリエステル、ポリ塩化ビニール、アクリル、ビニリデン及びアセテートの合成繊維、並びに麻、綿、やし、竹、羊毛及び絹の天然繊維から選ばれる少なくとも一種からなる繊維である燃料電池車の消音器用吸音材である。
コスト、耐含水性、汎用性から、ポリプロピレン、ポリエチレン、ポリエチレンテレフタレートが好ましい。これらの繊維を複数混綿しても良いが、リサイクルの面で１種類の材質で使用する方が好ましい。
天然繊維を使用する場合は、繊維自身に吸水性があるので、後述する第５の発明を適用し撥水剤で表面処理を施すことが好ましい。
【００１１】
（３）第３の発明は、前記有機繊維が、平均繊維径３〜２７μｍとする繊維である燃料電池車の消音器用吸音材である。
平均繊維径が３μｍ未満では、調達が困難となりコストが著しく高くなる。平均繊維径が２７μｍを超えた場合は、吸音性能の低下が著しい。平均繊維径はコスト面と吸音性能を考慮すると、１０〜１８μｍがより望ましい。
【００１２】
（４）第４の発明は、前記有機繊維が、クリンプを有する繊維である燃料電池車の消音器用吸音材である。
クリンプを有する繊維とすることで、繊維間の空隙が歪曲やくびれを有する状態となり、空気の粘性摩擦抵抗が増大し、吸音性能を良くすることができる。
【００１３】
（５）第５の発明は、前記有機繊維が、撥水剤で表面処理を施した繊維である燃料電池車の消音器用吸音材である。
撥水剤としては、特に限定されないが、フッ素系化合物やシリコーン系（オイル、エマルジョン等）を例示でき、繊維表面に施すことで、水はけをさらに良くすることができる。
【００１４】
（６）第６の発明は、前記有機繊維をフェルト状とした板状、棒状、ブロック状等の要素を、少なくとも一部の要素間接合面が内周から外周方向に向かうように接合することにより筒状に形成した燃料電池車の消音器用吸音材である。
合わせ面を内周から外周に向かって積層することで、繊維間に含水した水分が排気ガスの流圧と微振動にて合わせ面に沿って吹き出すことができ、より有効に排水することができる。
【００１５】
（７）第７の発明は、燃料電池車の排気管に配される消音器筐体の内部空間の少なくとも一部に、主に有機繊維を用いて嵩密度２０〜２００ｋｇ／ｍ^３に調整した吸音材を充填した燃料電池車の消音器である。
ここで、「排気管」は排気が通り消音器を構成する管であれば特に限定されず、燃料電池から延出する排気管や、該排気管に連結された消音器筐体の内部仕切板に設けられたインナーパイプ等を例示できる。吸音材は、その全体が前記有機繊維の吸音材よりなるものが望ましい。
また、吸音材の設け方としては、特に限定されないが、フェルト状の有機繊維を長い帯状にし排気管の外周に巻き付ける方法や、前記第６の発明のような筒状のものを排気管の外周に形成する方法を例示できる。または、多数の細孔が開いたフィルムを予め消音器の形状に作っておき、その中へフェルト状の有機繊維を挿入し、入口を封止する方法も例示できる。また、有機繊維を圧縮空気で解繊しながら直接消音器筐体内に充填する方法も適用できる。
その他の詳細は、上記第１〜第６の発明の詳細と同様である。
【００１６】
（８）第８の発明は、前記消音器筐体の少なくとも一部に排水孔を設けた燃料電池車の消音器である。
消音器筐体の少なくとも一部（例えば下部）に排水孔を設けることにより、燃料電池から排気ガスである水蒸気が吸音材に拡散し水が下部に溜まったとしても、排ガス流により吸音材内部を透水した水を適度に消音器の外に排水することができる。排水孔の開口面積を微小にすることで、吸音性能の低下を抑制できる。また、排水性を高めるため、消音器筐体内面または吸音材外面に、排水用の溝を任意に設けても良く、吸音材の固定支持を兼ねたスペーサを消音器筐体と吸音材の間に挿入し、適度な空気層を設けても良い。
【００１７】
【発明の実施の形態】
以下、本発明を具体化した消音器の実施形態について説明する。なお、実施形態で記す材料、構成、数値等は例示であって、適宜変更できる。
（試験１）
実施例１として、繊維径１７．５μｍ・繊維長５０ｍｍのポリプロピレン繊維を用い、クリンプがないものとクリンプがあるもの（図４（ａ）にクリンプがある繊維１０を示す。）とをそれぞれニードルパンチでフェルト状とし、嵩密度３５、５０、１００ｋｇ／ｍ^３に調整した吸音材を作成した。また、比較例１として、Ｅガラス繊維を用い、同様にニードルパンチにて嵩密度１００ｋｇ／ｍ^３に調整した吸音材を作成した。これら実施例１及び比較例１の各吸音材からＪＩＳ−Ａ−１４０５に規定される厚さ１０ｍｍの円板形状の試験片を作成し、管内法による垂直入射吸音率測定法に従って各周波数における吸音率を測定した。表１にその測定結果を示す。
【００１８】
【表１】

