JP3729003B2

JP3729003B2 - Anti-vibration bush and anti-vibration bush assembly

Info

Publication number: JP3729003B2
Application number: JP34944499A
Authority: JP
Inventors: 啓全中浦
Original assignee: Sumitomo Riko Co Ltd
Current assignee: Sumitomo Riko Co Ltd
Priority date: 1999-12-08
Filing date: 1999-12-08
Publication date: 2005-12-21
Anticipated expiration: 2019-12-08
Also published as: JP2001165219A

Description

【０００１】
【技術分野】
本発明は、例えば自動車用のサスペンションブッシュ等として用いられる防振ブッシュおよび防振ブッシュ組立体に係り、特にゴム弾性体における応力集中が緩和されて優れた耐久性が発揮される防振ブッシュおよび防振ブッシュ組立体に関するものである。
【０００２】
【背景技術】
従来から、自動車のサスペンションアームの車体への枢支連結部位等に介装されるブッシュ組立体の一種として、例えば実開平２−１１２４４号公報等に記載されているように、インナ金具とアウタ筒金具を径方向で互いに離間して配設すると共に、それらインナ金具とアウタ筒金具の軸方向一端部にそれぞれフランジ部を一体形成せしめて、それらインナ金具とアウタ筒金具の径方向対向面間および各フランジ部の軸方向対向面間にゴム弾性体を介装せしめて弾性的に連結した構造を有する防振ブッシュの一対を用い、それらの防振ブッシュを、サスペンションアームの端部に形成された筒状のアームアイに対して、フランジ部が形成されていない軸方向端部側からそれぞれ内挿した後、車体側に固設された一対の取付板部間に嵌め込んで、両インナ金具をそれら取付板部間で軸支せしめることにより、サスペンションアームを車体側に防振連結せしめるようにしたものが、知られている。
【０００３】
ところで、このようなブッシュ組立体には、その装着状態下で、インナ金具とアウタ筒金具の間に軸方向荷重やこじり方向荷重が入力された際に、インナ金具とアウタ筒金具の両フランジ部間に介装されたゴム弾性体に対して引張荷重が及ぼされることがある。特に、従来構造の防振ブッシュでは、図６に示されているように、インナ金具２のフランジ部４とアウタ筒金具６のフランジ部８の間に介装されたゴム弾性体９の外周面が全体に亘って単一の略円弧形断面形状とされていることから、図中に仮想線で示されているようにこじり荷重の入力時には、ゴム弾性体９の表面に略沿った方向でゴム弾性体９をアウタ筒金具６のフランジ部８から引き剥がす方向の引張荷重：Ｆが及ぼされて、ゴム弾性体９におけるアウタ筒金具６のフランジ部８への接着端面に集中応力が作用するためにゴム弾性体９に亀裂等が発生し易く、十分な耐久性が得られ難いという問題があったのである。
【０００４】
【解決課題】
ここにおいて、本発明は、上述の如き事情を背景として為されたものであって、その解決課題とするところは、軸方向やこじり方向の荷重入力時におけるゴム弾性体の引張応力の集中が軽減乃至は防止されて、耐久性の向上が達成される、新規な構造の防振ブッシュと、かかる防振ブッシュを用いた防振ブッシュ組立体を提供することにある。
【０００５】
【解決手段】
以下、このような課題を解決するために為された本発明の態様を記載する。なお、以下に記載の各態様は、可能な限り任意の組み合わせで採用することが出来る。また、本発明の態様および技術的特徴は、以下に記載のものに限定されることなく、明細書全体および図面に記載され、或いはそれらの記載から当業者が把握することの出来る発明思想に基づいて認識されるものであることが理解されるべきである。
【０００６】
すなわち、防振ブッシュ組立体に関する本発明の第一の態様は、防振連結される各被連結部材に対して固定的に取り付けられるインナ部材とアウタ筒部材を、径方向で互いに離間して配設すると共に、それらインナ部材とアウタ筒部材の少なくとも軸方向一端部にそれぞれフランジ部を一体形成せしめて、それらインナ部材とアウタ筒部材の軸直角方向対向面間および各フランジ部の軸方向対向面間にゴム弾性体を介装せしめて弾性的に連結した防振ブッシュであって、前記インナ部材と前記アウタ筒部材の各フランジ部間に位置せしめられた前記ゴム弾性体の外周面に対して、湾曲した軸方向両側の立ち上がり面をもって径方向外方に突出し、周方向に延びる環状突出部を一体形成すると共に、該環状突出部を、該各フランジ部間の軸方向中央よりも該アウタ筒部材の該フランジ部側に接近して位置せしめ、且つ、該各フランジ部間に位置せしめられた該ゴム弾性体の外径寸法を、該各フランジ間の軸方向中央よりも該アウタ筒部材の該フランジ部側において、該軸方向中央において最も小さくした前記防振ブッシュを一対用いて、該各防振ブッシュの該インナ部材同士と該アウタ部材同士を、該フランジ部と反対の軸方向端面で対向位置せしめて互いに固定的に連結することにより、それら各防振ブッシュにおいて、該インナ部材と該アウタ筒部材の該各フランジ部間に位置せしめられた該ゴム弾性体に対して軸方向の予圧縮を及ぼしめたことを、特徴とする。
【０００７】
このような本態様に従う構造とされた防振ブッシュにおいては、インナ部材とアウタ筒部材のフランジ部間に介装されたゴム弾性体に引張荷重が及ぼされると、ゴム弾性体に軸方向の引張応力が生ぜしめられることとなるが、ゴム弾性体の外周面では引張応力が表面に沿って発生することから、アウタ筒金具のフランジ部の近くに形成された環状突出部を拡張する方向に引張応力が作用して、この環状突出部が軸方向に広がって弾性変形することにより、ゴム弾性体の外周面における引張応力が緩和される。
【０００８】
また、かかる環状突出部は、アウタ筒部材のフランジ部の近くに形成されていることから、その弾性変形に基づくゴム弾性体の引張応力の軽減作用に基づいて、ゴム弾性体の特に問題となるアウタ筒部材との接着部位における亀裂等の発生が防止されて、耐久性の向上が図られ得るのである。
【０００９】
なお、本態様において、インナ部材とアウタ筒部材の径方向対向面は、例えば円筒形状や楕円形状，多角形筒体形状等の各種の筒形状をもって形成され得る。また、インナ部材とアウタ部材を弾性連結するゴム弾性体は、インナ部材とアウタ部材の径方向対向面間と、それら両部材におけるフランジ部の軸方向対向面間との間に跨がって一体的に形成されることが望ましい。また、環状突出部は、弾性変形特性や成形性などの点を考慮して、例えば、平坦な或いは円弧状の突出先端部を有する末広がりの略山形断面形状をもって有利に形成され得る。
【００１０】
また、このような本態様に従う構造とされた防振ブッシュ組立体においては、その装着状態下、ゴム弾性体に及ぼされる圧縮力によってゴム弾性体の表面に沿った圧縮応力が生ぜしめられて、アウタ筒金具のフランジ部の近くに形成された環状突出部が軸方向に押し縮められて径方向に突出させられる方向に弾性変形せしめることとなり、それによって、かかる環状突出部において圧縮方向の弾性変形量が有利に蓄えられる。それ故、本態様に係る防振ブッシ組立体においては、その装着状態下でゴム弾性体に引張荷重が及ぼされた際に、予め環状突出部に蓄えられた圧縮方向の弾性変形量によって、ゴム弾性体に生ぜしめられる軸方向の引張応力がより効果的に軽減され得るのである。なお、インナ部材とアウタ筒部材のフランジ部間においてゴム弾性体に加える軸方向の圧縮変形量は、好ましくは寸法比（圧縮量／初期寸法）で５〜３０％に設定される。
【００１１】
また、防振ブッシュに関する本発明の第二の態様は、前記第一の態様に係る防振ブッシュ組立体において、前記ゴム弾性体における前記環状突出部と前記アウタ筒部材のフランジ部の間の外周面が、全体に亘って円弧形の断面形状とされており、且つその曲率半径が、該環状突出部における軸方向反対側の湾曲した立ち上がり面の曲率面径よりも小さくされていることを、特徴とする。このような本態様においては、環状突出部とアウタ筒部材のフランジ部との間におけるゴム弾性体の自由長を円弧状外周面によって確保しつつ、環状突出部をアウタ筒部材のフランジ部に近づけて形成することが出来ると共に、環状突出部におけるインナ部材のフランジ部側の立ち上がり面の表面距離も大きく設定することが出来るのであり、それによって、環状突出部が軸方向に広がる弾性変形量を大きく確保することができると共に、そのような環状突出部の弾性変形に基づく、ゴム弾性体とアウタ筒部材のフランジ部との接着部位における引張応力の軽減効果がより効果的に発揮されるのである。
【００１２】
