JP4436620B2

JP4436620B2 - Shock absorber

Info

Publication number: JP4436620B2
Application number: JP2003140866A
Authority: JP
Inventors: 寛吉田; 宏後藤; 晃治下津
Original assignee: Asteer Co Ltd
Current assignee: Asteer Co Ltd
Priority date: 2002-05-29
Filing date: 2003-05-19
Publication date: 2010-03-24
Anticipated expiration: 2023-05-19
Also published as: JP2004051084A

Description

【０００１】
【発明の属する技術分野】
本発明は、衝撃エネルギーを塑性変形の変形エネルギーとして吸収する衝撃吸収体、例えば自動車等の車両の車体メンバ側部を構成するサイドメンバとしたり、自動車等のバンパに加えられた衝撃エネルギーを吸収して車体メンバへの前記衝撃エネルギーの伝達を防止又は抑制するバンパ支持型衝撃吸収体として利用しうる衝撃吸収体に関する。
【０００２】
【従来の技術】
自動車等の車両では、衝突時における衝撃から乗員を保護するため、衝撃エネルギーを塑性変形の変形エネルギーとして吸収する衝撃吸収体が各所に使用される。例えば、車両のバンパ補強材を車体メンバに対して支持する管体からなるバンパ支持型衝撃吸収体に衝撃吸収体(以下、バンパ支持型衝撃吸収体)を利用する。
【０００３】
衝撃吸収体として利用するバンパ支持型衝撃吸収体は、特許文献１や特許文献２に見られるように、軸方向(小管体及び大管体の並び方向、通常車両の前後方向に一致)から受けた衝撃エネルギーにより小管体を大管体に押し込むことにより塑性変形を引き起こし、衝撃エネルギーを塑性変形の変形エネルギーとして吸収する。衝撃吸収体を利用したバンパ支持型衝撃吸収体は、構造が簡素ながら衝撃エネルギーの吸収性能に優れており、車両重量の違いに応じて柔軟に設計を変更できる利点もある。
【０００４】
また、乗員区画を保持する車体メンバとして、車両の車体メンバ側部を構成する管体からなるサイドメンバに前記衝撃吸収体(以下、サイドメンバ型衝撃吸収体)を利用する。サイドメンバに衝撃吸収体を利用した先行技術には、特許文献３〜７がある。
【０００５】
特許文献３は、２つの筒状部材の端部を同軸で付き合わせ、両筒状部材の前記端部から内側に捲れ込む塑性変形(特許文献３図１参照)によって衝撃を吸収する。特許文献４は、上下２段に配列した複数の穴により対衝撃強度を長さ方向に変化させ、衝撃の程度に合わせて塑性変形する範囲を調節する。特許文献５は、比較的剛性の低い材料で構成し、内部にブラケットを断続的に架設している。特許文献６は、鏡面対称な多段筒体を接合している。そして、特許文献７は、細長い孔又は空隙を設けた衝撃吸収部材をサイドメンバの構造の一部として介在させる。
【０００６】
【特許文献１】
特公昭４７−０４５９８６号公報（２〜６頁、第１〜４図）
【特許文献２】
特開２００１−１３８８４１号公報（２〜５頁、図２）
【特許文献３】
特開２００１−２４１４７８号公報（２〜５頁、図２）
【特許文献４】
特許第２９８４４３４号公報（２〜３頁、図２）
【特許文献５】
特公昭５１−０２１８５０号公報（１〜４頁、第４〜８図）
【特許文献６】
米国特許第３，９９８，４８５号明細書（３〜４頁、図２）
【特許文献７】
米国特許第６，３１２，０２８号明細書（６〜７頁、図１〜図２）
【０００７】
【発明が解決しようとする課題】