【００１９】
（試験２）
実施例２として、繊維径が１１．５μｍから２７．１μｍまで異なるレーヨン繊維を用い、それぞれニードルパンチでフェルト状とし、嵩密度５０ｋｇ／ｍ^３に調整した吸音材を作成した。また、比較例２として、平均繊維径２４μｍのガラス長繊維（オーウェンスコーニングジャパン社の商品名；Ａｄｖａｎｔｅｘ（アドバンテックス））を用いて、同様にニードルパンチにて嵩密度１００ｋｇ／ｍ^３に調整した吸音材を作成した。これら実施例２及び比較例２の各吸音材からＪＩＳ−Ａ−１４０５に規定される厚さ１０ｍｍの円板形状の試験片を作成し、管内法による垂直入射吸音率測定法に従って各周波数における吸音率を測定した。表２にその測定結果を示す（前記比較例１の測定結果も併記する）。
【００２０】
【表２】

【００２１】
（試験３）
次に、実施例１及び比較例１の各吸音材について、透水性試験を行った。試料サイズは、直径９１．５ｍｍ×厚さ１０ｍｍの円板とした。同試験は、大気中で室温の条件にて、水中浸漬後、円板の側面を一箇所持ち上げ、垂直方向に２分間の水切りをして取出し、増加重量を求めた。
【００２２】
【表３】

【００２３】
（試験４）
同様に、実施例３及び比較例３として、実施例１及び比較例１の各吸音材に撥水剤で表面処理を施したものを作成し、透水性試験を行った。撥水剤としては、シリコーン系撥水剤（東レダウコーニングシリコーン社の商品名；ＳＭ８７０６）を用いて含浸塗布し、絞り後、乾燥した。含浸量を調整することで、乾燥後の重量を測り、ねらいとする嵩密度を求めた。試料サイズは、直径９１．５ｍｍ×厚さ１０ｍｍの円板とした。同試験は、大気中で室温の条件にて、水中浸漬後、円板の側面を一箇所持ち上げ、垂直方向に２分間の水切りをして取出し、増加重量を求めた。
【００２４】
【表４】