また、このような本態様においては、アウタ筒部材とゴム弾性体の接着部位から環状突出部までの表面距離（ゴム弾性体の表面に沿った距離）を十分に小さくして、インナ部材のフランジ部側の立ち上がり面の表面距離を大きくすることにより、環状突出部が軸方向に広がる弾性変形量を大きくすることが出来、環状突出部によって発揮されるゴム弾性体とアウタ筒部材の接着部位における引張応力の軽減効果が向上され得る。
【００１３】
また、防振ブッシュに関する本発明の第三の態様は、前記第一又は第二の態様に係る防振ブッシュ組立体において、前記インナ部材と前記アウタ筒部材の各フランジ部間に位置せしめられた前記ゴム弾性体の外周面に対して、湾曲した軸方向両側の立ち上がり面をもって径方向外方に突出し、周方向に連続して延びる第二の環状突出部を、軸方向中央よりもインナ部材のフランジ部側に位置せしめて一体形成したことを、特徴とする。このような本態様においては、上述の如き環状突出部によるゴム弾性体とアウタ筒部材の接着部位における引張応力の軽減効果に加えて、第二の環状突出部により、ゴム弾性体とインナ筒部材の接着部位における引張応力の軽減効果が発揮されることから、ゴム弾性体における亀裂の発生の防止と耐久性の向上が一層有利に図られ得る。
【００１６】
また、防振ブッシュ組立体に関する本発明の特徴とするところは、インナ部材およびアウタ筒部材の各軸方向一端部にフランジ部が一体形成された前記第一乃至第三の何れの態様に係る防振ブッシュを一対用いて、各防振ブッシュのインナ部材同士とアウタ部材同士を、フランジ部と反対の軸方向端面で対向位置せしめて互いに固定的に連結することにより、それら各防振ブッシュにおいて、インナ部材とアウタ筒部材の各フランジ部間に位置せしめられたゴム弾性体に対して軸方向の予圧縮を及ぼしめた防振ブッシュ組立体にある。
【００１７】
このような本発明に従う構造とされた防振ブッシュ組立体においては、一対の防振ブッシュを軸方向に対向配置せしめたことにより、何れの軸方向荷重に対しても、何れか一方の防振ブッシュにおけるフランジ部間のゴム弾性体に圧縮荷重が及ぼされることとなり、両軸方向での防振性能と耐荷重性能が有利に確保される。しかも、フランジ部間のゴム弾性体に引張荷重が及ぼされる側の防振ブッシュにおいても、環状突出部によるゴム弾性体の引張応力軽減効果が発揮されることから、優れた耐久性が発揮されるのである。
【００１８】
【発明の実施形態】
以下、本発明を更に具体的に明らかにするために、本発明の実施形態について、図面を参照しつつ、詳細に説明する。
【００１９】
先ず、図１には、本発明の一実施形態として、自動車の車輪懸架装置におけるサスペンションアームの車体に対する枢支連結部に介装されて、該サスペンションアームを車体に対して揺動可能に防振連結せしめる防振ブッシュ組立体１０が、示されている。この防振ブッシュ組立体１０は、一対の防振ブッシュ１２，１２が、図示しないサスペンションアームの軸方向端部に一体形成された被連結部材である取付筒部材としてのアームアイ１４と、図示しない車体に固設された被連結部材である一対の取付板部材としての固定対向板１６，１６の間に介装されて、アームアイ１４（サスペンションアーム）を固定対向板１６，１６（車体）に対して中心軸回りに揺動可能に防振連結するようになっている。
【００２０】
より詳細には、一対の防振ブッシュ１２としては、それぞれ、図２に示されているような同一構造のものが用いられている。この防振ブッシュ１２は、インナ部材としての内筒金具１８とアウタ筒部材としての外筒金具２０を有している。内筒金具１８は、厚肉円筒形状の筒状部２２と、該筒状部２２の軸方向一方の端部から径方向外方に広がるフランジ部２４から構成されている。また、外筒金具２０も、同様に、円筒形状の筒状部２６と、該筒状部２６の軸方向一方の端部から径方向外方に広がるフランジ部２８から構成されている。これら内外筒金具１８，２０は、プレス加工や鍛造加工，切削加工等によって有利に形成される。ここにおいて、外筒金具２０は、内筒金具１８よりも薄肉で、その筒状部２６が、内筒金具１８の筒状部２２よりも所定寸法大径で且つ軸方向長さが短くされており、内筒金具１８の径方向外方に所定距離を隔てて略同一軸上に配設されている。
【００２１】
さらに、内筒金具１８のフランジ部２４と外筒金具２０のフランジ部２８は、軸方向の同じ側に位置せしめられていると共に、外筒金具２０が内筒金具１８に対してフランジ部２４とは反対の軸方向端部側に偏倚して配設されており、外筒金具２０におけるフランジ部２８が形成されていない側の軸方向端面３３が、内筒金具におけるフランジ部２４が形成されていない側の軸方向端面３６よりも、所定距離：Ｌ１だけ軸方向内方に位置せしめられている。また、内外筒金具１８，２０のフランジ部２４，２８は、互いに軸方向に所定距離：Ｌ２を隔てて対向位置せしめられている。
【００２２】
なお、外筒金具２０のフランジ部２８は、内筒金具１８の筒状部２２の外径寸法よりも大きく且つ内筒金具１８のフランジ部２４の外径寸法よりも小さな内径寸法と、内筒金具１８のフランジ部２４の外径寸法よりも大きな外径寸法をもって形成されている。また、内筒金具１８のフランジ部２４の軸方向内側面３０は、径方向内方に行くに従って次第に外筒金具２０側に接近する略円弧形状の湾曲断面とされている。更にまた、内筒金具１８のフランジ部２４側の軸方向端面は、中央部分３６が環状にセレーション加工および焼入加工されて、固定対向板１６に対する圧着固定面とされている。また、内筒金具１８の内孔３２は、フランジ部２４と反対側の軸方向端部が軸方向に所定長さに亘って大径化されており、軸方向一方の側に開口する大径の連結固定部３４とされている。
【００２３】
そして、前述の如く径方向に離間配置された内筒金具１８と外筒金具２０の間に、ゴム弾性体３８が介装されている。そして、ゴム弾性体３８に対して、内筒金具１８における筒状部２２の外周面とフランジ部２４の軸方向内面および外筒金具２０における筒状部２６の内周面とフランジ部２８の軸方向外面が、それぞれ加硫接着された一体加硫成形品とされている。要するに、ゴム弾性体３８は、全体として厚肉の略円筒形状を有しており、内外筒金具１８，２０間において、各筒状部２２，２６の径方向対向面間に介装された筒状ゴム部４０と、各フランジ部２４，２８の軸方向対向面間に介装された環状ゴム部４２を含んで構成されている。そして、これら筒状ゴム部４０と環状ゴム部４２によって、内外筒金具１８，２０の軸方向および径方向の対向面間が略全体に亘って充満されるようになっている。
【００２４】
また、ゴム弾性体３８の加硫成形後には、必要に応じて、外筒金具２０の筒状部２６に対して、八方絞り加工等による縮径が施されて、ゴム弾性体３８の引張応力が解消され、予圧縮が加えられることとなる。
【００２５】
さらに、筒状ゴム部４０には、内外筒金具１８，２０の筒状部２２，２６間の軸方向端面に向かって開口する断面半円状乃至はＵ字状の凹所４４が、周方向に連続して若しくは不連続に形成されている。また一方、環状ゴム部４２は、内外筒金具１８，２０の各フランジ部２４，２８の軸方向対向面の略全体に亘って配設されているが、内筒金具１８のフランジ部２４側端部よりも外筒金具２０のフランジ部２８側端部の方が僅かに大径とされている。また、環状ゴム部４２の外周面は、全体として軸方向中央部分が小径化された凹状湾曲断面とされており、環状ゴム部４２の軸方向両端部における各フランジ部２４，２８への接着部位には、それぞれ、フィレットアールが付されている。
【００２６】
また、環状ゴム部４２の外周面上には、軸方向中間部分が径方向外方に向かって突出せしめられることにより、軸方向中間部分を周方向に連続して延びる環状突出部としての環状弾性突部４６が一体形成されている。この環状弾性突部４６は、図２に示された軸方向断面において、先端部分が略平坦な頂部４８とされていると共に、該頂部４８を挟んだ軸方向両側が次第に軸方向に広がる湾曲面５０，５０とされており、全体として略一定の山形断面形状をもって周方向に連続して形成されている。換言すれば、環状ゴム部４２の外周面は、軸方向中間部分において、湾曲した両側立上り面５０，５０をもって径方向外方に突出せしめられて環状弾性突部４６が形成されている。また、ゴム弾性体３８の外周面において、環状弾性突部４６を挟んだ軸方向両側には、径方向外方に開口して周方向に延びる凹溝状部がそれぞれ形成されている。特に、ゴム弾性体３８において、内筒金具１８のフランジ部２４への接着部位と環状弾性突部４６との間には、それらフランジ部２４への接着部位と環状弾性突部４６の何れよりも小さな外径寸法部分が形成されており、ゴム弾性体３８の外周部分のフランジ部２４への接着部位にフィレットアールが付されている。
【００２７】