上記各先行技術に見られる各衝撃吸収体は、衝撃により塑性変形を引き起こして衝撃エネルギーを変形エネルギーとして吸収する働きを有する。この働きは、基本的に、バンパ支持型衝撃吸収体でもサイドメンバ型衝撃吸収体でも変わらない。これから、衝撃吸収体は、安定して塑性変形することが望ましく、とりわけ偏荷重が加わった場合でも屈曲せず、かつ塑性変形を正しく発生させる必要がある。
【０００８】
特許文献１のバンパ支持型衝撃吸収体は、小管体及び大管体が並ぶ軸方向から衝撃が加わる場合、必要十分な吸収性能を発揮できる。しかし、小管体及び大管体の境界となる段差は、塑性変形しやすくなっているため、例えば小管体に軸方向斜めから衝撃が加わると、衝撃の軸直交方向成分fhによって小管体が傾倒し、小管体を大管体に没入することによる塑性変形が発生せず、衝撃エネルギーを吸収できなくなる問題がある。
【０００９】
特許文献２のバンパ支持型衝撃吸収体は、小管体、中管体及び大管体からなる３段構成のバンパ支持型衝撃吸収体により、小管体の傾倒を中管体で防止又は抑制する。しかし、中管体による小管体の傾倒防止又は抑制の作用は、限定的(およそ軸方向30度まで)であり、より大きな角度の軸方向斜めからの衝撃に対して、依然として小管体の傾倒防止が十分に達成できない。
【００１０】
また、特許文献３のサイドメンバ型衝撃吸収体は、小径の筒状部材の端縁を大径の筒状部材の端縁に設けた段差平面に当接させるため、筒状部材が並ぶ軸方向に衝撃が加われば、確かに段差平面を介して両筒状部材の端縁に塑性変形を引き起こすことができる。しかし、偏荷重の場合、小径の筒状部材が段差平面上で傾倒し、屈曲してしまう問題がある。
【００１１】
このほか、特許文献４、特許文献５及び特許文献７に見られるサイドメンバ型衝撃吸収体は、安定した衝撃吸収性能を得にくく(特に、特許文献４の図４荷重特性参照)、特許文献６に見られるサイドメンバ型衝撃吸収体は特許文献３同様、偏荷重によって屈曲する可能性がある。
【００１２】
そこで、バンパ支持型衝撃吸収体又はサイドメンバ型衝撃吸収体について、より大きな角度の軸方向斜めから衝撃が加えられても、なお大管体に対する小管体の没入が確保して、塑性変形による衝撃エネルギーの吸収が達成できることを課題として検討した。
【００１３】
【課題を解決するための手段】
検討の結果、塑性加工可能な直管を部分的に縮径又は拡径して段差を介して繋がる小管体及び大管体を形成し、段差を介して繋がる小管体の折返縁及び大管体の折返縁は共に円弧角度９０度超の円弧状断面で、段差は前記小管体の折返縁及び大管体の折返縁を結んだＳ字断面にした衝撃吸収体において、小管体は、大管体への没入に際して小管体自身の傾倒を抑制又は防止する傾倒防止体を、小管体の折返縁を大管体の内面に向けて拡開して一体に形成してなり、傾倒防止体は、小管体の折返縁の円弧状断面の半径を、大管体の折返縁の円弧状断面の半径より相対的に小さくしたＳ字断面の段差の前記小管体の折返縁を、大管体の内面に向けて拡開して形成した衝撃吸収体を開発した。
【００１４】
本発明に言う「90度超」とは、小管体側面から段差への折れ曲がりである小管体の折返縁の円弧部分の角度範囲、又は大管体側面から段差への折れ曲がりである小管体の折返縁の円弧部分の角度範囲が、90度(直角)ではないことを意味する。
【００１５】
ここで、車両のバンパ補強材を車体メンバに対して支持する直管を部分的に縮径又は拡径して段差を介して繋がる小管体及び大管体を形成すると、バンパ補強材を支持する構造要素を兼ねることのできる衝撃吸収体(以下、バンパ支持型衝撃吸収体)となる。また、車両の車体メンバ側部を構成する直管を部分的に縮径又は拡径して段差を介して繋がる小管体及び大管体を形成すると、車体メンバを構成する構造要素自体となる衝撃吸収体(以下、サイドメンバ型衝撃吸収体)となる。
【００１６】
