JP3675881B2

JP3675881B2 - Bush assembly

Info

Publication number: JP3675881B2
Application number: JP9346395A
Authority: JP
Inventors: 一成中原
Original assignee: Kurashiki Kako Co Ltd
Current assignee: Kurashiki Kako Co Ltd
Priority date: 1995-04-19
Filing date: 1995-04-19
Publication date: 2005-07-27
Anticipated expiration: 2020-07-27
Also published as: JPH08284993A

Description

【０００１】
【産業上の利用分野】
本発明は、例えば自動車の分野で部品を車体に弾性支持させるために介装させる等の用途に用いられるブッシュ組立体に関する。
【０００２】
【従来の技術】
従来より、この種のブッシュ組立体としては、一般に、大小の円筒形の外筒体と内筒体とを同軸配置にし両筒体を内筒体の筒軸に直交する第１方向に延ばしたゴム弾性体により連結したものが知られている。そして、円筒形内筒体の外周囲に他の部材を固着して肉盛りすることにより横断面形状における外周形状が四角形になるようにするとともに、円筒形外筒体の内周面の一部に厚肉部を設け、これにより、上記ゴム弾性体の内筒体側及び外筒体側の各接合面を円弧面ではなく平面とするようにしたもの（例えば、特開平２−９３１３４号公報参照）や、上記円筒形内筒体に角筒を外嵌固定してこの角筒の一平面にゴム弾性体を連結するとともに、その一平面に平行な平面を有する中間板を角筒と円筒形外筒体との間のゴム弾性体内に介在させたもの（例えば、実開昭５６−４５６３５号公報参照）が知られている。
【０００３】
【発明が解決しようとする課題】
ところで、ブッシュ組立体において、大小の円筒形の外筒体と内筒体とを同軸配置にし両筒体を内筒体の筒軸に直交する第１方向に延ばしたゴム弾性体により連結したものを用いて、例えば自動車の操縦安定性及び部品の防振支持の両立を図るために、内筒体の筒軸方向（例えば車体の上下方向）と、上記第１方向（例えば車体の左右方向）と、筒軸方向及び第１方向に共に直交する第２方向（例えば車体の前後方向）とからなる三次元方向に対し弾性支持を可能とし、かつ、その三次元方向の各ばね定数を個別に独立して所望のものに設定可能にしたいという要請がある。
【０００４】
例えば、フロントエンジン・リヤドライブのいわゆるＦＲ車において、リヤサスペンションのサブフレームを車体にマウントするためにブッシュ組立体の筒軸方向を上下方向に、ゴム弾性体が延びる方向（上記の第１方向）を車体の左右方向に配置して用いる場合、そのブッシュ組立体には、筒軸方向及び車体の前後方向（上記の第２方向）の各ばね定数、すなわち、力がゴム弾性体に対しせん断力として作用する方向の各ばね定数を、防振性能上、共に軟らかいものにする必要がある。その一方、上記の左右方向、すなわち、力がゴム弾性体に対し圧縮・引張力として作用する方向のばね定数を、自動車の操縦安定性の面からある程度硬いものにする必要がある。
【０００５】
ところが、上記筒軸方向のばね定数については、ゴム弾性体に基づく筒軸方向のばねに基づき上記のサブフレームを支持しなくてはならないため、その筒軸方向のばね定数を軟らかいものにするのには限界がある。すなわち、上記サブフレームにはデファレンシャルギヤが載置されており、加速時にはそのトルクが作用して上記サブフレームが倒れようとするため、この倒れや傾きを抑制した状態で支持する上でも、筒軸方向のばね定数をある一定値以上に硬いものにする必要があり、上記の要求性能とは相反する要求を併せ持っている。
【０００６】
また、上記筒軸方向と前後方向とのせん断二方向の両ばね定数における互いの関係においては、ゴム弾性体の一端を円筒形の外筒体の内周面に接合させる関係上、上記筒軸及び前後の各方向のせん断力に抵抗するゴム弾性体部分の長さが上記外筒体側の円弧部分の存在により互いに異なるものになるため、上記前後方向ばね定数は上記筒軸方向のそれよりも一般に硬いものになる。この点、上記の従来技術における外筒体の内周面に厚肉部を設けて平面にしたものでは、上記の円弧部分の影響がなくなり上記せん断二方向の両ばね定数は一致するものの、外筒体に対し上記の厚肉部を形成するための工程が増える上、ゴム弾性体の一体加硫成形時の外筒体のセッティングにも手間がかかることになる。
【０００７】
このため、上記せん断二方向に対する筒軸方向ばね定数と前後方向ばね定数との関係においては、筒軸方向のばね定数をあまり軟らかいものにならない一定値に抑えると同時に、上記厚肉部の形成を省略して円筒形の外筒体をそのまま用いたとしても、上記筒軸方向ばね定数よりも硬くなる傾向にある前後方向ばね定数を上記筒軸方向ばね定数に一致もしくは極力近付け得るブッシュ組立体の開発が要請されている。
【０００８】
さらに、このような筒軸方向及び前後方向に対する両ばね定数についての目標性能を具備した上で、上記左右方向のばね定数を相対的に硬いものにすることは困難なものとなり左右方向ばね定数に対する要求性能よりも軟らかいものになってしまう。すなわち、上記左右方向ばね定数を硬いものにするためには、左右方向からの圧縮力を受けるゴム弾性体の断面積をより増大させるように形状を設定しなければならない。しかし、そうすると、上記の筒軸方向及び前後方向の両せん断方向ばね定数が変化してこれらに対する目標性能についての要求を満足させることができなくなる。この点、上記従来技術における中間板を介装させることにより左右方向のばね定数を増大させる方策を採ることもできるが、その中間板を介装させるための工程が増加する上に、その中間板の存在により筒軸方向及び前後方向のばね定数も変化してしまうことになる。
【０００９】
本発明は、このような事情に鑑みてなされたものであり、その目的とするところは、筒軸方向、前後方向及び左右方向の各ばね定数を互いに独立して設定可能とし、かつ、要求性能に対する設定の容易化を図ることにある。これにより、左右方向ばね定数を比較的硬いものとしつつ、円筒形の外筒体をそのまま用いても筒軸方向ばね定数及び前後方向ばね定数のせん断二方向のばね定数を一致もしくは可及的に近付けて、操縦安定性上の要求と、弾性支持性能上及び防振性能上の要求との両立を図ることにある。
【００１０】
【課題を解決するための手段】
上記目的を達成するために、請求項１記載の発明は、内筒体と、この内筒体の筒軸に平行にその内筒体を囲む外筒体と、上記内筒体から上記筒軸に直交する第１方向の両側に延びてその内筒体の外面と上記外筒体の内面とを互いに連結するゴム弾性体とを備えるものを前提とする。このものにおいて、上記内筒体を、取付け用軸体が挿通される本体筒部と、上記本体筒部から、上記筒軸方向及び第１方向に対し共に直交する第２方向の両側にそれぞれ上記ゴム弾性体内に突出されて上記ゴム弾性体内に介装された一対の障壁部と、上記ゴム弾性体の筒軸方向形成範囲内であって上記本体筒部の筒軸方向に互いに離れた両側各位置からそれぞれ上記第１方向の両側に上記ゴム弾性体内に張出した一対の張出し部と、上記本体筒部を挟んで第１方向両側の各位置に上記一対の張出し部の筒軸方向相対向面間に区画されてゴム弾性体が配設される一対の凹溝部とを備え、内筒体の障壁部の第１方向に対する肉厚を、本体筒部の第１方向に対する幅の範囲内に設定し、内筒体の筒軸方向両側の各張出し部を、障壁部の第２方向に対する形成範囲と同じ第２方向範囲にわたり設け、筒軸方向から見た形状が略四角形になるように形成するものである。
【００１１】
請求項２記載の発明は、請求項１記載の発明において、ゴム弾性体は、一対の張出し部及び一対の障壁部の第２方向幅と略等しく設定された第２方向幅を有しているものである。
【００１２】
請求項３記載の発明は、請求項１記載の発明において、内筒体の障壁部を、筒軸方向両側の各張出し部と互いに一体に連結するものである。
【００１３】
請求項４記載の発明は、請求項１記載の発明において、内筒体として、本体筒部と、筒軸方向両側の各張出し部と、障壁部とを互いに同一材料により一体に形成して構成するものである。
【００１４】
また、請求項５記載の発明は、請求項１記載の発明において、内筒体として、本体筒部に対し、筒軸方向両側の各張出し部と、障壁部とが上記本体筒部とを異なる材料により一体に形成して構成するものである。
【００１５】
さらに、請求項６記載の発明は、請求項１記載の発明において、外筒体を、円筒形に形成するものである。
【００１６】
【作用】
上記の構成により、請求項１記載の発明では、本体筒部の筒軸方向両側位置から第１方向両側にそれぞれ張出し部が突出されているため、内筒体もしくは外筒体に筒軸方向の外力が入力した場合に、この一対の張出し部間に挟まれたゴム弾性体部分が上記外力に対し抵抗要素とはならない、いわゆる死にゴムとなり、上記張出し部の張出し端から外筒体の内周面までの範囲のゴム弾性体部分が上記外力に対し有効に抵抗することになる。このため、本体筒部から外筒体の内周面までの範囲のゴム弾性体が上記筒軸方向外力に抵抗する場合と比べ、その筒軸方向外力に抵抗するゴム弾性体の第１方向長さが上記張出し部の張出し長さ分短くなり、これに伴い、筒軸方向ばね定数が硬いものとなる。従って、上記張出し部の張出し長さを大にする程、筒軸方向ばね定数をより硬いものにすることが可能になる。
【００１７】
一方、上記内筒体もしくは外筒体に第２方向からの外力が入力した場合には、上記筒軸方向両側の一対の張出し部の間に存在するゴム弾性体部分も上記第２方向外力に有効に抵抗するため、本体筒部から外筒体の内周面近傍までの範囲のゴム弾性体が上記第２方向外力に抵抗する。このため、上記の張出し部間のゴム弾性体部分が死にゴムとなる場合と比べてその第２方向に対するばね定数は軟らかいものとなる。これにより、ゴム弾性体の端部が外筒体の内周面の円周面に結合されていても、上記筒軸方向ばね定数よりも硬くなりがちな第２方向ばね定数を、上記筒軸方向ばね定数が硬いものとなり、かつ、第２方向ばね定数が軟らかいものとなることにより、上記筒軸方向ばね定数に一致もしくは近付け得る。
