JP3767545B2

JP3767545B2 - Cylindrical vibration isolator

Info

Publication number: JP3767545B2
Application number: JP2002343097A
Authority: JP
Inventors: 和彦加藤; 淳一朗鈴木
Original assignee: Sumitomo Riko Co Ltd
Current assignee: Sumitomo Riko Co Ltd
Priority date: 2002-11-26
Filing date: 2002-11-26
Publication date: 2006-04-19
Anticipated expiration: 2022-11-26
Also published as: JP2004176803A

Description

【０００１】
【発明の属する技術分野】
この発明は、ゴムブッシュを筒形の相手部材に圧入し、嵌合状態に保持するようになした筒形防振装置に関し、特にゴムブッシュの外筒が樹脂にて構成されたものに関する。
【０００２】
【従来の技術】
従来より、剛性の外筒及び内筒と、それら外筒及び内筒間に配置されたゴム弾性体とを有するゴムブッシュを、外筒の外面において筒形の剛性の相手部材に圧入して、ゴムブッシュを相手部材にて嵌合状態に保持するようになした筒形防振装置が、自動車のトレーリングアームブッシュ，トルクロッドブッシュ等のサスペンションブッシュやエンジンマウント等として広く用いられている。
【０００３】
この種の筒形防振装置は、従来ゴムブッシュの外筒，内筒，相手部材が何れも金属製であり、ゴムブッシュの外筒を所定の締め代で相手部材に圧入すると、外筒の外面と相手部材の内面との間に発生する強い摩擦力に基づいてゴムブッシュが相手部材から抜け防止される。
【０００４】
ところで、近年ゴムブッシュの外筒を樹脂化することが検討されており、この場合、樹脂から成る外筒の弾性復元力が応力緩和により低下し、更に熱影響を受けることにより大きく応力緩和を生じ、初期には所定の締め代をもって圧入したとしても、その後の経時変化により外筒の相手部材に対する弾性復元力が低下し、抜き力が低下してしまう問題が内在する。
【０００５】
この問題の対策の一例が下記特許文献１に開示されている。
図１１はその具体例を示している。同図において２００はゴムブッシュで、金属製の内筒２０２と、その外周面に一体に固着されたゴム弾性体２０４と、更にそのゴム弾性体２０４の外周面に一体に固着された樹脂製の外筒２０６とを有している。
２０８は金属製の筒形をなす相手部材で、ゴムブッシュ２００は、この相手部材２０８内部に圧入されて嵌合状態に保持されている。
【０００６】
樹脂製の外筒２０６及びゴム弾性体２０４は、それぞれ軸方向端部（図中下端部）にフランジ部２１０及び２１２を有しており、また外筒２０６は、これとは反対側の軸方向端部且つ相手部材２０８から軸方向に突き出した部分に、互いに逆方向に傾斜する傾斜面２１４，２１６を備えた、部分的に厚肉の係合部２１８を有している。
ゴムブッシュ２００は、相手部材２０８への圧入後において、この係合部２１８が相手部材２０８の軸端に係合することによって相手部材２０８から抜け防止される。
【０００７】
【特許文献１】
実開平５−７７６３７号公報
【０００８】
【発明が解決しようとする課題】
しかしながら図１１に示す筒形防振装置の場合、外筒２０６の一部、詳しくは係合部２１８の部分が相手部材２０８から軸方向に突き出し、外部に露出して外気に曝されていることから劣化を生じ易い問題の外、相手部材２０８から突き出して露出した部分に飛び石等が当ったりして割れを生じ易い問題がある。
更にこの筒形防振装置の場合、必然的にゴムブッシュ２００の軸方向長が相手部材２０８よりも長くなければならず、形状的な制約を受ける問題がある。
【０００９】
更にこの例の筒形防振装置の場合、外筒２０６が割れを生じない範囲で最大の締め代をもって外筒２０６を相手部材２０８に圧入することが望ましいが、この場合相手部材２０８との嵌合部分において最大の締め代を設定すると、圧入時に部分的な厚肉部分である係合部２１８の部分が過大に縮径させられることとなって、同部分で割れを生じ易いといった問題がある。
一方で係合部２１８の部分で割れを生じないように圧入時の締め代を設定すると、圧入後において外筒２０６の、相手部材２０８との嵌合部分での締め代が不足してしまうといった問題を生ずる。
【００１０】
【課題を解決するための手段】
本発明の筒形防振装置はこのような課題を解決するために案出されたものである。
而して請求項１のものは、樹脂製の外筒と、内筒と、それら外筒及び内筒間に配置されたゴム弾性体とを有するゴムブッシュを、該外筒の外面において筒形の剛性の相手部材に圧入して該ゴムブッシュを該相手部材にて嵌合状態に保持するようになした筒形防振装置において、前記相手部材の内面に、径方向外方に凹陥した形態の凹陥部を軸方向に部分的に形成して該相手部材の内面の形状を、該凹陥部と非凹陥部との境界部に段付部を有する段付形状となす一方、前記外筒の外面を該相手部材への圧入前の状態で前記非凹陥部よりも大径となし、樹脂の弾性変形を利用して該外筒を縮径させながら該相手部材内部に圧入し、該外筒の前記凹陥部に対向して位置する部分を圧入後の弾性復元力で拡径させて、該外筒の外面形状を前記相手部材の内面形状に倣った段付形状となし、該相手部材の段付部と該外筒の段付部とを軸方向に且つ抜け方向に互いに係合させたことを特徴とする。
【００１１】
請求項２のものは、請求項１において、前記外筒の、前記凹陥部に対向して位置する部分の前記弾性復元力による拡径方向の戻り変形の変形量を他部よりも大となし、以って該外筒の外面形状を前記相手部材の内面形状に倣った段付形状となしたことを特徴とする。
【００１２】
請求項３のものは、請求項１，２の何れかにおいて、前記外筒の外面を前記相手部材への圧入前の状態で実質的に軸方向のストレート形状となしてあることを特徴とする。
【００１３】
請求項４のものは、請求項１〜３の何れかにおいて、前記凹陥部を軸方向の中間部に設けて、該凹陥部の軸方向両側の非凹陥部と該凹陥部との境界部に、軸方向に互いに逆向きをなす一対の段付部を形成してあることを特徴とする。
【００１４】
請求項５のものは、請求項１〜４の何れかにおいて、前記相手部材を軸方向の分割構成とし、大径の内径を有する分割筒体にて前記凹陥部を形成したことを特徴とする。
【００１５】
請求項６のものは、請求項１〜５の何れかにおいて、前記相手部材の内面には、径方向外方に凹陥した形態の凹陥部を周方向に部分的に形成して該相手部材の内面を周方向に段付部を有する段付形状となしてあることを特徴とする。
