JP2004132511A

JP2004132511A - Bush bearing

Info

Publication number: JP2004132511A
Application number: JP2002299548A
Authority: JP
Inventors: Hidetoshi Kaita; 貝田　英俊; Yoshiro Kusumi; 久住　美朗; Shuichi Kubota; 久保田　修市
Original assignee: Oiles Industry Co Ltd
Current assignee: Oiles Industry Co Ltd
Priority date: 2002-10-11
Filing date: 2002-10-11
Publication date: 2004-04-30
Anticipated expiration: 2022-10-11
Also published as: JP4363025B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bush bearing for slidingly supporting a shaft member such as a rack shaft with prescribed rigidity in the radial direction and with low frictional resistance in the shaft direction, and reducing a performance change in a heat history. <P>SOLUTION: This bush bearing 1 has a cylindrical inner peripheral surface 3 for allowing the rack shaft 2 to slidingly contact in the shaft direction A, and has a slit 6 extending up to the other end surface 5 from one end surface 4 of the shaft direction A so that the inner peripheral surface 3 freely diametrally contracts, and has a bush body 10 having an annular circumferential directional groove 8 on a cylindrical outer peripheral surface 7 and an endless annular elastic member 11 installed in the circumferential directional groove 8 of the bush body 10 and having an outer diameter D2 larger than a diameter D1 of the outer peripheral surface 7 of the bush body 10. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、ブッシュ軸受、特に自動車のステアリング機構におけるラック軸を摺動自在に支持するために用いて好適なブッシュ軸受に関する。
【０００２】
【従来の技術】
ブッシュ軸受として合成樹脂製のものが種々提案されているが、斯かる合成樹脂製のブッシュ軸受は、通常、締め代をもって軸部材を摺動自在に支持するようになっている。
【０００３】
【特許文献１】
実公昭６２−３４０２８号公報
【特許文献２】
実開平４−１３５８７５号公報
【特許文献３】
実開昭６１−８７７７５号公報
【０００４】
【発明が解決しようとする課題】
ところで、合成樹脂製のブッシュ軸受において、支持する軸部材に対して大きな締め代をもつようにすると、軸部材を径方向に関して所定の剛性をもってしっかりと支持できるが、軸部材をきつく締め付けることになるので、摺動摩擦抵抗が大きくなって、軸部材を良好な摺動特性をもって支持できなくなる一方、支持する軸部材に対して小さな締め代をもつようにすると、軸部材に対して低い摺動摩擦抵抗をもった良好な摺動特性は期待できるが、軸部材に大きな心ずれが生じ易くなったり、軸部材との間に隙間が生じ易くなって、径方向の剛性的支持が低下し、しかも、斯かる隙間が生じると軸部材の摺動において軸部材との間に打音が発生することにもなる。
【０００５】
また、合成樹脂製のブッシュ軸受では、熱履歴に伴う合成樹脂の応力緩和によって、軸部材との間又は軸部材が取り付けられる取り付け部材との間に隙間が生じて、径方向の剛性的支持が低下し、打音が発生するような不具合が生じ易く、また、合成樹脂の応力緩和によって特に径方向の収縮が生じる場合には、軸部材に対する締め代が増加して摺動摩擦抵抗が大きくなる虞がある。
【０００６】
本発明は、前記諸点に鑑みてなされたものであって、その目的とするところは、ラック軸等の軸部材を径方向に関しては所定の剛性をもって軸方向に関しては低い摩擦抵抗をもって摺動自在に支持できる上に、熱履歴における性能変化の低減を図り得、しかも、自動車のステアリング機構におけるラック軸を摺動自在に支持するために用いても、ギアボックス内の空気圧に起因する空気流をギアボックス内に対して問題なく流出入させることができるブッシュ軸受を提供することにある。
【０００７】
【課題を解決するための手段】
本発明の第一の態様のブッシュ軸受は、支持すべき軸部材が摺動自在に接触する円筒状の内周面を有すると共に、当該内周面が縮径自在となるように軸方向の一方の端面から他方の端面まで伸びた少なくとも一つのスリットを有しており、しかも、外周面に少なくとも一つの環状の円周方向溝を有する合成樹脂製のブッシュ本体と、ブッシュ本体の円周方向溝に装着されていると共に、ブッシュ本体の外周面の径よりも大きな外径を有する無端環状弾性部材とを具備しており、ここで、ブッシュ本体及び無端環状弾性部材の夫々は、軸方向の一方の端面から他方の端面まで伸びている少なくとも一つの軸方向溝をその外周面に有しており、ブッシュ本体の少なくとも一つの軸方向溝は、無端環状弾性部材の少なくとも一つの軸方向溝に連通し得るようになっている。
【０００８】
第一の態様のブッシュ軸受によれば、支持すべき軸部材、例えば自動車のステアリング機構におけるラック軸が摺動自在に接触する円筒状の内周面を有する合成樹脂製のブッシュ本体が軸方向の一方の端面から他方の端面まで伸びた少なくとも一つのスリットを有していると共に、無端環状弾性部材が合成樹脂製のブッシュ本体の外周面の径よりも大きな外径を有しているために、ブッシュ本体の外周面との間に隙間をもって、しかも、無端環状弾性部材を弾性変形させて潰した状態でラック軸の取り付け部材の貫通孔、例えばギアボックスの貫通孔に嵌装することができ、而して、潰しに起因する無端環状弾性部材の弾性反発力に抗する径方向力に基づく軸部材の径方向の大きな変位をブッシュ本体の外周面で規制でき、しかも、潰しに起因する無端環状弾性部材の弾性力でもってブッシュ本体を軸部材に締め付ける結果、軸部材を径方向に関しては所定の剛性をもって軸方向に関しては低い摩擦抵抗をもって摺動自在に支持できる上に、熱履歴に伴う合成樹脂の応力緩和による円筒状の内周面と軸部材との間又は無端環状弾性部材とブッシュ軸受が取り付けられる取り付け部材との間に隙間が生じないようにし得ると共に、合成樹脂の応力緩和に基づく径方向の収縮による締め代に対する影響を小さくできる結果、熱履歴における性能変化の低減を図り得、加えて、ブッシュ本体の軸方向溝が無端環状弾性部材の軸方向溝に連通し得るようになっているために、自動車のステアリング機構におけるラック軸を摺動自在に支持するために用いても、相互に連通した軸方向溝を介してギアボックス内を外部に連通させることができるために、ギアボックス内の空気圧に起因する空気流を軸方向溝を介してギアボックス内に対して問題なく流出入させることができる。
【０００９】
ブッシュ本体の形成材料としての合成樹脂は、耐摩耗性に優れて低摩擦特性を有し、しかも、所定の撓み性と剛性とを有すると共に熱伸縮の少ないものが好ましく、具体的には、ポリアミド樹脂、ポリオレフィン樹脂及びフッ素樹脂のうちの少なくとも一つを含む合成樹脂等を挙げることができる。
【００１０】
第一の態様のブッシュ軸受では、ブッシュ本体及び無端環状弾性部材は、少なくとも一つの軸方向溝を具備していればよいのであるが、本発明の第二の態様のブッシュ軸受のように、ブッシュ本体は、軸方向の一方の端面から他方の端面まで伸びている複数の軸方向溝をその外周面に有しており、無端環状弾性部材は、軸方向の一方の端面から他方の端面まで伸びていると共にブッシュ本体の複数の軸方向溝の個数と同一の個数の複数の軸方向溝をその外周面に有していても、本発明の第三の態様のブッシュ軸受のように、ブッシュ本体は、軸方向の一方の端面から他方の端面まで伸びている複数の軸方向溝をその外周面に有しており、無端環状弾性部材は、軸方向の一方の端面から他方の端面まで伸びていると共にブッシュ本体の複数の軸方向溝の個数と異なる個数の複数の軸方向溝をその外周面に有していてもよい。
【００１１】
第二又は第三の態様のブッシュ軸受では、本発明の第四の態様のブッシュ軸受のように、ブッシュ本体及び無端環状弾性部材の夫々の複数の軸方向溝は、円周方向において同一の間隔をもって配されていてもよい。
【００１２】
またブッシュ本体及び無端環状弾性部材の夫々が複数の軸方向溝を具備している場合には、好ましくは本発明の第五の態様のブッシュ軸受のように、ブッシュ本体の複数の軸方向溝は、無端環状弾性部材の複数の軸方向溝の円周方向幅と同一の若しくは異なる円周方向幅又は無端環状弾性部材の複数の軸方向溝の円周方向幅よりも大きい若しくは小さい円周方向幅を有している。
【００１３】
本発明においては、ブッシュ本体の円筒状の内周面は、無端環状弾性部材がブッシュ本体の溝に装着された状態であって、支持すべき軸部材がブッシュ本体の内周面で規定される貫通孔に挿着されていない状態で、その径が支持すべき軸部材の外周面の径に締め代分を差し引いた径と実質的に同一となるように、形成されるのが好ましく、そして、斯かる円筒状の内周面が軸部材の外周面にぴたりと隙間なしに接触した場合に、熱履歴に伴う合成樹脂の応力緩和を吸収できるような幅をスリットが有しているとよく、また、無端環状弾性部材は、それがブッシュ本体の溝に装着された場合に、本発明の第六の態様のブッシュ軸受のように、円筒状の内周面が縮径して上記の径を呈するようにブッシュ本体に弾性力を与える内径を有していても、これに代えて、円筒状の内周面が実質的に縮径することなしに上記の径を呈するように円周方向溝においてブッシュ本体に単に接触する内径を有していてもよく、ここで、円筒状の内周面を縮径させるような内径を有した無端環状弾性部材を用いる場合には、スリットは、熱履歴に伴う合成樹脂の応力緩和を吸収できる上に、無端環状弾性部材の弾性力に起因する円筒状の内周面の縮径を可能とする程度の幅を有することが要求される。円筒状の内周面が２４ｍｍの径を有する場合に、スリットの幅として１ｍｍ程度を好ましい例として提示することができる。
【００１４】
スリットは一個でもよいが複数個でもよく、この場合には、ブッシュ本体は、少なくとも一対の分割体からなる。
【００１５】
ブッシュ本体は、一個だけの環状の円周方向溝を有していてもよいのであるが、本発明の第七の態様のブッシュ軸受のように、複数個の環状の円周方向溝を有していてもよく、この場合、好ましくは無端環状弾性部材は各円周方向溝に装着されることになる結果、ブッシュ軸受は、複数個の無端環状弾性部材を具備することになる。
【００１６】
無端環状弾性部材は、好ましくは本発明の第八の態様のブッシュ軸受のように、断面において円形、楕円形、矩形又は扁平状の長円形を有しているが、本発明は、これらに限定されず、他の形状であってもよく、また、好ましくは本発明の第九の態様のブッシュ軸受のように、天然ゴム製又は合成ゴム製である。
【００１７】
本発明において、環状の円周方向溝は、無端環状弾性部材の弾性を十分に得るようにする観点からは好ましくはその第十の態様のブッシュ軸受のように、当該円周方向溝に装着される無端環状弾性部材の体積よりも大きい容積を有しているが、これに代えて、その第十一の態様のブッシュ軸受のように、当該円周方向溝に装着される無端環状弾性部材の体積よりも小さい容積を有していてもよい。
【００１８】
第十一の態様のブッシュ軸受のような容積を有した環状の円周方向溝であると、径方向の力で無端環状弾性部材が大きく潰れて円周方向溝一杯に広がった際に、無端環状弾性部材の剛性を大きくできて、これによっても軸部材を径方向に関しては所定の剛性をもって支持できるようになる。
【００１９】
本発明のブッシュ軸受は、ブッシュ本体に加えて、その第十二の態様のブッシュ軸受のように、ブッシュ本体の外周面において当該ブッシュ本体に一体形成された合成樹脂製の鍔部を更に具備していてもよく、斯かる鍔部を具備していると、ブッシュ軸受を軸方向に移動しないようにして取り付け部材の貫通孔の開口端側に取り付けることができる。
【００２０】