本発明の衝撃吸収体は、段差を１以上有する多段管体に適用できるが、小管体及び大管体からなる二段管体、又は小管体、中管体及び大管体からなる三段管体が好ましい。ここで、三段管体は、小管体及び中管体、中管体及び大管体の関係それぞれが二段管体の小管体及び大管体の関係に相当し、全体として衝撃吸収体を連結した構成である。
【００１７】
本発明の衝撃吸収体は、塑性加工可能な直管を部分的に縮径又は拡径して小管体又は大管体を形成するため、小管体より大管体の肉厚が薄く、相対的に大管体の方が塑性変形しやすい。また、小管体及び大管体の間に介在する段差が、小管体が大管体に対して少し没入し、段差が内向きに捲れ込んだＳ字断面になっており、大管体に小管体を没入しやすい。
【００１８】
これから、本発明の衝撃吸収体は、小管体がそのまま大管体に没入し、段差から大管体側面にかけて内向きに捲り込ませる塑性変形を起こし、衝撃エネルギーを前記塑性変形の変形エネルギーとして吸収する。
【００１９】
小管体の折返縁及び大管体の折返縁の各円弧状断面の円弧角度は、90度を超えて360度未満の範囲で考えられる。具体的な円弧角度は、(1)小管体の外径と、大管体の内径との差、(2)小管体の折返縁の円弧状断面と大管体の折返縁の円弧状断面との半径(半径の定義は後述)の異同、によって決定する。より具体的な両側縁の円弧状断面の各円弧角度は、180度前後が好ましい。
【００２０】
小管体がそのまま大管体に没入し、段差から大管体側面にかけて内向きに捲り込ませる塑性変形を確実に生起するには、小管体の折返縁の円弧状断面の半径を、大管体の折返縁の円弧状断面の半径より相対的に小さくしたＳ字断面の段差にする。ここで、厚みの異なる小管体側面及び大管体側面に連続する小管体の折返縁及び大管体の折返縁は、それぞれ厚みを変化しながら湾曲しているので、前記各円弧状断面の半径はそれぞれ板厚の中心線の半径とする。
【００２１】
上記断面構造の段差は、相対的に急峻な折返となる小管体の折返縁を介した小管体側面の捲れ込みを抑制し、逆に相対的に緩やかな折返となる大管体の折返縁を介した大管体側面の捲れ込みを誘引する。これにより、小管体はそのまま大管体に没入し、大管体の折返縁から大管体側面にかけて内側に捲れ込む塑性変形を実現できる。
【００２２】
本発明は、上述のように、段差の構造を工夫することにより、小管体を必ず大管体に向けて没入させる塑性変形を実現する。しかし、小管体に斜め方向からの衝撃(偏荷重)が印加された場合、大管体に対して小管体が傾倒し、小管体側面が大管体の折返縁に当たって小管体の前記没入が遮られる虞れもある。
【００２３】
そこで、段差は小管体の折返縁及び大管体の折返縁を環状側面で結んだＳ字断面にするとよい。小管体の折返縁及び大管体の折返縁の各円弧状断面の半径は同じであっても、異なってもよい。すなわち、上述のように、小管体の折返縁の円弧状断面の半径を、大管体の折返縁の円弧状断面の半径より相対的に小さくした場合でも、環状側面が捲れ込みを引き起こす阻害要素にはならない。
【００２４】
環状側面は、円弧角度が共に180度で等しい小管体の折返縁及び大管体の折返縁を結ぶＳ字断面の段差を形成した場合、小管体側面及び大管体側面に平行となる。しかし、小管体の折返縁及び大管体の折返縁の各円弧状断面の半径を異ならせて、環状側面を小管体から大管体に向けて徐変に縮径又は拡径する錐台側面にすると好ましい。より好ましくは、小管体の折返縁の円弧状断面の半径を、大管体の折返縁の円弧状断面の半径より相対的に小さくしたＳ字断面の段差を形成し、小管体に向かって開いた逆錐台形状の環状側面にする。
【００２５】
小管体の折返縁及び大管体の折返縁を結ぶ環状側面は、斜め方向からの衝撃により小管体が傾倒する場合、傾倒軸となる小管体の折返縁を大管体の折返縁から遠ざけているので、早い段階で小管体側面を大管体の折返縁又は環状側面に当接させ、小管体が大きく傾倒することを防止する。そして、小管体が大管体に没入を始めた段階では、大管体の折返縁又は環状側面に小管体側面を摺接させながら傾倒を補正し、確実な小管体の大管体への没入を保証する。