【００１６】
請求項７のものは、請求項１〜６の何れかにおいて、前記凹陥部の内径を、圧入前の状態において前記外筒の対応する部分の最大外径と同等以下となしてあることを特徴とする。
【００１７】
【作用及び発明の効果】
以上のように本発明は、相手部材の内面の形状を、凹陥部を有する段付形状となし、ゴムブッシュにおける樹脂製の外筒の外面を、圧入により樹脂の弾性変形を利用して相手部材の内面の形状に倣った段付形状となし、それらの段付部をゴムブッシュの抜け方向に係合させたもので、本発明によれば、それら外筒及び相手部材の段付部の係合作用によってゴムブッシュの抜き力を効果的に高め得、ゴムブッシュの抜けを良好に防止することができる。
【００１８】
本発明は、相手部材の内面と外筒の外面とを係合させるものであり、従って外筒が相手部材から軸方向に突出しない形態で筒形防振装置を構成することが可能となる。
そしてこのようになした場合、外筒の、相手部材から突き出した部分が外気に曝されて劣化し、また飛び石等が当って割れを生じる等の問題を解決することができる。
またゴムブッシュを相手部材よりも長くすることの制約が除かれて筒形防振装置の設計の自由度が増す効果が得られる。
【００１９】
本発明においては、外筒の、凹陥部に対向して位置する部分の弾性復元力による拡径方向の戻り変形の変形量を他部よりも大となすことによって、外筒の外面形状を相手部材の内面形状に倣った段付形状となすことができる（請求項２）。
更に外筒の外面を相手部材への圧入前の状態で実質的に軸方向のストレート形状となしておくことができる（請求項３）。
【００２０】
このように外筒の外面を軸方向のストレート形状とすることで、図１１に示す筒形防振装置における問題、即ち外筒２０６に径方向外方に突出する部分的な厚肉部を形成することによって、圧入の際に同部分が過度に縮径方向に締め付けられ、割れを生じてしまうといった問題を解決することができる。
【００２１】
請求項４は、上記凹陥部を軸方向の中間部に設けて、その凹陥部の軸方向両側の非凹陥部との境界部に、軸方向において互いに逆向きをなす一対の段付部を形成したもので、この場合、相手部材に圧入されたゴムブッシュは、相手部材に対し軸方向且つ互いに逆方向に係合した状態となり、何れの方向に対しても良好に抜け防止される。
本発明は、特に外筒がフランジ部を有しない形態のものに適用して効果が大である。
【００２２】
請求項５は、相手部材を軸方向に複数分割し、そして大径の内径を有する分割筒体にて前記凹陥部を形成したもので、このようになすことで容易に相手部材の内面に凹陥部及び段付部を形成することができる。
【００２３】
本発明においてはまた、相手部材の内面に凹陥部を周方向に部分的に形成しておくことができ（請求項６）、この場合、相手部材とそこに圧入されたゴムブッシュとを周方向に係合させ得て、同方向の相対移動を阻止することが可能となる。
【００２４】
本発明ではまた上記凹陥部の内径を、圧入前の状態において上記外筒の対応する部分の最大外径と同等以下となしておくことができる（請求項７）。
【００２５】
【実施例】
次に本発明の実施例を図面に基づいて詳しく説明する。
この例は自動車のトーションビーム式リヤサスペンションにおけるトレーリングアームと車体との連結部分に用いられる筒形防振装置の例で、図２はゴムブッシュ１０を、図３は図２のゴムブッシュ１０を圧入すべき相手部材１２を、図１は図３の相手部材１２に図２のゴムブッシュ１０を圧入して組み付けた状態をそれぞれ示している。
尚、図１において１４は相手部材１２から延び出したアームである。
【００２６】
図２に示しているように、ゴムブッシュ１０は円筒形状をなす内筒１６と、同じく円筒形状をなす外筒１８と、それらの間に配置されて内筒１６及び外筒１８を弾性的に連結するゴム弾性体２０とを有している。
ここで内筒１６は金属製とされ、また外筒１８は樹脂製とされている。
尚、内筒１６については剛性のある樹脂を用いることも可能である。
またゴム弾性体２０には、同図に示しているように一対の空所（すぐり）２２が軸方向に沿って形成されている。
【００２７】
外筒１８には、図２（Ｂ）に示しているように軸方向一端（図中左端）にフランジ部２４が形成されており、またこれに対応してゴム弾性体２０にも軸方向一端にフランジ部２６が形成されている。
【００２８】
ここでゴムブッシュ１０は、図４に示す外筒１８の外径、詳しくはフランジ部２４を除いた部分の外径ｄ_１が直径６７ｍｍとされている。
また外筒１８の軸方向長、詳しくはフランジ部２４を除いた部分の軸方向長ｌ_１が、相手部材１２の軸方向長Ｌ_１とほぼ同等とされている。
【００２９】
尚本例において、外筒１８を構成する樹脂としては各種のものを用いることができる。
詳しくは、かかる外筒１８の構成樹脂として熱可塑性樹脂や熱硬化性樹脂等を用いることができ、その中でも振動入力に対する耐衝撃強度や外筒１８としての成形性に優れる熱可塑性樹脂が好適に用いられる。
【００３０】
また熱可塑性樹脂材料としてはポリアミド（芳香族ポリアミドや変性ポリアミドを含む），ポリエステル（変性ポリエステルを含む），ポリプロピレン，ポリカーボネート，ポリアセタール，ポリフェニレンサルファイド，変性ポリフェニレンエーテル等があり、その中でも強度や充填材による補強効果，コストのバランスに優れるポリアミドが好適に用いられる。
【００３１】
またそのような樹脂材料を補強するために樹脂材料に配合ないしは混合される充填材としてガラス繊維，炭素繊維，アラミド繊維，ボロン繊維，アルミナ繊維，金属繊維，炭化珪素繊維，ガラスビーズ，ウィスカー，ワラスナイト，カオリナイト，タルク，マイカ，カーボンナノチューブ他、珪酸マグネシウム若しくは珪酸アルミニウムの層で構成される層状フィロ珪酸塩、例えばモンモリロナイト，ヘクトライト，バーミキュライト，ハロサイト等があるが、その中でも補強効果の高さやコストの点からガラス繊維が好適に用いられる。
また使用部位によっては充填材のない非強化樹脂材料も用いることができる。
本例の外筒１８の樹脂材料は、ポリアミド６６（ＰＡ６６）に充填材としてガラス繊維３０％を混合したものを用いている。
【００３２】
一方図３に示す相手部材１２は、全体としてゴムブッシュ１０に対応した円筒形状をなしている。
ここで相手部材１２はその全体が金属にて構成されている。
【００３３】
図３（Ｂ）に示しているように、相手部材１２にはその内面に軸方向半分に亘って径方向外方に凹陥する形態の凹陥部２８が環状に形成されており、かかる凹陥部２８と非凹陥部３０との境界に段付部３２が形成されている。
【００３４】
ここで凹陥部２８の内径Ｄ_２（図４参照）は、圧入前のゴムブッシュ１０の外筒１８の外径ｄ_１と等しい寸法とされている。