さらに、この環状弾性突部４６は、環状ゴム部４２において、軸方向中間部分よりも外筒金具２０のフランジ部２８側に接近して形成位置せしめられている。換言すれば、環状弾性突部４６と内筒金具１８のフランジ部２４の軸方向間距離：Ｌ２ａよりも、環状弾性突部４６と外筒金具２０のフランジ部２８の軸方向間距離：Ｌ２ｂの方が小さく設定されている。特に、本実施形態では、Ｌ２ａ≧Ｌ２ｂ×２とされている。また、本実施形態では、図２に示されている如き軸方向断面において、環状弾性突部４６を挟んだ軸方向両側に位置する環状ゴム部４２の外周面が、何れも略円弧形状とされており、環状弾性突部４６と外筒金具２０のフランジ部２８の間に位置する外周面の曲率半径：Ｒｂが、環状弾性突部４６と内筒金具１８のフランジ部２４の間に位置する外周面の曲率半径：Ｒａよりも小さく設定されている。また、これにより、環状弾性突部４６と外筒金具２０のフランジ部２８の間における環状ゴム部４２の最小外径寸法：ｒｂが、環状弾性突部４６と内筒金具１８のフランジ部２４の間における環状ゴム部４２の最小外径寸法：ｒａよりも大きく設定されている。
【００２８】
そして、それぞれ上述の如き構造とされた一対の防振ブッシュ１２，１２は、図１に示されているように、アームアイ１４に対して、各外筒金具２０が、フランジ部２８が形成されていない側の軸方向端部において、アームアイ１４の軸方向両側から圧入されることにより、挿入されて組み付けられている。ここにおいて、外筒金具２０の筒状部２６は、その全体によってアームアイ１４に対する圧入部が構成されている。また、各防振ブッシュ１２は、外筒金具２０の筒状部２６の軸方向長さがアームアイ１４の軸方向長さの半分よりも短くされており、外筒金具２０のフランジ部２８がアームアイ１４の軸方向端面に当接することによって、アームアイ１４に対する挿入端が位置決めされるようになっている。そして、そのような位置決め状態下、両外筒金具２０，２０および両筒状ゴム部４０，４０の軸方向端面間には、周方向に連続して延びる環状の隙間５２が形成されている。
【００２９】
更に、そのような一対の防振ブッシュ１２，１２のアームアイ１４に対する組み付け時には、両内筒金具１８，１８の連結固定部３４，３４に対して、円筒形状の連結筒金具５４の軸方向両端部が圧入固定されており、この連結筒金具５４によって、両内筒金具１８，１８が、互いに軸方向端面を突き合わされた状態で相互に連結固定されている。また、このような内筒金具１８，１８の連結による一対の防振ブッシュ１２，１２の組付状態下において、両内筒金具１８，１８のフランジ部２４側の軸方向端面間の距離、換言すれば、アームアイ１４に組み付けられた一対の防振ブッシュ１２，１２の軸方向最大寸法：Ｌ３が、アームアイ１４が防振連結される一対の固定対向板１６，１６の対向面間寸法に略等しくなるように、好ましくは該一対の固定対向板１６，１６の対向面間寸法よりも僅かに小さくなるように、内筒金具１８の軸方向長さが一対の固定対向板１６，１６間の寸法等を考慮して設定されている。
【００３０】
要するに、上述の如く内筒金具１８，１８が連結筒金具５４で相互に連結一体化されて、アームアイ１４に組み付けられた一対の防振ブッシュ１２，１２からなる防振ブッシュ組立体１０においては、各防振ブッシュ１２が、単体での無負荷状態よりも、図２に仮想線で示されているように、内筒金具１８と外筒金具２０が軸方向に相互に変位せしめられて、両筒金具１８，２０のフランジ部２４，２８間の軸方向対向面間距離が小さくされているのである。また、それら内外筒金具１８，２０の軸方向の相対変位に基づいて、両フランジ部２４，２８間に配設された環状ゴム部４２に対して軸方向に圧縮荷重が及ぼされており、該環状ゴム部４２が、内外筒金具１８，２０の軸方向の相対変位量：Ｌ４だけ軸方向に圧縮変形せしめられている。
【００３１】
そして、環状ゴム部４２が軸方向に圧縮変形せしめられる際、環状ゴム部４２の外周部分に及ぼされる軸方向圧縮力が、環状ゴム部４２の外周面に略沿って作用する結果、環状弾性突部４６の形成部位には、軸方向両側から径方向外方に向かう圧縮力が及ぼされることとなり、環状弾性突部４６が軸方向に押し縮められながら径方向外方に突出する方向に弾性変形せしめられる。これにより、軸方向両側から環状弾性突部４６に向かって圧縮変形が集められるようにして、環状弾性突部４６が積極的に弾性変形せしめられているのである。
【００３２】
このようにしてアームアイ１４に組み付けられた一対の防振ブッシュ１２，１２は、更に、図１に示されているように、車体側に固設された一対の固定対向板１６，１６の対向面間に嵌め込まれて、それら一対の固定対向板１６，１６間に跨がって、二つの防振ブッシュ１２，１２が直列的に配列せしめられた状態で配設されている。そして、一対の固定対向板１６，１６に設けられた貫通孔に挿通されて、それら一対の固定対向板１６，１６間に跨がって配設された支持ボルト５６が、防振ブッシュ１２，１２の内孔３２，３２に嵌挿されることによって、防振ブッシュ組立体１０が、支持ボルト５６を介して、固定対向板１６，１６に対して軸支されている。
【００３３】
また、防振ブッシュ組立体１０に挿通された支持ボルト５６が締め付けられて、一対の固定対向板１６，１６が相互に接近する方向に変形せしめられることにより、軸方向に連結一体化された内筒金具１８，１８に対して軸方向の締め付け力が及ぼされている。この締め付け力により、両内筒金具１８の軸方向外面３６におけるセレーション加工部が、各固定対向板１６の当接面に対して圧着されている。
【００３４】
すなわち、このようにして組み付けられた防振ブッシュ組立体１０においては、内筒金具１８，１８が固着された一対の固定対向板１６，１６と、外筒金具２０，２０が固着されたアームアイ１４とを、ゴム弾性体３８，３８を介して弾性的に連結せしめることとなり、ゴム弾性体３８，３８の弾性変形作用に基づいて、アームアイ１４側のサスペンションアームが、固定対向板１６側の車体に対して、揺動可能に防振連結されることとなるのである。
【００３５】
そこにおいて、かくの如く組み付けられた防振ブッシュ組立体１０においては、軸直角方向だけでなく、軸方向やこじり方向の荷重が入力されることとなるが、特に、本実施形態では、環状ゴム部４２に一体形成された環状突部４６が軸方向に積極的に圧縮変形されていることによって、荷重入力時におけるゴム弾性体３８への引張応力の集中が軽減乃至は回避されて、亀裂等の発生が防止されるのである。
【００３６】
すなわち、例えば図３に示されているように、内外筒金具１８，２０間にこじり方向の荷重が入力されて、仮想線で示されている如く、内外筒金具１８，２０が相対的にこじり変位せしめられると、こじり面内での径方向一方の側において内外筒金具１８，２０のフランジ部２４，２８が軸方向で相互に離間する方向に相対変位せしめられることにより、それらの間に介装された環状ゴム部４２の特に外周面に引張変形が生ぜしめられることとなる。ところが、環状ゴム部４２の外周面には、積極的に圧縮変形せしめられた環状弾性突部４６が形成されていることから、環状ゴム部４２に引張力が及ぼされると、この環状弾性突部４６が、蓄えた圧縮変形を放出するようにして、軸方向両側に広がる方向に弾性変形せしめられるのであり、それによって、環状弾性突部４６の付近での引張応力が軽減乃至は回避されることとなる。そして、かかる環状弾性突部４６が、特に引張応力の集中が問題となり易い、外筒金具２０のフランジ部２８への接着部近くに形成されていることから、環状ゴム部４２に生ぜしめられる最大引張応力が抑えられて、環状ゴム部４２における亀裂等の発生が防止され、以て、優れた耐久性が実現されるのである。
【００３７】
また、特に本実施形態では、環状ゴム部４２において、環状弾性突部４６を挟んだ軸方向両側の外周面が、それぞれ、略一定の曲率半径を有する連続した円弧状断面とされていることから、環状ゴム部４２の表面における応力の集中が一層有利に図られ得て、一層の耐久性の向上が図られ得る。
【００３８】
さらに、本実施形態では、組付前の単体状態での防振ブッシュ１２の環状ゴム部４２において、環状弾性突部４６を軸方向に挟んだ両側の外周面がそれぞれ略円弧形状とされていると共に、内筒金具１８のフランジ部２４側の曲率半径：Ｒａよりも外筒金具２０のフランジ部２８側の曲率半径：Ｒｂの方が小さくされており、内筒金具１８のフランジ部２４側の最小外径寸法：ｒａよりも外筒金具２０のフランジ部２８側の最小外径寸法：ｒｂの方が大きくされていることから、上述の如き、環状弾性突部４６の作用によるゴム弾性体３８の外筒金具２０への接着部付近における引張応力の軽減効果がより効果的に発揮され得るのである。
【００３９】
以上、本発明の一実施形態について詳述してきたが、これはあくまでも例示であって、本発明は、かかる具体例にのみ限定して解釈されるものではない。
【００４０】
