JP3704422B2

JP3704422B2 - Steering bush

Info

Publication number: JP3704422B2
Application number: JP22078597A
Authority: JP
Inventors: 一成中原; 勝敏太田
Original assignee: Kurashiki Kako Co Ltd
Current assignee: Kurashiki Kako Co Ltd
Priority date: 1997-08-01
Filing date: 1997-08-01
Publication date: 2005-10-12
Anticipated expiration: 2017-08-01
Also published as: JPH1148988A

Description

【０００１】
【発明の属する技術分野】
本発明は、自動車のステアリング装置において振動吸収のために装備されるステアリングブッシュに関する。
【０００２】
【従来の技術】
従来、自動車のステアリング装置においては、路面側からステアリングシャフトを介してステアリングホイールに伝達される振動を吸収するための種々のものが提案され、実用化されており、以下にその代表的な３種類のものについて説明する。
【０００３】
第１のものは、例えば実開昭６２−１０４０２４号公報に開示されるように、ステアリングシャフト系の軸部材と該軸部材に遊嵌する管状部材との間に介設されるステアリングブッシュである。この種のブッシュは、軸部材の外周面又は軸部材が貫通する内筒の外周面と管状部材内に嵌着される外筒の内周面との間にラバーブッシュを充填し、かつ該ラバーブッシュを軸部材又は内筒の外周面及び外筒の内周面にそれぞれ固着してなる。
【０００４】
第２のものは、例えば特公平７−１１２９２号公報に開示されるように、ステアリングシャフト系の二つの軸部材同士の間に介設されるステアリングラバーカップリングである。この種のラバーカップリングは、一般的には補強帯を埋設したラバーからなる盤体と、該盤体の軸芯周りに保持された偶数個の取付け具とで構成され、使用時には上記偶数個の取付け具のうち、盤体の軸芯周りに一つ置きのものを一方の軸部材に取り付け、残りのものを他方の軸部材に取り付けるようになっている（上記例示の公報の第６図及び第７図参照）。
【０００５】
第３のものは、例えば実開昭５６−１５２７７１号公報に開示されるように、ステアリングシャフト自体に振動吸収機能を待たせた振動吸収ステアリングシャフトである。この種のシャフトは、断面太鼓形の嵌合孔を内腔に有する管軸と、該管軸の嵌合孔よりも適宜小さい断面太鼓形に形成されかつ嵌合孔に挿通される中実軸と、該中実軸の外周面と上記管軸の嵌合孔の内周面との間に充填されかつそれらの面にそれぞれ固着されたラバーブッシュとで構成されている。
【０００６】
【発明が解決しようとする課題】
ところで、ステアリング装置の振動吸収手段としては、振動吸収性と操舵安定性とを両立させる必要があるために、軸方向のばね定数を小さくし、捩り方向のばね定数を大きくすることが望ましい。
【０００７】
しかるに、上記従来のステアリングブッシュでは、ラバーブッシュの硬さにより軸方向のばね定数と捩り方向のばね定数とが共に定まり、両ばね定数の比を適宜設定することができない。
【０００８】
これに対し、ラバーカップリングでは、上記例示の公報（特公平７−１１２９２号）に開示するように、盤体を樹脂や金属等の剛性を有する材質で形成する一方、該盤体の各取付け具を保持する貫通孔の内周面と各取付け具の外周面と間に弾性スリーブを介設することにより、軸方向のばね定数を小さくし、捩り方向のばね定数を大きくすることができる。しかし、この場合、部品点数が多くなり、コストが高くなるという問題がある。また、ラバーカップリングは径が比較的大きなものであるため、その配置に関し制約を受け、汎用性に欠けるという問題もある。
【０００９】
また、振動吸収ステアリングシャフトでは、管軸の嵌合孔及び中実軸の断面形状が太鼓形であり、操舵力等が作用したときの両軸の軸回りの相対的変位が規制されることから、その両軸間に充填されるラバーブッシュの硬さを低くして軸方向のばね定数を小さくした場合でも操舵力等が作用したときの捩り方向のばね定数を大きくすることができる。しかし、操舵力等が作用して両軸の軸回りの相対的変位が規制されているとき、つまり中実軸の外周面と管軸の嵌合孔の内周面とがその間のラバーブッシュを圧縮して互いに押圧し合っているときには、ラバーブッシュの弾性変形が抑制されるため、軸方向のばね定数が大きくなり、振動吸収機能が損なわれる欠点がある。
【００１０】
本発明はかかる諸点に鑑みてなされたものであり、その課題とするところは、特に従来のステアリングブッシュの利点つまりコンパクトで汎用性に優れた点を維持しつつ、その軸方向のばね定数を小さく、捩り方向のばね定数を大きくし得るようにして、振動吸収性と操舵安定性との両立を図ることができ、また操舵力等が作用しているときでも軸方向のばね定数が大きくなるのを防止して振動吸収性を良好に維持し得るステアリングブッシュを提供するものである。
【００１１】
【課題を解決するための手段】
上記の課題を解決するため、請求項１に係る発明は、ステアリングホイールの操舵力をステアリングギヤボックスに伝達するステアリングシャフト系の軸部材と該軸部材に遊嵌する管状部材との間に介設されるステアリングブッシュとして、上記軸部材が貫通し該軸部材と結合される内筒と、該内筒の外周に同心状に配置されかつ上記管状部材内に嵌着される外筒と、上記内筒と外筒との間でこれら両筒と同心状に配置されかつ軸方向の長さが内筒及び外筒のそれよりも短い中間筒と、少なくとも上記中間筒の外周面と外筒の内周面との間及び中間筒が存在しない軸方向の位置における内筒の外周面と外筒の内周面との間に充填されかつそれらの面にそれぞれ固着されたラバーブッシュとを備える構成とする。また、上記中間筒の内周面と内筒の外周面とを、円周方向全周に亘って該両筒の軸方向の相対的変位を許容し得る略一定の隙間を隔てて近接して対向させるとともに、両筒の軸回りの相対的変位を規制するように断面の輪郭を真円以外の形状に形成する。