【００２５】
以上のとおり、実施例の吸音材によれば、次の作用効果が得られる。
▲１▼ 表１に示す測定結果のとおり、実施例１の吸音材は、軽量な有機繊維を用いているにも拘わらず、ガラス繊維を用いた比較例１の吸音材と略同等の吸音性能を有する。特に、１０００Ｈｚ以下の周波数域にて吸音性能が優れている。
▲２▼ 表２に示す測定結果のとおり、実施例２の吸音材は、繊維径が太めの有機繊維を用いているにも拘わらず、太めのガラス長繊維を用いた比較例２の吸音材に対し同等以上の吸音性能を有する。特に、１０００Ｈｚ以下の周波数域にて吸音性能が優れている。
▲３▼ 表３に示すとおり、実施例１の吸音材は、ガラス繊維と比較し、良好な透水性を示している。
▲４▼ 表４に示すとおり、実施例３の撥水剤で繊維に表面処理を施した吸音材は、良好な透水性を示している。
【００２６】
次に、図１〜図３に示すように、燃料電池車の排気管１（インナーパイプ）であって多数の小孔２を貫通させた箇所の外周に、実施例１〜３のフェルト状の各吸音材を、長い帯１１（例えば帯幅２０〜１００ｍｍ、帯厚１〜１０ｍｍ）にまとめて排気管１の外周に複数重にぐるぐる巻きする方法により巻き付けて、全体がこの吸音材からなる吸音材３を構成した。その後、外径φ８９×内径φ８７×全長２９８ｍｍのアルミメッキ鋼管製の消音器筐体４（アウターパイプ）を外挿し、排気管１と消音器筐体４との当接部の隙間を溶接し、消音器を完成させた。消音器筐体４の内部空間には各吸音材が充填されたことになる。消音器筐体４の少なくとも一部には排水孔１５を貫設した。この消音器は、排気ガスが水蒸気である環境下で、水はけが良く、長期にわたり良好な吸音性能を維持することができた。
【００２７】
また、実施例１〜３のフェルト状の各吸音材を、図４（ｂ）に示すように板状の要素１２に形成したり、図４（ｃ）に示すように棒状の要素１３に形成したりしたものを、少なくとも一部の要素間接合面が内周から外周方向に向かうように接合することにより筒状の吸音材３に形成した。この吸音材３についても、前記燃料電池車の排気管１に配される消音器筐体４の内部空間に充填して、消音器を完成させた。この消音器は、さらに水はけが良く、長期にわたり良好な吸音性能を維持することができた。
【００２８】
なお、本発明は上記実施形態に限定されるものではなく、発明の趣旨から逸脱しない範囲で適宜変更して具体化することもできる。
【００２９】
【発明の効果】
以上詳述したように、本発明に係る燃料電池車の消音器及びその吸音材によれば、排気ガスが水蒸気である環境下で、水はけが良く、長期にわたり良好な吸音性能を維持することができ、かつ軽量でリサイクルも可能であるという優れた効果を奏する。
【図面の簡単な説明】
【図１】本発明の実施形態の消音器を一部破断して示す斜視図である。
【図２】同消音器を一部破断して示す断面図である。
【図３】同消音器の吸音材形成時の斜視図である。
【図４】（ａ）は同消音器に用いる吸音材のクリンプを有する有機繊維を示す拡大図、（ｂ）は吸音材の別例を示す斜視図、（ｃ）は吸音材の他の別例を示す斜視図である。
【符号の説明】
１排気管
２小孔
３吸音層
４消音器筐体
１０有機繊維
１１帯
１２要素
１３要素
１５排水孔[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a muffler provided in an exhaust pipe of a fuel cell vehicle using a fuel cell and a sound absorbing material thereof.
[0002]
[Prior art]
2. Description of the Related Art A conventional automobile silencer has a structure in which a large number of ventilation holes are provided in a part of an exhaust pipe, glass wool as a sound absorbing material is provided on a part of an outer circumference of the exhaust pipe, and an outer pipe made of metal is provided on the outer circumference. Is generally applied. In some cases, a scattering prevention layer made of metal fiber is provided between the exhaust pipe and the glass wool to prevent thermal deterioration and scattering of the glass wool. Also, replacement of glass wool itself as a sound absorbing material with metal fibers such as stainless steel fibers has been studied. These have, of course, been developed to be provided in the exhaust pipe from an internal combustion engine.
[0003]
By the way, as one of the alternative technologies of the internal combustion engine type automobile, a so-called fuel cell vehicle, which drives a wheel by operating a motor by an electric current from a fuel cell, is coming to practical use. A fuel cell is a power generation device utilizing a reverse reaction of water electrolysis. Hydrogen and oxygen are supplied to two electrodes, respectively, to cause an electrochemical reaction (the above-described reverse reaction), and a current is supplied from the same electrode to the outside. The water vapor generated by the reaction is discharged as exhaust gas. The silencer using glass wool or stainless steel fiber as the above-described sound absorbing material can be provided in an exhaust pipe from this fuel cell, but at this time, a new point to be taken into account is the water content of the sound absorbing material by the water vapor. . Since water accumulates at the bottom of the muffler housing due to the condensation of the water vapor, the water accumulated at the bottom is sucked up by capillary action, and the entire sound absorbing material is likely to be hydrated. When the sound absorbing material contains water, voids (air layers) between the fibers of the sound absorbing material disappear, so that the sound absorbing performance is reduced.
[0004]
However, recently, the interior space of the silencer housing is partitioned into an upper chamber and a lower chamber by a partition plate having a communication hole, and the upper chamber is filled with glass wool to prevent water from being contained in the glass wool. A muffler for a fuel cell vehicle has been disclosed (JP-A-2002-206413).
[0005]
[Patent Document 1]
JP-A-2002-206413
[Problems to be solved by the invention]
The muffler for a fuel cell vehicle and its sound absorbing material have the following problems.
(1) In order to improve the recycling rate of automobiles, sound absorbing materials should be recyclable.
(2) To improve the fuel efficiency of automobiles, the sound absorbing material per weight (weight efficiency) is increased to reduce the weight of the sound absorbing material.