例えば、防振ブッシュ１２のばね特性を調節するために、ゴム弾性体３８に対して、周方向に連続して若しくは所定長さで延びるすぐり部や肉抜部等を形成することも可能である。また、内筒金具１８と外筒金具２０の対向面間を周方向に連続して延びる中間筒金具や或いは周方向に所定長さで延びる中間板金具等を配設してゴム弾性体３８内に埋設固着することも可能である。なお、前記実開平２−１１２４４号公報等に記載されているように、内外筒金具１８，２０の対向面間において、それら両金具１８，２０のフランジ部２４，２８間にまで延びるフランジ状部を備えた中間筒金具を採用する場合には、外筒金具２０に対して、作用的にこの中間筒金具が内筒金具となることから、かかる中間筒金具を内筒金具として、本発明が適用されることとなる。
【００４１】
また、環状ゴム部４２において、環状弾性突部４６を挟んだ軸方向両側の外周面は、必ずしも円弧形断面とする必要はない。例えば、図４に示されているように、環状弾性突部４６と内筒金具１８や外筒金具２０のフランジ部２４，２８の間の軸方向中間部分において、軸方向にストレートに延びる円筒形外周面部分６０を設けても良い。
【００４２】
更にまた、図５に示されているように、前述の如き環状弾性突部４６と同じような構造とされた第二の環状突部６２を、環状ゴム部４２の外周面において、軸方向中央よりも内筒金具１８のフランジ部２４に近い位置に形成しても良く、そのような第二の環状突部６２を形成することによって、環状ゴム部４２の内筒金具１８への接着部付近においても、引張応力も軽減されて亀裂等の発生が防止される。なお、図４及び図５においては、何れも、その理解を容易とするために、前記第一の実施形態における防振ブッシュ１２と同様な構造とされた部材および部位に対して、それぞれ、図中に、第一の実施形態と同一の符号を付しておく。
【００４３】
また、上述の如き、環状ゴム部４２の外周面における環状弾性突部４６や、第二の環状弾性突部６２は、環状ゴム部４２の軸方向に離間して複数形成することも可能である。
【００４４】
更にまた、内筒金具１８や外筒金具２０は、例えば、略一定の内外径寸法を有する筒状金具の軸方向端部に円環平板形状のフランジ部を溶接等で固着した構造のものを採用することも可能である。
【００４５】
また、前記実施形態における防振ブッシュ組立体１０では、軸方向一方の端部にフランジ部や環状ゴム部を備えた一対の防振ブッシュ１２，１２を、アームアイ１４の軸方向両側開口部から嵌入して組み付けるようになっていたが、その他、予め一対の防振ブッシュを軸方向で連結一体化せしめた後、周方向に分割された筒状部を径方向両側から外筒金具に嵌め込むことによって、防振ブッシュを装着することも可能である。また、そのような装着構造を採用する場合には、軸方向両端部にそれぞれフランジ部を備えた各単一部材からなる内筒金具と外筒金具を採用することも可能であり、それによって、前記実施形態における防振ブッシュ組立体を、単一の防振ブッシュで実現することも可能である。
【００４６】
加えて、前実施例では、本発明を自動車のサスペンションアームの車体に対する防振連結体に対して適用したものの一具体例を示したが、本発明は、その他、枢支連結部に介装される弾性連結体等に対して、広く適用され得るものであることは、勿論である。
【００４７】
その他、一々列挙はしないが、本発明は、当業者の知識に基づいて、種々なる変更，修正，改良等を加えた態様において実施され得るものであり、また、そのような実施態様が、本発明の趣旨を逸脱しない限り、何れも、本発明の範囲内に含まれるものであることは、言うまでもないところである。
【００４８】
【発明の効果】
上述の説明から明らかなように、本発明に従う構造とされた防振ブッシュと、それを用いた防振ブッシュ組立体においては、何れも、インナ部材とアウタ筒部材の各フランジ部間に介装されたゴム弾性体の外周面のうち、特に問題となるアウタ部材への接着部付近での引張応力の集中が、ゴム弾性体の外周面に一体形成された環状突出部によって軽減されるのであり、それによって、ゴム弾性体への亀裂の発生が防止されて、耐久性の向上が図られ得る。
【図面の簡単な説明】
【図１】本発明の一実施形態としての防振ブッシュ組立体を示す縦断面説明図である。
【図２】図１に示された防振ブッシュ組立体を構成する防振ブッシュの単体を示す縦断面図である。
【図３】図１に示された防振ブッシュ組立体へのこじり荷重入力時における防振ブッシュの作動を説明するための縦断面説明図である。
【図４】本発明の別の実施形態としての防振ブッシュ単体の要部を示す縦断面図である。
【図５】本発明の更に別の実施形態としての防振ブッシュ単体の要部を示す縦断面図である。
【図６】従来構造の防振ブッシュにおけるこじり荷重入力状態を示す縦断面説明図である。
【符号の説明】
１０防振ブッシュ組立体
１２防振ブッシュ
１４アームアイ
１６固定対向板
１８内筒金具
２０外筒金具
２２筒状部
２４フランジ部
２６筒状部
２８フランジ部
３８ゴム弾性体
４０筒状ゴム部
４２環状ゴム部
４６環状弾性突部
５６支持ボルト[0001]
【Technical field】
The present invention relates to an anti-vibration bush and an anti-vibration bush assembly used as, for example, a suspension bush for an automobile, and more particularly to an anti-vibration bush and an anti-vibration bush that exhibit excellent durability by reducing stress concentration in a rubber elastic body. The present invention relates to a vibration bush assembly.
[0002]
[Background]
2. Description of the Related Art Conventionally, as described in Japanese Utility Model Laid-Open No. 2-112244, etc., an inner metal fitting and an outer cylinder are used as a kind of bush assembly that is interposed in a pivot joint connection portion of a vehicle suspension arm to a vehicle body. The metal fittings are spaced apart from each other in the radial direction, and a flange portion is integrally formed at one axial end portion of each of the inner metal fitting and the outer cylinder metal fitting, and between the radially opposed surfaces of the inner metal fitting and the outer cylinder metal fitting and A pair of anti-vibration bushes having a structure in which a rubber elastic body is interposed between the opposing surfaces in the axial direction of the flange portions and elastically connected to each other, and the anti-vibration bushes are formed at the end of the suspension arm. After inserting into the cylindrical arm eye from the axial direction end side where the flange part is not formed, it is fitted between a pair of mounting plate parts fixed on the vehicle body side. By allowed to pivotally supporting both inner fitting between these attachment plate portion, that as vibration-damping coupling the suspension arm to the vehicle body are known.