【００２６】
より積極的に小管体の傾倒防止を図るには、大管体への没入に際して小環体自身の傾倒を抑制又は防止する傾倒防止体を小管体の内面に固着するとよい。この傾倒防止体は、小管体の内径に等しい外径の小径環部と、大管体の内径に等しい外径の大径環部とからなり、小径環部は小管体の内面に固着し、段差を越えて小管体から大管体に突出させ、大径環部は前記小径環部が段差を越えた位置で大管体の内面に当接させることにより、軸方向斜めから小管体に加えられた衝撃に対し、小管体と一体となる傾倒防止体が大管体の内面を基礎として対抗し、小管体の傾倒を防止又は抑制する。
【００２７】
ここで、「大管体の内面に当接する」とは、大管体に対して小管体が没入する際に、大径環部が大管体の内面に、継続的に又は断続的に、点接触、線接触又は面接触する場合を含む。また、大径環部が全体的に接する必要はなく、点接触であれば小環体の傾倒を防止したい方向に複数点接触点があればよく、線接触又は面接触の場合は、周方向に断続的に接すればよい。
【００２８】
傾倒防止体が、大管体に没入する小環体自身の傾倒を抑制又は防止する機能を発揮するには、小管体が円滑に大管体に没入する必要がある。これから、傾倒防止体の適用と共に、小管体の折返縁の円弧状断面の半径を、大管体の折返縁の円弧状断面の半径より相対的に小さくしたＳ字断面の段差を形成することが望ましい。
【００２９】
上記傾倒防止体を構成する小径環部及び大径環部は、それぞれ別部材で構成して連結してもよいし、衝撃吸収体を構成する有段管体同様、塑性変形可能な環体を部分的に縮径又は拡径して段差を介して一体成形してもよい。この場合、小径環部が小管体、大径環部が大管体に相当するが、傾倒防止体は塑性変形による衝撃吸収作用を必要としないので、小径環部及び大径環部を結ぶ段差には、上述までの構造的限定は必要ない。
【００３０】
塑性変形可能な環体を部分的に縮径又は拡径して段差を介して一体成形した傾倒防止体は、小管体から大管体に突出する小径環部を大管体の内面に当接するまで拡径して大径環部を形成するとよい。すなわち、小径環部は相対的に長尺な管体状に構成し、この小径環部の端縁を大管体の内面に当接するまで拡径する。
【００３１】
また、傾倒防止体は、小管体から大管体に突出する小径環部を大管体の内面に当接するまで拡径し、小管体に向けて折り返したカーリングとして大径環部を形成したり、小管体から大管体に突出する小径環部を大管体の内面に当接するまで拡径し、大管体の半径内向きに折り返したカーリングとして大径環部を形成してもよい。このように、大径環部をカーリングして形成することで、軸方向斜めから加えられる衝撃に対抗する構造強度を大径環部に与えることができる。
【００３２】
更に、傾倒防止体は、大管体の内面に接面する筒状環を大径環部に設けるとよい。広い面積で大管体の内面に接面する筒状環は、軸方向斜めから加えられる衝撃による圧力(衝撃力/接面面積)を低下させ、小管体の傾倒を防止又は抑制する傾倒防止体の働きを強化する。この筒状環は、大管体の内面に接面することから、基本的には大管体の相似形状となる。上記カーリングは、筒状環の端縁に形成するとよい。
【００３３】
本発明の傾倒防止体は、小管体の傾倒に対して大管体を基礎に対抗することができればよい。これから、小管体は、大管体への没入に際して小管体自身の傾倒を抑制又は防止する傾倒防止体を、小管体の折返縁を大管体の内面に向けて拡開して一体に形成する。
【００３４】