本発明のブッシュ軸受は、回転する軸部材、軸方向に直動する軸部材等を摺動自在に支持するために用いることができ、特に、その第十三の態様のブッシュ軸受のように、自動車のステアリング機構における軸部材としてのラック軸を摺動自在に支持するために好適であって、斯かるラック軸に対して用いることによって、路面から加わる振動に基づくラック軸の径方向の心ずれを無端環状弾性部材の弾性変形でもって好ましく吸収してラック軸を軸方向に直動自在に低摩擦抵抗をもって剛性的に支持できることになる。
【００２１】
本発明による自動車のステアリング機構は、軸部材としてのラック軸と、このラック軸を摺動自在に支持している上記のいずれかのブッシュ軸受と、このブッシュ軸受が取り付けられた貫通孔を有した取り付け部材とを具備しており、ここで、取り付け部材の貫通孔を規定する内周面とブッシュ本体の外周面との間には環状の隙間が形成されており、無端環状弾性部材は、取り付け部材の貫通孔を規定する内周面にその外周面で摺動自在に接触している。
【００２２】
次に本発明を、図に示す実施の形態の好ましい例を参照して更に詳細に説明する。なお、本発明はこれら例に何等限定されないのである。
【００２３】
【発明の実施の形態】
図１から図６において、自動車のステアリング機構におけるラック軸２（図７参照）を軸方向Ａに摺動自在に支持するための本例のブッシュ軸受１は、支持すべき軸部材としてのラック軸２が軸方向Ａに摺動自在に接触する円筒状の内周面３を有すると共に、当該内周面３が縮径自在となるように軸方向Ａの一方の端面４から他方の端面５まで伸びた少なくとも一つのスリット、本例では一つのスリット６を有しており、しかも、円筒状の外周面７に少なくとも一つの環状の円周方向溝、本例では一つの環状の円周方向溝８を有する合成樹脂製のブッシュ本体１０と、ブッシュ本体１０の円周方向溝８に装着されていると共に、ブッシュ本体１０の外周面７の径Ｄ１よりも大きな外径Ｄ２を有しており、天然ゴム製又は合成ゴム製の無端環状弾性部材１１と、ブッシュ本体１０の外周面７において当該ブッシュ本体１０に一体形成された合成樹脂製の鍔部１３とを具備している。
【００２４】
スリット６は、軸方向Ａと平行に伸びた軸方向スリット部２１及び２２と、軸方向スリット部２１及び２２の夫々と連続して配されていると共に軸方向Ａに直交して伸びた直交スリット部２３及び２４と、直交スリット部２３及び２４と連続して配されていると共に軸方向Ａと平行に伸びた軸方向スリット部２５とを有しており、軸方向スリット部２１及び２２、直交スリット部２３及び２４並びに軸方向スリット部２５の夫々は、本例では１ｍｍ程度の幅ｔを有している。
【００２５】
環状の円周方向溝８は、本例では、当該円周方向溝８に装着される無端環状弾性部材１１の体積よりも大きい容積を有しており、これにより、円周方向溝８は、無端環状弾性部材１１が弾性変形されて潰されてブッシュ本体１０の外周面７から突出しないようになっても、弾性変形されて潰された無端環状弾性部材１１で完全に埋められないようになっている。
【００２６】
ブッシュ本体１０は、軸方向Ａにおいて広幅の円筒状の内周面３に加えて、内周面３の軸方向Ａの両側において当該円筒状の内周面３に連続して配されていると共に、円筒状の内周面３から軸方向Ａの端面４及び５に夫々向かうに連れて大径となる一対の環状のテーパ内周面２６及び２７と、端面５側に環状の面取面２８とを有する上に、軸方向Ａの一方の端面４から円周方向溝８を通って他方の端面５まで伸びている少なくとも一つの軸方向溝、本例では複数個（図においては十二個）の軸方向溝２９を円周方向おいて同一の間隔（等角度間隔）をもって外周面７に有しており、中間部で円周方向溝８の一部ともなっている軸方向溝２９の夫々は、互いに同一の円周方向幅Ｔ１を有しており、各軸方向溝２９により鍔部１３は、円周方向において十二個に分断されている。
【００２７】
断面において矩形状を有する無端環状弾性部材１１は、ブッシュ本体１０の内周面３を縮径させて径Ｄ３とする弾性力をブッシュ本体１０に与えるような内径Ｄ４を有していると共に、軸方向Ａの一方の端面３１から他方の端面３２まで伸びている少なくとも一つの軸方向溝、本例では、複数個（図では八個）の軸方向溝３３を円周方向において同一の間隔（等角度間隔）をもってその外周面３４に有している。
【００２８】
無端環状弾性部材１１の複数の軸方向溝３３の夫々は、互いに同一であってブッシュ本体１０の複数の軸方向溝２９の夫々の円周方向幅Ｔ１と同一の円周方向幅Ｔ２を有しており、而して、軸方向溝２９と軸方向溝３３との個数の相違に起因して、ブッシュ本体１０の少なくとも一つの軸方向溝２９、本例では、八個の軸方向溝２９の夫々は、無端環状弾性部材１１の軸方向溝３３の夫々に連通し得るようになっており、この連通でもって特に図２に示すように端面４から端面５まで伸びる八個の連通路３５が形成されるようになっている。
【００２９】
ブッシュ本体１０の内周面３の径Ｄ３は、締め代をδｍｍとするとラック軸２の径Ｄ５よりも２δだけ小さい。なお、斯かるブッシュ本体１０の内周面３は、ラック軸２がブッシュ本体１０の内周面３で規定される貫通孔３６に挿着された場合（図７に示す場合）とそうでない場合（図１に示す場合）とで原理的にはその曲率が異なることになるので、前者の場合では、ラック軸２の外面３７にぴったりと合致しなくなるが、締め代δに対して内周面３の径Ｄ３が十分に大きく、換言すれば締め代δが極めて小さく、例えば内周面３の径Ｄ３が２４ｍｍ程度であって、締め代δが最大で０．７ｍｍ程度の場合には、ラック軸２が貫通孔３６に挿着されても、ブッシュ本体１０の撓みを含む弾性的変形によってラック軸２の外面３７に実質的にぴったりと合致するものとみなし得る。
【００３０】
以上のブッシュ軸受１は、図７に示すように、無端環状弾性部材１１が弾性変形されて潰され、しかも、鍔部１３が取り付け部材としてのギアボックス４１の端面４２に当接した状態で、当該ギアボックス４１の内周面４３で規定されると共に無端環状弾性部材１１の外径Ｄ２よりも小さい径Ｄ６を有する貫通孔４４に装着されると共に、内周面３で規定される貫通孔３６に軸部材としてのラック軸２が挿着されて、ラック軸２を軸方向Ａに摺動自在にギアボックス４１に対して支持するために用いられる。
【００３１】
通常の状態では、ブッシュ軸受１は、ギアボックス４１の内周面４３と円筒状の外周面７との間に隙間４５、例えば径方向Ｒの幅が０．１７ｍｍ乃至０．１９ｍｍの隙間４５が生じるようになって、しかも、ギアボックス４１の貫通孔４４を規定する内周面４３に外周面３４で摺動自在に接触している無端環状弾性部材１１の拡径とその弾性変形とに基づく弾性押圧力と締め代δとをもってラック軸２を軸方向Ａに摺動自在に支持している。
【００３２】
ブッシュ軸受１に支持されたラック軸２に径方向Ｒの変位が生じてラック軸２に心ずれが生じようとしても、ブッシュ軸受１は、その径方向Ｒの変位力が小さい場合には、無端環状弾性部材１１の弾性変形でこれを規制する一方、その径方向Ｒの変位力が大きい場合には、無端環状弾性部材１１の大きな弾性変形の後に、隙間４５を消失させてブッシュ本体１０の外周面７がギアボックス４１の内周面４３に当接して隙間４５を消失させこれを剛性的に規制する。
【００３３】
以上のようにブッシュ軸受１によれば、ブッシュ本体１０の外周面７との間に隙間４５をもって、しかも、無端環状弾性部材１１を潰した状態でギアボックス４１の貫通孔４４に嵌装することができ、而して、潰しに起因する無端環状弾性部材１１の弾性反発力に抗する径方向力に基づくラック軸２の径方向の大きな変位をブッシュ本体１０の外周面７で規制でき、しかも、潰しに起因する無端環状弾性部材１１の弾性力でもってブッシュ本体１０をラック軸２に締め付ける結果、ラック軸２を径方向に関しては所定の剛性をもって軸方向Ａに関しては低い摩擦抵抗をもって摺動自在に支持できる。
【００３４】
また、ブッシュ軸受１によれば、ブッシュ本体１０がスリット６を有すると共に、無端環状弾性部材１１がブッシュ本体１０の円周方向溝８に装着されていると共に、ブッシュ本体１０の外周面７の径Ｄ１よりも大きな外径Ｄ２を有しているために、熱履歴に伴う合成樹脂の応力緩和による内周面３とラック軸２との間又は無端環状弾性部材１１とギアボックス４１の内周面４３との間に隙間が生じないようにし得ると共に、合成樹脂の応力緩和に基づく径方向の収縮による締め代δに対する影響を小さくできる結果、熱履歴における性能変化の低減を図り得る。
【００３５】
更に、ブッシュ軸受１は、ブッシュ本体１０の外周面７の径Ｄ１よりも大きな外径Ｄ２を有している無端環状弾性部材１１を具備して、これを介してギアボックス４１に嵌装するようになっているために、防振、消音特性に優れている上に、ブッシュ本体１０、ラック軸２及びギアボックス４１等に製作誤差があっても、無端環状弾性部材１１の弾性変形によってこれを吸収することができる結果、軸方向Ａの摺動におけるラック軸２のこじり等の事態を軽減できる。
【００３６】
また、ブッシュ軸受１では、ブッシュ本体１０がその端面５側に環状の面取面２８を有しているために、無端環状弾性部材１１の円周方向溝８への装着を極めて容易に行い得る。
【００３７】
なお、環状の隙間４５の径方向Ｒの幅を適宜変えることにより、ブッシュ軸受１におけるラック軸２に対する心ずれ許容量、即ち径方向Ｒの剛性を最適値に調節することができる。
【００３８】
更にまたブッシュ軸受１では、ブッシュ本体１０の軸方向溝２９が無端環状弾性部材１１の軸方向溝３３に連通して連通路３５が形成されるようになっているために、相互に連通した軸方向溝２９及び３３で構成される連通路３５を介してギアボックス４１の内部５１を外部５２に連通させることができるために、内周面３とラック軸２の外面３７との間に通常配される潤滑用のグリースの消失及びブッシュ本体１０の外周面７とギアボックス４１の内周面４３との間の隙間を通る空気流に起因する異音を生じさせないでギアボックス４１の内部５１の空気圧に起因する空気流を軸方向溝２９及び３３で構成される連通路３５を介してギアボックス４１内に対して問題なく流出入させることができる。
【００３９】
ところで上記では、ブッシュ本体１０の軸方向溝２９と無端環状弾性部材１１の軸方向溝３３との個数を異ならせたが、これに代えて、例えば図９に示すようにブッシュ本体１０の軸方向溝２９と無端環状弾性部材１１の軸方向溝３３との個数を同一としてもよく、この場合には、例えば図１０に示すように軸方向溝２９と軸方向溝３３との夫々が連通して夫々で連通路３５が形成されるようにブッシュ本体１０に対して無端環状弾性部材１１を装着するとよい。
【００４０】
また、上記では、軸方向溝２９の夫々の円周方向幅Ｔ１と軸方向溝３３の夫々の円周方向幅Ｔ２とを同一としたが、これに代えて、円周方向幅Ｔ１と円周方向幅Ｔ２とを互いに異なるようにしてもよく、要は、ブッシュ本体１０に対する無端環状弾性部材１１の円周方向の装着態様との関連で連通路３５が形成されるように軸方向溝２９及び３２の円周方向幅、円周方向間隔、個数を決定すればよい。
【００４１】
加えて、複数個の環状の円周方向溝８を有したブッシュ本体１０を用いて、この複数個の環状の円周方向溝８の夫々に無端環状弾性部材１１を装着して複数の無端環状弾性部材１１を有したブッシュ軸受１を構成してもよく、更には、円周方向溝８の容積を無端環状弾性部材１１の体積よりも大きくする代わりに、円周方向溝８の容積を当該円周方向溝８に装着される無端環状弾性部材１１の体積よりも小さくして、無端環状弾性部材１１が径方向Ｒの力で大きく弾性変形されて潰された際には無端環状弾性部材１１が円周方向溝８一杯に広がるようにして、無端環状弾性部材１１の剛性が増大するようにしてもよい。
【００４２】
【発明の効果】
本発明によれば、ラック軸等の軸部材を径方向に関しては所定の剛性をもって軸方向に関しては低い摩擦抵抗をもって摺動自在に支持できる上に、熱履歴における性能変化の低減を図り得、しかも、自動車のステアリング機構におけるラック軸を摺動自在に支持するために用いても、異音及びグリースの消失を生じさせないでギアボックス内の空気圧に起因する空気流をギアボックス内に対して問題なく流出入させることができるブッシュ軸受を提供することができる。
【図面の簡単な説明】
【図１】本発明の好ましい実施の形態の一例の図２に示すＩ−Ｉ線矢視断面図である。
【図２】図１に示す例の左側面図である。
【図３】図１に示す例のブッシュ本体の左側面図である。
【図４】図３に示すブッシュ本体の断面図である。
【図５】図１に示す例の無端環状弾性部材の側面図である。
【図６】図５に示す無端環状弾性部材の断面図である。
【図７】図１に示す例を自動車のステアリング機構におけるギアボックスに用いた例の説明図である。
【図８】図７に示す例の断面説明図である。
【図９】図１に示す例のブッシュ本体の他の例の左側面図である。
【図１０】図９に示す例を自動車のステアリング機構におけるギアボックスに用いた場合の断面説明図である。
【符号の説明】
１　ブッシュ軸受
２　ラック軸
３　内周面
４、５　端面
６　スリット
８　円周方向溝
１０　ブッシュ本体
１１　無端環状弾性部材
２９、３３　軸方向溝[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bush bearing, particularly to a bush bearing suitable for slidably supporting a rack shaft in a steering mechanism of an automobile.
[0002]
[Prior art]