一方非凹陥部３０の内径Ｄ_１は、外筒１８の外径ｄ_１よりも小さい寸法、具体的にはここでは直径６５ｍｍの寸法とされている。
尚、凹陥部２８の軸方向長Ｌ_２は、全体の軸方向長Ｌ_１に対して丁度１／２の寸法とされている。但しＬ_２の寸法は適宜変更可能である。
【００３５】
本例の筒形防振装置では、図４に示すようにしてゴムブッシュ１０を相手部材１２内部に軸方向に圧入して、ゴムブッシュ１０を相手部材１２にて嵌合状態に保持するようにする。
このとき、樹脂製の外筒１８は弾性変形を伴って縮径しつつその外面において相手部材１２の内部に圧入される。
そして圧入後、外筒１８の相手部材１２における凹陥部２８に対向して位置する部分が弾性復元力によって拡径し、凹陥部２８内に部分的に入り込んだ状態となる。
【００３６】
そして外筒１８の外面形状は相手部材１２の内面形状に倣った段付形状に変形する。
詳しくは、図１において凹陥部２８に対応した部分が大径部３４、非凹陥部３０に対応した部分が小径部３６をなす段付形状に変形し、そして外筒１８における段付部３８が、相手部材１２の内面に形成された段付部３２に対して軸方向且つ抜け方向、即ち図中左向きに係合した状態となる。
そしてこれら段付部３２と３８との係合作用によって、ゴムブッシュ１０の相手部材１２からの高い抜き力が得られ、ゴムブッシュ１０が良好に抜け防止される。
【００３７】
因みに図５は、図１〜図４に示す実施例品の抜き力を図６（Ｂ），（Ｃ）に示す比較例品１及び比較例品２（但し相手部材１２-１，１２-２のみ開示）との比較において示したものである。
【００３８】
ここで比較例品１は、図６（Ａ）に示す実施例品の相手部材１２と異なって、相手部材１２-１の内面に凹陥部２８及び段付部３２を設けず、その内面の形状を軸方向のストレート形状となしたものである。
尚その内径はＤ_１で、上記実施例の非凹陥部３０の内径と同等である。
また比較例品２は、相手部材１２-２の内面をブラスト処理して表面粗さを粗くしたものである（通常は表面粗さが数μｍであるのに対しここでは３０μｍ程度の表面粗さとしている）。
【００３９】
図５において、（Ａ）は圧入後に常温放置した場合の抜き力の経時変化の測定結果であり、また（Ｂ）は熱間放置（８０℃）した場合の抜き力の経時変化の測定結果である。
【００４０】
図５（Ａ）の常温放置の場合の結果において、比較例品２は初期抜き力が高く、その分、時間経過後（５００時間経過後）も高い抜き力を保持している。
また比較例品１は初期抜き力が低い分だけ、時間経過後の抜き力は低くなっている。
これに対し実施例品の場合、初期抜き力が低いために時間経過後の抜き力は比較例品２に比べれば低くなっているが、初期抜き力に対する時間経過後の抜き力の低下率（経時変化率）は比較例品１，比較例品２に比べて格段と優れている。
【００４１】
一方図５（Ｂ）の熱間放置の場合、比較例品１，比較例品２ともに経時変化による抜き力は大幅に低下しているにも拘わらず、実施例品の場合、抜き力の低下は少なく抑えられている。
【００４２】
以上のように本例の筒形防振装置の場合、外筒１８及び相手部材１２の各段付部３２，３８の係合作用によって、ゴムブッシュ１０の抜き力を効果的に高め得、ゴムブッシュ１０が相手部材１２から抜けるのを良好に防止することができる。
【００４３】
また本例ではゴムブッシュ１０の外筒１８を相手部材１２から軸方向に突出させず、相手部材１２の内面で外筒１８を軸方向に係合させていることから、図１１に示す従来の筒形防振装置のように、相手部材２０８から外筒２０６が外部に露出することによって劣化し、或いはまたそこに飛び石等が当って外筒２０６が割れを生じるといった不具合を生じない。
【００４４】
またゴムブッシュ１０を相手部材１２よりも必ず長くしなければならないといった制約がなく、筒形防振装置の設計の自由度が増す利点が得られる。
また本例では、外筒１８の外面が軸方向にストレート形状をなしているため、図１１に示す筒形防振装置における問題、即ち外筒２０６に径方向外方に突出する部分的な厚肉部を形成することによって、圧入の際に同部分が過度に縮径方向に締め付けられ、割れを生じてしまうといった問題を解決することができる。
【００４５】
図７は本発明の他の実施例を示している。
この内（Ａ）は、相手部材１２における段付部３２をテーパ状に形成した例で、また（Ｂ）は相手部材１２を分割筒体１８Ａと１８Ｂとの２分割構成とし、内径の大きな分割筒体１８Ｂによって凹陥部２８を形成し、そしてその凹陥部２８と非凹陥部３０との境界に段付部３２を形成した例である。
【００４６】
更にまた（Ｃ）は、相手部材１２を分割筒体１８Ｃ，１８Ｄ，１８Ｅの３分割構成とし、そして軸方向の中間部に位置する内径の最も大きな分割筒体１８Ｄにて凹陥部２８を形成し、凹陥部２８とその軸方向両側の非凹陥部３０との境界に、軸方向において互いに向きが逆となる一対の段付部３２を形成した例である。
【００４７】
これら図７（Ｂ），（Ｃ）に示すように、相手部材１２を軸方向に複数分割し、そして大径の内径を有する分割筒体１８Ｂ，１８Ｄにて凹陥部２８を形成するようになした場合、容易に筒形の相手部材１２の内面に凹陥部２８及び段付部３２を形成することができる。
【００４８】
また図７（Ｃ）の場合、相手部材１２に圧入されたゴムブッシュ１０が、軸方向且つ互いに反対向きの両方向に抜止めされた状態となり、従って図７（Ｃ）によれば、ゴムブッシュ１０がフランジ部２４を有しないものであっても、即ちフランジ部２４による相手部材１２への当接によって、軸方向の抜けを防止するといったことができない場合であっても、相手部材１２内部に圧入されたゴムブッシュ１０を支障なく軸方向の両方向に抜け防止することができる。
【００４９】
図８は本発明の更に他の実施例を示したもので、この例は相手部材１２の内面に且つ周方向に沿って、径方向外方に凹陥する形態の凹陥部４０と非凹陥部４２とを交互に設け、それら凹陥部４０と非凹陥部４２との境界に段付部４４を形成したものである。
【００５０】
相手部材１２の内面をこのような段付形状になしておいた場合、そこに圧入したゴムブッシュ１０の樹脂製の外筒１８が、その内面形状に倣った形状に変形し、これによってゴムブッシュ１０が相手部材１２に対し周方向に強く拘束された状態となる。
【００５１】
以上は外筒１８の外面を軸方向のストレート形状となした例であるが、外筒１８の外面を軸方向の非ストレート形状となすことも可能である。
図９はその具体例を示している。
図９（Ｂ）において（イ）は外筒１８の外面形状の、凹陥部２８に対向する部分の軸方向の一部を径方向外方に突出する周方向の環状の突出部４６として形成した例である。
【００５２】