【００１２】
これにより、ステアリングブッシュに対し軸方向の振動が入力するとき、つまり内筒と外筒との間で軸方向の相対的変位が生じるときには、内筒と中間筒との間の軸方向の相対的変位が許容されることから、ラバーブッシュのうち、内筒の外周面と外筒の内周面との間に充填された部分のみが弾性変形を生じることになり、その結果、軸方向のばね定数は小さく、振動が効果的に吸収される。一方、ステアリングブッシュに対し操舵力等の捩り力が入力するとき、つまり内筒と外筒との間で軸回りの相対的変位が生じるときには、内筒と中間筒との間の軸回りの相対的変位が規制され、両筒が一体となって外筒に対し軸回りに相対変位することから、ラバーブッシュは、内筒の外周面と外筒の内周面との間に充填された部分のみならず中間筒の外周面と外筒の内周面との間に充填された部分も弾性変形を生じることになり、その結果、捩り方向のばね定数は大きく、操舵力等の伝達が確実にかつ迅速に行われて操舵安定性が良好なものとなる。しかも、操舵力等の捩り力が入力しているときでも、内筒の外周面と外筒の内周面との間の間隔が変化することはないので、その間のラバーブッシュの弾性変形により軸方向のばね定数は小さいままであり、振動吸収性は良好に維持される。さらに、ステアリングブッシュは、ステアリングシャフト系の軸部材と該軸部材に遊嵌する管状部材との間に介設されるコンパクトなもので、他の部品の配置レイアウトを変更することなく使用することができ、汎用性に優れる。ここで、ステアリングシャフト系とは、ステアリングホイールとステアリングギヤボックスとの間の一連の部材を意味し、ステアリングギヤボックスの軸部材等も含む。
【００１３】
請求項２に係る発明は、請求項１記載のステアリングブッシュにおいて、上記中間筒の内周面と内筒の外周面との間にもラバーブッシュを充填する構成とする。これにより、中間筒と内筒とが直接接触することはなく、騒音の発生が防止される。但し、この場合、ラバーブッシュは中間筒の内周面と内筒の外周面の両方に固着されるものではない。
【００１４】
【発明の実施の形態】
以下、本発明の実施の形態を図面に基づいて説明する。
【００１５】
図１ないし図３は本発明の第１の実施形態に係わるステアリングブッシュＡを示す。ステアリングブッシュＡは、図示していないがステアリングホイールの操舵力をステアリングギヤボックスに伝達するステアリングシャフト系の軸部材と該軸部材が遊嵌する管状部材との間に介設されるものであり、その大きさは、車種や介設される個所により異なるが、通常は外径が３２〜３５mm、軸方向長さが２５mm程度である。
【００１６】
上記ステアリングブッシュＡは、中空円筒状の内筒１と、該内筒１の外周に同心状に配置されかつ軸方向の長さが内筒１のそれと同一である中空円筒状の外筒２と、上記内筒１と外筒２との間でこれら両筒１，２と同心状に配置されかつ軸方向の長さが内筒１及び外筒２のそれよりも短い中空円筒状の中間筒３と、これら三つの筒１〜３の間つまり中間筒３が存在しない軸方向の位置における内筒１の外周面と外筒２の内周面との間、中間筒３の外周面と外筒２の内周面との間及び内筒１の外周面と中間筒３の内周面との間に充填されたラバーブッシュ４とからなる。上記内筒１、外筒２及び中間筒３はいずれも鉄鋼等の金属又は樹脂からなり、内筒１はその中空内をステアリングシャフト系の軸部材が貫通し該軸部材と結合され、外筒２はステアリングシャフト系の管状部材に嵌着される。上記ラバーブッシュ４は内筒１の外周面、外筒２の内周面及び中間筒３の外周面にそれぞれ接着剤により固着されているが、中間筒３の内周面には固着されていない。尚、以下の説明では、ラバーブッシュ４のうち、中間筒３が存在しない軸方向の位置における内筒１の外周面と外筒２の内周面との間に充填された部分を４ａ、中間筒３の外周面と外筒２の内周面との間に充填された部分を４ｂ、内筒１の外周面と中間筒３の内周面との間に充填された部分を４ｃとして区別して説明する。
【００１７】
上記中間筒３の内周面と内筒１の外周面とは、円周方向全周に亘って該両筒１，３の軸方向の相対的変位を許容し得る略一定（具体的には０．２〜１．０mm）の隙間ｅを隔てて近接して対向しているとともに、両筒１，３の軸回りの相対的変位を規制するように断面の輪郭が略楕円形状に形成されている。内筒１の内周面、中間筒３の外周面、外筒２の内周面及び外周面はいずれも断面の輪郭が真円形状に形成されている。
【００１８】
次に、上記第１の実施形態の作用・効果について説明するに、ステアリングブッシュＡに対し軸方向の振動が入力するとき、つまり内筒１と外筒２との間で軸方向の相対的変位が生じるときには、内筒１と中間筒３との間に軸方向の相対的変位を許容し得る隙間ｅが形成され、かつその隙間ｅに充填されたラバーブッシュ４ｃは内筒１の外周面に固着されているが中間筒３の内周面には固着されていないので、ラバーブッシュ４のうち、内筒１の外周面と外筒２の内周面との間に充填された部分４ａのみが弾性変形を生じることになる。その結果、ステアリングブッシュＡにおける軸方向のばね定数は小さく、自動車の加速時及び悪路走行時におけるステアリングシャフト方向の振動を効果的に吸収することができる。
【００１９】