上記傾倒防止体は、小管体の折返縁の円弧状断面の半径を、大管体の折返縁の円弧状断面の半径より相対的に小さくしたＳ字断面の段差の前記小管体の折返縁を、大管体の内面に向けて拡開して形成したり、小管体の折返縁及び大管体の折返縁を環状側面で結んだＳ字断面の段差の前記小管体の折返縁を、大管体の内面に向けて拡開して形成する。各傾倒防止体は、それぞれ大管体に対して小管体を確実に没入させながら、かつ小管体の折返縁を傾倒防止体として大管体の内面に摺接させることができる。
【００３５】
【発明の実施の形態】
以下、バンパ支持型衝撃吸収体の実施形態について図を参照しながら説明する。図１は本発明が応用されるバンパ支持型衝撃吸収体１０５及びサイドメンバ型衝撃吸収体１１２の参考例を表す斜視図、図２は小管体１０１に向けて折り返したカーリング１０２により大径環部１０３を形成した傾倒防止体１０４を取り付けた二段管体構成のバンパ支持型衝撃吸収体１０５の断面図、図３は同バンパ支持型衝撃吸収体１０５に軸方向の衝撃Ｆが加わり始めた段階を表した図２相当断面図、図４は同バンパ支持型衝撃吸収体１０５に軸方向斜めから衝撃Ｆが加わり始めた段階を表した図２相当断面図で、図５は同バンパ支持型衝撃吸収体１０５が軸方向の衝撃Ｆを吸収し終えた段階を表した図２相当断面図である。
【００３６】
参考例のバンパ支持型衝撃吸収体１０５は、図２に見られるように、塑性加工可能な直管体を部分的に縮径又は拡径して段差を介した小管体１０１及び大管体１０６を形成した二段管体からなる。参考例は、小管体１０１及び大管体１０６を軸方向（図２中一点鎖線参照、以下同じ）に縮退し、小曲率半径断面の小管体の折返縁１０７と大曲率半径断面の大管体の折返縁１０８とを環状側面１０９で結んだＳ字断面の段差１１０を形成している。こうしたバンパ支持型衝撃吸収体１０５は、図１に見られるように、車体メンバ１１１を構成するサイドメンバ型衝撃吸収体１１２の前端それぞれに大管体１０６を接続し、小管体１０１，１０１にバンパ補強材１１３を架設する態様で使用される。
【００３７】
参考例の傾倒防止体１０４は、小管体１０１の内径に等しい外径の小径環部１１４と、大管体１０６の内径に等しい外径の大径環部１０３とからなる。大径環部１０３は、小管体１０１から大管体１０６に突出する小径環部１１４を大管体１０６の内面に当接するまで拡径し、小管体１０１に向けて折り返したカーリング１０２であり、段差１１０を越えた位置で大管体１０６の内面に前記カーリング１０２の端縁を当接させている。この傾倒防止体１０４は、小管体１０１の内面にスポット溶接（図２中スポット溶接痕１１５を図示）で固着している。
【００３８】
小管体101に軸方向からの衝撃Ｆ(図３中白抜き矢印)が加わると、図３に見られるように、大管体106に対して小管体101が没入していき、段差110が有する環状側面109を延ばしながら、段差110を介して小管体101により大管体106を内側へ捲り込ませ(塑性変形：図３中黒塗り矢印)、衝撃Ｆの衝撃エネルギーを大管体106の変形エネルギーとして吸収する。ここで、環状側面109と大管体106とはそれぞれに塑性変形(延性)を伴うが、大部分の塑性変形は、大管体106が捲れ込む量に合わせて環状側面109が延びる態様で生じる。
【００３９】
参考例の場合、段差１１０を挟んだ小管体の折返縁１０７は相対的に半径の小さな円弧状断面、大管体の折返縁１０８は相対的に半径の大きな円弧状断面であるため、相対的に大管体の折返縁１０８が塑性変形しやすくなっており、小管体１０１が捲れることなく、大管体１０６のみが一方的に捲れ込んでいく。このように、衝撃Ｆの衝撃エネルギーを吸収する塑性変形は、専ら径の大きな大管体１０６の捲れ込みにより達成されるので、小管体１０１が捲れ込む同種バンパ支持型衝撃吸収体に比べ、吸収できる衝撃エネルギーの総量は多い。
【００４０】