(3) As described above, it is necessary to prevent the sound absorbing material from containing water.
The silencer using the glass wool has good lightness but poor recyclability. In addition, because of poor drainage, when used in a fuel cell vehicle, water absorption tends to lower the sound absorbing performance. Therefore, it is necessary to take countermeasures by partitioning the internal space of the silencer housing as in the known example of the above-mentioned publication, but this complicates the structure of the silencer and increases the cost. Further, the silencer using the stainless steel fiber has good recyclability, but is not good in lightness.
[0007]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a light-weight and recyclable silencer for a fuel cell vehicle and a sound-absorbing material for the fuel cell vehicle, which are well drained in an environment where exhaust gas is water vapor, can maintain good sound absorbing performance for a long period of time, and can be recycled Is to provide.
[0008]
[Means for Solving the Problems]
There are various types of fuel cells, and when classified by reaction temperature, they can be classified into a low-temperature type where the reaction temperature is 300 ° C. or lower and a high-temperature type where the reaction temperature is higher. The present invention mainly using organic fibers can be applied to a fuel cell vehicle using a low-temperature fuel cell having a reaction temperature of 300 ° C. or less in terms of heat resistance. At this time, examples of such a low-temperature fuel cell include a polymer electrolyte fuel cell (PEFC), an alkali fuel cell (AFC), and a phosphoric acid fuel cell (PAFC).
[0009]
(1) The first invention is a sound absorbing material for a silencer of a fuel cell vehicle, which is adjusted to a bulk density of 20 to 200 kg / m ³ mainly using organic fibers. The adjustment value of the bulk density is a value at the time of filling the internal space of the silencer housing.
The type of the “organic fiber” is not particularly limited. The term “mainly organic fibers” means a case in which an organic or inorganic binder is mixed with the fibers to enhance the shape retention and facilitate filling. In this case, when the amount of the binder is large, the number of the bonding points of the fibers increases and the strength increases, but the sound absorbing performance decreases. Therefore, it is desirable to reduce the number as much as possible.
If the bulk density is less than 20 kg / m ³ , sound absorption performance comparable to that of glass wool cannot be provided. When the bulk density exceeds 200 kg / m ³ , water content is remarkably generated due to capillary action, drainage is poor, and sound absorbing performance is reduced. The bulk density is more preferably from 35~50kg / ^{m 3.}
[0010]
(2) The second invention is that the organic fiber is a synthetic fiber of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), rayon, vinylon, nylon, polyester, polyvinyl chloride, acrylic, vinylidene, and acetate; And a sound absorbing material for a silencer of a fuel cell vehicle, which is a fiber made of at least one kind selected from natural fibers of hemp, cotton, palm, bamboo, wool and silk.
Polypropylene, polyethylene, and polyethylene terephthalate are preferred in view of cost, water resistance, and versatility. Although a plurality of these fibers may be mixed, it is preferable to use one kind of material from the viewpoint of recycling.
When natural fibers are used, the fibers themselves have water absorbency, so it is preferable to apply a fifth invention described later and perform a surface treatment with a water repellent.
[0011]
(3) A third invention is a sound absorber for a silencer of a fuel cell vehicle, wherein the organic fibers are fibers having an average fiber diameter of 3 to 27 μm.
When the average fiber diameter is less than 3 μm, it is difficult to procure the fiber and the cost is significantly increased. When the average fiber diameter exceeds 27 μm, the sound absorbing performance is significantly reduced. The average fiber diameter is more preferably 10 to 18 μm in consideration of cost and sound absorbing performance.
[0012]
(4) A fourth invention is a sound absorbing material for a silencer of a fuel cell vehicle, wherein the organic fibers are fibers having crimps.
By using a crimped fiber, the space between the fibers becomes distorted or constricted, the viscous frictional resistance of air increases, and the sound absorbing performance can be improved.