一方、ステアリングブッシュＡに対し捩り力が入力するとき、つまり内筒１と外筒２との間で軸回りの相対的変位が生じるときには、内筒１の外周面及び中間筒３の内周面は、その間の隙間ｅが極僅かでありかつ断面の輪郭が真円以外の略楕円形状に形成されているため、両筒１，３の軸回りの相対的変位が規制され、両筒１，３が一体となって外筒２に対し軸回りに相対変位する。そのため、ラバーブッシュ４は、内筒１の外周面と外筒２の内周面との間に充填された部分４ａのみならず中間筒３の外周面と外筒２の内周面との間に充填された部分４ｂも弾性変形を生じることになり、ステアリングブッシュＡにおける捩り方向のばね定数は大きくなる。その結果、ステアリングホイールの操舵力がステアリングギヤボックス側に迅速かつ確実に伝達され、また操舵輪に外力が作用したときステアリングブッシュＡの軸回りの弾性変形に起因して操舵輪が操舵方向に変位するのを防止することができ、操舵安定性を高めることができる。
【００２０】
その上、ステアリングブッシュＡにおける軸方向のばね定数と捩り方向のばね定数との比は、中間筒３の外周面と外筒２の内周面との間に充填されたラバーブッシュ４ｂの長さ（つまり中間筒３の軸方向長さ）及び肉厚（つまり中間筒３の外周面と外筒２の内周面との間の間隔）によって容易にかつ適切に調節することができる。また、ステアリングブッシュＡに操舵力等の捩り力が入力しているときでも、内筒１の外周面と外筒２の内周面との間の間隔が変化することはないので、その間のラバーブッシュ４ａの弾性変形により軸方向のばね定数は小さいままであり、振動吸収性を良好に維持できる。さらに、上記中間筒３の内周面と内筒１の外周面との間にラバーブッシュ４ｃが充填されているため、捩り力が入力しているときでも該両筒１，３が直接接触することはなく、騒音の発生を防止することができる。
【００２１】
加えて、ステアリングブッシュＡは、ステアリングシャフト系の軸部材と該軸部材に遊嵌する管状部材との間に介設されるコンパクトなもので、他の部品の配置レイアウトを変更することなく使用することができるので、小型車等にも適用することができ、汎用性に優れる。
【００２２】
尚、上記第１の実施形態では、内筒１と中間筒３との軸回りの相対的変位を規制するために、内筒１の外周面及び中間筒３の内周面を、断面の輪郭が略楕円形状になるように形成したが、本発明は、これらの断面の輪郭を真円以外の形状にすればよく、図４ないし図６はそれぞれ別の実施形態を示す。
【００２３】
すなわち、図４に示す第２の実施形態では、中間筒３の内周面には軸芯を挟んで対向する２個所にそれぞれ半径方向外方に凹陥してなる凹部５，５が形成され、内筒１の外周面には該凹部５,５に対応して半径方向外方に突出する凸部６，６が形成されている。図５に示す第３の実施形態では、内筒１の外周面及び中間筒３の内周面は、円周方向に凹部と凸部を交互に形成して断面の輪郭が波を打った形状に形成されている。図６に示す第４の実施形態では、内筒１の外周面及び中間筒３の内周面は、軸芯に対称な二つの円弧面と二つの平坦面とからなる断面の輪郭が太鼓形に形成されている。尚、第２〜第４の実施形態の場合、いずれもステアリングブッシュＡのその他の構成は、第１の実施形態のそれと同じであり、同一部材には同一符号を付してその説明は省略する。
【００２４】
そして、上記第２〜第４のいずれの実施形態においても、第１の実施形態の場合と同様の作用効果を奏することができるのは勿論である。
【００２５】
また、上記第１〜第４の実施形態では、ステアリングブッシュＡの製造方法としては、内筒１の外周面、外筒２の内周面及び中間筒３の外周面にそれぞれ接着剤を塗布し、これらを成形型内に所定状態でセットした後、型閉じをし溶融したラバー材料を型内に注入するいわゆる一体成形法が用いられるが、図７に示す第５の実施形態では、ステアリングブッシュＢの製造方法は、別体成形と圧入とを用いてなる。
【００２６】
すなわち、上記ステアリングブッシュＢは、中空円筒状の内筒１１と、該内筒１１の外周に同心状に配置されかつ軸方向の長さが内筒１１のそれと同一である中空円筒状の外筒１２と、上記内筒１１と外筒１２との間でこれら両筒１１，１２と同心状に配置されかつ軸方向の長さが内筒１１及び外筒１２のそれよりも短い中空円筒状の中間筒１３と、上記外筒１２の内周面に外周面が接触した状態で該外筒１２と中間筒１３との間に配置されかつ軸方向の長さが中間筒１３のそれと同一である中空円筒状のシールスリーブ１４と、上記中間筒１３及びシールスリーブ１４が存在しない軸方向の位置における内筒１１の外周面と外筒１２の内周面との間に充填されかつそれらの面にそれぞれ固着された第１のラバーブッシュ１５と、上記中間筒１３の外周面とシールスリーブ１４の内周面との間に充填されかつそれらの面にそれぞれ固着された第２のラバーブッシュ１６とからなる。
【００２７】
上記中間筒１３の内周面と内筒１１の外周面とは、第１の実施形態の場合と同様に、円周方向全周に亘って該両筒１１，１３の軸方向の相対的変位を許容し得る略一定の隙間ｅを隔てて近接して対向しているとともに、両筒１１，１３の軸回りの相対的変位を規制するように断面の輪郭が真円以外の形状、例えば第１の実施形態の如く楕円形状等に形成されている。但し、中間筒１３の内周面と内筒１１の外周面との間には、第１の実施形態の場合のようにラバーブッシュは充填されていない。尚、図７中、Ｃ．Ｌ．はステアリングブッシュＢの中心線であり、図ではステアリングブッシュＢの下半分を省略している。
【００２８】
そして、ステアリングブッシュＢの製造方法としては、先ず、内筒１１の外周面と外筒１２の内周面との間に第１のラバーブッシュ１５を充填してなる第１の組体を一体成形法により形成する。続いて、中間筒１３の外周面とシールスリーブ１４の内周面との間に第２のラバーブッシュ１６を充填してなる第２の組体を同じく一体成形法により形成する。しかる後、上記第１の組体における内筒１１の外周面と外筒１２の内周面との間で第１のラバーブッシュ１５が存在しない空間内に、上記第２の組体を圧入し、以上によって、ステアリングブッシュＢが製造される。