【００１８】
しかも、上記内筒体もしくは外筒体に第１方向から外力が作用した場合には、本体筒部から障壁部が第２方向両側に突出して形成され、その障壁部の第１方向厚みの分だけゴム弾性体が上記第１方向外力に抵抗して圧縮される第１方向長さが短くなり、これにより、上記第１方向に対するばね定数が硬いものとなる。従って、上記障壁部の第１方向厚みを大とする程、上記第１方向ばね定数をより硬いものとすることが可能となる上、この障壁部の第１方向厚みを変更しても、上記の筒軸方向及び第２方向からの外力に抵抗するゴム弾性体部分に殆ど影響を与えることがないため、上記筒軸方向及び第２方向の両ばね定数とは互いに独立して上記第１方向ばね定数の変更設定が可能になる。
【００１９】
このように本発明の如く障壁部と張出し部とを備えた内筒体を用いることにより、筒軸方向、第２方向、及び、第１方向の各方向に対する３つのばね定数を互いに独立して設定することが可能になり、第１方向ばね定数を比較的硬いものにしつつ、筒軸方向及び第２方向の両ばね定数を互いに一致もしくは近似したものにする設定が可能になる。
【００２０】
内筒体の障壁部の第１方向肉厚が本体筒部の第１方向幅の範囲内に設定されているため、第２方向ばね定数に影響を与えることのない範囲で第１方向ばね定数の増大化が図られる。
【００２１】
内筒体の各張出し部が障壁部の形成範囲と同じ第２方向範囲にわたり設けられて筒軸方向から見た形状が略四角形に形成されているため、筒軸方向外力に対する死にゴム部分の端面が第２方向に延びる平面となり、筒軸方向ばね定数の増大化と、第２方向ばね定数の低減化とが効率よく行われる。
【００２２】
請求項２記載の発明では、上記請求項１記載の発明による作用に加えて、ゴム弾性体は、一対の張出し部及び一対の障壁部の第２方向幅と略等しく設定された第２方向幅を有しているため、筒軸方向ばね定数の増大化と、第２方向ばね定数の低減化とがより効率的にかつ効果的に図られる。また、上記の第１方向ばね定数の増大化がより効率的にかつ効果的に図られる。
【００２３】
請求項３記載の発明では、上記請求項１記載の発明による作用に加えて、内筒体の障壁部が筒軸方向両側の各張出し部と互いに一体に連結されているため、筒軸方向、第２方向及び第１方向に対する各ばね定数を発現するゴム弾性体部分を区分、形成もしくは切換る上記障壁部や各張出し部がそれぞれ確実に作用し、これにより、上記各ゴム弾性体によりそれぞれの方向に対するばね定数が確実に所定のものが発揮される。
【００２４】
請求項４記載の発明では、上記請求項１記載の発明による作用に加えて、内筒体が、本体筒部と、各張出し部と、障壁部とを互いに同一材料により一体に形成されているため、内筒体の構造的強度が高まる上、その形成工程の合理化が図られる。
【００２５】
また、請求項５記載の発明では、上記請求項１記載の発明による作用に加えて、本体筒部に対し、各張出し部と、障壁部とが上記本体筒部とは異なる材料により内筒体が一体に形成されているため、上記各張出し部や障壁部の寸法の変更に合わせて所望形状の内筒体の量産が容易に行い得る。
【００２６】
さらに、請求項６記載の発明では、円筒形状の外筒体をそのまま用い、その外筒体の円周面である内周面にゴム弾性体の端部を接合しても、筒軸方向両側の両張出し部間ゴム弾性体部分が筒軸方向外力に対しては死にゴムとなり、第２方向外力に対しては有効な抵抗要素となり、これにより、筒軸方向ばね定数の増大化と、第２方向ばね定数の低減化とが図られるという請求項１記載の発明による作用が確実に得られ、従来の如く円筒形外筒体の内周面に厚肉部を形成するという面倒な加工を省略することが可能となる。
【００２７】
【実施例】
以下、本発明の実施例を図面に基いて説明する。
【００２８】
図１〜図３は、本発明の実施例に係るブッシュ組立体を示し、１は内筒体、２はこの内筒体１を囲むよう内筒体１の筒軸Ｚと同軸に配置された円筒形状の外筒体、３は上記内筒体１から上記筒軸Ｚに直交する第１方向であるＹ方向の両側に延びてこれら内筒体１と外筒体２との間を連結するゴム弾性体である。
【００２９】
上記内筒体１は、図４にも詳細を示すように、上記筒軸Ｚに沿って配置された円筒状の本体筒部１１と、この本体筒部１１の筒軸Ｚ方向（図２及び図４の上下方向）両側位置であって、上記内筒体１へのゴム弾性体３の形成範囲の筒軸Ｚ方向両側端位置の周囲からそれぞれから上記筒軸Ｚに直交する方向に張出した一対の張出し部１２，１２と、上記本体筒部１１から上記一対の張出し部１２，１２間を互いに連結するように上記筒軸Ｚ及びＹ方向に共に直交する第２方向であるＸ方向の両側方に突出された一対の障壁部１３とを備えており、これら１１，１２，１２，１３，１３が同一の金属材料を用いて一体に形成されている。例えば、焼結金属により、または、各張出し部１２と各障壁部１３とを旋盤加工により別体で形成して本体筒部１１に溶着することにより形成すればよい。
【００３０】
上記本体筒部１１の筒軸Ｚに沿って貫通する貫通孔１４には、取付け用軸体として例えばリヤサスペンションのサブフレーム取付け軸（図示省略）が挿通されて内筒体１と接続されるようになっている。
【００３１】
上記各張出し部１２は上記本体筒部１１からＹ方向及びＸ方向にそれぞれ所定量突出して筒軸Ｚ方向から見て略四角形状となるように形成されている。また、上記各張出し部１２のＸ方向端面は上記各障壁部１３と同一平面を構成するようにされている。すなわち、上記各張出し部１２は、上記各障壁部１３のＸ方向形成範囲と同範囲にわたり本体筒部１１を挟んでＸ方向に張出されたＸ方向寸法Ｆを有し、Ｙ方向に対しては筒軸Ｚ方向及びＸ方向の各ばね定数の目標設定値に応じてその張出し寸法Ｗが定められている。上記Ｘ方向寸法Ｆは、ゴム弾性体３のＸ方向幅の範囲内に設定され、好ましくは、そのゴム弾性体３のＸ方向幅に等しく設定される。また、上記各障壁部１３のＹ方向の肉厚ｔはＹ方向入力に対するゴム弾性体のばね定数（以下、Ｙ方向ばね定数という）の目標設定値に応じて定められるが、その肉厚ｔの設定は上記本体筒部１１のＹ方向幅、すなわち、その外径ｄと同等以下の範囲で定めるのが好ましい。
【００３２】
そして、上記内筒体１は、筒軸Ｚ方向に延びる各障壁部１３及び本体筒部１１と、上記本体筒部１１からＹ方向両側に延びる一対の張出し部１２，１２とでＹ方向ら見てエの字状に形成され、上記の一対の張出し部１２，１２の間にはＸ方向に延びる凹溝部１５，１５が本体筒部１１を挟んでＹ方向両側に形成されている。上記一対の張出し部１２，１２の筒軸Ｚ方向両外側端間の全体寸法Ｌ、すなわち、上記一対の張出し部１２，１２と一対の障壁部１３，１３とが形成される部分の筒軸Ｚ方向全体寸法Ｌは、上記一対の張出し部１２，１２が上記の如く筒軸内筒体１位置におけるゴム弾性体３の筒軸Ｚ方向両外側端位置に設けられるため、そのゴム弾性体３の筒軸Ｚ方向幅と略等しくなる。加えて、上記一対の張出し部１２，１２の筒軸Ｚ方向相対向面間隔Ｌ1 、つまり、上記凹溝部１５の筒軸Ｚ方向溝幅Ｌ1 は、筒軸Ｚ方向入力に対するゴム弾性体３のばね定数（以下、筒軸Ｚ方向ばね定数という）と、Ｘ方向入力に対するゴム弾性体３のばね定数（以下、Ｘ方向ばね定数という）との関係をどのように定めるのかに基づいて定められる。
【００３３】
上記ゴム弾性体３は、上記の内筒体１のＸ方向幅、つまり、一対の張出し部１２，１２及び一対の障壁部１３，１３のＸ方向幅と略等しく設定された幅を有し、上記内筒体１からＹ方向の両側にほぼ一直線状に延びて、外筒体２の内周面に結合されている。また、図１及び図２中３１，３１は、上記外筒体２の上記内筒体１に対しＸ方向に相対向する内周面位置に形成されたストッパー部である。このようなゴム弾性体３及び各ストッパー部３１は、上記内筒体１及び外筒体２をインサート材とする一体加硫成形により形成され、これにより、上記ゴム弾性体３及びストッパー部３１は、上記内筒体１の外面及び外筒体２の内周面と加硫接着されている。
【００３４】
なお、図２及び図３中、２１は外筒体２の筒軸Ｚ方向一端側が外周方向に拡開されたフランジ部、３２，３２，…はそのフランジ部２１から筒軸Ｚ方向外方に突出されたストッパー片部である。
【００３５】
上記構成のブッシュ組立体において、例えばリヤサスペンションのサブフレームを車体にマウントするために用いる場合には、ストッパー片部３２，３２，…を上側にして筒軸Ｚ方向を上下方向に配置し、Ｙ方向を上記車体の左右方向（幅方向）に、Ｘ方向を上記車体の前後方向にそれぞれ配置する。そして、上記サブフレームの取付け軸体を貫通孔１４に挿通して内筒体１に連結する一方、外筒体２をブラケット等を介して車体側に連結する。
【００３６】
この場合、上記筒軸Ｚ方向からの外力に対し、図５及び図６に示すように、ゴム弾性体３の筒軸Ｚ方向両側端位置の一対の張出し部１２，１２により挟まれる両凹溝１５，１５内のゴム弾性体部分３３，３３は上記内筒体１と一体に相対変位して、上記外力に対する抵抗要素とならない死にゴム部分となる。このため、上記筒軸Ｚ方向外力に対しては、上記各ゴム弾性体部分３３を除いたゴム弾性体部分３４，３４が有効に抵抗し、この両ゴム弾性体部分３４，３４に基づいて筒軸Ｚ方向ばね定数が決まることになる。従って、本体筒部１１の外周面から外筒体２の内周面までのゴム弾性体３の全体が抵抗要素となる場合と比べ、上記死にゴム部分（３３，３３）の存在により筒軸Ｚ方向外力によりせん断力を受ける長さＳz が短くなり、これに対応して筒軸Ｚ方向ばね定数が相対的に増大化、すなわち、硬いものになる。
【００３７】
一方、Ｘ方向（車体前後方向）からの外力に対しては、図７に示すように、ゴム弾性体３のＸ方向に対し連続していない、外筒体２の内周面側の円弧状部分３５，３５は有効な抵抗要素とならないが、その円弧状部分３５，３５を除いて、上記の両凹溝１５，１５内のゴム弾性体部分３３，３３を含むゴム弾性体３のほぼ全体部分３６，３６が有効に抵抗することになる。つまり、上記筒軸Ｚ方向外力に対する場合と比べ、上記の円弧状部分３５，３５は除かれるものの、その代わりに上記各凹溝１５内のゴム弾性体部分３３，３３が抵抗要素として加わることになる。このため、Ｘ方向外力によりせん断力を受ける長さＳx が、上記の筒軸Ｚ方向外力をゴム弾性体部分３４が受ける場合と比べ長くなり、これに対応してＸ方向ばね定数が相対的に低減化、すなわち、軟らかいものとなる。