また（ロ）は外筒１８の外面形状を、フランジ部２４から反対側の軸方向端に向って外径が漸次増大した後、一定軸方向長に亘って同じ外径を保ち、その後外径が漸次小となるような形状で形成し、以って相手部材１２における非凹陥部３０から凹陥部２８にかけて外筒１８の外面形状を径方向外方に突出する突出部４８として形成した例を示している。
【００５３】
更に（ハ）は外筒１８の外面形状をフランジ部２４から反対側の軸方向端に向って外径が漸次増大するような形状で形成した例を示している。
更に（ニ）は外筒１８の外面形状を微細な凹凸５０を有する形状に形成した例を示している。
【００５４】
一方図１０は外筒１８の内面形状を非ストレート形状となした例を示したもので、この内（Ｂ）（イ）は外筒１８の内面形状の、凹陥部２８に対向する部分の軸方向の一部を部分的に径方向内方に突出させて成る周方向の環状の突出部５２として形成した例を示している。
また（ロ）は外筒１８の内面形状の、凹陥部２８に対向する部分をほぼ全体的に径方向内方に且つ周方向に環状に突出させて成る突出部５４として形成した例を示している。
【００５５】
以上本発明の実施例を詳述したがこれはあくまで一例示であり、本発明は上記自動車のトーションビーム式リヤサスペンションにおける筒形防振装置以外の各種筒形防振装置に適用することが可能であるなど、その趣旨を逸脱しない範囲において種々変更を加えた形態で構成可能である。
【図面の簡単な説明】
【図１】本発明の一実施例である筒形防振装置を示す図である。
【図２】同実施例におけるゴムブッシュを圧入前の状態で示す図である。（Ａ）：（Ｂ）の左側面図である。
（Ｂ）：（Ａ）のＢ−Ｂ断面図である。
【図３】同実施例における相手部材を示す図である。
【図４】同実施例におけるゴムブッシュと相手部材との寸法関係を圧入方向とともに示す図である。
【図５】本実施例におけるゴムブッシュの抜き力の経時変化を比較例とともに示す図である。
【図６】図５の測定に用いた比較例品における相手部材の内面形状を実施例品のそれと比較して示した図である。
【図７】本発明の更に他の各実施例の要部を示した図である。
【図８】本発明の更に他の実施例の要部を示した図である。
【図９】本発明の更に他の各実施例の要部を示した図である。
【図１０】本発明の更に他の各実施例の要部を示した図である。
【図１１】従来の筒形防振装置の一例を示す図である。
【符号の説明】
１０ゴムブッシュ
１２相手部材
１６内筒
１８外筒
１８Ａ，１８Ｂ，１８Ｃ，１８Ｄ，１８Ｅ分割筒体
２０ゴム弾性体
２８，４０凹陥部
３０，４２非凹陥部
３２，３８，４４段付部
ｄ_１外筒の外径
Ｄ_２凹陥部の内径[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cylindrical vibration isolator in which a rubber bush is press-fitted into a cylindrical mating member and held in a fitted state, and particularly relates to a rubber bush whose outer cylinder is made of resin.
[0002]
[Prior art]
Conventionally, a rubber bush having a rigid outer cylinder and an inner cylinder, and a rubber elastic body disposed between the outer cylinder and the inner cylinder, is press-fitted into a cylindrical rigid counterpart member on the outer surface of the outer cylinder, 2. Description of the Related Art Cylindrical vibration damping devices that hold a rubber bush in a mating state with a mating member are widely used as suspension bushes such as a trailing arm bush and a torque rod bush of an automobile, an engine mount, and the like.
[0003]
In this type of cylindrical vibration isolator, the outer cylinder, the inner cylinder, and the mating member of the rubber bush are all made of metal, and when the outer cylinder of the rubber bush is press-fitted into the mating member with a predetermined tightening allowance, The rubber bush is prevented from coming off from the mating member based on a strong frictional force generated between the outer surface and the inner surface of the mating member.
[0004]
By the way, in recent years, it has been studied to use an outer cylinder of the rubber bush as a resin. In this case, the elastic restoring force of the outer cylinder made of resin is reduced due to stress relaxation, and the stress is greatly reduced due to thermal influence. Even if it is press-fitted with a predetermined allowance at the initial stage, there is a problem that the elastic restoring force against the mating member of the outer cylinder is lowered due to the subsequent change with time, and the pulling force is lowered.