【００２９】
図８は本発明のステアリングブッシュ及び従来技術１〜３について、それぞれ捩り方向の静ばね定数と軸方向の静ばね定数との関係を示す特性図であり、図９は本発明のステアリングブッシュ及び従来技術１，２について、それぞれ捩り方向の動ばね定数と軸方向の動ばね定数との関係を示す特性図である。ここで、従来技術１は従来の技術の項で述べたステアリングブッシュに属するものであり、従来技術２は同じくステアリングラバーカップリングに属するものであり、従来技術３は同じく振動吸収ステアリングシャフトに属するものである。
【００３０】
図８及び図９から分かるように、本発明のステアリングブッシュは、従来のステアリングブッシュ及び振動吸収ステアリングシャフトに比べて、軸方向のばね定数（Ｋ１）と捩り方向のばね定数（Ｋ２）との比（Ｋ１／Ｋ２）が小さく、ステアリングラバーカップリングのそれに近い値となる。
【００３１】
図１０は本発明のステアリングブッシュＡ，Ｂのうち、内筒１，１１の外周面と中間筒３，１３の内周面との間の隙間ｅの異なる２種類のものについて、捩り角度と捩りトルクとの関係を示す特性図であり、図中実線は上記隙間ｅが大きいものの特性線を示し、破線は隙間ｅが小さいものの特性線を示す。この図からは、捩り角度が小さい範囲で生じるリニア領域（捩りトルクが殆どゼロの領域）Ｒ１，Ｒ２（Ｒ１＞Ｒ２）が内筒１，１１の外周面と中間筒３，１３の内周面との間の隙間ｅに応じて変化することが分かる。
【００３２】
【発明の効果】
以上のように、本発明のステアリングブッシュによれば、ブッシュ本来のコンパクトで汎用性に優れるという利点を有しながら、軸方向のばね定数を小さくし、捩り方向のばね定数を大きくすることができるので、振動吸収性と操舵安定性との両立を有効に図ることができる。しかも、操舵力等が作用しているときでも軸方向のばね定数が変化することはなく、振動吸収性を良好に維持することができる。
【００３３】
特に、請求項２に係る発明では、中間筒と内筒との接触による騒音の発生を防止できるという効果をも併有する。
【図面の簡単な説明】
【図１】本発明の第１の実施形態に係るステアリングブッシュの一部を切開した側面図である。
【図２】図１のＸ−Ｘ線における断面図である。
【図３】図１のＹ−Ｙ線における断面図である。
【図４】本発明の第２の実施形態を示す図３相当図である。
【図５】同じく第３の実施形態を示す図３相当図である。
【図６】同じく第４の実施形態を示す図３相当図である。
【図７】本発明の第５の実施形態に係るステアリングブッシュの縦断側面図である。
【図８】本発明のステアリングブッシュ及び従来技術についての捩り方向の静ばね定数と軸方向の静ばね定数との関係を示す特性図である。
【図９】同じく捩り方向の動ばね定数と軸方向の動ばね定数との関係を示す特性図である。
【図１０】本発明のステアリングブッシュにおける捩り角度と捩りトルクとの関係を示す特性図である。
【符号の説明】
Ａ，Ｂステアリングブッシュ
１，１１内筒
２，１２外筒
３，１３中間筒
４，１５，１６ラバーブッシュ
ｅ隙間[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steering bush provided for vibration absorption in an automobile steering device.
[0002]
[Prior art]
Conventionally, various automobile steering devices for absorbing vibration transmitted from the road surface side to the steering wheel via the steering shaft have been proposed and put into practical use. Will be described.
[0003]
The first one is a steering bush interposed between a shaft member of a steering shaft system and a tubular member loosely fitted to the shaft member as disclosed in, for example, Japanese Utility Model Publication No. 62-104024. . In this type of bush, a rubber bush is filled between the outer peripheral surface of the shaft member or the outer peripheral surface of the inner cylinder through which the shaft member passes and the inner peripheral surface of the outer cylinder fitted into the tubular member, and the rubber The bush is fixed to the outer peripheral surface of the shaft member or the inner cylinder and the inner peripheral surface of the outer cylinder.