[0013]
(5) A fifth invention is a sound absorbing material for a silencer of a fuel cell vehicle, wherein the organic fibers are fibers subjected to a surface treatment with a water repellent.
The water repellent is not particularly limited, but examples thereof include a fluorine compound and a silicone (oil, emulsion, etc.). By applying the water repellent to the fiber surface, drainage can be further improved.
[0014]
(6) In the sixth invention, a plate-like, rod-like, block-like element or the like in which the organic fibers are felt is joined so that at least a part of the joint surface between the elements goes from the inner periphery to the outer periphery. This is a sound absorbing material for a silencer of a fuel cell vehicle, which is formed into a tubular shape by the above.
By laminating the mating surfaces from the inner periphery to the outer periphery, the water contained between the fibers can be blown out along the mating surfaces by the flow pressure and the minute vibration of the exhaust gas, and the water can be drained more effectively. .
[0015]
(7) In the seventh invention, the bulk density is adjusted to 20 to 200 kg / m ³ mainly using organic fibers in at least a part of the internal space of the muffler housing arranged in the exhaust pipe of the fuel cell vehicle. This is a silencer for a fuel cell vehicle filled with a sound absorbing material.
Here, the “exhaust pipe” is not particularly limited as long as it is a pipe through which exhaust gas passes and forms a silencer, and an exhaust pipe extending from the fuel cell and an internal partition plate of a silencer housing connected to the exhaust pipe. Can be exemplified. It is desirable that the sound absorbing material is entirely made of the organic fiber sound absorbing material.
The method of providing the sound absorbing material is not particularly limited, but a method in which felt-like organic fibers are formed into a long band and wound around the outer periphery of the exhaust pipe, Can be exemplified. Alternatively, a method in which a film having a large number of open pores is formed in advance in the shape of a muffler, a felt-like organic fiber is inserted therein, and the inlet is sealed. Further, a method of directly filling the silencer housing while defibrating the organic fibers with compressed air can also be applied.
Other details are the same as the details of the first to sixth inventions.
[0016]
(8) An eighth invention is a muffler for a fuel cell vehicle, wherein a drain hole is provided in at least a part of the muffler housing.
By providing a drain hole in at least a part (for example, a lower part) of the silencer housing, even if water vapor as an exhaust gas diffuses from the fuel cell to the sound absorbing material and water accumulates in the lower part, the exhaust gas flow causes the inside of the sound absorbing material to flow. The permeated water can be appropriately drained out of the silencer. By making the opening area of the drain hole minute, it is possible to suppress a decrease in sound absorbing performance. Further, in order to enhance drainage, a drainage groove may be provided on the inner surface of the silencer housing or the outer surface of the sound absorbing material, and a spacer serving as a fixed support for the sound absorbing material is provided between the silencer housing and the sound absorbing material. And an appropriate air layer may be provided.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a muffler embodying the present invention will be described. The materials, configurations, numerical values, and the like described in the embodiments are merely examples, and can be changed as appropriate.
(Test 1)
In Example 1, a polypropylene fiber having a fiber diameter of 17.5 μm and a fiber length of 50 mm was needle-punched with no crimp and with crimp (FIG. 4A shows the crimped fiber 10). To produce a sound absorbing material adjusted to a bulk density of 35, 50 and 100 kg / m ³ . Also, as Comparative Example 1, a sound absorbing material was prepared using E glass fiber and similarly adjusted to a bulk density of 100 kg / m ³ by needle punch. From each of the sound absorbing materials of Example 1 and Comparative Example 1, a disk-shaped test piece having a thickness of 10 mm specified in JIS-A-1405 was prepared, and sound absorption at each frequency was performed according to a normal incidence sound absorption measurement method by a pipe method. The rate was measured. Table 1 shows the measurement results.
[0018]
[Table 1]