また、参考例は、小管体の折返縁１０７と大管体の折返縁１０８とを環状側面１０９で結んだ段差１１０を形成していることから、小管体１０１が大管体１０６に没入する過程で延びる環状側面１０９が、小管体１０１及び大管体１０６の間に介在することになる。この小管体１０１及び大管体１０６の間に介在する環状側面１０９は、小管体１０１の傾倒を防止又は抑制する働きがあり、図３に見られるように、ある程度小管体１０１が大管体１０６に没入した段階では、もはや小管体１０１が傾倒する虞れはない。
【００４１】
問題は、衝撃Ｆが最初から軸方向斜めから加わる場合である。軸方向斜めから加わる衝撃Ｆは、図４に見られるように、大管体106に対して小管体101を押し込んでいく軸方向成分fv(図４中下向き実線矢印)と、小管体101を傾倒させようとする軸直交成分fh(図４中右向き実線矢印)とに分解できる。
【００４２】
傾倒防止体104は、前記軸直交成分fhを受けて傾倒しようとする小管体101に対し、軸直交成分fh上流側では小管体の折返縁107が大管体106の内面に接近することに対抗し(図４中右側における実線矢印及び破線矢印参照)、また軸直交成分fh下流側では小管体の折返縁107が大管体106の内面から離隔することに対抗する(図４中左側における実線矢印及び破線矢印参照)。
【００４３】
上記各対抗は、大径環部103が大管体106の内面に当接し、傾倒防止体104が小管体101の傾倒方向に対して自由を制限されていることで実現している。すなわち、小管体101が傾倒するには、前記自由の制限を破壊する程度の負荷＝傾倒防止体104全体を変形させるに足りる衝撃が加わらなければならない。傾倒防止体104は、小径環部114を小管体101に接面して固着しており、また大管体106に対しても大径環部103を構成するカーリング102を当接させているため、傾倒防止体104の変形には全体の変形を必要とする。
【００４４】
更に、参考例の傾倒防止体１０４は略円筒状であるため、小管体１０１に対する軸直交成分ｆｈがどの方向から加わっても、傾倒防止体１０４の変形に必要な負荷は等しくできる。このように、小径環部１１４を小管体１０１の内面に固着し、大径環部１０３を大管体１０６の内面に当接させる傾倒防止体１０４を設けることにより、小管体１０１の傾倒（特に衝撃Ｆが加わり始めた初期段階の傾倒）は防止できる。
【００４５】
そして、既述したように、小管体101がある程度大管体106に没入すれば、環状側面109が小管体101の傾倒を防止できるから、本発明のバンパ支持型衝撃吸収体105は、仮に最初から軸方向斜めの衝撃Ｆが加わっても、小管体101を傾倒させることなく、確実に大管体106に没入させて、衝撃Ｆの衝撃エネルギーを吸収できる。
【００４６】
傾倒を防止された小管体101は、図５に見られるように、傾倒防止体104の大径環部103を構成するカーリング102がサイドメンバ型衝撃吸収体112の前端(図１参照、大管体106の端縁に一致)に当接するまで、大管体106に対して没入できる。バンパ支持型衝撃吸収体としてどれほどの衝撃Ｆの衝撃エネルギーを吸収できるかは、小管体の没入量で決定されるため、例えば、サイドメンバの前端に傾倒防止体が没入できる没入孔等を開孔しておけば、更に小管体の没入を図ることができる。この場合、大径環部が当接する基礎がなくなるため、前記没入孔に連続して大径環部が当接できるガイドを設けておくとよい。
【００４７】
図６は大管体１０６の半径内向きに折り返したカーリング１１６及び大管体１０６の内面に接面する筒状環１１７により大径環部１０３を形成した別の参考例の傾倒防止体１１８を取り付けた二段管体構成のバンパ支持型衝撃吸収体１１９の図２相当断面図であり、図７は同バンパ支持型衝撃吸収体１１９が軸方向の衝撃Ｆの衝撃エネルギーを吸収し終えた段階を表した図６相当断面図である。
【００４８】