[0004]
The second one is a steering rubber coupling interposed between two shaft members of a steering shaft system, as disclosed in, for example, Japanese Patent Publication No. 7-11292. This type of rubber coupling is generally composed of a disc body made of rubber with an embedded reinforcing band and an even number of fixtures held around the axis of the disc body. Of these attachments, every other one around the axis of the panel is attached to one shaft member, and the remaining ones are attached to the other shaft member (FIG. 6 of the above-mentioned publication). And FIG. 7).
[0005]
The third one is a vibration absorbing steering shaft in which the steering shaft itself waits for a vibration absorbing function, as disclosed in, for example, Japanese Utility Model Publication No. 56-152771. This type of shaft includes a tube shaft having a drum-shaped fitting hole in its inner cavity, and a solid shaft that is formed in a drum shape that is appropriately smaller than the fitting hole of the tube shaft and is inserted into the fitting hole. And a rubber bush filled between the outer peripheral surface of the solid shaft and the inner peripheral surface of the fitting hole of the tube shaft and fixed to each of the surfaces.
[0006]
[Problems to be solved by the invention]
By the way, as the vibration absorbing means of the steering device, since it is necessary to achieve both vibration absorption and steering stability, it is desirable to reduce the spring constant in the axial direction and increase the spring constant in the torsion direction.
[0007]
However, in the above-described conventional steering bush, both the spring constant in the axial direction and the spring constant in the torsional direction are determined depending on the hardness of the rubber bush, and the ratio between the two spring constants cannot be set as appropriate.
[0008]
On the other hand, in the rubber coupling, as disclosed in the above-mentioned official gazette (Japanese Patent Publication No. 7-11292), the panel body is formed of a material having rigidity such as resin or metal, and each mounting of the panel body is performed. By inserting an elastic sleeve between the inner peripheral surface of the through hole holding the tool and the outer peripheral surface of each fixture, the spring constant in the axial direction can be reduced and the spring constant in the torsional direction can be increased. However, in this case, there is a problem that the number of parts increases and the cost increases. In addition, since the rubber coupling has a relatively large diameter, there is a problem that the arrangement is restricted and the versatility is lacking.
[0009]
Further, in the vibration absorbing steering shaft, the fitting shape of the tube shaft and the cross-sectional shape of the solid shaft are drum-shaped, and the relative displacement around the shafts of both shafts when the steering force is applied is restricted. Even when the hardness of the rubber bush filled between the two shafts is lowered to reduce the spring constant in the axial direction, the spring constant in the torsional direction when a steering force or the like is applied can be increased. However, when the relative displacement about the axis of both shafts is restricted by the action of the steering force, etc., that is, the outer peripheral surface of the solid shaft and the inner peripheral surface of the fitting hole of the pipe shaft are When compressed and pressed against each other, elastic deformation of the rubber bushing is suppressed, so that the spring constant in the axial direction increases and the vibration absorbing function is impaired.
[0010]
The present invention has been made in view of such various points, and the object of the present invention is to reduce the axial spring constant while maintaining the advantage of the conventional steering bush, that is, the compact and excellent versatility. The torsional spring constant can be increased to achieve both vibration absorption and steering stability, and the axial spring constant increases even when steering force is applied. And a steering bush that can maintain good vibration absorption.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is provided between a shaft member of a steering shaft system that transmits a steering force of a steering wheel to a steering gear box and a tubular member loosely fitted to the shaft member. An inner cylinder through which the shaft member penetrates and is coupled to the shaft member; an outer cylinder that is concentrically disposed on the outer periphery of the inner cylinder and fitted into the tubular member; An intermediate cylinder that is concentrically disposed between the cylinder and the outer cylinder and has an axial length shorter than that of the inner cylinder and the outer cylinder, and at least the outer peripheral surface of the intermediate cylinder and the inner cylinder A rubber bush that is filled between the outer peripheral surface of the inner cylinder and the inner peripheral surface of the outer cylinder at a position in the axial direction between the peripheral surface and in the absence of the intermediate cylinder, and is fixed to each of the surfaces. To do. Further, the inner peripheral surface of the intermediate cylinder and the outer peripheral surface of the inner cylinder are brought close to each other with a substantially constant gap that allows the relative displacement in the axial direction of both cylinders over the entire circumference. The contour of the cross section is formed in a shape other than a perfect circle so as to oppose each other and restrict relative displacement around the axis of both cylinders.
[0012]
Thereby, when axial vibration is input to the steering bush, that is, when relative displacement in the axial direction occurs between the inner cylinder and the outer cylinder, relative axial movement between the inner cylinder and the intermediate cylinder is caused. Since the displacement is allowed, only the portion of the rubber bush filled between the outer peripheral surface of the inner cylinder and the inner peripheral surface of the outer cylinder is elastically deformed. As a result, the axial spring The constant is small and vibrations are effectively absorbed. On the other hand, when a torsional force such as a steering force is input to the steering bush, that is, when relative displacement about the axis occurs between the inner cylinder and the outer cylinder, the relative rotation about the axis between the inner cylinder and the intermediate cylinder The rubber bush is a portion filled between the outer peripheral surface of the inner cylinder and the inner peripheral surface of the outer cylinder because the two cylinders are integrated and relatively displaced about the axis relative to the outer cylinder. In addition to this, the portion filled between the outer peripheral surface of the intermediate cylinder and the inner peripheral surface of the outer cylinder also undergoes elastic deformation. As a result, the spring constant in the torsion direction is large, and transmission of steering force and the like is ensured. And the steering stability is good. In addition, even when a torsional force such as a steering force is input, the distance between the outer peripheral surface of the inner cylinder and the inner peripheral surface of the outer cylinder does not change. The spring constant in the direction remains small and the vibration absorption is well maintained. Furthermore, the steering bush is a compact one interposed between a shaft member of the steering shaft system and a tubular member loosely fitted to the shaft member, and can be used without changing the layout of other components. And versatility. Here, the steering shaft system means a series of members between the steering wheel and the steering gear box, and includes a shaft member of the steering gear box and the like.