Various types of bush bearings made of synthetic resin have been proposed. Such bush bearings made of synthetic resin usually support a shaft member slidably with an interference.
[0003]
[Patent Document 1]
Japanese Utility Model Publication No. Sho 62-34028 [Patent Document 2]
Japanese Utility Model Application Laid-Open No. 4-135875 [Patent Document 3]
Japanese Utility Model Application Laid-Open No. 61-87775
[Problems to be solved by the invention]
By the way, in a bush bearing made of synthetic resin, if a large interference is provided for the shaft member to be supported, the shaft member can be firmly supported with a predetermined rigidity in the radial direction, but the shaft member is tightly tightened. Therefore, the sliding friction resistance increases, and the shaft member cannot be supported with good sliding characteristics. On the other hand, if the supporting shaft member has a small interference, the sliding member has low sliding friction resistance. Although good sliding characteristics can be expected, large misalignment is likely to occur in the shaft member, and a gap is easily generated between the shaft member and the rigid support in the radial direction is reduced. When such a gap occurs, a striking noise is generated between the shaft member and the shaft member when the shaft member slides.
[0005]
Further, in the bush bearing made of synthetic resin, a gap is generated between the shaft member and a mounting member to which the shaft member is attached due to stress relaxation of the synthetic resin caused by the heat history, and rigid support in the radial direction is not achieved. When the synthetic resin is relieved of stress, particularly in the case of radial shrinkage, the interference with the shaft member increases and the sliding friction resistance may increase. There is.
[0006]
The present invention has been made in view of the above points, and an object of the present invention is to allow a shaft member such as a rack shaft to slide freely with a predetermined rigidity in the radial direction and a low frictional resistance in the axial direction. In addition to being able to support, it is possible to reduce the performance change in the heat history, and even if it is used to slidably support the rack shaft in the steering mechanism of the automobile, the air flow caused by the air pressure in the gear box is used as a gear. It is an object of the present invention to provide a bush bearing that can flow into and out of a box without any problem.
[0007]
[Means for Solving the Problems]
The bush bearing according to the first aspect of the present invention has a cylindrical inner peripheral surface with which a shaft member to be supported is slidably contacted, and one of the axial directions so that the inner peripheral surface can be reduced in diameter. A bush body made of a synthetic resin having at least one slit extending from one end face to the other end face, and further having at least one annular circumferential groove on the outer peripheral surface; and a circumferential groove of the bush body. And an endless annular elastic member having an outer diameter larger than the diameter of the outer peripheral surface of the bush main body, wherein each of the bush main body and the endless annular elastic member has one end in the axial direction. The bush body has at least one axial groove extending from the end face of the bush to the other end face, and at least one axial groove of the bush body communicates with at least one axial groove of the endless annular elastic member. And It has become to so that.
[0008]
According to the bush bearing of the first aspect, a bush body made of a synthetic resin having a cylindrical inner peripheral surface with which a shaft member to be supported, for example, a rack shaft in a steering mechanism of an automobile slidably contacts, is formed in an axial direction. Because it has at least one slit extending from one end face to the other end face, and the endless annular elastic member has an outer diameter larger than the diameter of the outer peripheral surface of the bush body made of synthetic resin, With a gap between the outer peripheral surface of the bush main body, and in a state where the endless annular elastic member is elastically deformed and crushed, it can be fitted into a through hole of a mounting member of a rack shaft, for example, a through hole of a gear box, Thus, a large radial displacement of the shaft member based on a radial force against the elastic repulsive force of the endless annular elastic member caused by the crushing can be restricted by the outer peripheral surface of the bush body, and furthermore, the crushing can be prevented. As a result of tightening the bush body to the shaft member by the elastic force of the endless annular elastic member, the shaft member can be slidably supported with a predetermined rigidity in the radial direction and low frictional resistance in the axial direction, and has a thermal history. The clearance between the cylindrical inner peripheral surface and the shaft member or between the endless annular elastic member and the mounting member to which the bush bearing is mounted can be prevented from occurring due to the stress relaxation of the synthetic resin, and the stress relaxation of the synthetic resin can be prevented. As a result, it is possible to reduce the performance change in the heat history, and in addition, the axial groove of the bush body can communicate with the axial groove of the endless annular elastic member. Therefore, even if it is used to slidably support the rack shaft in the steering mechanism of an automobile, it can be connected via the axial groove communicating with each other. In order to be able to communicate through the gearbox to the outside, it is possible to flow and out without problems with respect to the gearbox via the axial grooves airflow caused by the air pressure in the gearbox.