[0005]
An example of a countermeasure for this problem is disclosed in Patent Document 1 below.
FIG. 11 shows a specific example thereof. In the figure, reference numeral 200 denotes a rubber bush, which is made of a metal inner cylinder 202, a rubber elastic body 204 that is integrally fixed to the outer peripheral surface thereof, and a resin made of resin that is integrally fixed to the outer peripheral surface of the rubber elastic body 204. And an outer cylinder 206.
Reference numeral 208 denotes a mating member made of a metal cylinder, and the rubber bush 200 is press-fitted into the mating member 208 and held in a fitted state.
[0006]
The resin-made outer cylinder 206 and the rubber elastic body 204 have flange portions 210 and 212 at axial end portions (lower end portions in the drawing), respectively, and the outer cylinder 206 has an axial direction opposite to this. An end portion and a portion protruding in the axial direction from the counterpart member 208 have a partially thick engaging portion 218 provided with inclined surfaces 214 and 216 inclined in opposite directions.
The rubber bushing 200 is prevented from coming off the mating member 208 when the engaging portion 218 engages the shaft end of the mating member 208 after press-fitting into the mating member 208.
[0007]
[Patent Document 1]
Japanese Utility Model Publication No. 5-77737
[Problems to be solved by the invention]
However, in the case of the cylindrical vibration isolator shown in FIG. 11, a part of the outer cylinder 206, specifically, the engaging part 218 protrudes from the mating member 208 in the axial direction and is exposed to the outside by being exposed to the outside. In addition to the problem of being easily deteriorated, there is a problem that a stepping stone or the like protrudes from the mating member 208 and hits a stepped stone or the like to cause a crack.
Further, in the case of this cylindrical vibration isolator, the length of the rubber bush 200 in the axial direction is necessarily longer than that of the mating member 208, and there is a problem that the shape is restricted.
[0009]
Further, in the case of the cylindrical vibration isolator of this example, it is desirable to press-fit the outer cylinder 206 into the mating member 208 with the maximum tightening margin within a range in which the outer cylinder 206 does not crack. If the maximum tightening allowance is set in the joint portion, the portion of the engaging portion 218 that is a partial thick portion at the time of press-fitting is excessively reduced in diameter, and there is a problem that cracks are likely to occur in the same portion. .
On the other hand, if the tightening allowance at the time of press-fitting is set so as not to cause cracks at the engaging portion 218, the tightening allowance at the fitting portion of the outer cylinder 206 with the mating member 208 will be insufficient after the press-fitting. Cause problems.
[0010]
[Means for Solving the Problems]
The cylindrical vibration isolator of the present invention has been devised to solve such problems.
Thus, according to the first aspect of the present invention, a rubber bush having a resin outer cylinder, an inner cylinder, and a rubber elastic body disposed between the outer cylinder and the inner cylinder is formed into a cylindrical shape on the outer surface of the outer cylinder. In a cylindrical vibration isolator that is press-fitted into a mating member of the above-mentioned rigidity so as to hold the rubber bush in a fitted state with the mating member, a configuration in which the inner surface of the mating member is recessed radially outward And forming the shape of the inner surface of the mating member into a stepped shape having a stepped portion at the boundary between the recessed portion and the non-recessed portion. The outer surface has a diameter larger than that of the non-recessed portion before being pressed into the mating member, and the outer cylinder is press-fitted into the mating member while reducing the diameter of the outer cylinder using elastic deformation of resin. The portion of the outer cylinder is expanded by the elastic restoring force after press-fitting, and the outer surface shape of the outer cylinder is changed to the counterpart member. It stepped shape and without which following the inner surface shape, characterized in that engaged with each other and a stepped portion of the stepped portion and the outer cylinder of the mating member and omission direction in the axial direction.
[0011]
According to a second aspect of the present invention, in the first aspect, the amount of return deformation in the diameter-enlarging direction due to the elastic restoring force of the portion of the outer cylinder facing the recessed portion is larger than that of the other portions. Thus, the outer surface shape of the outer cylinder is a stepped shape that follows the inner surface shape of the mating member.
[0012]
According to a third aspect of the present invention, in any one of the first and second aspects, the outer surface of the outer cylinder has a substantially axial straight shape before being press-fitted into the mating member. .
[0013]
According to a fourth aspect of the present invention, in any one of the first to third aspects, the concave portion is provided in an intermediate portion in the axial direction, and a boundary portion between the non-concave portion and the concave portion on both axial sides of the concave portion is provided. A pair of stepped portions that are opposite to each other in the axial direction are formed.
[0014]
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the counterpart member is divided in the axial direction, and the recessed portion is formed by a divided cylindrical body having a large inner diameter. .
[0015]
According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the inner surface of the mating member is partially formed in the circumferential direction with a concave portion that is recessed radially outward. The inner surface has a stepped shape having a stepped portion in the circumferential direction.
[0016]
According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the inner diameter of the recessed portion is equal to or less than a maximum outer diameter of a corresponding portion of the outer cylinder in a state before press-fitting. And
[0017]
[Operation and effect of the invention]
As described above, in the present invention, the shape of the inner surface of the mating member is a stepped shape having a recessed portion, and the mating member is made by utilizing the elastic deformation of the resin by press-fitting the outer surface of the resin outer cylinder in the rubber bush. A stepped shape that follows the shape of the inner surface of the rubber bushing, and the stepped portions are engaged in the direction in which the rubber bushing is pulled out. The pulling force of the rubber bush can be effectively increased by the combined action, and the rubber bush can be satisfactorily prevented from coming off.
[0018]
According to the present invention, the inner surface of the mating member and the outer surface of the outer cylinder are engaged. Therefore, the cylindrical vibration isolator can be configured in a form in which the outer cylinder does not protrude in the axial direction from the mating member.
And when it does in this way, the problem that the part which protruded from the other party member of the outer cylinder is exposed to external air, deteriorates, and a stepping stone etc. hits and a crack etc. can be solved.
Further, the restriction of making the rubber bush longer than the counterpart member is removed, and the effect of increasing the degree of freedom in designing the cylindrical vibration isolator can be obtained.
[0019]
In the present invention, the outer surface shape of the outer cylinder is controlled by increasing the amount of return deformation in the diameter-enlarging direction due to the elastic restoring force of the portion of the outer cylinder facing the recessed portion more than the other parts. A stepped shape that follows the shape of the inner surface of the member can be obtained.