[0013]
According to a second aspect of the present invention, in the steering bush according to the first aspect, a rubber bush is also filled between the inner peripheral surface of the intermediate cylinder and the outer peripheral surface of the inner cylinder. As a result, the intermediate cylinder and the inner cylinder are not in direct contact with each other, and the generation of noise is prevented. However, in this case, the rubber bush is not fixed to both the inner peripheral surface of the intermediate cylinder and the outer peripheral surface of the inner cylinder.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0015]
1 to 3 show a steering bush A according to a first embodiment of the present invention. Although not shown, the steering bush A is interposed between a shaft member of a steering shaft system that transmits the steering force of the steering wheel to the steering gear box and a tubular member in which the shaft member is loosely fitted. The size varies depending on the type of vehicle and the location where it is installed, but usually the outer diameter is 32 to 35 mm and the axial length is about 25 mm.
[0016]
The steering bush A includes a hollow cylindrical inner cylinder 1 and a hollow cylindrical outer cylinder 2 that is disposed concentrically on the outer periphery of the inner cylinder 1 and has an axial length identical to that of the inner cylinder 1. A hollow cylindrical intermediate cylinder disposed concentrically with the cylinders 1 and 2 between the inner cylinder 1 and the outer cylinder 2 and having an axial length shorter than that of the inner cylinder 1 and the outer cylinder 2 3 and between the three cylinders 1 to 3, that is, between the outer peripheral surface of the inner cylinder 1 and the inner peripheral surface of the outer cylinder 2 at an axial position where the intermediate cylinder 3 does not exist, and between the outer peripheral surface of the intermediate cylinder 3 and the outer The rubber bush 4 is filled between the inner peripheral surface of the tube 2 and between the outer peripheral surface of the inner tube 1 and the inner peripheral surface of the intermediate tube 3. The inner cylinder 1, the outer cylinder 2 and the intermediate cylinder 3 are all made of a metal such as steel or resin, and the inner cylinder 1 is coupled with the shaft member through the shaft member of the steering shaft system through the hollow. 2 is fitted to the tubular member of the steering shaft system. The rubber bush 4 is fixed to the outer peripheral surface of the inner cylinder 1, the inner peripheral surface of the outer cylinder 2, and the outer peripheral surface of the intermediate cylinder 3 with an adhesive, but is not fixed to the inner peripheral surface of the intermediate cylinder 3. . In the following description, a portion of the rubber bush 4 filled between the outer peripheral surface of the inner cylinder 1 and the inner peripheral surface of the outer cylinder 2 at an axial position where the intermediate cylinder 3 does not exist is indicated as 4a. A portion filled between the outer peripheral surface of the cylinder 3 and the inner peripheral surface of the outer tube 2 is defined as 4b, and a portion filled between the outer peripheral surface of the inner tube 1 and the inner peripheral surface of the intermediate tube 3 is defined as 4c. It explains separately.
[0017]
The inner circumferential surface of the intermediate cylinder 3 and the outer circumferential surface of the inner cylinder 1 are substantially constant (specifically, the axial displacement of both the cylinders 1 and 3 can be allowed over the entire circumference in the circumferential direction. 0.2 to 1.0 mm), and the cross-sectional outline is formed in a substantially elliptical shape so as to restrict the relative displacement around the axes of the cylinders 1 and 3. ing. The inner peripheral surface of the inner cylinder 1, the outer peripheral surface of the intermediate cylinder 3, and the inner peripheral surface and outer peripheral surface of the outer cylinder 2 are all formed in a perfect circle shape in cross section.
[0018]
Next, the operation and effect of the first embodiment will be described. When axial vibration is input to the steering bush A, that is, relative displacement between the inner cylinder 1 and the outer cylinder 2 in the axial direction. Is formed between the inner cylinder 1 and the intermediate cylinder 3, and a rubber bush 4 c filled in the gap e is formed on the outer peripheral surface of the inner cylinder 1. Since it is fixed but not fixed to the inner peripheral surface of the intermediate cylinder 3, only the portion 4a of the rubber bush 4 filled between the outer peripheral surface of the inner cylinder 1 and the inner peripheral surface of the outer cylinder 2 is used. Will cause elastic deformation. As a result, the axial spring constant of the steering bush A is small, and vibrations in the steering shaft direction when the vehicle is accelerating and traveling on rough roads can be effectively absorbed.
[0019]
On the other hand, when a torsional force is input to the steering bush A, that is, when a relative displacement around the axis occurs between the inner cylinder 1 and the outer cylinder 2, the outer peripheral surface of the inner cylinder 1 and the inner peripheral surface of the intermediate cylinder 3 Since the gap e between them is very small and the cross-sectional outline is formed in a substantially elliptical shape other than a perfect circle, the relative displacement around the axis of both cylinders 1 and 3 is restricted, and both cylinders 1 and 1 are restricted. 3 is integrally displaced relative to the outer cylinder 2 around the axis. Therefore, the rubber bush 4 is not only between the outer peripheral surface of the inner cylinder 1 and the inner peripheral surface of the outer cylinder 2 but also between the outer peripheral surface of the intermediate cylinder 3 and the inner peripheral surface of the outer cylinder 2. The portion 4b filled in the cylinder also undergoes elastic deformation, and the spring constant of the steering bush A in the torsion direction increases. As a result, the steering force of the steering wheel is quickly and reliably transmitted to the steering gear box, and when an external force is applied to the steering wheel, the steering wheel is displaced in the steering direction due to elastic deformation around the axis of the steering bush A. Can be prevented, and the steering stability can be improved.