[0009]
The synthetic resin as the material for forming the bush body is preferably a material having excellent wear resistance, low friction characteristics, and having a predetermined flexibility and rigidity and a small thermal expansion and contraction. Examples include a synthetic resin containing at least one of a resin, a polyolefin resin, and a fluororesin.
[0010]
In the bush bearing according to the first aspect, the bush body and the endless annular elastic member may have at least one axial groove, but as in the bush bearing according to the second aspect of the present invention, The main body has a plurality of axial grooves extending from one end face in the axial direction to the other end face, and the endless annular elastic member extends from one end face in the axial direction to the other end face. And the bush body has a plurality of axial grooves of the same number as the plurality of axial grooves of the bush body, but the bush body does not have the same number of axial grooves as the bush bearing of the third aspect of the present invention. Has a plurality of axial grooves extending from one end surface in the axial direction to the other end surface, and the endless annular elastic member extends from one end surface in the axial direction to the other end surface. And multiple axes of the bush body A plurality of axial grooves of a different number as the direction groove may have on its outer peripheral surface.
[0011]
In the bush bearing according to the second or third aspect, as in the bush bearing according to the fourth aspect of the present invention, each of the plurality of axial grooves of the bush body and the endless annular elastic member has the same interval in the circumferential direction. May be arranged.
[0012]
Further, when each of the bush body and the endless annular elastic member has a plurality of axial grooves, preferably, as in the bush bearing of the fifth aspect of the present invention, the plurality of axial grooves of the bush body are A circumferential width that is the same as or different from the circumferential width of the plurality of axial grooves of the endless annular elastic member, or a circumferential width that is larger or smaller than the circumferential width of the plurality of axial grooves of the endless annular elastic member. have.
[0013]
In the present invention, the cylindrical inner peripheral surface of the bush main body is in a state where the endless annular elastic member is mounted in the groove of the bush main body, and the shaft member to be supported is defined by the inner peripheral surface of the bush main body. In a state not inserted in the through hole, the diameter is preferably formed to be substantially the same as the diameter of the outer peripheral surface of the shaft member to be supported minus the interference, and When such a cylindrical inner peripheral surface comes into contact with the outer peripheral surface of the shaft member without any gap, the slit preferably has a width capable of absorbing stress relaxation of the synthetic resin caused by heat history. Further, when the endless annular elastic member is mounted in the groove of the bush main body, the cylindrical inner peripheral surface is reduced in diameter as in the bush bearing of the sixth aspect of the present invention, and the above-described diameter is reduced. Even if it has an inner diameter that gives an elastic force to the bush body so as to exhibit Alternatively, the cylindrical inner peripheral surface may have an inner diameter that simply contacts the bush body in the circumferential groove so as to exhibit the above-mentioned diameter without substantially reducing the diameter. In the case of using an endless annular elastic member having an inner diameter that reduces the diameter of the cylindrical inner peripheral surface, the slit can absorb the stress relaxation of the synthetic resin caused by the heat history, and the slit of the endless annular elastic member. It is required to have a width enough to reduce the diameter of the cylindrical inner peripheral surface due to the elastic force. When the cylindrical inner peripheral surface has a diameter of 24 mm, about 1 mm can be presented as a preferable example of the width of the slit.
[0014]
One or a plurality of slits may be provided, and in this case, the bush body includes at least a pair of divided bodies.
[0015]
Although the bush body may have only one annular circumferential groove, it has a plurality of annular circumferential grooves as in the bush bearing of the seventh aspect of the present invention. In this case, preferably, the endless annular elastic member is mounted in each circumferential groove, so that the bush bearing includes a plurality of endless annular elastic members.
[0016]
The endless annular elastic member preferably has a circular, elliptical, rectangular or flat oblong cross section in cross section, like the bush bearing of the eighth aspect of the present invention, but the present invention is not limited to these. However, the bush bearing according to the ninth aspect of the present invention is preferably made of natural rubber or synthetic rubber, as in the bush bearing according to the ninth aspect of the present invention.
[0017]
In the present invention, from the viewpoint of sufficiently obtaining the elasticity of the endless annular elastic member, the annular circumferential groove is preferably mounted in the circumferential groove, like the bush bearing of the tenth aspect. It has a larger volume than the volume of the endless annular elastic member, but instead of this, like the bush bearing of the eleventh aspect, the endless annular elastic member is mounted in the circumferential groove. It may have a smaller volume than the volume.