Furthermore, the outer surface of the outer cylinder can be formed into a substantially straight shape in the axial direction before being pressed into the mating member.
[0020]
In this way, by forming the outer surface of the outer cylinder in a straight shape in the axial direction, a problem with the cylindrical vibration isolator shown in FIG. 11, that is, a partial thick portion protruding radially outward in the outer cylinder 206 is formed. By doing so, it is possible to solve the problem that the same portion is excessively tightened in the direction of diameter reduction during the press-fitting and causes cracking.
[0021]
According to a fourth aspect of the present invention, the concave portion is provided in an intermediate portion in the axial direction, and a pair of stepped portions that are opposite to each other in the axial direction is formed at a boundary portion between the concave portion and the non-concave portion on both sides in the axial direction. Therefore, in this case, the rubber bush press-fitted into the mating member is engaged with the mating member in the axial direction and in the opposite directions, and can be prevented from coming off in any direction.
The present invention is particularly effective when applied to a configuration in which the outer cylinder does not have a flange portion.
[0022]
According to a fifth aspect of the present invention, the mating member is divided into a plurality of parts in the axial direction, and the recessed portion is formed by a divided cylindrical body having a large inner diameter. A part and a stepped part can be formed.
[0023]
In the present invention, a recessed portion can be partially formed in the circumferential direction on the inner surface of the mating member (Claim 6). In this case, the mating member and the rubber bush press-fitted therein are circumferentially arranged. The relative movement in the same direction can be prevented.
[0024]
In the present invention, the inner diameter of the recessed portion can be made equal to or less than the maximum outer diameter of the corresponding portion of the outer cylinder in a state before press-fitting (Claim 7).
[0025]
【Example】
Next, embodiments of the present invention will be described in detail with reference to the drawings.
This example is an example of a cylindrical vibration isolator used in a connecting portion between a trailing arm and a vehicle body in a torsion beam type rear suspension of an automobile. FIG. 2 is press-fitted with a rubber bush 10 and FIG. 3 is press-fitted with a rubber bush 10 in FIG. FIG. 1 shows a state in which the rubber member 10 to be pressed is assembled into the mating member 12 shown in FIG.
In FIG. 1, reference numeral 14 denotes an arm extending from the mating member 12.
[0026]
As shown in FIG. 2, the rubber bush 10 includes a cylindrical inner cylinder 16, a cylindrical outer cylinder 18, and an inner cylinder 16 and an outer cylinder 18 that are disposed between the inner cylinder 16 and the outer cylinder 18. And a rubber elastic body 20 to be connected.
Here, the inner cylinder 16 is made of metal, and the outer cylinder 18 is made of resin.
For the inner cylinder 16, a rigid resin can be used.
The rubber elastic body 20 is formed with a pair of voids (straight) 22 along the axial direction as shown in FIG.
[0027]
As shown in FIG. 2B, the outer cylinder 18 is formed with a flange portion 24 at one end in the axial direction (left end in the figure), and the rubber elastic body 20 also has one end in the axial direction corresponding thereto. A flange portion 26 is formed on the bottom.
[0028]
Here the rubber bushing 10 has an outer diameter of the outer cylinder 18 shown in Figure 4, details outer diameter d ₁ of the portion excluding the flange portion 24 is the diameter 67 mm.
The axial length of the outer tube 18, specifically axial length l ₁ of the portion excluding the flange portion 24 is substantially the same as the axial length L ₁ of the mating member 12.
[0029]
In this example, various resins can be used as the resin constituting the outer cylinder 18.
Specifically, a thermoplastic resin, a thermosetting resin, or the like can be used as a constituent resin of the outer cylinder 18, and among them, a thermoplastic resin excellent in impact strength against vibration input and moldability as the outer cylinder 18 is preferable. Used.
[0030]
Thermoplastic resin materials include polyamide (including aromatic polyamide and modified polyamide), polyester (including modified polyester), polypropylene, polycarbonate, polyacetal, polyphenylene sulfide, and modified polyphenylene ether. A polyamide having an excellent balance between reinforcing effect and cost is preferably used.
[0031]
In addition, glass fiber, carbon fiber, aramid fiber, boron fiber, alumina fiber, metal fiber, silicon carbide fiber, glass beads, whiskers, and wollastonite are used as fillers to be blended or mixed with resin materials to reinforce such resin materials. , Kaolinite, talc, mica, carbon nanotubes, etc., and layered phyllosilicates composed of magnesium silicate or aluminum silicate layers such as montmorillonite, hectorite, vermiculite, halosite, etc. Glass fiber is preferably used from the viewpoint of cost.
Depending on the use site, a non-reinforced resin material without a filler can also be used.
As the resin material of the outer cylinder 18 in this example, a material obtained by mixing 30% glass fiber as a filler in polyamide 66 (PA66) is used.
[0032]
On the other hand, the mating member 12 shown in FIG. 3 has a cylindrical shape corresponding to the rubber bush 10 as a whole.
Here, the entire counterpart member 12 is made of metal.
[0033]
As shown in FIG. 3 (B), the mating member 12 is formed with an annular recess 28 in the form of a recess in the radially outward direction on the inner surface of the mating member 12. A stepped portion 32 is formed at the boundary between the concave portion 30 and the non-recessed portion 30.
[0034]
Here, the inner diameter D ₂ (see FIG. 4) of the recessed portion 28 is the same as the outer diameter d ₁ of the outer cylinder 18 of the rubber bush 10 before press-fitting.
Meanwhile the inner diameter D ₁ of the non-recessed portion 30 is smaller than the outer diameter d ₁ of the outer cylinder 18, wherein is specifically is sized with a diameter 65 mm.
Incidentally, the axial length L ₂ of the recessed portion 28 is exactly half the size with respect to the axial direction length L ₁ of the total. However the dimensions of the L ₂ can be appropriately changed.
[0035]
In the cylindrical vibration isolator of this example, as shown in FIG. 4, the rubber bush 10 is pressed into the mating member 12 in the axial direction so that the mating member 12 holds the rubber bush 10 in a fitted state. To do.
At this time, the resin outer cylinder 18 is press-fitted into the mating member 12 on the outer surface thereof while being reduced in diameter with elastic deformation.