【００３８】
これらの結果、ゴム弾性体３のＹ方向両側端が外筒体２の内周面、すなわち、円周面にそのまま接合されてその接合部位が円弧状になっていても、Ｘ方向ばね定数を筒軸Ｚ方向ばね定数に近付けるもしくは一致させることができる。すなわち、上記ゴム弾性体３の外筒体２への接合部位である円弧状部分３５，３の存在に起因して、従来、Ｘ方向ばね定数が筒軸Ｚ方向ばね定数よりも大きく（硬く）なる傾向にあったのを解消することができる。この結果、外筒体として円筒形のものをそのまま用いることができ、従来の如く外筒体の内周面に厚肉部を形成して平面部を形成するという工程を省略することができる。そして、上記のせん断二方向であるＸ方向ばね定数と筒軸Ｚ方向ばね定数との相対関係は、上記の外力の入力方向により死にゴムとなったり抵抗要素となったりするゴム弾性体部分３３の大きさ、すなわち、一対の張出し部１２，１２の相対向面間隔Ｌ1 等を変更することにより容易に調整することができる。
【００３９】
また、Ｙ方向からの外力に対しては、本体筒部１１からＹ方向に直交するＸ方向のほぼ全幅の範囲を横切るように障壁部１３，１３がゴム弾性体３に埋め込まれているため、その障壁部１３，１３のＹ方向厚みｔの分だけゴム弾性体３が上記Ｙ方向外力に基づく圧縮されるＹ方向長さが短くなり、これにより、Ｙ方向ばね定数が硬いものとなる。従って、上記障壁部のＹ方向厚みｔを大とする程、上記Ｙ方向ばね定数をより硬いものとすることができ、この各障壁部１３のＹ方向厚みｔを変更しても、その変更に係る部分は上記の筒軸Ｚ方向外力に対しては死にゴムとなる各ゴム弾性体部分３３であり、Ｘ方向外力に対してはその外力に抵抗するゴム弾性体部分３６に殆ど影響を与えることがない部分であるため、上記のせん断二方向である筒軸Ｚ方向及びＸ方向の両ばね定数とは互いに独立して、Ｙ方向ばね定数を設定調整することができ、しかも、その変更設定も各障壁部１３の肉厚（Ｙ方向幅ｔ）を変更するだけと容易に行うことができる。
【００４０】
以上の如く、本ブッシュ組立体によれば、筒軸Ｚ方向、Ｘ方向、及び、Ｙ方向の三次元方向の外力に対しそれぞれ所望のばね定数を発揮させることができ、しかも、それらの筒軸Ｚ方向ばね定数、Ｘ方向ばね定数、及び、Ｙ方向ばね定数のそれぞれを、本ブッシュ組立体が適用されるマウント部位において要求される目標性能に応じて、互いに独立して設定することができ、しかも、その設定調整を容易に行うことができる。このため、上記のリヤサスペンションのサブフレームの車体にするマウント部位に適用する場合には、上記の如く筒軸Ｚ方向ばね定数をあまり硬くならない程度に増大化しつつＸ方向ばね定数を上記筒軸Ｚ方向ばね定数に近付けもしくは一致させて、上記サブフレームの支持剛性を確保しつつせん断二方向に対する防振性能を満足させ、なおかつ、これらを満足させた状態でＹ方向ばね定数を上記のせん断二方向のばね定数とは独立して硬いものに設定調整することができ、操縦安定性からの要求性能をも満足させることができる。
【００４１】
＜解析結果＞
次に、本発明のブッシュ組立体について有限要素法を用いて解析した解析結果を説明する。
【００４２】
［各部寸法が各ばね定数に及ぼす影響］
図８〜図１０は、内筒体１の各部の寸法を種々に変化させた場合の筒軸Ｚ方向ばね定数Ｋz 、Ｘ方向ばね定数Ｋx 、及び、Ｙ方向ばね定数ＫY に及ぼす影響を示したものである。
【００４３】
−相対向面間隔Ｌ1 による影響−
まず、図８は、一対の張出し部１２，１２による凹溝１５，１５の存在、及び、その各凹溝１５の大きさが上記の三次元の各ばね定数Ｋz 、Ｋx 、ＫY に及ぼす影響について示したものである。本解析では、一対の張出し部１２，１２の全体寸法Ｌ（図４参照）等を固定値とし、その相対向面間隔Ｌ1 をのみ変化させた場合の上記各ばね定数Ｋz 、Ｋx 、ＫY の各値を求めた。
【００４４】
固定値として、上記全体寸法Ｌを４０ｍｍ、張出し寸法Ｗを４０ｍｍ、本体筒部の外径ｄを３０ｍｍ、障壁部１３の肉厚ｔを２０ｍｍに設定した。そして、上記相対向面間隔Ｌ1 を０〜３０ｍｍの範囲で変化させた。図８には、この場合の各ばね定数Ｋz 、Ｋx 、ＫY の変化を相対向面間隔Ｌ1 の実際値、及び、全体寸法Ｌに対するそのＬ1 の比率（Ｌ1 ／Ｌ）をそれぞれ横軸として示した。
【００４５】
この結果、Ｌ1 ＝０（Ｌ1 ／Ｌ＝０）の場合、すなわち、凹溝１５が存在せず外表面が略角柱の状態の内筒体を用いた場合には、Ｘ方向ばね定数Ｋx が筒軸Ｚ方向ばね定数Ｋz よりもかなり大きく、従って、かなり硬いものになるのに対し、上記凹溝１５を設けた場合には、その溝幅（相対向面間隔Ｌ1 ）を大値にする程、上記Ｘ方向ばね定数Ｋx は筒軸Ｚ方向ばね定数Ｋz に近付く傾向にある。また、ここで、上記溝幅Ｌ1 を大値に変更しても、筒軸Ｚ方向ばね定数Ｋz の値自体は凹溝１５が存在しない場合（Ｌ1 ＝０の場合）と比べ殆ど変化せず、筒軸Ｚ方向外力に対しては上記凹溝１５内のゴム弾性体部分３３は死にゴムとなっていることを示している。
【００４６】
一方、Ｙ方向ばね定数Ｋy は、凹溝１５が存在しない場合（Ｌ1 ＝０の場合）から、凹溝１５を設けその溝幅Ｌ1 を大値にする程低減することを示している。これは、Ｙ方向外力に対し、Ｌ1 ＝０の場合にはゴム弾性体の圧縮長さが上記の略角柱の内筒体によりゴム弾性体の断面全体で短縮されてＹ方向ばね定数Ｋy が大値となるのに対し、凹溝１５が設けられて溝幅Ｌ1 が大きくなるに従い、上記圧縮長さが短縮される断面部分が上記凹溝１５の分だけ小さくなり、その結果、Ｙ方向ばね定数Ｋy が低減されるものと考えられる。つまり、各張出し部１２のＹ方向端面も各障壁部１３と同じＹ方向ばね定数Ｋy の増大化に関与しているものと考えられる。このように、Ｙ方向ばね定数Ｋy において、溝幅Ｌ1 が大きくなるに従い、他のせん断二方向のばね定数Ｋx 及びＫz よりも大値であることを保ちつつその値が低減することは、操縦安定性の面からはできるだけ大値である方がよいもののロードノイズの悪化を招くため防振面からもう少し値を小さくしたいという性能要求と合致するものである。
【００４７】
なお、上記の図８におけるＫz1，Ｋz2、Ｋx1，Ｋx2、Ｋy1，Ｋy2は上記凹溝１５のないもの（Ｌ1 ／Ｌ＝０）と、あるもの（Ｌ1 ／Ｌ＝０．７）との試験体を製作し、それぞれ筒軸Ｚ方向、Ｘ方向、Ｙ方向の各ばね定数を実測した値をプロットしたものである。この試験体の各部寸法はＬ＝４２、ｔ＝１５、Ｗ＝４０であり、ゴム弾性体３のゴム硬度Ｈs ＝６０°である。上記の実測は上記解析の有効性について確認するために行ったものであり、この結果、上記実測値は、前提の各部寸法において上記解析のそれとはわずかに相違があるものの、解析結果と同傾向を示しほぼ合致するものであった。
【００４８】
−障壁部１３の肉厚ｔによる影響−
図９は、障壁部１３の肉厚ｔの大小が上記の三次元の各ばね定数Ｋz 、Ｋx 、ＫY に及ぼす影響について示したものである。本解析では、固定値として、全体寸法Ｌを４０ｍｍ、張出し寸法Ｗを４０ｍｍ、本体筒部の外径ｄを３０ｍｍ、凹溝の溝幅Ｌ1 を３０ｍｍ（Ｌ1 ／Ｌ＝０．７５）にそれぞれ設定し、障壁部１３の肉厚ｔを１０〜２０ｍｍの範囲で変化させて、各ばね定数Ｋz 、Ｋx 、ＫY の値を求めた。
【００４９】
この結果、障壁部１３の肉厚ｔの値が増大すると、それに対応してＹ方向ばね定数Ｋy は増大して硬いものに変化するものの、ばね定数Ｋz 及びＸ方向ばね定数Ｋx は変化せずほぼ同じ値を維持した。つまり、このことは、上記障壁部１３の肉厚ｔを変更調整すれば、Ｋz 及びＫx の値を変化させることなく、Ｋy の値のみを独立にチューニングすることが可能であることを示している。従って、Ｙ方向ばね定数Ｋy のチューニングを、何ら特別の機構を設けなくても、障壁部１３の肉厚ｔの寸法変更という容易な手段により他方向の特性を変更することなく独立して行うことができることになる。
【００５０】
−張りだし部１２の張出し寸法Ｗによる影響−
図１０は、張出し部１２の張出し寸法Ｗの大小が上記の三次元の各ばね定数Ｋz 、Ｋx 、ＫY に及ぼす影響について示したものである。本解析では、固定値として、全体寸法Ｌを４０ｍｍ、凹溝の溝幅Ｌ1 を３０ｍｍ（Ｌ1 ／Ｌ＝０．７５）、本体筒部の外径ｄを３０ｍｍ、障壁部１３の肉厚ｔを１５ｍｍにそれぞれ設定し、上記の張出し寸法Ｗを３５〜４２ｍｍの範囲で変化させて、各ばね定数Ｋz 、Ｋx 、ＫY の値を求めた。
【００５１】
この結果、張出し寸法Ｗの値が増大すると、それに対応してＫz 、Ｋx 、及び、Ｋy の３者共、増大して硬いものに変化する。つまり、張出し寸法Ｗの値を大にすれば、上記の３方向の各ばね定数Ｋz ，Ｋx ，Ｋy を共に同じ傾向で硬くすることが可能であることを示している。
【００５２】
［モデルの変形性状］
図１１〜図１４は、本解析モデルにおいて、外筒体２を固定とし内筒体１に対し筒軸Ｚ方向，Ｘ方向，または，Ｙ方向への外力を与えた場合のゴム弾性体３の変形後の形状を示すものである。
【００５３】
−Ｘ方向外力による変形−
図１１は、図３のＣ−Ｃ線断面における凹溝１５内のゴム弾性体部分、すなわち、本体筒部１１の外周面及び各障壁部１３の外面と、外筒体２の内周面とに挟まれたゴム弾性体３について、上記内筒体１にＸ方向外力を作用させた場合の変形前の形状（破線で示す形状）と、変形後の形状（実線で示す形状）とを示している。また、図１２は、図３のＤ−Ｄ線断面における張出し部１２及びゴム弾性体３について、上記内筒体１にＸ方向外力を作用させた場合の変形前の形状（破線で示す形状）と、変形後の形状（実線で示す形状）とを示している。
【００５４】
これによれば、図１１の凹溝１５内のゴム弾性体３は、Ｘ方向外力を受けて、外筒体２直近のゴム弾性体部分（図７の円弧状部分３５に相当）を除き、本体筒部１１の外周面から外筒体２までのＹ方向寸法ｙ1 のほぼ全体が変形を受けている。これに対し、図１２の張出し部１２位置のゴム弾性体３では、Ｘ方向外力を受けて変形するＹ方向寸法が、上記張出し部１２の外面位置から外筒体２までの寸法ｙ2 と短くなる。この図１２の場合は、上記図１１の断面位置で凹溝１５が存在せず、張出し部１２が筒軸Ｚ方向に連続している場合のゴム弾性体の変形に相当する。従って、上記凹溝１５のある場合（図１１の場合）には、ない場合（図１２の場合）と比べ、より長い範囲のゴム弾性体がせん断方向の力による曲げを受けてＸ方向ばね定数Ｋx がより軟らかいものとなる。