[0003]
By the way, in such a bush assembly, when an axial load or a twisting direction load is input between the inner metal fitting and the outer cylinder metal fitting in the mounted state, both flange portions of the inner metal fitting and the outer cylinder metal fitting are provided. A tensile load may be applied to the rubber elastic body interposed therebetween. In particular, in the vibration isolating bush having the conventional structure, as shown in FIG. 6, the outer peripheral surface of the rubber elastic body 9 interposed between the flange portion 4 of the inner metal fitting 2 and the flange portion 8 of the outer cylinder metal fitting 6. Is formed into a single substantially arc-shaped cross-sectional shape over the whole, and therefore, when a twisting load is input as indicated by a virtual line in the drawing, the direction substantially along the surface of the rubber elastic body 9 A tensile load (F) is applied in the direction in which the rubber elastic body 9 is peeled off from the flange portion 8 of the outer tubular fitting 6, and concentrated stress acts on the end face of the rubber elastic body 9 to the flange portion 8 of the outer tubular fitting 6. For this reason, there is a problem that the rubber elastic body 9 is easily cracked and the like, and it is difficult to obtain sufficient durability.
[0004]
[Solution]
Here, the present invention has been made in the background as described above, and the problem to be solved is to reduce the concentration of tensile stress of the rubber elastic body at the time of axial or twisting load input. Another object of the present invention is to provide a vibration-proof bushing having a novel structure that is prevented and improved in durability, and a vibration-proof bushing assembly using the vibration-proof bushing.
[0005]
[Solution]
Hereinafter, the aspect of this invention made | formed in order to solve such a subject is described. In addition, each aspect described below can be employed in any combination as much as possible. The aspects and technical features of the present invention are not limited to those described below, but are described in the whole specification and drawings, or based on the inventive concept that can be grasped by those skilled in the art from these descriptions. It should be understood that
[0006]
  That is, anti-vibration bushAssemblyThe first aspect of the present invention relates to an inner member and an outer cylinder member fixedly attached to each connected member to be vibration-proof connected, and spaced apart from each other in the radial direction. And at least one axial end portion of the outer cylindrical member are integrally formed with a flange portion, and a rubber elastic body is interposed between the axially opposed surfaces of the inner member and the outer cylindrical member and between the axially opposed surfaces of the flange portions. Anti-vibration bush that is elastically connectedSoAnd projecting radially outward with rising surfaces on both sides in the axial direction with respect to the outer peripheral surface of the rubber elastic body positioned between the flange portions of the inner member and the outer cylindrical member, An annular projecting portion that extends is integrally formed, and the annular projecting portion isBetween each flangeThan the axial centerTheOf the outer cylinder memberTheClose to the flange sideAnd, the outer diameter of the rubber elastic body positioned between the flange portions is set to be the most at the center in the axial direction on the flange portion side of the outer tubular member than the center in the axial direction between the flanges. By using a pair of the reduced vibration-proof bushings, the inner members and the outer members of the vibration-proof bushes are opposed to each other on the axial end surface opposite to the flange portion and fixedly connected to each other. The anti-vibration bushes are characterized in that axial pre-compression is exerted on the rubber elastic body positioned between the flange portions of the inner member and the outer cylinder member.
[0007]
In the vibration isolating bush having the structure according to this aspect, when a tensile load is applied to the rubber elastic body interposed between the flange portions of the inner member and the outer cylindrical member, the rubber elastic body is pulled in the axial direction. Although stress is generated, tensile stress is generated along the outer peripheral surface of the rubber elastic body, so that the annular protrusion formed near the flange portion of the outer tube bracket is pulled in the direction of expansion. When the stress acts and this annular protrusion spreads in the axial direction and elastically deforms, the tensile stress on the outer peripheral surface of the rubber elastic body is relaxed.
[0008]
In addition, since the annular projecting portion is formed near the flange portion of the outer cylindrical member, it becomes a particular problem of the rubber elastic body based on the action of reducing the tensile stress of the rubber elastic body based on the elastic deformation. It is possible to prevent the occurrence of cracks and the like at the site of adhesion with the outer cylinder member and improve durability.
[0009]
In this aspect, the radially opposing surfaces of the inner member and the outer cylindrical member can be formed with various cylindrical shapes such as a cylindrical shape, an elliptical shape, and a polygonal cylindrical shape. Further, the rubber elastic body that elastically connects the inner member and the outer member is integrally formed between the radially opposing surfaces of the inner member and the outer member and between the axially facing surfaces of the flange portions of these two members. It is desirable to form it automatically. In consideration of the elastic deformation characteristics, moldability, and the like, the annular projecting portion can be advantageously formed, for example, with a divergent substantially chevron cross-sectional shape having a flat or arcuate projecting tip.
[0010]
  AlsoThisAnti-vibration bushing structured according to this embodimentAssemblyIn the mounting state, a compression stress along the surface of the rubber elastic body is generated by the compressive force exerted on the rubber elastic body, and an annular protrusion formed near the flange portion of the outer cylinder fitting is attached to the shaft. It is compressed in the direction and elastically deformed in the direction in which it protrudes in the radial direction, whereby the amount of elastic deformation in the compression direction is advantageously stored in the annular protrusion. Therefore, the vibration isolating bush according to this embodimentAssemblyIn this case, when a tensile load is applied to the rubber elastic body in the mounted state, the axial tensile stress generated in the rubber elastic body is caused by the amount of elastic deformation in the compression direction stored in advance in the annular protrusion. It can be reduced more effectively. Note that the amount of compressive deformation in the axial direction applied to the rubber elastic body between the flange portions of the inner member and the outer cylindrical member is preferably set to 5 to 30% in a dimensional ratio (compression amount / initial dimension).
[0011]
  Further, the first aspect of the present invention relating to the vibration isolating bushtwoThe aspect of the aboveoneAnti-vibration bushAssemblyThe outer peripheral surface of the rubber elastic body between the annular projecting portion and the flange portion of the outer cylindrical member extends over the entire surface.CircleAn arc-shaped cross-sectional shape is used, and the radius of curvature is smaller than the radius of curvature of the curved rising surface on the opposite side in the axial direction of the annular protrusion. In this embodiment, the annular protrusion is brought close to the flange portion of the outer cylinder member while the free length of the rubber elastic body is secured between the annular protrusion and the flange portion of the outer cylinder member by the arc-shaped outer peripheral surface. In addition, the surface distance of the rising surface on the flange side of the inner member in the annular protrusion can be set large, thereby increasing the amount of elastic deformation in which the annular protrusion extends in the axial direction. In addition to being able to ensure, the effect of reducing the tensile stress at the bonding site between the rubber elastic body and the flange portion of the outer cylindrical member based on the elastic deformation of the annular projecting portion is more effectively exhibited.
[0012]
  AlsoThisIn this aspect, the surface distance (the distance along the surface of the rubber elastic body) from the adhesion portion of the outer cylinder member and the rubber elastic body to the annular protrusion is sufficiently small, and the flange portion side of the inner member By increasing the surface distance of the rising surface, the amount of elastic deformation in which the annular protrusion extends in the axial direction can be increased, and the tensile stress at the bonded portion between the rubber elastic body and the outer cylindrical member exhibited by the annular protrusion The mitigating effect can be improved.
[0013]
  Further, the first aspect of the present invention relating to the vibration isolating bushthreeThe aspect of the firstOr secondAnti-vibration bush according to aspectAssemblyThe outer surface of the rubber elastic body positioned between the flange portions of the inner member and the outer cylinder member protrudes radially outward with curved rising surfaces on both sides in the axial direction. The second annular projecting portion that extends continuously is positioned on the flange portion side of the inner member from the center in the axial direction and is integrally formed. In this embodiment, in addition to the effect of reducing the tensile stress at the bonded portion of the rubber elastic body and the outer cylindrical member by the annular protrusion as described above, the rubber elastic body and the inner cylindrical member are provided by the second annular protrusion. Since the effect of reducing the tensile stress at the bonded site is exhibited, the occurrence of cracks in the rubber elastic body and the improvement of the durability can be achieved more advantageously.
[0016]
  In addition, a feature of the present invention relating to the vibration isolating bushing assembly is that the flange portion is integrally formed at one axial end of each of the inner member and the outer cylindrical member.threeBy using a pair of anti-vibration bushes according to any of the above, the inner members and the outer members of the anti-vibration bushes are opposed to each other on the axial end surface opposite to the flange portion and fixedly connected to each other. In each of the vibration isolating bushes, the anti-vibration bushing assembly is configured to exert axial pre-compression on the rubber elastic body positioned between the flange portions of the inner member and the outer cylindrical member.