Then, after the press-fitting, the portion of the outer member 18 that faces the recessed portion 28 of the counterpart member 12 is expanded in diameter by the elastic restoring force and partially enters the recessed portion 28.
[0036]
The outer surface shape of the outer cylinder 18 is deformed into a stepped shape following the inner surface shape of the mating member 12.
Specifically, in FIG. 1, the portion corresponding to the recessed portion 28 is deformed into a stepped shape in which the portion corresponding to the large diameter portion 34 and the portion corresponding to the non-recessed portion 30 forms the small diameter portion 36, and the stepped portion 38 in the outer cylinder 18 is formed. In this state, the stepped portion 32 formed on the inner surface of the mating member 12 is engaged in the axial direction and the withdrawal direction, that is, in the left direction in the figure.
The engaging action of the stepped portions 32 and 38 provides a high pulling force from the mating member 12 of the rubber bush 10 and prevents the rubber bush 10 from coming off well.
[0037]
Incidentally, FIG. 5 shows the pulling force of the example product shown in FIGS. 1 to 4 as Comparative Example Product 1 and Comparative Example Product 2 (the mating members 12-1, 12-2 shown in FIGS. 6B and 6C). Only disclosed).
[0038]
Here, unlike the counterpart member 12 of the example product shown in FIG. 6 (A), the comparative example product 1 is not provided with the recessed portion 28 and the stepped portion 32 on the inner surface of the counterpart member 12-1, but the shape of the inner surface thereof. Is a straight shape in the axial direction.
Note that the inner diameter is D _1, is equivalent to the inner diameter of the non-recessed portions 30 of the above embodiment.
The comparative product 2 is obtained by blasting the inner surface of the mating member 12-2 to roughen the surface roughness (normally the surface roughness is several μm, but here the surface roughness is about 30 μm). )
[0039]
In FIG. 5, (A) is the measurement result of the change over time of the pulling force when left at room temperature after press-fitting, and (B) is the measurement result of the change over time of the pulling force when left standing hot (80 ° C.). is there.
[0040]
In the result of standing at room temperature in FIG. 5A, the comparative example product 2 has a high initial pulling force, and accordingly, a high pulling force is maintained even after a lapse of time (after 500 hours).
Further, the comparative example product 1 has a lower pulling force after the lapse of time by a lower initial pulling force.
On the other hand, in the case of the example product, since the initial pulling force is low, the pulling force after the lapse of time is lower than that of the comparative example product 2, but the decrease rate of the pulling force after the lapse of time with respect to the initial pulling force ( The rate of change over time) is much better than Comparative Example Product 1 and Comparative Example Product 2.
[0041]
On the other hand, in the case of being left in the hot state in FIG. 5B, in both the comparative product 1 and the comparative product 2, the pulling force due to the change over time is greatly reduced, but in the case of the example product, the pulling force is decreased. Has been kept low.
[0042]
As described above, in the case of the cylindrical vibration isolator of this example, the pulling force of the rubber bush 10 can be effectively increased by the engaging action of the stepped portions 32 and 38 of the outer cylinder 18 and the mating member 12, and the rubber It is possible to satisfactorily prevent the bush 10 from coming off the counterpart member 12.
[0043]
Further, in this example, the outer cylinder 18 of the rubber bush 10 is not protruded from the mating member 12 in the axial direction, and the outer cylinder 18 is engaged in the axial direction on the inner surface of the mating member 12. As in the case of the cylindrical vibration isolator, the outer cylinder 206 is deteriorated by being exposed to the outside from the mating member 208, or another problem such as a stepping stone hitting the outer cylinder 206 and causing the outer cylinder 206 to crack does not occur.
[0044]
Further, there is no restriction that the rubber bush 10 must be longer than the counterpart member 12, and an advantage of increasing the degree of freedom in designing the cylindrical vibration isolator can be obtained.
Further, in this example, since the outer surface of the outer cylinder 18 has a straight shape in the axial direction, there is a problem in the cylindrical vibration isolator shown in FIG. 11, that is, a partial thickness that protrudes radially outward from the outer cylinder 206. By forming the flesh portion, it is possible to solve the problem that the same portion is excessively tightened in the direction of reduced diameter during the press-fitting and a crack occurs.
[0045]
FIG. 7 shows another embodiment of the present invention.
Among these, (A) is an example in which the stepped portion 32 of the mating member 12 is formed in a tapered shape, and (B) is a bipartition configuration in which the mating member 12 is divided into divided cylindrical bodies 18A and 18B, and a large inner diameter is divided. In this example, a recessed portion 28 is formed by the cylindrical body 18B, and a stepped portion 32 is formed at the boundary between the recessed portion 28 and the non-recessed portion 30.
[0046]
Further, in (C), the counterpart member 12 is divided into three divided cylinders 18C, 18D, and 18E, and the recessed portion 28 is formed by the divided cylinder 18D having the largest inner diameter located at the intermediate portion in the axial direction. This is an example in which a pair of stepped portions 32 whose directions are opposite to each other in the axial direction are formed at the boundary between the recessed portion 28 and the non-recessed portion 30 on both sides in the axial direction.
[0047]
As shown in FIGS. 7B and 7C, the mating member 12 is divided into a plurality of parts in the axial direction, and the recessed portions 28 are formed by the divided cylinders 18B and 18D having a large inner diameter. In this case, the recessed portion 28 and the stepped portion 32 can be easily formed on the inner surface of the cylindrical mating member 12.
[0048]
In the case of FIG. 7C, the rubber bush 10 press-fitted into the mating member 12 is held in the axial direction and in both directions opposite to each other. Therefore, according to FIG. 7C, the rubber bush 10 Even if the flange member 24 does not have the flange portion 24, that is, even if the flange portion 24 cannot contact the mating member 12 due to contact with the mating member 12, it can be press-fitted into the mating member 12 inside. The rubber bush 10 thus made can be prevented from coming off in both axial directions without hindrance.
[0049]
FIG. 8 shows still another embodiment of the present invention. In this example, a recessed portion 40 and a non-recessed portion 42 are formed so as to be recessed radially outwardly on the inner surface of the mating member 12 along the circumferential direction. Are provided alternately, and a stepped portion 44 is formed at the boundary between the recessed portion 40 and the non-recessed portion 42.