[0020]
In addition, the ratio of the spring constant in the axial direction to the spring constant in the torsional direction in the steering bush A is such that the length of the rubber bush 4 b filled between the outer peripheral surface of the intermediate cylinder 3 and the inner peripheral surface of the outer cylinder 2. (That is, the axial length of the intermediate cylinder 3) and the thickness (that is, the distance between the outer peripheral surface of the intermediate cylinder 3 and the inner peripheral surface of the outer cylinder 2) can be easily and appropriately adjusted. Even when a torsional force such as a steering force is input to the steering bush A, the distance between the outer peripheral surface of the inner cylinder 1 and the inner peripheral surface of the outer cylinder 2 does not change. Due to the elastic deformation of the bush 4a, the spring constant in the axial direction remains small, and the vibration absorption can be maintained well. Further, since the rubber bush 4c is filled between the inner peripheral surface of the intermediate tube 3 and the outer peripheral surface of the inner tube 1, both the tubes 1 and 3 are in direct contact even when a torsional force is input. This can prevent the generation of noise.
[0021]
In addition, the steering bush A is a compact one interposed between a shaft member of the steering shaft system and a tubular member loosely fitted to the shaft member, and is used without changing the layout of other components. Therefore, it can be applied to a small car or the like, and is excellent in versatility.
[0022]
In the first embodiment, the outer peripheral surface of the inner cylinder 1 and the inner peripheral surface of the intermediate cylinder 3 are contoured in cross section in order to regulate the relative displacement of the inner cylinder 1 and the intermediate cylinder 3 around the axis. However, in the present invention, the outline of these cross sections may be a shape other than a perfect circle, and FIGS. 4 to 6 show different embodiments.
[0023]
That is, in the second embodiment shown in FIG. 4, recesses 5 and 5 are formed on the inner peripheral surface of the intermediate cylinder 3, which are respectively recessed outward in the radial direction at two opposing positions across the axis. Convex portions 6 and 6 projecting outward in the radial direction are formed on the outer peripheral surface of the inner cylinder 1 corresponding to the concave portions 5 and 5. In the third embodiment shown in FIG. 5, the outer peripheral surface of the inner cylinder 1 and the inner peripheral surface of the intermediate cylinder 3 are formed in such a manner that the concave and convex portions are alternately formed in the circumferential direction and the profile of the cross section is waved. Is formed. In the fourth embodiment shown in FIG. 6, the outer peripheral surface of the inner cylinder 1 and the inner peripheral surface of the intermediate cylinder 3 have a drum-shaped cross section consisting of two arc surfaces symmetrical to the axis and two flat surfaces. Is formed. In the second to fourth embodiments, the other configuration of the steering bush A is the same as that of the first embodiment, and the same members are denoted by the same reference numerals and the description thereof is omitted. .
[0024]
In any of the second to fourth embodiments, it is needless to say that the same effects as those of the first embodiment can be obtained.
[0025]
In the first to fourth embodiments, the steering bush A is manufactured by applying an adhesive to the outer peripheral surface of the inner cylinder 1, the inner peripheral surface of the outer cylinder 2, and the outer peripheral surface of the intermediate cylinder 3. A so-called integral molding method is used in which these are set in a mold in a predetermined state, and then the mold is closed and a molten rubber material is injected into the mold. In the fifth embodiment shown in FIG. The manufacturing method of B uses separate molding and press-fitting.
[0026]
That is, the steering bush B includes a hollow cylindrical inner cylinder 11 and a hollow cylindrical outer cylinder that is arranged concentrically on the outer periphery of the inner cylinder 11 and has the same axial length as that of the inner cylinder 11. 12 and the inner cylinder 11 and the outer cylinder 12 are arranged concentrically with both the cylinders 11 and 12 and have a hollow cylindrical shape whose axial length is shorter than that of the inner cylinder 11 and the outer cylinder 12. The intermediate cylinder 13 is disposed between the outer cylinder 12 and the intermediate cylinder 13 with the outer peripheral surface being in contact with the inner peripheral surface of the outer cylinder 12, and the axial length is the same as that of the intermediate cylinder 13. A hollow cylindrical seal sleeve 14 is filled between the outer peripheral surface of the inner cylinder 11 and the inner peripheral surface of the outer cylinder 12 at an axial position where the intermediate cylinder 13 and the seal sleeve 14 do not exist, and these surfaces are filled. The first rubber bush 15 fixed to each other and the intermediate cylinder Of 3 of the outer peripheral surface and is filled between the inner peripheral surface of the sealing sleeve 14 and the second rubber bushing 16 for secured respectively to their surface.
[0027]
As in the case of the first embodiment, the inner peripheral surface of the intermediate tube 13 and the outer peripheral surface of the inner tube 11 are relatively displaced in the axial direction of both the tubes 11 and 13 over the entire circumference. The cross-sectional outline is a shape other than a perfect circle, for example, a first shape so as to restrict the relative displacement around the axis of both the cylinders 11 and 13 with a substantially constant gap e that can be It is formed in an elliptical shape or the like as in the first embodiment. However, the rubber bush is not filled between the inner peripheral surface of the intermediate cylinder 13 and the outer peripheral surface of the inner cylinder 11 as in the case of the first embodiment. In FIG. L. Is the center line of the steering bush B, and the lower half of the steering bush B is omitted in the figure.