【００５５】
−筒軸Ｚ方向外力による変形−
図１３は、図３の下半部の断面におけるゴム弾性体３について、内筒体１に筒軸Ｚ方向外力（図１３の上方への外力）を作用させた場合の変形前の形状（破線で示す形状）と、変形後の形状（実線で示す形状）とを示している。
【００５６】
これによれば、凹溝１５内のゴム弾性体部分３３（図６参照）は筒軸Ｚ方向外力を受けても殆ど変形せず、この筒軸Ｚ方向外力を受けて変形する範囲は上記のゴム弾性体部分３３を除くゴム弾性体部分３４（図６参照）に止められる。つまり、上記の上下の両張出し部１２，１２により囲まれる凹溝１５内のゴム弾性体部分３３は上記筒軸Ｚ方向外力に対しては死にゴムとなり、実際には凹溝１５があっても、張出し部１２が筒軸Ｚ方向に連続して凹溝１５が存在しない場合と同じことになる。従って、各張出し部１２の形成により筒軸Ｚ方向外力に対するばね定数の増大化を図ることができる。
【００５７】
−Ｙ方向外力による変形−
図１４は、一側の張出し部１２と一側の障壁部１３との交差部付近のゴム弾性体３について、内筒体１にＹ方向外力を作用させた場合の変形前の形状（破線で示す形状）と、変形後の形状（実線で示す形状）とを示している。
【００５８】
これによれば、上記Ｙ方向力を受けて障壁部１３の前面のゴム弾性体部分が側方に、張出し部１２の前面のゴム弾性体部分が上方にそれぞれかなり大きく膨出変形している。つまり、上記の障壁部１３及び張出し部１２の存在によりゴム弾性体３がより圧縮されＹ方向外力に対するばね定数Ｋy が増大することを示している。
【００５９】
＜他の態様＞
なお、本発明は上記実施例に限定されるものではなく、その他種々の変形例を包含するものである。すなわち、上記実施例では、内筒体１として、本体筒部１１と、両張出し部１２，１２と、両障壁部１３，１３とが同一材料により一体に形成されている場合を示したが、これに限らず、例えば、金属製の本体筒部１１をインサート材にして、両張出し部１２，１２と両障壁部１３，１３とを、硬質樹脂、例えばナイロン６６にガラス繊維を混入（例えば３０％程度混入）したものを用いたモールド成形により一体的に形成するようにしてもよい。これにより、ブッシュ組立体に要求される性能に応じて各部寸法の異なる内筒体の量産が容易になる。
【００６０】
また、上記実施例では、内筒体１として、本体筒部１１に対し両張出し部１２，１２と両障壁部１３，１３とを付設したような形状を示したが、これに限らず、内筒体を本体筒部が張出し部及び障壁部の内部に完全に埋め込まれた如き形状にしてもよい。例えば、図１５に示すように、円柱材料の軸Ｚに沿って貫通孔１４を削孔して本体筒部とし、軸Ｚ方向中間位置の外周面に凹溝１５，１５を形成することにより軸Ｚ方向の両側位置に張出し部１２，１２を、Ｘ方向に障壁部１３，１３を形成するようにして内筒体１′を構成してもよい。また、図１６に示すように、角柱材料の上下軸Ｚに沿って貫通孔１４を削孔して本体筒部とし、軸Ｚ方向中間位置の外周面に凹溝１５，１５を形成することにより軸Ｚ方向の両側位置に張出し部１２，１２を、Ｘ方向に障壁部１３，１３を形成するようにして内筒体１″を構成してもよい。
【００６１】
【発明の効果】
以上説明したように、請求項１記載の発明におけるブッシュ組立体によれば、本体筒部の筒軸方向両側位置から第１方向両側にそれぞれ張出し部が突出されているため、この一対の張出し部間に挟まれたゴム弾性体部分を、筒軸方向からの外力に対しては死にゴムとさせて、その分、筒軸方向ばね定数の増大化を図ることができる。一方、第２方向からの外力に対しては、その外力を上記ゴム弾性体部分にも負担させて、その分、第２方向ばね定数を軟らかいものとすることができる。従って、外筒体として円筒形のものを用い、ゴム弾性体の端部を円周面である外筒体の内周面に接合する場合に筒軸方向ばね定数よりも硬くなりがちな第２方向ばね定数を、上記の筒軸方向ばね定数の増大化と第２方向ばね定数の低減化とによって、筒軸方向ばね定数に一致もしくは近付けることができる。しかも、このような筒軸方向もしくは第２方向のばね特性の変更を上記張出し部の寸法設定により容易に行うことができる。
【００６２】
一方、第１方向からの外力に対しては、本体筒部から第２方向両側に突出した各障壁部の第１方向厚みの分だけゴム弾性体が圧縮される第１方向長さを短くなり、かつ、上記各障壁部がゴム弾性体を有効に圧縮させるため、上記第１方向に対するばね定数を硬いものとすることができる。従って、上記障壁部の第１方向厚みを大とする程、上記第１方向ばね定数をより硬いものとすることが可能となる上、この障壁部の第１方向厚みを変更しても、上記の筒軸方向及び第２方向からの外力に抵抗するゴム弾性体部分に殆ど影響を与えることがないため、上記筒軸方向及び第２方向の両ばね定数とは互いに独立して上記第１方向ばね定数の変更設定を行うことができる。
【００６３】
このように本発明の如く障壁部と張出し部とを備えた内筒体を用いることにより、筒軸方向、第２方向、及び、第１方向の各方向に対する３つのばね定数を互いに独立して設定することができ、しかも、要求性能に応じた設定を上記障壁部もしくは張出し部等の寸法変更により容易に行うことができる。これにより、例えば、ブッシュ組立体について第１方向ばね定数を比較的硬いものにしつつ、筒軸方向及び第２方向の両ばね定数を互いに一致もしくは近似したものにするという要求性能も容易に実現することができる。
【００６４】
内筒体の障壁部の第１方向幅が本体筒部の第１方向幅の範囲内に設定されているため、第２方向ばね定数に影響を与えることのない範囲で第１方向ばね定数の増大化を図ることができる。
【００６５】
内筒体の各張出し部が各障壁部の形成範囲と同じ第２方向範囲にわたり設けられて筒軸方向から見た形状が略四角形に形成されているため、筒軸方向外力に対する死にゴム部分の端面を第２方向に延びる平面とすることができ、筒軸方向ばね定数の増大化と、第２方向ばね定数の低減化とを効率よく行うことができる。
【００６６】
請求項２記載の発明によれば、上記請求項１記載の発明による効果に加えて、ゴム弾性体は、一対の張出し部及び一対の障壁部の第２方向幅と略等しく設定された第２方向幅を有しているため、筒軸方向ばね定数の増大化と、第２方向ばね定数の低減化とをより効率的にかつ効果的に図ることができる。また、上記の第１方向ばね定数の増大化をより効率的にかつ効果的に図ることができる。
【００６７】
請求項３記載の発明によれば、上記請求項１記載の発明による効果に加えて、内筒体の各障壁部が筒軸方向両側の各張出し部と互いに一体に連結されているため、筒軸方向、第２方向及び第１方向に対する各ばね定数を発現するゴム弾性体部分を区分、形成もしくは切換る上記各障壁部や各張出し部がそれぞれ確実に作用し、これにより、上記各ゴム弾性体部分によりそれぞれの方向に対するばね定数をとして確実に所定のものを発揮させることができる。
【００６８】
請求項４記載の発明によれば、上記請求項１記載の発明による効果に加えて、内筒体が、本体筒部と、各張出し部と、障壁部とを互いに同一材料により一体に形成されているため、内筒体の構造的強度が高まる上、その形成工程の合理化を図ることができる。
【００６９】
また、請求項５記載の発明によれば、上記請求項１記載の発明による効果に加えて、本体筒部に対し、各張出し部と、障壁部とが上記本体筒部とは異なる材料により内筒体が一体に形成されているため、本ブッシュ組立体を適用する部位で要求される性能に応じて変更される上記各張出し部や障壁部の寸法設定に合わせて所望の寸法形状の内筒体の量産を容易に製作することができる。
【００７０】
さらに、請求項６記載の発明によれば、円筒形状の外筒体をそのまま用い、その外筒体の円周面である内周面にゴム弾性体の端部を接合しても、両張出し部間のゴム弾性体部分が筒軸方向外力に対しては死にゴムとなる一方、第２方向外力に対しては有効な抵抗要素となるため、筒軸方向ばね定数の増大化と、第２方向ばね定数の低減化とが図られるという請求項１記載の発明による効果を確実に得ることができる。これにより、従来の場合に必要としていた外筒体の内周面に厚肉部を形成する等の面倒な工程を省略することができる。
【図面の簡単な説明】
【図１】本発明の実施例を示す横断面図である。
【図２】図１のＡ−Ａ線における断面図である。
【図３】図１のＢ−Ｂ線における断面図である。
【図４】内筒体の拡大斜視図である。
【図５】筒軸Ｚ方向外力を受けた場合のゴム弾性体を示す図１対応図である。
【図６】筒軸Ｚ方向外力を受けた場合のゴム弾性体を示す図３対応図である。
【図７】Ｘ方向外力を受けた場合のゴム弾性体を示す図１対応図である。
【図８】張出し部間隔Ｌ1 等と各ばね定数Ｋz ，Ｋx ，Ｋy との関係図である。
【図９】障壁部肉厚ｔと各ばね定数Ｋz ，Ｋx ，Ｋy との関係図である。
【図１０】張出し部寸法Ｗと各ばね定数Ｋz ，Ｋx ，Ｋy との関係図である。
【図１１】Ｘ方向外力を受けた場合の凹溝部位置のゴム弾性体の変形状態を示す解析モデル図である。
【図１２】Ｘ方向外力を受けた場合の張出し部位置のゴム弾性体の変形状態を示す解析モデル図である。
【図１３】筒軸Ｚ方向外力を受けた場合のゴム弾性体の変形状態を示す解析モデル図である。
【図１４】Ｙ方向外力を受けた場合のゴム弾性体の変形状態を示す解析モデル図である。
【図１５】内筒体の他の態様を示す斜視図である。
【図１６】内筒体の図１５とは異なる他の態様を示す斜視図である。
【符号の説明】
１，１′，１″ 内筒体
２外筒体
３ゴム弾性体
１１本体筒部
１２張出し部
１３障壁部
１４貫通孔
１５凹溝部
Ｚ筒軸
ＸＸ方向（第２方向）
ＹＹ方向（第１方向）[0001]
[Industrial application fields]
  The present invention relates to a bushing assembly used for applications such as interposing a part to be elastically supported by a vehicle body in the field of automobiles, for example.