[0050]
When the inner surface of the mating member 12 has such a stepped shape, the resin-made outer cylinder 18 of the rubber bush 10 press-fitted therein is deformed into a shape that follows the inner surface shape, thereby the rubber bush. 10 is in a state of being strongly restrained in the circumferential direction with respect to the counterpart member 12.
[0051]
The above is an example in which the outer surface of the outer cylinder 18 has a straight shape in the axial direction, but the outer surface of the outer cylinder 18 can also have a non-straight shape in the axial direction.
FIG. 9 shows a specific example thereof.
In FIG. 9 (B), (a) is formed as a circumferential annular projecting portion 46 projecting radially outward from a part of the outer surface of the outer cylinder 18 facing the recessed portion 28 in the axial direction. It is an example.
[0052]
(B) shows the shape of the outer surface of the outer cylinder 18, and after the outer diameter gradually increases from the flange portion 24 toward the opposite axial end, the same outer diameter is maintained over a certain axial length. Is formed in a shape that gradually becomes smaller, so that the outer surface shape of the outer cylinder 18 is formed as a protruding portion 48 that protrudes radially outward from the non-recessed portion 30 to the recessed portion 28 in the counterpart member 12. Show.
[0053]
Further, (c) shows an example in which the outer surface shape of the outer cylinder 18 is formed in such a shape that the outer diameter gradually increases from the flange portion 24 toward the opposite axial end.
Further, (d) shows an example in which the outer surface shape of the outer cylinder 18 is formed into a shape having fine irregularities 50.
[0054]
On the other hand, FIG. 10 shows an example in which the inner surface shape of the outer cylinder 18 is a non-straight shape. Among these, (B) and (A) are the axes of the inner surface shape of the outer cylinder 18 facing the recessed portion 28. An example is shown in which a part of the direction is formed as a circumferential annular projecting portion 52 that is partially projected radially inward.
(B) shows an example in which the portion of the inner shape of the outer cylinder 18 facing the recessed portion 28 is formed as a protruding portion 54 that protrudes in a generally radially inward and circumferentially annular manner. Yes.
[0055]
Although the embodiment of the present invention has been described in detail above, this is only an example, and the present invention can be applied to various cylindrical vibration isolators other than the cylindrical vibration isolator in the torsion beam type rear suspension of the automobile. For example, it can be configured in various forms without departing from the spirit thereof.
[Brief description of the drawings]
FIG. 1 is a view showing a cylindrical vibration isolator according to an embodiment of the present invention.
FIG. 2 is a view showing a rubber bush in the same embodiment before press-fitting. (A): It is a left view of (B).
(B): It is BB sectional drawing of (A).
FIG. 3 is a view showing a mating member in the same embodiment.
FIG. 4 is a view showing a dimensional relationship between a rubber bush and a mating member in the same embodiment together with a press-fitting direction.
FIG. 5 is a view showing a change with time of a pulling force of a rubber bush in this example together with a comparative example.
6 is a view showing the inner surface shape of the mating member in the comparative example product used for the measurement of FIG. 5 in comparison with that of the example product. FIG.
FIG. 7 is a view showing a main part of still another embodiment of the present invention.
FIG. 8 is a view showing a main part of still another embodiment of the present invention.
FIG. 9 is a view showing a main part of still another embodiment of the present invention.
FIG. 10 is a view showing a main part of still another embodiment of the present invention.
FIG. 11 is a diagram showing an example of a conventional cylindrical vibration isolator.
[Explanation of symbols]
10 Rubber bush 12 Mating member 16 Inner cylinder 18 Outer cylinder 18A, 18B, 18C, 18D, 18E Split cylinder 20 Rubber elastic body 28, 40 Depressed part 30, 42 Non-recessed part 32, 38, 44 Stepped part d ₁ Out inner diameter of the outer diameter D ₂ recess of the cylinder

Claims

A rubber bush having a resin outer cylinder, an inner cylinder, and a rubber elastic body disposed between the outer cylinder and the inner cylinder is press-fitted into a cylindrical rigid counterpart member on the outer surface of the outer cylinder. In the cylindrical vibration isolator adapted to hold the rubber bush in the mating state with the mating member,
On the inner surface of the mating member, a concave portion that is recessed radially outward is partially formed in the axial direction so that the shape of the inner surface of the mating member is stepped on the boundary between the concave portion and the non-concave portion. The outer surface of the outer cylinder is made larger in diameter than the non-recessed portion in a state before being press-fitted into the mating member, and the outer cylinder is formed using elastic deformation of resin. Press-fitting into the mating member while reducing the diameter, and expanding the diameter of the portion of the outer cylinder facing the recessed portion with the elastic restoring force after press-fitting, thereby changing the outer surface shape of the outer cylinder to that of the mating member A cylindrical vibration isolator having a stepped shape following the inner surface shape, wherein the stepped portion of the mating member and the stepped portion of the outer cylinder are engaged with each other in the axial direction and in the withdrawal direction. .

2. The outer cylinder according to claim 1, wherein the outer cylinder has a larger amount of return deformation in the diameter-expanding direction due to the elastic restoring force of a portion of the outer cylinder facing the recessed portion than the other section. A cylindrical anti-vibration device characterized in that the outer surface shape is a stepped shape following the inner surface shape of the mating member.

The cylindrical vibration isolator according to any one of claims 1 and 2, wherein the outer surface of the outer cylinder has a substantially axial straight shape before being press-fitted into the mating member.

4. The method according to claim 1, wherein the concave portion is provided in an intermediate portion in the axial direction, and is opposite to each other in the axial direction at a boundary portion between the non-concave portion on both sides in the axial direction of the concave portion and the concave portion. A cylindrical vibration isolator characterized by forming a pair of stepped portions.

The cylindrical vibration isolator according to any one of claims 1 to 4, wherein the mating member is divided in the axial direction, and the recessed portion is formed by a divided cylindrical body having a large inner diameter.

6. The inner surface of the mating member according to any one of claims 1 to 5, wherein the inner surface of the mating member is partially formed in the circumferential direction so as to be recessed radially outward, and the inner surface of the mating member is stepped in the circumferential direction. A cylindrical vibration isolator having a stepped shape having a portion.

7. The cylindrical vibration isolator according to claim 1, wherein an inner diameter of the recessed portion is equal to or less than a maximum outer diameter of a corresponding portion of the outer cylinder in a state before press-fitting. .