[0028]
As a method of manufacturing the steering bush B, first, a first assembly formed by filling the first rubber bush 15 between the outer peripheral surface of the inner cylinder 11 and the inner peripheral surface of the outer cylinder 12 is integrally formed. Form by the method. Subsequently, a second assembly formed by filling the second rubber bush 16 between the outer peripheral surface of the intermediate cylinder 13 and the inner peripheral surface of the seal sleeve 14 is also formed by the integral molding method. Thereafter, the second assembly is press-fitted into a space where the first rubber bush 15 does not exist between the outer peripheral surface of the inner cylinder 11 and the inner peripheral surface of the outer cylinder 12 in the first assembly. Thus, the steering bush B is manufactured.
[0029]
FIG. 8 is a characteristic diagram showing the relationship between the static spring constant in the torsional direction and the static spring constant in the axial direction for the steering bushing of the present invention and the prior arts 1 to 3, respectively. FIG. It is a characteristic view which shows the relationship between the dynamic spring constant of a torsion direction, and the dynamic spring constant of an axial direction about the techniques 1 and 2, respectively. Here, the prior art 1 belongs to the steering bush described in the section of the prior art, the prior art 2 also belongs to the steering rubber coupling, and the prior art 3 also belongs to the vibration absorbing steering shaft. It is.
[0030]
As can be seen from FIGS. 8 and 9, the steering bush according to the present invention has a ratio of the spring constant (K1) in the axial direction to the spring constant (K2) in the torsional direction as compared with the conventional steering bush and vibration absorbing steering shaft. (K1 / K2) is small and close to that of the steering rubber coupling.
[0031]
FIG. 10 shows two types of steering bushes A and B according to the present invention having different clearances e between the outer peripheral surface of the inner cylinders 1 and 11 and the inner peripheral surface of the intermediate cylinders 3 and 13. FIG. 4 is a characteristic diagram showing a relationship with torque, in which a solid line indicates a characteristic line with a large gap e and a broken line indicates a characteristic line with a small gap e. From this figure, it can be seen that the linear regions R1 and R2 (R1> R2) generated in the range where the twist angle is small are the outer peripheral surfaces of the inner cylinders 1 and 11 and the inner peripheral surfaces of the intermediate tubes 3 and 13. It turns out that it changes according to the clearance gap e between.
[0032]
【The invention's effect】
As described above, according to the steering bush of the present invention, the spring constant in the axial direction can be reduced and the spring constant in the torsional direction can be increased while having the advantage that the bush is inherently compact and excellent in versatility. Therefore, it is possible to effectively achieve both vibration absorption and steering stability. Moreover, even when a steering force or the like is acting, the axial spring constant does not change, and vibration absorption can be maintained well.
[0033]
In particular, the invention according to claim 2 also has the effect of preventing the generation of noise due to contact between the intermediate cylinder and the inner cylinder.
[Brief description of the drawings]
FIG. 1 is a side view in which a part of a steering bushing according to a first embodiment of the present invention is cut open.
FIG. 2 is a cross-sectional view taken along line XX in FIG.
FIG. 3 is a cross-sectional view taken along line YY in FIG.
FIG. 4 is a view corresponding to FIG. 3, showing a second embodiment of the present invention.
FIG. 5 is a view corresponding to FIG. 3 showing a third embodiment.
FIG. 6 is a view corresponding to FIG. 3 and showing a fourth embodiment.
FIG. 7 is a longitudinal side view of a steering bush according to a fifth embodiment of the present invention.
FIG. 8 is a characteristic diagram showing the relationship between the static spring constant in the torsional direction and the static spring constant in the axial direction for the steering bush of the present invention and the prior art.
FIG. 9 is a characteristic diagram showing the relationship between the dynamic spring constant in the torsional direction and the dynamic spring constant in the axial direction.
FIG. 10 is a characteristic diagram showing a relationship between a twist angle and a twist torque in the steering bush of the present invention.
[Explanation of symbols]
A, B Steering bush 1,11 Inner cylinder 2,12 Outer cylinder 3,13 Intermediate cylinder 4,15,16 Rubber bush e Gap

Claims

A steering bushing interposed between a shaft member of a steering shaft system that transmits a steering force of a steering wheel to a steering gear box and a tubular member loosely fitted to the shaft member,
An inner cylinder through which the shaft member passes and is coupled to the shaft member;
An outer cylinder disposed concentrically on the outer periphery of the inner cylinder and fitted into the tubular member;
An intermediate cylinder disposed concentrically with the two cylinders between the inner cylinder and the outer cylinder and having an axial length shorter than that of the inner cylinder and the outer cylinder;
At least between the outer peripheral surface of the intermediate cylinder and the inner peripheral surface of the outer cylinder and between the outer peripheral surface of the inner cylinder and the inner peripheral surface of the outer cylinder at an axial position where the intermediate cylinder does not exist and those surfaces With rubber bushes fixed to each,
The inner peripheral surface of the intermediate cylinder and the outer peripheral surface of the inner cylinder are opposed to each other with a substantially constant gap that allows the relative displacement in the axial direction of both cylinders over the entire circumference. And a steering bushing characterized in that the contour of the cross section is formed in a shape other than a perfect circle so as to restrict relative displacement about the axis of both cylinders.

The steering bush according to claim 1, wherein a rubber bush is also filled between the inner peripheral surface of the intermediate cylinder and the outer peripheral surface of the inner cylinder.