[0002]
[Prior art]
  Conventionally, as this kind of bush assembly, generally, a large and small cylindrical outer cylinder and an inner cylinder are arranged coaxially, and both cylinders are extended in a first direction orthogonal to the cylinder axis of the inner cylinder. Those connected by a rubber elastic body are known. Then, by fixing other members around the outer periphery of the cylindrical inner cylindrical body, the outer peripheral shape in the cross-sectional shape becomes a quadrangle, and a part of the inner peripheral surface of the cylindrical outer cylindrical body A thick-walled portion is provided in the rubber elastic body so that the joint surfaces of the rubber elastic body on the inner cylinder side and the outer cylinder side are flat surfaces instead of arc surfaces (see, for example, JP-A-2-93134) In addition, a rectangular tube is externally fitted and fixed to the cylindrical inner cylindrical body, and a rubber elastic body is connected to one plane of the rectangular tube, and an intermediate plate having a plane parallel to the one plane is connected to the rectangular cylinder and the cylindrical outer surface. There are known ones interposed in a rubber elastic body between the cylinders (for example, see Japanese Utility Model Laid-Open No. 56-45635).
[0003]
[Problems to be solved by the invention]
  By the way, in the bush assembly, large and small cylindrical outer cylinders and inner cylinders are coaxially arranged, and both cylinders are connected by a rubber elastic body extending in a first direction perpendicular to the cylinder axis of the inner cylinder. For example, in order to achieve both the steering stability of the automobile and the vibration isolation support of the parts, the cylinder axis direction of the inner cylinder (for example, the vertical direction of the vehicle body) and the first direction (for example, the horizontal direction of the vehicle body) And elastic support in a three-dimensional direction composed of a cylinder axis direction and a second direction (for example, the front-rear direction of the vehicle body) orthogonal to the first direction, and each spring constant in the three-dimensional direction is individually set. There is a demand to be able to set the desired thing independently.
[0004]
  For example, in a so-called FR vehicle of a front engine / rear drive, the direction in which the rubber elastic body extends (the first direction described above), with the cylinder axis direction of the bushing assembly extending vertically in order to mount the subframe of the rear suspension on the vehicle body Are used in the left-right direction of the vehicle body, the bush assembly has spring constants in the cylinder axis direction and the front-rear direction of the vehicle body (the second direction described above), that is, the force exerts a shear force on the rubber elastic body. It is necessary to make each spring constant in the direction acting as a soft one in terms of vibration-proof performance. On the other hand, the spring constant in the left-right direction, that is, the direction in which the force acts as a compressive / tensile force on the rubber elastic body, needs to be made somewhat stiff from the viewpoint of driving stability of the automobile.
[0005]
  However, with respect to the spring constant in the cylinder axis direction, the subframe must be supported on the basis of the spring in the cylinder axis direction based on the rubber elastic body, so that the spring constant in the cylinder axis direction is made soft. Has its limits. That is, a differential gear is placed on the subframe, and the torque acts upon acceleration to cause the subframe to fall. Therefore, the cylinder shaft can be supported even in a state where the fall and inclination are suppressed. It is necessary to make the spring constant in the direction harder than a certain value, which has a requirement that is contrary to the above required performance.
[0006]
  In addition, in the mutual relation in the two spring constants in the shearing two directions of the cylindrical axis direction and the front-rear direction, the cylindrical axis is in view of joining one end of the rubber elastic body to the inner peripheral surface of the cylindrical outer cylindrical body. And the length of the rubber elastic body portion that resists the shearing force in each direction in the front and rear directions becomes different from each other due to the presence of the arc portion on the outer cylinder side. Generally hard. In this regard, in the above-described prior art in which the thick wall portion is provided on the inner peripheral surface of the outer cylindrical body and the surface is flat, the influence of the circular arc portion is eliminated and the two spring constants in the two shear directions coincide with each other. In addition to an increase in the number of steps for forming the thick portion on the cylindrical body, it takes time to set the outer cylindrical body at the time of integral vulcanization molding of the rubber elastic body.
[0007]
  For this reason, in the relationship between the cylindrical axial spring constant and the longitudinal spring constant with respect to the two shear directions, the spring constant in the cylindrical axis direction is suppressed to a constant value that does not become so soft, and at the same time, the formation of the thick portion is performed. Even if the cylindrical outer cylinder is omitted and used as it is, a bushing assembly capable of making the longitudinal spring constant, which tends to be harder than the cylindrical axial spring constant, coincide with or as close as possible to the cylindrical axial spring constant. Development is required.
[0008]
  Furthermore, it is difficult to make the spring constant in the left-right direction relatively stiff with the target performance for both the spring constants in the cylinder axis direction and the front-rear direction, and the left-right direction spring constant. It will be softer than the required performance. That is, in order to make the left-right spring constant hard, the shape must be set so as to further increase the cross-sectional area of the rubber elastic body that receives the compressive force from the left-right direction. However, if it does so, both said shear direction spring constants of a cylinder axial direction and the front-back direction will change, and it will become impossible to satisfy the request | requirement about the target performance with respect to these. In this respect, it is possible to take measures to increase the spring constant in the left-right direction by interposing the intermediate plate in the above-mentioned prior art, but in addition to increasing the steps for interposing the intermediate plate, the intermediate plate Therefore, the spring constants in the cylinder axis direction and the front-rear direction also change.
[0009]
  The present invention has been made in view of such circumstances, and the object of the present invention is to make it possible to set the spring constants in the cylinder axis direction, the front-rear direction, and the left-right direction independently of each other and to achieve the required performance. The purpose is to facilitate the setting for. As a result, the spring constant in the two shear directions of the cylindrical axial spring constant and the front-rear spring constant can be matched or made as much as possible even if the cylindrical outer cylinder is used as it is, while making the left and right spring constant relatively hard. In the near future, the aim is to satisfy both the requirements for handling stability and the requirements for elastic support performance and vibration isolation performance.
[0010]
[Means for Solving the Problems]
  In order to achieve the above object, an invention according to claim 1 is directed to an inner cylinder, an outer cylinder surrounding the inner cylinder in parallel to the cylinder axis of the inner cylinder, and the cylinder axis from the inner cylinder. And a rubber elastic body that extends on both sides in a first direction orthogonal to the inner cylinder and connects the outer surface of the inner cylinder and the inner surface of the outer cylinder. In this, the inner cylindrical body is inserted into the main body cylinder portion through which the mounting shaft body is inserted and the main body cylinder portion on both sides in the second direction perpendicular to the cylindrical axis direction and the first direction, respectively. A pair of barrier portions that protrude into the rubber elastic body and are interposed in the rubber elastic body, and both sides that are within the formation range of the rubber elastic body in the cylinder axis direction and are separated from each other in the cylinder axis direction of the main body cylinder portion A pair of projecting portions projecting into the rubber elastic body on both sides in the first direction from the position, and the pair at each position on both sides in the first direction across the main body cylinder portion.ofAnd a pair of concave groove portions provided between the opposing surfaces of the projecting portion in the axial direction of the cylinder and provided with a rubber elastic body, and the thickness of the inner cylindrical body portion in the first direction is set to the thickness of the main body cylindrical portion. Set within the width range for one directionAnd each overhang | projection part of the cylinder axial direction both sides of an inner cylinder body is provided over the 2nd direction range same as the formation range with respect to the 2nd direction of a barrier part, and it forms so that the shape seen from the cylinder axis direction may become a substantially square shape.Is.
[0011]
  The invention according to claim 2 is the invention according to claim 1,The rubber elastic body has a second direction width set substantially equal to the second direction width of the pair of overhang portions and the pair of barrier portions.Is.
[0012]
  Claim3In the invention described in the first aspect, the barrier portion of the inner cylindrical body is integrally connected to each projecting portion on both sides in the cylinder axial direction.
[0013]
  Claim4In the invention described in claim 1, as the inner cylinder body, the main body cylinder part, each overhang part on both sides in the cylinder axial direction, and the barrier part are integrally formed of the same material. is there.
[0014]
  Claims5In the invention described in claim 1, in the invention according to claim 1, as the inner cylindrical body, each overhanging portion on both sides in the cylindrical axis direction and the barrier portion are integrally formed with different materials from the main body cylindrical portion with respect to the main body cylindrical portion. Is configured.
[0015]
  And claims6In the invention described in the first aspect, the outer cylinder is formed in a cylindrical shape.
[0016]
[Action]
  With the above configuration, in the first aspect of the present invention, since the overhanging portions protrude from the both sides in the first axial direction from the both sides in the first axial direction of the main body cylindrical portion, the inner cylindrical body or the outer cylindrical body has a cylindrical axial direction. When an external force is input, the rubber elastic body portion sandwiched between the pair of overhanging portions does not become a resistance element against the external force, so-called dead rubber, and from the overhanging end of the overhanging portion to the inner periphery of the outer cylinder body The rubber elastic body portion in the range up to the surface effectively resists the external force. For this reason, compared with the case where the rubber elastic body in the range from the main body cylinder portion to the inner peripheral surface of the outer cylinder resists the external force in the cylinder axial direction, the length in the first direction of the rubber elastic body that resists the external force in the cylinder axial direction Is shortened by the overhang length of the overhang portion, and accordingly, the cylindrical axial spring constant becomes hard. Therefore, the larger the overhang length of the overhang portion, the harder the cylinder axis direction spring constant.
[0017]
  On the other hand, when an external force from the second direction is input to the inner cylinder body or the outer cylinder body, the rubber elastic body portion existing between the pair of projecting portions on both sides of the cylinder axis direction is also subjected to the second direction external force. In order to effectively resist, the rubber elastic body in a range from the main body tubular portion to the vicinity of the inner peripheral surface of the outer tubular body resists the second direction external force. For this reason, the spring constant with respect to the second direction is softer than in the case where the rubber elastic body portion between the overhanging portions becomes dead rubber. Thereby, even if the end of the rubber elastic body is coupled to the circumferential surface of the inner circumferential surface of the outer cylinder, the second direction spring constant that tends to be harder than the cylinder axis direction spring constant is When the directional spring constant is hard and the second directional spring constant is soft, the directional spring constant can be equal to or close to the cylindrical axial spring constant.
[0018]
  In addition, when an external force is applied to the inner cylinder body or the outer cylinder body from the first direction, the barrier portion protrudes from the main body cylinder portion on both sides in the second direction, and the thickness of the barrier portion in the first direction is the same. Therefore, the length of the first direction in which the rubber elastic body is compressed while resisting the external force in the first direction is shortened, so that the spring constant with respect to the first direction becomes hard. Accordingly, as the thickness in the first direction of the barrier portion is increased, the first direction spring constant can be made harder, and even if the thickness in the first direction of the barrier portion is changed, Since the rubber elastic body portion that resists external force from the cylinder axis direction and the second direction of the cylinder is hardly affected, both the spring constants in the cylinder axis direction and the second direction are independent of each other in the first direction. The spring constant can be changed and set.
[0019]
  As described above, by using the inner cylinder body having the barrier portion and the overhang portion as in the present invention, the three spring constants for the respective directions of the cylinder axis direction, the second direction, and the first direction can be made independent of each other. It is possible to set the first direction spring constant to be relatively hard, and to set both the spring constants in the cylinder axis direction and the second direction to be equal to or approximate to each other.
[0020]
  Since the first direction wall thickness of the barrier portion of the inner cylinder is set within the range of the first direction width of the main body cylinder portion, the first direction spring constant is within a range that does not affect the second direction spring constant. Is increased.