[0018]
When the annular circumferential groove having a capacity like the bush bearing of the eleventh aspect is used, when the endless annular elastic member is greatly crushed by the radial force and spreads completely in the circumferential groove, the endless annular elastic member is closed. The rigidity of the annular elastic member can be increased, so that the shaft member can be supported with a predetermined rigidity in the radial direction.
[0019]
The bush bearing of the present invention further includes, in addition to the bush body, a synthetic resin flange integrally formed with the bush body on the outer peripheral surface of the bush body, as in the bush bearing of the twelfth aspect. If such a flange is provided, the bush bearing can be attached to the opening end side of the through hole of the attachment member so as not to move in the axial direction.
[0020]
The bush bearing of the present invention can be used to slidably support a rotating shaft member, a shaft member that moves directly in the axial direction, and the like.Especially, as in the bush bearing of the thirteenth aspect, It is suitable for slidably supporting a rack shaft as a shaft member in a steering mechanism of an automobile. By using the rack shaft, a radial misalignment of the rack shaft due to vibration applied from a road surface is achieved. Is preferably absorbed by the elastic deformation of the endless annular elastic member, and the rack shaft can be rigidly supported with low frictional resistance so as to be able to move directly in the axial direction.
[0021]
A steering mechanism for an automobile according to the present invention has a rack shaft as a shaft member, any one of the above bush bearings that slidably supports the rack shaft, and a through hole to which the bush bearing is attached. An annular gap is formed between an inner peripheral surface defining a through hole of the attaching member and an outer peripheral surface of the bush body, and the endless annular elastic member is provided with an attaching member. The inner peripheral surface that defines the through hole of the member is slidably contacted on the outer peripheral surface.
[0022]
Next, the present invention will be described in more detail with reference to preferred examples of embodiments shown in the drawings. The present invention is not limited to these examples.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
1 to 6, a bush bearing 1 of this embodiment for supporting a rack shaft 2 (see FIG. 7) in an automobile steering mechanism slidably in an axial direction A is a rack shaft as a shaft member to be supported. 2 has a cylindrical inner peripheral surface 3 slidably contacting in the axial direction A, and from one end surface 4 to the other end surface 5 in the axial direction A such that the inner peripheral surface 3 can be reduced in diameter. It has at least one elongated slit, in this example one slit 6, and at least one annular circumferential groove on the cylindrical outer peripheral surface 7, in this example one annular circumferential groove. A bush body 10 made of a synthetic resin having an outer peripheral surface 7 of the bush body 10 and having an outer diameter D2 larger than a diameter D1 of the outer peripheral surface 7 of the bush body 10; Endless ring made of natural rubber or synthetic rubber A sexual member 11, and a flange portion 13 made of integrally formed synthetic resin to the bushing body 10 at the outer peripheral surface 7 of the bushing body 10.
[0024]
The slit 6 is provided with the axial slit portions 21 and 22 extending in parallel with the axial direction A, and the orthogonal slits which are arranged continuously with each of the axial slit portions 21 and 22 and extend perpendicular to the axial direction A. Parts 23 and 24 and an axial slit part 25 which is arranged continuously with the orthogonal slit parts 23 and 24 and extends in parallel with the axial direction A. Each of the slits 23 and 24 and the axial slit 25 has a width t of about 1 mm in this example.
[0025]
In this example, the annular circumferential groove 8 has a larger volume than the volume of the endless annular elastic member 11 mounted on the circumferential groove 8, whereby the circumferential groove 8 is Even if the endless annular elastic member 11 is elastically deformed and crushed so as not to protrude from the outer peripheral surface 7 of the bush body 10, the endless annular elastic member 11 elastically deformed and crushed cannot be completely filled. ing.
[0026]
The bush main body 10 is continuously arranged on the cylindrical inner peripheral surface 3 on both sides of the inner peripheral surface 3 in the axial direction A, in addition to the cylindrical inner peripheral surface 3 having a wide width in the axial direction A. A pair of annular tapered inner peripheral surfaces 26 and 27 each having a larger diameter from the cylindrical inner peripheral surface 3 toward the end surfaces 4 and 5 in the axial direction A, and an annular chamfered surface 28 on the end surface 5 side. And at least one axial groove extending from one end face 4 in the axial direction A through the circumferential groove 8 to the other end face 5, in this example a plurality (12 in the figure) ) Are provided on the outer peripheral surface 7 at the same interval (equal angular interval) in the circumferential direction, and each of the axial grooves 29 which is also a part of the circumferential groove 8 at the intermediate portion. Have the same circumferential width T1 as each other, and each axial groove 29 causes the flange portion 13 to move in the circumferential direction. It has been divided into twelve to have.
[0027]