[0017]
In the anti-vibration bush assembly having the structure according to the present invention, a pair of anti-vibration bushes are arranged to face each other in the axial direction, so that either one of the anti-vibration bushes is applied to any axial load. A compressive load is applied to the rubber elastic body between the flange portions of the bush, and the vibration-proof performance and load-bearing performance in both axial directions are advantageously ensured. In addition, even in the vibration-proof bushing on the side where the tensile load is applied to the rubber elastic body between the flange portions, the tensile stress reduction effect of the rubber elastic body by the annular protrusion is exhibited, so that excellent durability is exhibited. It is.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.
[0019]
First, in FIG. 1, as one embodiment of the present invention, a suspension arm of a wheel suspension device of an automobile is interposed in a pivot joint for a vehicle body so that the suspension arm can swing relative to the vehicle body. An interlocking anti-vibration bushing assembly 10 is shown. The anti-vibration bushing assembly 10 includes an arm eye 14 as a mounting cylinder member which is a connected member in which a pair of anti-vibration bushes 12 and 12 are integrally formed at an axial end of a suspension arm (not shown), and a vehicle body (not shown). The arm eye 14 (suspension arm) is fixed to the fixed opposing plates 16 and 16 (vehicle body) by being interposed between a pair of fixed opposing plates 16 and 16 as a pair of mounting plate members that are fixedly connected members. The anti-vibration connection is made to be swingable around the central axis.
[0020]
More specifically, as the pair of anti-vibration bushes 12, those having the same structure as shown in FIG. 2 are used. This anti-vibration bushing 12 has an inner cylinder fitting 18 as an inner member and an outer cylinder fitting 20 as an outer cylinder member. The inner cylinder fitting 18 includes a thick cylindrical cylindrical portion 22 and a flange portion 24 that extends radially outward from one axial end of the cylindrical portion 22. Similarly, the outer cylinder fitting 20 is also composed of a cylindrical cylindrical portion 26 and a flange portion 28 that extends radially outward from one axial end of the cylindrical portion 26. These inner and outer cylindrical fittings 18 and 20 are advantageously formed by pressing, forging, cutting or the like. Here, the outer cylindrical fitting 20 is thinner than the inner cylindrical fitting 18, and its cylindrical portion 26 has a larger diameter than the cylindrical portion 22 of the inner cylindrical fitting 18 and its axial length is shortened. The inner cylinder fitting 18 is disposed on the substantially same axis at a predetermined distance outward in the radial direction.
[0021]
Further, the flange portion 24 of the inner cylinder fitting 18 and the flange portion 28 of the outer cylinder fitting 20 are positioned on the same axial side, and the outer cylinder fitting 20 is connected to the flange portion 24 with respect to the inner cylinder fitting 18. Are arranged in a biased manner toward the opposite axial end, and the axial end surface 33 on the side where the flange portion 28 is not formed in the outer tube fitting 20 is formed with the flange portion 24 in the inner tube fitting. It is positioned inward in the axial direction by a predetermined distance: L1 from the axial end surface 36 on the non-side. Further, the flange portions 24 and 28 of the inner and outer cylindrical fittings 18 and 20 are opposed to each other with a predetermined distance L2 in the axial direction.
[0022]
The flange portion 28 of the outer cylinder fitting 20 has an inner diameter dimension that is larger than the outer diameter dimension of the cylindrical portion 22 of the inner cylinder fitting 18 and smaller than the outer diameter dimension of the flange portion 24 of the inner cylinder fitting 18. The outer diameter of the flange portion 24 of the metal fitting 18 is larger than the outer diameter. Further, the inner side surface 30 in the axial direction of the flange portion 24 of the inner cylinder fitting 18 has a substantially arc-shaped curved cross section that gradually approaches the outer cylinder fitting 20 side as it goes radially inward. Furthermore, the axial end surface on the flange portion 24 side of the inner cylindrical metal fitting 18 is serrated and quenched into the center portion 36 in an annular shape, and is used as a pressure fixing surface for the fixed counter plate 16. In addition, the inner hole 32 of the inner cylindrical metal fitting 18 has an axial end opposite to the flange portion 24 having a large diameter over a predetermined length in the axial direction, and has a large diameter that opens on one side in the axial direction. It is set as the connection fixation part 34 of this.
[0023]
A rubber elastic body 38 is interposed between the inner cylinder fitting 18 and the outer cylinder fitting 20 that are spaced apart in the radial direction as described above. And with respect to the rubber elastic body 38, the outer peripheral surface of the cylindrical part 22 in the inner cylindrical metal fitting 18 and the axial inner surface of the flange part 24, and the inner peripheral surface of the cylindrical part 26 in the outer cylindrical metal fitting 20 and the shaft of the flange part 28 The outer surface in the direction is an integrally vulcanized molded product with each vulcanized and bonded. In short, the rubber elastic body 38 has a thick, generally cylindrical shape as a whole, and is a cylinder interposed between the radially opposing surfaces of the cylindrical portions 22 and 26 between the inner and outer cylinder fittings 18 and 20. The annular rubber portion 40 and the annular rubber portion 42 interposed between the axially opposed surfaces of the flange portions 24 and 28 are configured. The cylindrical rubber part 40 and the annular rubber part 42 fill the substantially entire space between the axial and radial facing surfaces of the inner and outer cylindrical metal parts 18 and 20.
[0024]
Further, after the vulcanization molding of the rubber elastic body 38, if necessary, the tubular portion 26 of the outer cylindrical fitting 20 is subjected to a reduction in diameter by an eight-way drawing process or the like, and the tensile stress of the rubber elastic body 38 Will be eliminated and pre-compression will be applied.
[0025]
Further, the cylindrical rubber portion 40 has a semicircular or U-shaped recess 44 that opens toward the axial end surface between the cylindrical portions 22 and 26 of the inner and outer cylindrical metal fittings 18 and 20, in the circumferential direction. Are formed continuously or discontinuously. On the other hand, the annular rubber portion 42 is disposed over substantially the entire axially opposed surface of the flange portions 24 and 28 of the inner and outer cylindrical fittings 18 and 20, but the end of the inner cylindrical fitting 18 on the flange portion 24 side. The end portion on the flange portion 28 side of the outer cylinder fitting 20 is slightly larger in diameter than the portion. Further, the outer peripheral surface of the annular rubber portion 42 has a concave curved cross section with the axial center portion being reduced in diameter as a whole, and the adhesion portions to the flange portions 24 and 28 at both axial end portions of the annular rubber portion 42. Each is marked with a fillet are.
[0026]
An annular elastic portion as an annular projecting portion extending continuously in the circumferential direction is formed on the outer peripheral surface of the annular rubber portion 42 by projecting an axially intermediate portion radially outward. The protrusion 46 is integrally formed. The annular elastic protrusion 46 is a curved surface in which the tip portion is a substantially flat top portion 48 in the axial cross section shown in FIG. 2 and both axial sides sandwiching the top portion 48 gradually expand in the axial direction. 50 and 50, which are continuously formed in the circumferential direction with a substantially constant chevron cross-sectional shape as a whole. In other words, the outer peripheral surface of the annular rubber portion 42 is protruded radially outward with curved both-side rising surfaces 50 and 50 at the axially intermediate portion to form the annular elastic protrusion 46. On the outer peripheral surface of the rubber elastic body 38, on both sides in the axial direction across the annular elastic protrusion 46, concave groove-like portions that open radially outward and extend in the circumferential direction are formed. In particular, in the rubber elastic body 38, the portion between the adhesion portion to the flange portion 24 of the inner cylinder fitting 18 and the annular elastic projection 46 is greater than any of the adhesion portion to the flange portion 24 and the annular elastic projection 46. A small outer diameter dimension portion is formed, and a fillet radius is attached to an adhesion portion of the outer peripheral portion of the rubber elastic body 38 to the flange portion 24.
[0027]
Further, the annular elastic protrusion 46 is formed and positioned in the annular rubber portion 42 closer to the flange portion 28 side of the outer tube fitting 20 than the intermediate portion in the axial direction. In other words, the axial distance between the annular elastic protrusion 46 and the flange portion 28 of the outer cylindrical fitting 20: L2b is greater than the axial distance L2a between the annular elastic protrusion 46 and the flange 24 of the inner cylindrical fitting 18. Is set smaller. In particular, in this embodiment, L2a ≧ L2b × 2. In the present embodiment, in the axial cross section as shown in FIG. 2, the outer peripheral surfaces of the annular rubber portions 42 located on both sides in the axial direction across the annular elastic protrusion 46 are substantially arc-shaped. The radius of curvature Rb of the outer peripheral surface located between the annular elastic protrusion 46 and the flange portion 28 of the outer cylinder fitting 20 is located between the annular elastic protrusion 46 and the flange portion 24 of the inner cylinder fitting 18. The radius of curvature of the outer peripheral surface is set smaller than Ra. In addition, the minimum outer diameter dimension rb of the annular rubber portion 42 between the annular elastic protrusion 46 and the flange portion 28 of the outer cylinder fitting 20 is thereby reduced between the annular elastic protrusion 46 and the flange portion 24 of the inner cylinder fitting 18. It is set larger than the minimum outer diameter dimension: ra of the annular rubber portion 42 between the two.