[0021]
  Since each overhang portion of the inner cylinder is provided over the same second direction range as the formation range of the barrier portion, and the shape seen from the cylinder axis direction is formed in a substantially square shape, the end surface of the rubber part is dead due to external force in the cylinder axis direction. Becomes a plane extending in the second direction, and an increase in the cylindrical axial direction spring constant and a reduction in the second direction spring constant are efficiently performed.
[0022]
  In the invention according to claim 2, in addition to the action of the invention according to claim 1,The rubber elastic body has a second direction width set substantially equal to the second direction width of the pair of overhang portions and the pair of barrier portions.For,Increasing the cylinder axis direction spring constant and reducing the second direction spring constant can be achieved more efficiently and effectively. Further, the increase in the first direction spring constant can be achieved more efficiently and effectively.
[0023]
  Claim3In the described invention, in addition to the operation of the invention described in the first aspect, the barrier portion of the inner cylindrical body is integrally connected to each overhanging portion on both sides in the cylindrical axis direction. And each of the barrier portions and the overhang portions for separating, forming or switching the rubber elastic body portions expressing the respective spring constants in the first direction surely act, whereby the springs in the respective directions are operated by the rubber elastic bodies. A constant value is reliably exhibited.
[0024]
  Claim4In the invention described above, in addition to the action of the invention described in claim 1, the inner cylinder body is integrally formed of the same material with the main body cylinder portion, each overhang portion, and the barrier portion. The structural strength of the cylinder is increased, and the formation process is rationalized.
[0025]
  Claims5In the invention described above, in addition to the operation of the invention described in claim 1, the overhanging portion and the barrier portion are integrally formed of a material different from that of the main body cylindrical portion with respect to the main body cylindrical portion. Therefore, the mass production of the inner cylindrical body having a desired shape can be easily performed in accordance with the change in the dimensions of the overhang portions and the barrier portions.
[0026]
  And claims6In the described invention, the cylindrical outer cylinder is used as it is, and even if the ends of the rubber elastic body are joined to the inner circumferential surface that is the circumferential surface of the outer cylinder, the gap between the two protruding portions on both sides in the cylinder axial direction The rubber elastic body part becomes dead rubber against the external force in the cylinder axial direction, and becomes an effective resistance element against the external force in the second direction, thereby increasing the cylindrical axial spring constant, The action according to the first aspect of the invention can be reliably achieved, and the troublesome processing of forming a thick portion on the inner peripheral surface of the cylindrical outer cylinder as in the prior art can be omitted. It becomes.
[0027]
【Example】
  Embodiments of the present invention will be described below with reference to the drawings.
[0028]
  1 to 3 show a bush assembly according to an embodiment of the present invention, wherein 1 is an inner cylinder, and 2 is disposed coaxially with a cylinder axis Z of the inner cylinder 1 so as to surround the inner cylinder 1. A cylindrical outer cylinder 3 extends from the inner cylinder 1 to both sides in the Y direction, which is a first direction orthogonal to the cylinder axis Z, and connects the inner cylinder 1 and the outer cylinder 2. It is a rubber elastic body.
[0029]
  As shown in detail in FIG. 4, the inner cylinder 1 includes a cylindrical main body cylinder portion 11 disposed along the cylinder axis Z, and a direction of the main body cylinder portion 11 in the cylinder axis Z direction (see FIG. 2 and FIG. 2). 4 (vertical direction in FIG. 4), both sides of the rubber cylinder 3 are formed in the direction perpendicular to the cylinder axis Z from the periphery of both ends of the cylinder elastic body 3 in the cylinder axis Z direction. From the pair of overhanging portions 12 and 12 and the main body cylinder portion 11, the pair ofOverhang partA pair of barrier portions 13 projecting on both sides in the X direction, which is a second direction orthogonal to the cylindrical axes Z and Y directions, so as to connect the 12 and 12 to each other. , 12, 13, and 13 are integrally formed using the same metal material. For example, it may be formed by sintered metal or by forming each overhang portion 12 and each barrier portion 13 separately by lathe processing and welding them to the main body cylinder portion 11.
[0030]
  For example, a subframe mounting shaft (not shown) of a rear suspension is inserted into the through hole 14 penetrating along the cylinder axis Z of the main body cylinder portion 11 so as to be connected to the inner cylinder 1. It has become.
[0031]
  Each of the overhang portions 12 is formed so as to protrude from the main body cylinder portion 11 by a predetermined amount in the Y direction and the X direction so as to have a substantially rectangular shape when viewed from the cylinder axis Z direction. Further, the end surface in the X direction of each overhang portion 12 is configured to be flush with the respective barrier portions 13. That is, each overhang portion 12 has an X-direction dimension F overhanging in the X direction across the main body cylinder portion 11 over the same range as the X-direction formation range of each of the barrier portions 13, and with respect to the Y direction. The overhang dimension W is determined according to the target set value of each spring constant in the cylinder axis Z direction and the X direction. The X-direction dimension F is set within the range of the X-direction width of the rubber elastic body 3, and is preferably set equal to the X-direction width of the rubber elastic body 3. Further, the thickness t in the Y direction of each of the barrier portions 13 is determined according to a target set value of a spring constant of the rubber elastic body (hereinafter referred to as a Y direction spring constant) with respect to the Y direction input. The setting is preferably determined within the range equal to or less than the width of the main body cylinder portion 11 in the Y direction, that is, the outer diameter d.
[0032]
  The inner cylinder 1 is seen from the Y direction by the respective barrier portions 13 and the main body cylinder portion 11 extending in the cylinder axis Z direction, and a pair of projecting portions 12 and 12 extending from the main body cylinder portion 11 to both sides in the Y direction. Grooves 15 and 15 extending in the X direction are formed between the pair of overhanging portions 12 and 12 on both sides in the Y direction with the main body cylinder portion 11 interposed therebetween. The overall dimension L between the outer ends of the pair of overhang portions 12, 12 in the cylinder axis Z direction, that is, the pairofThe overall dimension L in the cylinder axis Z direction of the portion where the overhang portions 12 and 12 and the pair of barrier portions 13 and 13 are formed is the rubber at the position of the cylinder body 1 in the cylinder shaft as described above. Since the elastic body 3 is provided at both outer end positions in the cylinder axis Z direction, it is substantially equal to the width of the rubber elastic body 3 in the cylinder axis Z direction. In addition, the cylinder axis Z-direction facing surface interval L1 of the pair of overhanging portions 12, 12, that is, the cylinder axis Z-direction groove width L1 of the concave groove portion 15, is the spring of the rubber elastic body 3 with respect to the cylinder axis Z-direction input. It is determined based on how the relationship between the constant (hereinafter referred to as the cylinder axis Z-direction spring constant) and the spring constant of the rubber elastic body 3 with respect to the X-direction input (hereinafter referred to as the X-direction spring constant) is determined.
[0033]
  The rubber elastic body 3 has a width that is set substantially equal to the X-direction width of the inner cylindrical body 1, that is, the X-direction width of the pair of overhang portions 12 and 12 and the pair of barrier portions 13 and 13. The inner cylinder 1 extends in a straight line on both sides in the Y direction and is coupled to the inner peripheral surface of the outer cylinder 2. Moreover, 31 and 31 in FIG.1 and FIG.2 are the stopper parts formed in the internal peripheral surface position which mutually opposes with respect to the said inner cylinder 1 of the said outer cylinder 2 in the X direction. Such a rubber elastic body 3 and each stopper part 31 are formed by integral vulcanization molding using the inner cylindrical body 1 and the outer cylindrical body 2 as insert materials, whereby the rubber elastic body 3 and the stopper part 31 are The outer surface of the inner cylindrical body 1 and the inner peripheral surface of the outer cylindrical body 2 are vulcanized and bonded.
[0034]
  2 and 3, 21 is a flange portion in which one end side of the outer cylinder 2 in the cylinder axis Z direction is expanded in the outer peripheral direction, 32, 32, ... are outward from the flange portion 21 in the cylinder axis Z direction. This is a protruding stopper piece.
[0035]
  In the bush assembly configured as described above, for example, when used to mount the subframe of the rear suspension on the vehicle body, the stopper pieces 32, 32,... The direction is arranged in the left-right direction (width direction) of the vehicle body, and the X direction is arranged in the front-rear direction of the vehicle body. The mounting shaft body of the subframe is inserted through the through hole 14 and connected to the inner cylinder 1, while the outer cylinder 2 is connected to the vehicle body via a bracket or the like.
[0036]
  In this case, as shown in FIGS. 5 and 6, both concave grooves sandwiched between the pair of projecting portions 12 and 12 at both end positions in the cylinder axis Z direction of the rubber elastic body 3 with respect to the external force from the cylinder axis Z direction. The rubber elastic body portions 33 and 33 in the 15 and 15 are relatively displaced integrally with the inner cylinder 1 and become a rubber portion that does not become a resistance element against the external force. For this reason, the rubber elastic body portions 34, 34 excluding the rubber elastic body portions 33 effectively resist the external force in the cylinder axis Z direction, and the cylinders are formed on the basis of the rubber elastic body portions 34, 34. The axial Z-direction spring constant is determined. Therefore, compared to the case where the entire rubber elastic body 3 from the outer peripheral surface of the main body cylindrical portion 11 to the inner peripheral surface of the outer cylindrical body 2 becomes a resistance element, the cylinder axis Z is caused by the presence of the dead rubber portion (33, 33). The length Sz that receives the shearing force due to the directional external force is shortened, and the cylinder axis Z-direction spring constant is relatively increased correspondingly, that is, becomes hard.
[0037]
  On the other hand, with respect to the external force from the X direction (vehicle body longitudinal direction), as shown in FIG. Although the portions 35 and 35 are not effective resistance elements, almost the entire rubber elastic body 3 including the rubber elastic body portions 33 and 33 in the both concave grooves 15 and 15 except for the arc-shaped portions 35 and 35. The portions 36, 36 will effectively resist. That is, compared to the case of the external force in the cylinder axis Z direction, the arc-shaped portions 35 and 35 are removed, but instead, the rubber elastic body portions 33 and 33 in the concave grooves 15 are added as resistance elements. Become. For this reason, the length Sx that receives the shearing force due to the external force in the X direction is longer than that in the case where the rubber elastic body portion 34 receives the external force in the cylinder axis Z direction. Reduction, that is, softness.
[0038]
  As a result, even if both ends in the Y direction of the rubber elastic body 3 are directly joined to the inner circumferential surface of the outer cylindrical body 2, that is, the circumferential surface, and the joining portion has an arc shape, the X direction spring constant is It can approach or match the cylindrical axis Z-direction spring constant. That is, the X-direction spring constant is conventionally larger (harder) than the cylinder axis Z-direction spring constant due to the presence of the arc-shaped portions 35 and 3 that are the joint portions of the rubber elastic body 3 to the outer cylinder 2. Can be eliminated. As a result, the cylindrical outer cylinder can be used as it is, and the step of forming the thick portion on the inner peripheral surface of the outer cylinder and forming the flat portion as in the prior art can be omitted. The relative relationship between the X-direction spring constant, which is the above-described two shear directions, and the cylindrical axis Z-direction spring constant is that of the rubber elastic body portion 33 that becomes a dead rubber or a resistance element depending on the input direction of the external force. It can be easily adjusted by changing the size, that is, the distance L1 between the opposing surfaces of the pair of overhanging portions 12, 12.