[0019]
(Test 2)
As Example 2, a sound-absorbing material was prepared using rayon fibers having different fiber diameters from 11.5 μm to 27.1 μm, each of which was made into a felt shape by a needle punch and adjusted to a bulk density of 50 kg / m ³ . In addition, as Comparative Example 2, using a glass long fiber having an average fiber diameter of 24 μm (trade name of Owens Corning Japan; Advantagex (Advantex)), the bulk density was similarly adjusted to 100 kg / m ³ by needle punching. A sound absorbing material was created. From each of the sound absorbing materials of Example 2 and Comparative Example 2, a disk-shaped test piece having a thickness of 10 mm specified in JIS-A-1405 was prepared, and sound absorption at each frequency was performed according to a normal incidence sound absorption measurement method by a pipe method. The rate was measured. Table 2 shows the measurement results (the measurement results of Comparative Example 1 are also shown).
[0020]
[Table 2]

[0021]
(Test 3)
Next, a water permeability test was performed on each of the sound absorbing materials of Example 1 and Comparative Example 1. The sample size was a disk having a diameter of 91.5 mm and a thickness of 10 mm. In this test, after immersion in water at room temperature in the atmosphere, the side surface of the disk was lifted at one place, drained vertically for 2 minutes, and taken out to determine the increased weight.
[0022]
[Table 3]