[0028]
As shown in FIG. 1, the pair of vibration isolating bushes 12, 12 each having the above-described structure has the outer cylindrical metal fitting 20 and the flange portion 28 formed with respect to the arm eye 14. At the end in the axial direction on the non-side, the arm eye 14 is inserted and assembled by being press-fitted from both sides in the axial direction. Here, the cylindrical part 26 of the outer cylinder fitting 20 constitutes a press-fitting part for the arm eye 14 as a whole. In addition, each vibration-proof bushing 12 has the axial length of the cylindrical portion 26 of the outer cylindrical fitting 20 shorter than half of the axial length of the arm eye 14, and the flange portion 28 of the outer cylindrical fitting 20 has the arm eye. The insertion end with respect to the arm eye 14 is positioned by abutting on the axial end surface of the arm 14. In such a positioning state, an annular gap 52 extending continuously in the circumferential direction is formed between the axial end surfaces of both the outer cylindrical metal members 20 and 20 and both the cylindrical rubber portions 40 and 40.
[0029]
Further, when assembling the pair of anti-vibration bushes 12 and 12 with respect to the arm eye 14, both end portions in the axial direction of the cylindrical connecting tube fitting 54 with respect to the connecting fixing portions 34 and 34 of the inner tube fittings 18 and 18. The inner cylindrical fittings 18 and 18 are connected and fixed to each other with the axial end faces thereof being abutted with each other by the connecting cylindrical fitting 54. Further, in the assembled state of the pair of vibration isolating bushes 12 and 12 by the connection of the inner cylinder fittings 18 and 18, the distance between the axial end surfaces of the inner cylinder fittings 18 and 18 on the flange portion 24 side, in other words, In this case, the maximum axial dimension L3 of the pair of anti-vibration bushes 12 and 12 assembled to the arm eye 14 is substantially equal to the dimension between the opposing surfaces of the pair of fixed opposing plates 16 and 16 to which the arm eye 14 is anti-vibrated. Preferably, the axial length of the inner cylindrical metal fitting 18 is a dimension between the pair of fixed opposing plates 16, 16 so that it is slightly smaller than the dimension between the opposing surfaces of the pair of fixed opposing plates 16, 16. Etc. are set in consideration.
[0030]
In short, in the anti-vibration bushing assembly 10 including the pair of anti-vibration bushes 12 and 12 assembled to the arm eye 14 in which the inner cylindrical fittings 18 and 18 are connected and integrated with each other by the connecting cylindrical fitting 54 as described above, As shown by the phantom lines in FIG. 2, the inner cylinder bracket 18 and the outer cylinder bracket 20 are displaced in the axial direction from each other so that each vibration isolating bush 12 is displaced in the axial direction. The distance between the opposing surfaces in the axial direction between the flange portions 24 and 28 of the tubular fittings 18 and 20 is reduced. Further, based on the relative displacement in the axial direction of the inner and outer cylindrical metal fittings 18 and 20, a compressive load is applied in the axial direction to the annular rubber portion 42 disposed between the flange portions 24 and 28. The annular rubber portion 42 is compressed and deformed in the axial direction by the relative displacement amount L4 in the axial direction of the inner and outer cylindrical fittings 18 and 20.
[0031]
When the annular rubber portion 42 is compressed and deformed in the axial direction, the axial compression force exerted on the outer peripheral portion of the annular rubber portion 42 acts substantially along the outer peripheral surface of the annular rubber portion 42. A compression force directed radially outward from both sides in the axial direction is exerted on the formation portion of the portion 46, and the annular elastic protrusion 46 is elastically deformed in a direction protruding outward in the radial direction while being compressed in the axial direction. I'm damned. As a result, the annular elastic protrusion 46 is positively elastically deformed so that compressive deformation is collected from both axial sides toward the annular elastic protrusion 46.
[0032]
As shown in FIG. 1, the pair of anti-vibration bushes 12 and 12 assembled to the arm eye 14 is further opposed to the pair of fixed opposed plates 16 and 16 fixed on the vehicle body side. The two anti-vibration bushes 12 and 12 are arranged in series so as to be fitted between them and straddle between the pair of fixed opposing plates 16 and 16. And the support bolt 56 inserted through the through-holes provided in the pair of fixed opposing plates 16 and 16 and straddling between the pair of fixed opposing plates 16 and 16 is provided with the vibration isolating bush 12, The anti-vibration bush assembly 10 is pivotally supported with respect to the fixed opposing plates 16 and 16 via the support bolts 56 by being inserted into the 12 inner holes 32 and 32.
[0033]
In addition, the support bolt 56 inserted through the vibration isolating bushing assembly 10 is tightened, and the pair of fixed opposing plates 16 and 16 are deformed in a direction approaching each other, thereby being integrated and integrated in the axial direction. An axial tightening force is exerted on the cylindrical fittings 18, 18. With this tightening force, the serrated portion on the axially outer surface 36 of both inner tubular fittings 18 is pressure-bonded to the contact surface of each fixed opposing plate 16.
[0034]
That is, in the vibration-proof bushing assembly 10 assembled in this way, the pair of fixed opposing plates 16 and 16 to which the inner cylindrical fittings 18 and 18 are fixed, and the arm eye 14 to which the outer cylindrical fittings 20 and 20 are fixed. Are elastically coupled via rubber elastic bodies 38, 38, and the suspension arm on the arm eye 14 side is connected to the vehicle body on the fixed opposing plate 16 side based on the elastic deformation action of the rubber elastic bodies 38, 38. On the other hand, it is vibration-proof connected so as to be swingable.
[0035]
Therefore, in the vibration-proof bushing assembly 10 assembled as described above, not only the direction perpendicular to the axis but also the load in the axial direction and the twisting direction are input. Since the annular protrusion 46 integrally formed with the portion 42 is positively compressed and deformed in the axial direction, the concentration of tensile stress on the rubber elastic body 38 at the time of load input is reduced or avoided, and a crack or the like Is prevented from occurring.
[0036]
That is, for example, as shown in FIG. 3, a load in the prying direction is input between the inner and outer cylindrical fittings 18 and 20, and the inner and outer cylindrical fittings 18 and 20 are relatively twisted as indicated by phantom lines. When displaced, the flange portions 24 and 28 of the inner and outer tube brackets 18 and 20 are relatively displaced in the axial direction on one side in the radial direction within the twisting surface, thereby interposing between them. Tensile deformation is caused on the outer peripheral surface of the mounted annular rubber portion 42 in particular. However, since an annular elastic protrusion 46 that is positively compressed and deformed is formed on the outer peripheral surface of the annular rubber portion 42, when a tensile force is applied to the annular rubber portion 42, the annular elastic protrusion 42. 46 is elastically deformed in the direction of spreading on both sides in the axial direction so as to release the stored compressive deformation, whereby the tensile stress in the vicinity of the annular elastic protrusion 46 is reduced or avoided. It becomes. Since the annular elastic protrusion 46 is formed near the adhesion portion to the flange portion 28 of the outer tubular metal fitting 20 where the concentration of the tensile stress is likely to be a problem, it is the maximum generated in the annular rubber portion 42. The tensile stress is suppressed, and the occurrence of cracks or the like in the annular rubber portion 42 is prevented, thereby realizing excellent durability.
[0037]
Further, particularly in the present embodiment, in the annular rubber portion 42, the outer peripheral surfaces on both sides in the axial direction sandwiching the annular elastic protrusion 46 are each formed as a continuous arc-shaped cross section having a substantially constant radius of curvature. The stress concentration on the surface of the annular rubber portion 42 can be more advantageously achieved, and the durability can be further improved.