The endless annular elastic member 11 having a rectangular cross section has an inner diameter D4 that reduces the diameter of the inner peripheral surface 3 of the bush body 10 to give the bush body 10 an elastic force to a diameter D3. At least one axial groove extending from one end face 31 in the direction A to the other end face 32, in this example, a plurality (eight in the figure) of axial grooves 33 is provided at the same interval (e.g., in the circumferential direction). (Angular intervals) on its outer peripheral surface 34.
[0028]
Each of the plurality of axial grooves 33 of the endless annular elastic member 11 has the same circumferential width T2 as the respective circumferential width T1 of each of the plurality of axial grooves 29 of the bush body 10. Therefore, due to the difference in the number of the axial grooves 29 and the axial grooves 33, at least one of the axial grooves 29 of the bush body 10, in this example, eight of the axial grooves 29. Each of them can communicate with each of the axial grooves 33 of the endless annular elastic member 11. With this communication, eight communication passages 35 extending from the end face 4 to the end face 5 are particularly formed as shown in FIG. Is formed.
[0029]
The diameter D3 of the inner peripheral surface 3 of the bush body 10 is smaller than the diameter D5 of the rack shaft 2 by 2δ when the interference is δmm. The inner peripheral surface 3 of the bush main body 10 has a case where the rack shaft 2 is inserted into a through hole 36 defined by the inner peripheral surface 3 of the bush main body 10 (the case shown in FIG. 7) and a case where it is not. (In the case shown in FIG. 1) in principle, the curvature is different, so in the former case, the outer surface 37 of the rack shaft 2 does not exactly fit, but the inner peripheral surface is 3, the diameter D3 of the inner peripheral surface 3 is about 24 mm, and the interference D is about 0.7 mm at the maximum. Even when the shaft 2 is inserted into the through hole 36, it can be regarded that the shaft 2 substantially conforms to the outer surface 37 of the rack shaft 2 by elastic deformation including bending of the bush body 10.
[0030]
As shown in FIG. 7, the above bush bearing 1 is in a state in which the endless annular elastic member 11 is elastically deformed and crushed, and the flange 13 is in contact with the end surface 42 of the gear box 41 as a mounting member. The through hole 36 defined by the inner peripheral surface 3 of the gear box 41 and having a diameter D6 smaller than the outer diameter D2 of the endless annular elastic member 11 and the through hole 36 defined by the inner peripheral surface 3. The rack shaft 2 as a shaft member is inserted into the shaft box 2, and is used to support the rack shaft 2 slidably in the axial direction A with respect to the gear box 41.
[0031]
In a normal state, the bush bearing 1 has a gap 45 between the inner peripheral surface 43 of the gear box 41 and the cylindrical outer peripheral surface 7, for example, a gap 45 having a width in the radial direction R of 0.17 mm to 0.19 mm. This is based on the expansion of the endless annular elastic member 11 slidably contacting the inner peripheral surface 43 defining the through hole 44 of the gear box 41 on the outer peripheral surface 34 and its elastic deformation. The rack shaft 2 is slidably supported in the axial direction A with the elastic pressing force and the interference δ.
[0032]
Even when the rack shaft 2 supported by the bush bearing 1 is displaced in the radial direction R and the rack shaft 2 is likely to be misaligned, the bush bearing 1 is endless if the displacement force in the radial direction R is small. While this is restricted by the elastic deformation of the annular elastic member 11, if the displacement force in the radial direction R is large, the gap 45 is eliminated after the large elastic deformation of the endless annular elastic member 11, and the outer periphery of the bush body 10 is reduced. The surface 7 comes into contact with the inner peripheral surface 43 of the gear box 41 to eliminate the gap 45 and rigidly regulate the gap 45.
[0033]
As described above, according to the bush bearing 1, the bush bearing 10 is fitted into the through hole 44 of the gear box 41 with the gap 45 between the outer peripheral surface 7 and the endless annular elastic member 11 in a crushed state. Thus, a large radial displacement of the rack shaft 2 based on a radial force against the elastic repulsion of the endless annular elastic member 11 caused by the crushing can be restricted by the outer peripheral surface 7 of the bush body 10. As a result of tightening the bush body 10 to the rack shaft 2 by the elastic force of the endless annular elastic member 11 caused by the crushing, the rack shaft 2 is slidable with predetermined rigidity in the radial direction and low frictional resistance in the axial direction A. Can be supported.
[0034]
According to the bush bearing 1, the bush body 10 has the slit 6, the endless annular elastic member 11 is mounted in the circumferential groove 8 of the bush body 10, and the diameter of the outer peripheral surface 7 of the bush body 10. Since the outer diameter D2 is larger than D1, the inner peripheral surface between the inner peripheral surface 3 and the rack shaft 2 or the inner peripheral surface of the endless annular elastic member 11 and the gear box 41 due to stress relaxation of the synthetic resin due to heat history. 43 can be prevented from occurring, and the effect on the interference δ due to radial shrinkage due to stress relaxation of the synthetic resin can be reduced, so that a change in performance in the thermal history can be reduced.
[0035]