[0023]
(Test 4)
Similarly, as Example 3 and Comparative Example 3, each sound absorbing material of Example 1 and Comparative Example 1 was subjected to a surface treatment with a water repellent, and a water permeability test was performed. As the water repellent, a silicone-based water repellent (trade name: SM8706, manufactured by Dow Corning Toray Silicone Co., Ltd.) was applied by impregnation, squeezed, and dried. By adjusting the impregnation amount, the weight after drying was measured, and the desired bulk density was determined. The sample size was a disk having a diameter of 91.5 mm and a thickness of 10 mm. In this test, after immersion in water at room temperature in the atmosphere, the side surface of the disk was lifted at one place, drained vertically for 2 minutes, and taken out to determine the increased weight.
[0024]
[Table 4]

[0025]
As described above, according to the sound absorbing material of the embodiment, the following operational effects can be obtained.
{Circle around (1)} As shown in the measurement results in Table 1, the sound absorbing material of Example 1 has substantially the same sound absorbing performance as the sound absorbing material of Comparative Example 1 using glass fiber, despite using lightweight organic fibers. Having. In particular, the sound absorbing performance is excellent in a frequency range of 1000 Hz or less.
{Circle around (2)} As shown in the measurement results in Table 2, the sound absorbing material of Example 2 used the sound absorbing material of Comparative Example 2 using a thick glass long fiber, despite using a thick organic fiber. Has equal or better sound absorption performance. In particular, the sound absorbing performance is excellent in a frequency range of 1000 Hz or less.
{Circle around (3)} As shown in Table 3, the sound absorbing material of Example 1 has better water permeability than glass fiber.
{Circle around (4)} As shown in Table 4, the sound-absorbing material obtained by subjecting the fiber to the surface treatment with the water-repellent agent of Example 3 has good water permeability.
[0026]
Next, as shown in FIGS. 1 to 3, the felt-shaped felt pipes of Examples 1 to 3 are provided around the outer periphery of a portion of the exhaust pipe 1 (inner pipe) of the fuel cell vehicle through which many small holes 2 pass. Each sound absorbing material is wound into a long band 11 (for example, a band width of 20 to 100 mm and a band thickness of 1 to 10 mm) and wound around the outer circumference of the exhaust pipe 1 by a plurality of layers, and the whole sound absorbing material is made of the sound absorbing material. Material 3 was formed. Thereafter, the silencer case 4 (outer pipe) made of an aluminum-plated steel pipe having an outer diameter of 89 mm, an inner diameter of 87 mm, and a total length of 298 mm is extrapolated, and a gap at a contact portion between the exhaust pipe 1 and the muffler case 4 is welded. Completed the silencer. This means that the internal space of the silencer housing 4 is filled with each sound absorbing material. A drain hole 15 is provided in at least a part of the silencer housing 4. This muffler was well drained in an environment where the exhaust gas was steam, and was able to maintain good sound absorbing performance for a long period of time.
[0027]
Further, each of the felt-shaped sound absorbing materials of Examples 1 to 3 is formed on a plate-shaped element 12 as shown in FIG. 4B, or formed on a rod-shaped element 13 as shown in FIG. 4C. It was formed into a tubular sound absorbing material 3 by joining such that at least a part of the joining surface between the elements goes from the inner circumference to the outer circumference. This sound absorbing material 3 was also filled in the internal space of the muffler housing 4 arranged in the exhaust pipe 1 of the fuel cell vehicle, thereby completing the muffler. This muffler was well drained and could maintain good sound absorption performance for a long period of time.
[0028]
Note that the present invention is not limited to the above embodiment, and can be embodied with appropriate modifications without departing from the spirit of the invention.
[0029]
【The invention's effect】
As described in detail above, according to the muffler for a fuel cell vehicle and the sound absorbing material thereof according to the present invention, in an environment where exhaust gas is water vapor, drainage is good, and good sound absorbing performance can be maintained for a long time. It has an excellent effect of being lightweight, lightweight and recyclable.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a silencer according to an embodiment of the present invention, partially cut away.
FIG. 2 is a cross-sectional view showing the silencer partially cut away.
FIG. 3 is a perspective view of the muffler when a sound absorbing material is formed.
4A is an enlarged view showing an organic fiber having a crimp of a sound absorbing material used in the silencer, FIG. 4B is a perspective view showing another example of the sound absorbing material, and FIG. It is a perspective view showing an example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Exhaust pipe 2 Small hole 3 Sound absorption layer 4 Silencer case 10 Organic fiber 11 Band 12 Element 13 Element 15 Drainage hole

Claims

A sound absorbing material for a silencer of a fuel cell vehicle, which is adjusted to a bulk density of 20 to 200 kg / m ³ mainly using organic fibers.

The organic fibers are synthetic fibers of polypropylene, polyethylene, polyethylene terephthalate, rayon, vinylon, nylon, polyester, polyvinyl chloride, acrylic, vinylidene and acetate, and natural fibers of hemp, cotton, palm, bamboo, wool and silk. The sound absorbing material for a muffler of a fuel cell vehicle according to claim 1, wherein the sound absorbing material is at least one selected fiber.

The sound absorbing material for a silencer of a fuel cell vehicle according to claim 1 or 2, wherein the organic fiber is a fiber having an average fiber diameter of 3 to 27 µm.

4. The sound absorbing material for a silencer of a fuel cell vehicle according to claim 1, wherein the organic fibers are fibers having crimps.

The sound absorbing material for a muffler of a fuel cell vehicle according to claim 1, wherein the organic fiber is a fiber that has been subjected to a surface treatment with a water repellent.

2. A tubular member formed by joining elements such as a plate, a rod, and a block in which the organic fibers are made in a felt shape such that at least a part of the joining surface between the elements is directed from the inner periphery to the outer periphery. The sound absorbing material for a muffler of a fuel cell vehicle according to 2, 3, 4, or 5.

A fuel cell vehicle in which at least a part of an internal space of a silencer housing arranged in an exhaust pipe of the fuel cell vehicle is filled with a sound absorbing material adjusted to a bulk density of 20 to 200 kg / m ³ using mainly organic fibers. Silencer.

The muffler for a fuel cell vehicle according to claim 7, wherein a drain hole is provided in at least a part of the muffler housing.