[0038]
Furthermore, in this embodiment, in the annular rubber portion 42 of the vibration isolating bush 12 in a single state before assembly, the outer peripheral surfaces on both sides sandwiching the annular elastic protrusion 46 in the axial direction are substantially arc-shaped. At the same time, the radius of curvature Rb on the flange portion 28 side of the outer cylinder fitting 20 is made smaller than the radius of curvature Ra on the flange portion 24 side of the inner cylinder fitting 18. Since the minimum outer diameter dimension: rb on the flange portion 28 side of the outer tube metal fitting 20 is larger than the minimum outer diameter dimension: ra, the rubber elastic body 38 due to the action of the annular elastic protrusion 46 as described above. The effect of reducing the tensile stress in the vicinity of the bonding portion to the outer cylinder fitting 20 can be more effectively exhibited.
[0039]
As mentioned above, although one Embodiment of this invention was described in full detail, this is an illustration to the last, Comprising: This invention is limited to this specific example, and is not interpreted.
[0040]
For example, in order to adjust the spring characteristics of the vibration-isolating bushing 12, it is possible to form a straight part or a hollow part extending continuously or circumferentially in the circumferential direction with respect to the rubber elastic body 38. . In addition, an intermediate cylinder fitting that continuously extends in the circumferential direction between the opposing surfaces of the inner cylinder fitting 18 and the outer cylinder fitting 20 or an intermediate plate fitting that extends in the circumferential direction by a predetermined length is disposed in the rubber elastic body 38. It is also possible to embed and adhere to. As described in Japanese Utility Model Laid-Open No. 2-1244, etc., a flange-like portion extending between the flange portions 24 and 28 of the two metal fittings 18 and 20 between the opposing surfaces of the inner and outer cylindrical metal fittings 18 and 20. When the intermediate cylinder fitting provided with the above is used, the intermediate cylinder fitting is operatively formed into the inner cylinder fitting with respect to the outer cylinder fitting 20, so that the present invention is used as the inner cylinder fitting. Will be applied.
[0041]
Further, in the annular rubber portion 42, the outer peripheral surfaces on both sides in the axial direction across the annular elastic protrusion 46 do not necessarily have an arc-shaped cross section. For example, as shown in FIG. 4, a cylindrical shape that extends straight in the axial direction at an intermediate portion in the axial direction between the annular elastic protrusion 46 and the flange portions 24, 28 of the inner cylinder fitting 18 and the outer cylinder fitting 20. An outer peripheral surface portion 60 may be provided.
[0042]
Furthermore, as shown in FIG. 5, the second annular protrusion 62 having the same structure as the annular elastic protrusion 46 as described above is provided on the outer peripheral surface of the annular rubber part 42 in the axial center. It may be formed at a position closer to the flange portion 24 of the inner cylinder fitting 18, and by forming such a second annular protrusion 62, the vicinity of the bonding portion of the annular rubber portion 42 to the inner cylinder fitting 18. In this case, the tensile stress is reduced and the occurrence of cracks is prevented. 4 and 5, in order to facilitate understanding thereof, the members and parts having the same structure as the vibration-proof bushing 12 in the first embodiment are respectively shown in FIG. Inside, the same reference numerals as those in the first embodiment are given.
[0043]
Further, as described above, a plurality of the annular elastic protrusions 46 and the second annular elastic protrusions 62 on the outer peripheral surface of the annular rubber portion 42 can be formed apart from each other in the axial direction of the annular rubber portion 42. .
[0044]
Furthermore, the inner cylinder fitting 18 and the outer cylinder fitting 20 have, for example, a structure in which an annular flat plate flange portion is fixed to an axial end portion of a cylindrical fitting having a substantially constant inner and outer diameter by welding or the like. It is also possible to adopt.
[0045]
Further, in the vibration isolating bush assembly 10 according to the above-described embodiment, a pair of vibration isolating bushes 12 and 12 each having a flange portion and an annular rubber portion at one end portion in the axial direction are inserted from both axial opening portions of the arm eye 14. In addition, after a pair of anti-vibration bushes are connected and integrated in advance in the axial direction, the cylindrical part divided in the circumferential direction is fitted into the outer cylinder fitting from both sides in the radial direction. It is also possible to attach a vibration-proof bush. In addition, when adopting such a mounting structure, it is also possible to adopt an inner cylinder fitting and an outer cylinder fitting made of each single member provided with flange portions at both ends in the axial direction. It is also possible to realize the vibration isolating bush assembly in the above embodiment with a single vibration isolating bush.
[0046]
In addition, in the previous embodiment, a specific example of applying the present invention to a vibration-proofing coupling body for a vehicle body of a suspension arm of an automobile has been shown. However, the present invention is also interposed in a pivot coupling portion. Of course, the present invention can be widely applied to an elastic connector or the like.
[0047]
In addition, although not listed one by one, the present invention can be implemented in a mode with various changes, modifications, improvements, and the like based on the knowledge of those skilled in the art. It goes without saying that all are included in the scope of the present invention without departing from the spirit of the invention.
[0048]
【The invention's effect】
As is clear from the above description, in the vibration isolating bush having the structure according to the present invention and the vibration isolating bush assembly using the same, each is interposed between the flange portions of the inner member and the outer cylindrical member. Of the outer peripheral surface of the rubber elastic body, the concentration of tensile stress in the vicinity of the adhesion portion to the outer member, which is particularly problematic, is reduced by the annular protrusion integrally formed on the outer peripheral surface of the rubber elastic body. Thereby, the occurrence of cracks in the rubber elastic body can be prevented, and the durability can be improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal cross-sectional explanatory view showing a vibration-proof bushing assembly as one embodiment of the present invention.
FIG. 2 is a longitudinal sectional view showing a single vibration isolating bush constituting the vibration isolating bushing assembly shown in FIG. 1;
FIG. 3 is a longitudinal cross-sectional explanatory view for explaining the operation of the vibration isolating bush at the time of inputting a twisting load to the vibration isolating bush assembly shown in FIG. 1;
FIG. 4 is a longitudinal sectional view showing a main part of a vibration isolating bush as another embodiment of the present invention.
FIG. 5 is a longitudinal sectional view showing a main part of a vibration-isolating bushing as still another embodiment of the present invention.
FIG. 6 is a longitudinal cross-sectional explanatory view showing a state in which a twisting load is input in a vibration proof bush having a conventional structure.
[Explanation of symbols]
10 Anti-vibration bushing assembly
12 Anti-vibration bush
14 Arm Eye
16 Fixed counter plate
18 Inner tube bracket
20 Outer cylinder fitting
22 cylindrical part
24 Flange
26 Cylindrical part
28 Flange
38 Rubber elastic body
40 Cylindrical rubber part
42 Annular rubber part
46 Annular elastic protrusion
56 Support bolt

Claims

An inner member and an outer cylinder member fixedly attached to each connected member to be anti-vibrated and connected are spaced apart from each other in the radial direction, and at least one axial end portion of the inner member and the outer cylinder member Each of the flange portions is integrally formed with each other, and a rubber elastic body is interposed between the axially opposed surfaces of the inner member and the outer cylindrical member and between the axially opposed surfaces of the flange portions, and is elastically coupled. We met Bush,
An annular ring that protrudes radially outward and has a rising surface on both sides in the axial direction with respect to the outer peripheral surface of the rubber elastic body positioned between the flange portions of the inner member and the outer cylindrical member, and extends in the circumferential direction. the protruding portion together with the integrally formed, the annular protruding portion, than an axial center between respective flange portions brought located close to the flange portion side of the outer cylindrical member, and, located between the respective flange A pair of the anti-vibration bushes having the outer diameter dimension of the rubber elastic body thus squeezed at the flange portion side of the outer cylindrical member smaller than the axial center between the flanges at the axial center. The inner members and the outer members of the anti-vibration bushes are opposed to each other on the end surface in the axial direction opposite to the flange portion and fixedly connected to each other. Oite, vibration damping bushing assembly, characterized in that had Me exert a precompression in the axial direction relative to the rubber elastic body is brought located between respective flange portions of the inner member and the outer tubular member.

The outer peripheral surface between the flange portion of the outer cylindrical member and the annular projecting portion of the rubber elastic body of the vibration isolating bushing are a circle arc-shaped cross section throughout, and has a radius of curvature, The vibration-isolating bushing assembly according to claim 1, wherein the vibration-proof bushing assembly is smaller than the curvature surface diameter of the curved rising surface on the opposite side in the axial direction of the annular protrusion.

In the anti-vibration bushing, the rubber elastic body positioned between the flange portions of the inner member and the outer cylindrical member protrudes radially outward with rising surfaces on both sides in the axial direction with respect to the outer peripheral surface of the rubber elastic body. The anti-vibration bushing assembly according to claim 1 or 2 , wherein the second annular projecting portion extending continuously in the circumferential direction is integrally formed by being positioned closer to the flange portion side of the inner member than the center in the axial direction.