Further, the bush bearing 1 is provided with an endless annular elastic member 11 having an outer diameter D2 larger than the diameter D1 of the outer peripheral surface 7 of the bush body 10, and fitted to the gear box 41 via this. As a result, the bush body 10, the rack shaft 2, the gear box 41, and the like have excellent manufacturing characteristics. As a result, it is possible to reduce a situation such as twisting of the rack shaft 2 in sliding in the axial direction A.
[0036]
Further, in the bush bearing 1, since the bush main body 10 has the annular chamfered surface 28 on the end face 5 side, the endless annular elastic member 11 can be mounted on the circumferential groove 8 extremely easily. .
[0037]
By appropriately changing the width of the annular gap 45 in the radial direction R, the allowable amount of misalignment of the bush bearing 1 with respect to the rack shaft 2, that is, the rigidity in the radial direction R can be adjusted to an optimum value.
[0038]
Furthermore, in the bush bearing 1, since the axial groove 29 of the bush body 10 communicates with the axial groove 33 of the endless annular elastic member 11 to form the communication passage 35, the shafts communicating with each other are formed. Since the inside 51 of the gearbox 41 can be communicated with the outside 52 through the communication passage 35 formed by the direction grooves 29 and 33, the gearbox 41 is normally disposed between the inner peripheral surface 3 and the outer surface 37 of the rack shaft 2. Of the inside 51 of the gear box 41 without generating the abnormal noise caused by the disappearance of the lubricating grease and the air flow passing through the gap between the outer peripheral surface 7 of the bush body 10 and the inner peripheral surface 43 of the gear box 41. The air flow caused by the air pressure can flow into and out of the gear box 41 through the communication path 35 formed by the axial grooves 29 and 33 without any problem.
[0039]
By the way, in the above, the number of the axial grooves 29 of the bush body 10 and the number of the axial grooves 33 of the endless annular elastic member 11 are made different. However, instead of this, for example, as shown in FIG. The number of the grooves 29 and the number of the axial grooves 33 of the endless annular elastic member 11 may be the same. In this case, for example, as shown in FIG. It is preferable to mount the endless annular elastic members 11 on the bush body 10 so that the communication passages 35 are formed respectively.
[0040]
In the above description, the circumferential width T1 of each of the axial grooves 29 and the circumferential width T2 of each of the axial grooves 33 are the same, but instead, the circumferential width T1 and the circumferential width T1 may be changed. The direction widths T2 may be different from each other. The point is that the axial grooves 29 and the axial grooves 29 and the axial grooves 29 are formed such that the communication passages 35 are formed in relation to the circumferential mounting of the endless annular elastic member 11 to the bush body 10. 32, a circumferential width, a circumferential interval, and a number may be determined.
[0041]
In addition, a plurality of endless annular elastic members 11 are attached to each of the plurality of annular circumferential grooves 8 by using a bush body 10 having a plurality of annular circumferential grooves 8. The bush bearing 1 having the elastic member 11 may be configured. Further, instead of making the volume of the circumferential groove 8 larger than the volume of the endless annular elastic member 11, the volume of the circumferential groove 8 is reduced. When the volume of the endless annular elastic member 11 is smaller than the volume of the endless annular elastic member 11 attached to the circumferential groove 8, and the endless annular elastic member 11 is largely elastically deformed by the force in the radial direction R and crushed, the endless annular elastic member 11 is formed. Of the endless annular elastic member 11 may be increased so as to fully cover the circumferential groove 8.
[0042]
【The invention's effect】
Advantageous Effects of Invention According to the present invention, a shaft member such as a rack shaft can be slidably supported with a predetermined rigidity in the radial direction and low frictional resistance in the axial direction, and a performance change in a heat history can be reduced, and Even when used to slidably support a rack shaft in a steering mechanism of an automobile, the air flow caused by the air pressure in the gearbox does not cause a problem in the gearbox without causing abnormal noise and loss of grease. A bush bearing capable of flowing out and in can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view taken along the line II shown in FIG. 2 of an example of a preferred embodiment of the present invention.
FIG. 2 is a left side view of the example shown in FIG.
FIG. 3 is a left side view of the bush body of the example shown in FIG.
FIG. 4 is a sectional view of the bush main body shown in FIG. 3;
FIG. 5 is a side view of the endless annular elastic member of the example shown in FIG.
FIG. 6 is a cross-sectional view of the endless annular elastic member shown in FIG.
7 is an explanatory diagram of an example in which the example shown in FIG. 1 is used for a gear box in a steering mechanism of an automobile.
8 is an explanatory sectional view of the example shown in FIG. 7;
FIG. 9 is a left side view of another example of the bush body of the example shown in FIG. 1;
FIG. 10 is an explanatory cross-sectional view when the example shown in FIG. 9 is used for a gear box in a steering mechanism of an automobile.
[Explanation of symbols]
Reference Signs List 1 bush bearing 2 rack shaft 3 inner peripheral surface 4, 5 end surface 6 slit 8 circumferential groove 10 bush body 11 endless annular elastic member 29, 33 axial groove