[0039]
  Further, for the external force from the Y direction, since the barrier portions 13 and 13 are embedded in the rubber elastic body 3 so as to cross a range of almost the entire width in the X direction orthogonal to the Y direction from the main body cylindrical portion 11, The rubber elastic body 3 is compressed in the Y-direction length based on the Y-direction external force by the Y-direction thickness t of the barrier portions 13 and 13, thereby making the Y-direction spring constant hard. Therefore, as the Y-direction thickness t of the barrier portion is increased, the Y-direction spring constant can be made harder. Even if the Y-direction thickness t of each of the barrier portions 13 is changed, the change can be made. These portions are the rubber elastic body portions 33 that become dead rubber against the external force in the cylinder axis Z direction, and almost affect the rubber elastic body portion 36 that resists the external force with respect to the X direction external force. Therefore, the Y-direction spring constant can be set and adjusted independently of the two spring constants in the cylindrical axis Z direction and the X direction, which are the two shear directions, and the change setting is also possible. This can be easily done by simply changing the thickness (Y-direction width t) of each barrier portion 13.
[0040]
  As described above, according to the present bush assembly, desired spring constants can be exhibited with respect to the external forces in the three-dimensional directions of the cylinder axis Z direction, the X direction, and the Y direction. Each of the Z-direction spring constant, the X-direction spring constant, and the Y-direction spring constant can be set independently of each other according to the target performance required in the mount portion to which the bush assembly is applied, In addition, the setting can be easily adjusted. For this reason, when applied to the mounting portion of the rear suspension sub-frame as the vehicle body, the X-direction spring constant is increased while the cylinder axis Z-direction spring constant is not so hard as described above. The vibration damping performance in the shearing two directions is satisfied while ensuring the support rigidity of the subframe by approaching or coinciding with the direction spring constant, and the Y direction spring constant is set in the shearing two directions while satisfying these. It can be set and adjusted to be hard and independent of the spring constant, and the required performance from steering stability can also be satisfied.
[0041]
<Analysis results>
  Next, analysis results obtained by analyzing the bushing assembly of the present invention using the finite element method will be described.
[0042]
  [Effect of each part size on each spring constant]
  FIGS. 8 to 10 show the influence on the cylinder axis Z-direction spring constant Kz, the X-direction spring constant Kx, and the Y-direction spring constant KY when the dimensions of the respective parts of the inner cylinder 1 are variously changed. Is.
[0043]
      -Effect of opposing surface spacing L1
  First, FIG. 8 shows the influence of the presence of the concave grooves 15, 15 by the pair of overhanging portions 12, 12 and the size of the concave grooves 15 on the three-dimensional spring constants Kz, Kx, KY. It is shown. In this analysis, each of the spring constants Kz, Kx, KY described above when the overall dimension L (see FIG. 4) of the pair of overhanging portions 12, 12 is fixed and only the distance L1 between the opposing faces is changed. The value was determined.
[0044]
  As fixed values, the overall dimension L was set to 40 mm, the overhang dimension W was set to 40 mm, the outer diameter d of the main body cylinder part was set to 30 mm, and the wall thickness t of the barrier part 13 was set to 20 mm. And the said opposing surface space | interval L1 was changed in the range of 0-30 mm. FIG. 8 shows changes in the spring constants Kz, Kx, and KY in this case with the actual value of the opposed surface spacing L1 and the ratio of L1 to the overall dimension L (L1 / L) as the horizontal axis. .
[0045]
  As a result, in the case of L1 = 0 (L1 / L = 0), that is, when an inner cylinder having no concave groove 15 and an outer surface of a substantially prismatic shape is used, the X-direction spring constant Kx is a cylinder. It is considerably larger than the axial Z-direction spring constant Kz and is therefore considerably harder. On the other hand, in the case where the concave groove 15 is provided, the larger the groove width (opposite surface spacing L1), The X-direction spring constant Kx tends to approach the cylindrical axis Z-direction spring constant Kz. Here, even if the groove width L1 is changed to a large value, the value of the cylindrical axis Z-direction spring constant Kz itself hardly changes compared to the case where the concave groove 15 does not exist (L1 = 0). With respect to the external force in the cylinder axis Z direction, the rubber elastic body portion 33 in the concave groove 15 is dead and becomes rubber.
[0046]
  On the other hand, the Y-direction spring constant Ky is shown to decrease as the concave groove 15 is provided and the groove width L1 is increased from the case where the concave groove 15 does not exist (when L1 = 0). This is because, when L1 = 0, the compression length of the rubber elastic body is shortened over the entire cross section of the rubber elastic body by the above-described substantially rectangular cylindrical inner cylinder, and the Y-direction spring constant Ky is large. On the other hand, as the groove 15 is provided and the groove width L1 is increased, the cross-sectional portion where the compression length is shortened is reduced by the amount of the groove 15, and as a result, the Y-direction spring constant is reduced. It is thought that Ky is reduced. That is, it is considered that the Y-direction end face of each overhang portion 12 is also involved in the same increase in the Y-direction spring constant Ky as that of each barrier portion 13. As described above, in the Y-direction spring constant Ky, as the groove width L1 increases, the value decreases while keeping the spring constants Kx and Kz in the other two shear directions larger. From the standpoint of performance, it should be as large as possible, but this will lead to worsening of road noise, which is in line with the performance requirement of reducing the value slightly from the vibration-proof surface.
[0047]
  Note that Kz1, Kz2, Kx1, Kx2, Ky1, and Ky2 in FIG. 8 above are specimens having no concave groove 15 (L1 / L = 0) and having one (L1 / L = 0.7). Are plotted, and the measured values of the spring constants in the cylinder axis Z direction, the X direction, and the Y direction are plotted. The dimensions of each part of this test body are L = 42, t = 15, W = 40, and the rubber hardness Hs of the rubber elastic body 3 is 60 °. The above actual measurements were carried out to confirm the effectiveness of the above analysis, and as a result, the above actual measurements have the same tendency as the analysis results, although there are slight differences in the dimensions of each part of the premise. It was almost consistent.
[0048]
      -Effect of wall thickness 13 of barrier 13-
  FIG. 9 shows the influence of the thickness t of the barrier portion 13 on the three-dimensional spring constants Kz, Kx, and KY. In this analysis, as fixed values, the overall dimension L is set to 40 mm, the overhang dimension W is set to 40 mm, the outer diameter d of the main body cylinder portion is set to 30 mm, and the groove width L1 of the concave groove is set to 30 mm (L1 / L = 0.75). Then, the wall thickness t of the barrier portion 13 was changed in the range of 10 to 20 mm, and the values of the spring constants Kz, Kx, and KY were obtained.
[0049]
  As a result, when the thickness t of the barrier portion 13 increases, the Y-direction spring constant Ky increases correspondingly and changes to a hard one, but the spring constant Kz and the X-direction spring constant Kx do not change and are substantially unchanged. The same value was maintained. That is, this indicates that if the thickness t of the barrier portion 13 is changed and adjusted, only the value of Ky can be tuned independently without changing the values of Kz and Kx. . Therefore, the Y-direction spring constant Ky can be tuned independently without changing the characteristics in the other direction by an easy means of changing the thickness t of the barrier portion 13 without providing any special mechanism. Will be able to.
[0050]
      -Influence of the overhang dimension W of the overhang portion 12-
  FIG. 10 shows the influence of the size of the overhanging dimension W of the overhanging portion 12 on the three-dimensional spring constants Kz, Kx, and KY. In this analysis, as a fixed value, the overall dimension L is 40 mm, the groove width L1 of the concave groove is 30 mm (L1 / L = 0.75), the outer diameter d of the main body cylinder part is 30 mm, and the wall thickness t of the barrier part 13 is Each of the spring constants Kz, Kx, and KY was determined by setting the overhang dimension W in the range of 35 to 42 mm.
[0051]
  As a result, when the value of the overhanging dimension W increases, Kz, Kx, and Ky correspondingly increase and become harder. That is, it is shown that if the value of the overhang dimension W is increased, the spring constants Kz, Kx, Ky in the above three directions can all be hardened with the same tendency.
[0052]
  [Model deformation properties]
  FIGS. 11 to 14 show the rubber elastic body 3 in this analysis model when the outer cylinder 2 is fixed and an external force is applied to the inner cylinder 1 in the cylinder axis Z direction, the X direction, or the Y direction. The shape after deformation is shown.
[0053]
      -Deformation due to external force in X direction-
  11 shows a rubber elastic body portion in the groove 15 in the cross section taken along the line C-C of FIG. 3, that is, the outer peripheral surface of the main body cylindrical portion 11 and the outer surface of each barrier portion 13, and the inner peripheral surface of the outer cylindrical body 2. The rubber elastic body 3 sandwiched between two shapes shows a shape before deformation (shape indicated by a broken line) and a shape after deformation (shape indicated by a solid line) when an external force in the X direction is applied to the inner cylindrical body 1. ing. FIG. 12 shows the shape before deformation when the X-direction external force is applied to the inner cylindrical body 1 with respect to the overhang portion 12 and the rubber elastic body 3 in the cross section taken along the line D-D in FIG. And the shape after deformation | transformation (shape shown as a continuous line) is shown.
[0054]
  According to this, the rubber elastic body 3 in the concave groove 15 in FIG. 11 receives an external force in the X direction, except for the rubber elastic body portion (corresponding to the arc-shaped portion 35 in FIG. 7) in the immediate vicinity of the outer cylindrical body 2, Almost the entire Y-direction dimension y1 from the outer peripheral surface of the main body cylinder portion 11 to the outer cylinder body 2 is deformed. On the other hand, in the rubber elastic body 3 at the position of the overhanging portion 12 in FIG. 12, the dimension in the Y direction that is deformed by receiving an external force in the X direction is shortened to the dimension y2 from the outer surface position of the overhanging portion 12 to the outer cylindrical body 2. . The case of FIG. 12 corresponds to the deformation of the rubber elastic body when the groove 15 does not exist at the cross-sectional position of FIG. 11 and the overhanging portion 12 is continuous in the cylinder axis Z direction. Therefore, in the case where the concave groove 15 is present (in the case of FIG. 11), the rubber elastic body in a longer range is subjected to bending due to the force in the shearing direction as compared with the case where it is not present (in the case of FIG. 12). Kx becomes softer.
[0055]
      -Deformation by external force in the cylinder axis Z direction-
  FIG. 13 shows a shape before deformation (broken line) in the case where an external force in the cylinder axis Z direction (external force upward in FIG. 13) is applied to the inner cylindrical body 1 with respect to the rubber elastic body 3 in the cross section of the lower half of FIG. And a shape after deformation (shape indicated by a solid line).
[0056]
  According to this, the elastic rubber portion 33 (see FIG. 6) in the concave groove 15 hardly deforms even when subjected to the external force in the cylinder axis Z direction, and the range of deformation due to the external force in the cylinder axis Z direction is as described above. The rubber elastic body portion 34 except the rubber elastic body portion 33 is stopped (see FIG. 6). That is, the rubber elastic body portion 33 in the concave groove 15 surrounded by the upper and lower projecting portions 12 and 12 becomes dead rubber against the external force in the cylinder axis Z direction. This is the same as the case where the overhanging portion 12 continues in the cylinder axis Z direction and the concave groove 15 does not exist. Accordingly, the formation of each overhang portion 12 can increase the spring constant with respect to the external force in the cylinder axis Z direction.