Claims

The shaft member to be supported has a cylindrical inner peripheral surface that slidably contacts, and at least one extending from one end surface in the axial direction to the other end surface so that the inner peripheral surface can be reduced in diameter. A bush body made of a synthetic resin having a slit and having at least one annular circumferential groove on the outer circumferential surface; and an outer circumferential surface of the bush body mounted in the circumferential groove of the bush body. And an endless annular elastic member having an outer diameter larger than the diameter of at least one of the bush body and the endless annular elastic member, each of which extends from one end surface in the axial direction to the other end surface. A bush bearing having a groove on an outer peripheral surface thereof, wherein at least one axial groove of the bush body can communicate with at least one axial groove of the endless annular elastic member.

The bush body has a plurality of axial grooves extending from one end surface in the axial direction to the other end surface on its outer peripheral surface, and the endless annular elastic member extends from one end surface in the axial direction to the other end surface. 2. The bush bearing according to claim 1, wherein the bush bearing has a plurality of axial grooves extending on the outer peripheral surface and having the same number as the plurality of axial grooves of the bush body. 3.

The bush body has a plurality of axial grooves extending from one end surface in the axial direction to the other end surface on its outer peripheral surface, and the endless annular elastic member extends from one end surface in the axial direction to the other end surface. 2. The bush bearing according to claim 1, wherein the bush bearing has a plurality of axial grooves extending on the outer peripheral surface thereof and having a number different from the number of the plurality of axial grooves of the bush body. 3.

4. The bush bearing according to claim 2, wherein the plurality of axial grooves of the bush body and the endless annular elastic member are arranged at equal intervals in the circumferential direction.

The plurality of axial grooves of the bush body are the same as or different from the circumferential width of the plurality of axial grooves of the endless annular elastic member, or the circumferential width of the plurality of axial grooves of the endless annular elastic member. The bush bearing according to any one of claims 2 to 4, wherein the bush bearing has a larger or smaller circumferential width.

The bush bearing according to any one of claims 1 to 5, wherein the endless annular elastic member has an inner diameter that gives the bush main body an elastic force that reduces the inner peripheral surface of the bush main body.

The bush bearing according to any one of claims 1 to 6, wherein the bush body has a plurality of annular circumferential grooves, and an endless annular elastic member is mounted in each circumferential groove.

The bush bearing according to any one of claims 1 to 7, wherein the endless annular elastic member has a circular, elliptical, rectangular, or flat oval cross section.

The bush bearing according to any one of claims 1 to 8, wherein the endless annular elastic member is made of natural rubber or synthetic rubber.

The bush bearing according to any one of claims 1 to 9, wherein the annular circumferential groove has a larger volume than a volume of the endless annular elastic member mounted in the circumferential groove.

The bush bearing according to any one of claims 1 to 9, wherein the annular circumferential groove has a smaller volume than a volume of the endless annular elastic member mounted in the circumferential groove.

The bush bearing according to any one of claims 1 to 11, further comprising a synthetic resin flange formed integrally with the bush body on an outer peripheral surface of the bush body.

The bush bearing according to any one of claims 1 to 12, for slidably supporting a rack shaft as a shaft member in a steering mechanism of an automobile.

The bush bearing according to any one of claims 1 to 12, which supports the rack shaft as a shaft member and the rack shaft so as to be slidable, and a mounting having a through hole to which the bush bearing is mounted. An annular gap is formed between an inner peripheral surface defining a through hole of the mounting member and an outer peripheral surface of the bush body, and the endless annular elastic member is provided with a through hole of the mounting member. The steering mechanism of an automobile, which is slidably in contact with the inner peripheral surface defining the outer peripheral surface.