[0057]
      -Deformation due to external force in the Y direction-
  FIG. 14 shows a shape before deformation (indicated by a broken line) when an external force is applied to the inner cylindrical body 1 with respect to the rubber elastic body 3 in the vicinity of the intersection between the one overhanging portion 12 and the one side barrier portion 13. The shape shown) and the shape after deformation (shape shown by a solid line) are shown.
[0058]
  According to this, the rubber elastic body portion on the front surface of the barrier portion 13 is swelled and deformed to the side, and the rubber elastic body portion on the front surface of the overhang portion 12 is bulged and deformed considerably upward in response to the Y-direction force. That is, it is shown that the rubber elastic body 3 is further compressed by the presence of the barrier portion 13 and the overhang portion 12, and the spring constant Ky with respect to the external force in the Y direction is increased.
[0059]
<Other aspects>
  In addition, this invention is not limited to the said Example, Other various modifications are included. That is, in the said Example, although the main body cylinder part 11, the both overhang | projection parts 12 and 12, and both the barrier parts 13 and 13 were integrally formed by the same material as the inner cylinder 1, Not limited to this, for example, the metal main body cylinder portion 11 is used as an insert material, and the both overhang portions 12 and 12 and the barrier portions 13 and 13 are mixed with hard resin, for example, nylon 66 with glass fiber (for example, 30). Alternatively, it may be formed integrally by molding using a mixture of about%. This facilitates mass production of inner cylinders having different dimensions according to the performance required for the bushing assembly.
[0060]
  Moreover, in the said Example, although the shape which attached both the overhang | projection parts 12 and 12 and both the barrier parts 13 and 13 with respect to the main body cylinder part 11 was shown as the inner cylinder 1, it is not restricted to this. The cylindrical body may be shaped such that the main body cylindrical portion is completely embedded in the overhanging portion and the barrier portion. For example, as shown in FIG. 15, the through hole 14 is drilled along the axis Z of the cylindrical material to form a main body cylinder portion, and the grooves 15 and 15 are formed on the outer peripheral surface of the intermediate position in the axis Z direction. The inner cylindrical body 1 ′ may be configured such that the overhang portions 12 and 12 are formed at both side positions in the Z direction and the barrier portions 13 and 13 are formed in the X direction. Further, as shown in FIG. 16, by drilling the through hole 14 along the vertical axis Z of the prismatic material to form a main body cylindrical portion, and forming the concave grooves 15, 15 on the outer peripheral surface of the intermediate position in the axis Z direction. The inner cylindrical body 1 ″ may be configured such that the overhang portions 12 and 12 are formed at both side positions in the axis Z direction and the barrier portions 13 and 13 are formed in the X direction.
[0061]
【The invention's effect】
  As described above, according to the bushing assembly of the first aspect of the present invention, since the overhanging portions protrude from the both sides in the cylinder axis direction of the main body tube portion to both sides in the first direction, this pair of overhanging portions. The rubber elastic body portion sandwiched between them can be made dead rubber against an external force from the cylinder axis direction, and the cylinder axis direction spring constant can be increased accordingly. On the other hand, with respect to the external force from the second direction, the external force can be borne by the rubber elastic body portion, and the second direction spring constant can be softened accordingly. Therefore, when the cylindrical outer cylindrical body is used and the end of the rubber elastic body is joined to the inner peripheral surface of the outer cylindrical body which is a circumferential surface, the second tends to be harder than the cylindrical axial spring constant. The directional spring constant can be made equal to or close to the cylindrical axial spring constant by increasing the cylindrical axial spring constant and decreasing the second directional spring constant. Moreover, such a change in the spring characteristic in the cylinder axis direction or the second direction can be easily performed by setting the dimensions of the overhang portion.
[0062]
  On the other hand, for the external force from the first direction, the length in the first direction in which the rubber elastic body is compressed by the thickness in the first direction of the respective barrier portions protruding from the main body cylinder portion on both sides in the second direction is shortened. And since each said barrier part compresses a rubber elastic body effectively, the spring constant with respect to the said 1st direction can be made hard. Accordingly, as the thickness in the first direction of the barrier portion is increased, the first direction spring constant can be made harder, and even if the thickness in the first direction of the barrier portion is changed, Since the rubber elastic body portion that resists external force from the cylinder axis direction and the second direction of the cylinder is hardly affected, both the spring constants in the cylinder axis direction and the second direction are independent of each other in the first direction. The spring constant can be changed and set.
[0063]
  As described above, by using the inner cylinder body having the barrier portion and the overhang portion as in the present invention, the three spring constants for the respective directions of the cylinder axis direction, the second direction, and the first direction can be made independent of each other. Moreover, the setting according to the required performance can be easily performed by changing the dimensions of the barrier portion or the overhang portion. Thereby, for example, the required performance of making the first spring constant of the bushing assembly relatively stiff and making both the spring constants in the cylindrical axis direction and the second direction coincide or approximate each other can be easily realized. be able to.
[0064]
  Since the first direction width of the barrier portion of the inner cylinder is set within the range of the first direction width of the main body cylinder portion, the first direction spring constant is within a range that does not affect the second direction spring constant. Increase can be achieved.
[0065]
  Since each overhang portion of the inner cylinder is provided in the second direction range that is the same as the formation range of each barrier portion, and the shape seen from the cylinder axis direction is formed in a substantially square shape, The end face can be a flat surface extending in the second direction, and the cylinder axis direction spring constant can be increased and the second direction spring constant can be reduced efficiently.
[0066]
  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1,The rubber elastic body has a second direction width set substantially equal to the second direction width of the pair of overhang portions and the pair of barrier portions.For,It is possible to increase the cylinder axis direction spring constant and reduce the second direction spring constant more efficiently and effectively. Also, the increase in the first direction spring constant can be achieved more efficiently and effectively.
[0067]
  Claim3According to the described invention, in addition to the effect of the invention according to the first aspect, each barrier portion of the inner cylindrical body is integrally connected to each overhanging portion on both sides in the cylindrical axis direction. Each of the barrier portions and the overhang portions for separating, forming or switching the rubber elastic body portions that express the respective spring constants in the second direction and the first direction surely act, thereby allowing the rubber elastic body portions to A predetermined thing can be reliably exhibited as a spring constant with respect to each direction.
[0068]
  Claim4According to the invention described above, in addition to the effect of the invention of the first aspect, the inner cylinder body is integrally formed of the same material with the main body cylinder portion, each overhang portion, and the barrier portion. Further, the structural strength of the inner cylinder is increased and the formation process can be rationalized.
[0069]
  Claims5According to the invention described above, in addition to the effect of the invention according to the first aspect, the inner cylindrical body is integrally formed of a material different from that of the main body cylindrical portion with respect to the main body cylindrical portion. Because it is formed, it is easy to mass-produce inner cylinders with the desired dimensions according to the dimensions of the overhangs and barriers that are changed according to the performance required at the site where this bushing assembly is applied. Can be produced.
[0070]
  And claims6According to the described invention, even if the cylindrical outer cylinder is used as it is and the end of the rubber elastic body is joined to the inner circumferential surface that is the circumferential surface of the outer cylinder, the rubber elasticity between the two overhanging portions is obtained. The body part becomes dead rubber against the external force in the cylinder axis direction, but becomes an effective resistance element against the external force in the second direction, so that the increase in the cylinder axis direction spring constant and the reduction in the second direction spring constant are achieved. Thus, the effect of the invention according to claim 1 can be reliably obtained. Thereby, a troublesome process such as forming a thick portion on the inner peripheral surface of the outer cylinder required in the conventional case can be omitted.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a cross-sectional view taken along line BB in FIG.
FIG. 4 is an enlarged perspective view of an inner cylinder.
FIG. 5 is a view corresponding to FIG. 1 and showing a rubber elastic body when receiving an external force in the cylinder axis Z direction.
6 is a view corresponding to FIG. 3 showing a rubber elastic body when an external force in the cylinder axis Z direction is applied.
FIG. 7 is a view corresponding to FIG. 1 and showing a rubber elastic body when receiving an external force in the X direction.
FIG. 8 is a diagram showing the relationship between the overhang portion spacing L1 and the like and the spring constants Kz, Kx, Ky.
FIG. 9 is a relationship diagram between a barrier wall thickness t and each spring constant Kz, Kx, Ky.
FIG. 10 is a diagram showing the relationship between the overhanging portion dimension W and each spring constant Kz, Kx, Ky.
FIG. 11 is an analysis model diagram showing a deformation state of the rubber elastic body at the position of the concave groove when receiving an external force in the X direction.
FIG. 12 is an analysis model diagram showing a deformation state of the rubber elastic body at the position of the overhang portion when receiving an external force in the X direction.
FIG. 13 is an analysis model diagram showing a deformation state of the rubber elastic body when subjected to an external force in a cylinder axis Z direction.
FIG. 14 is an analysis model diagram showing a deformed state of the rubber elastic body when receiving an external force in the Y direction.
FIG. 15 is a perspective view showing another aspect of the inner cylinder.
16 is a perspective view showing another aspect of the inner cylinder different from FIG. 15. FIG.
[Explanation of symbols]
1,1 ', 1 "inner cylinder
2 outer cylinder
3 Rubber elastic body
11 Body cylinder
12 Overhang part
13 Barrier part
14 Through hole
15 concave groove
Z cylinder shaft
XX direction (second direction)
Y Y direction (first direction)

Claims

An inner cylinder, an outer cylinder surrounding the inner cylinder parallel to the cylinder axis of the inner cylinder, and extending from the inner cylinder to both sides in a first direction perpendicular to the cylinder axis. In a bushing assembly comprising a rubber elastic body that connects the outer surface and the inner surface of the outer cylindrical body,
The inner cylinder is
A main body cylinder portion through which the mounting shaft is inserted;
A pair of barrier portions projecting into the rubber elastic body from both sides of the second direction perpendicular to the cylinder axis direction and the first direction from the main body cylindrical portion, and interposed in the rubber elastic body;
A pair of overhanging portions projecting into the rubber elastic body on both sides in the first direction from respective positions on both sides in the cylinder axial direction of the rubber elastic body and separated from each other in the cylinder axial direction of the main body cylinder portion; ,
A pair of concave groove portions that are partitioned between the opposed surfaces of the pair of projecting portions in the first axial direction across the main body cylindrical portion, and a rubber elastic body is disposed;
As for the barrier part of the inner cylinder, the thickness with respect to the first direction is set within the range of the width with respect to the first direction of the main body cylinder part ,
The overhang portions on both sides in the cylinder axis direction of the inner cylinder body are provided over the same second direction range as the formation range of the barrier portion in the second direction, and the shape viewed from the cylinder axis direction is formed in a substantially square shape. A bushing assembly characterized by the above.

In claim 1,
The rubber elastic body has a second direction width set substantially equal to the second direction width of the pair of overhang portions and the pair of barrier portions.
A bushing assembly characterized by that.

In claim 1,
The bushing assembly is characterized in that the barrier portion of the inner cylindrical body is integrally connected to each overhanging portion on both sides in the cylindrical axial direction.

In claim 1,
The inner cylinder includes a main body cylinder part, each overhang part on both sides in the cylinder axis direction, and a barrier part that are integrally formed of the same material.

In claim 1,
The inner cylindrical body, with respect to the main body tube portion, the bushing assembly of each overhang portion of the cylindrical axial sides, and a barrier portion, characterized in that it is constructed integrally formed from a material different from that of the above-mentioned main body tube portion Solid.

In claim 1,
The outer cylinder is formed in a cylindrical shape.