傾倒防止体は、小管体の傾倒に対抗するため、大管体の内面を基礎として衝撃Ｆの軸直交方向成分ｆｈに対抗しうる大径環部を有する構造であればよい。別の参考例の大径環部１０３は、図６に見られるように、小管体１０１から大管体１０６に突出する小径環部１１４を大管体１０６の内面に当接するまで拡径し、大管体１０６の内面に接面する筒状環１１７を形成した後、大管体１０６の半径内向きに折り返したカーリング１１６を形成した構造である。
【００４９】
別の参考例の大径環部１０３が、小管体１０１の傾倒防止を図る働きは、上述の参考例（図２以下参照）と変わりはない。大管体１０６の内面に広く接面する筒状環１１７は、小管体１０１の傾倒に対する対抗力を強化する働きを有する。別の参考例は、更に筒状環１１７に続いて大管体１０６の半径方向内向きのカーリング１１６を形成しているので、大径環部１０３の構造強度が高く、よりよく小管体の傾倒を防止できる。
【００５０】
ここで、筒状環117を含めて軸方向に幅のある大径環部103は、大管体106に没入する小管体101の小管体の折返縁107の変位を制限し、図７に見られるように、結果として小管体101の没入量を減少させる。この場合、筒状環に続くカーリングを省くことで、筒状環に至る大径環部平面が塑性変形できる余地を残し、例えば小管体の折返縁で前記大径環部103を圧潰して、小管体の没入量を稼ぐこともできる。
【００５１】
図８は小管体の折返縁１０７と大管体の折返縁１０８とを結んでなる段差１２０の前記小管体の折返縁を大管体１０６の内面に向けて拡開して形成した本発明の実施形態の例（本例）の傾倒防止体１２１を設けた二段管体構成のバンパ支持型衝撃吸収体１２２の図２相当断面図であり、図９は同バンパ支持型衝撃吸収体１２２が軸方向の衝撃Ｆの衝撃エネルギーを吸収し終えた段階を表した図８相当断面図である。
【００５２】
バンパ支持型衝撃吸収体と別体の傾倒防止体は、設計及び製造の自由度が高く好ましいが、大径環部と一体の小径環部を小管体に固着する組立工程を要求する。これに対し、図８に見られる傾倒防止体121は、小管体101と一体に大径環部103のみを成形するため、小径環部を小管体に固着する組立工程を必要としない利点がある。
【００５３】
本例の傾倒防止体１２１は、小曲率半径断面の小管体の折返縁１０７と大曲率半径断面の大管体の折返縁１０８とを結んだ段差１２０を作り、前記小管体の折返縁１０７を大管体１０６の内面に向けて拡開して大管体１０６の内面に当接し、形成している。上述の各参考例に見られるような上方に開いた形状ではないが、小管体の折返縁１０７及び大管体の折返縁１０８を結ぶ環状側面が環状側面１０９に相当し、小管体１０１と一体に形成した傾倒防止体１２１と共に小管体１０１の傾倒防止を図ることができる。
【００５４】
小管体101は、軸方向からの衝撃Ｆを受けて、小管体の折返縁107を大管体106の半径方向外向きに押し広げながら大管体106に没入していくため、前記小管体の折返縁107は大管体106に対して小管体101が没入していく過程で大管体106の内面に必ず摺接する。本例の傾倒防止体121は、小管体101から小管体の折返縁107にかけて緩やかな曲率で拡開しているので、小管体101が下端をサイドメンバ型衝撃吸収体112の前端(図１参照、大管体106の端縁に一致)に達すると、図９に見られるように、小管体の折返縁107から小管体101にかけて塑性変形して若干広がって没入を停止する。
【００５５】
次に、本発明をサイドメンバ型衝撃吸収体に応用した参考例について図を参照しながら説明する。図１０はサイドメンバ型衝撃吸収体１１２の軸方向断面図、図１１は別の参考例のサイドメンバ型衝撃吸収体１１２の軸方向断面図、図１２は図１０中Ａ部拡大断面図で、図１３は小管体２０１を大管体２０２に没入させる過程を表した図１２相当断面図である。
【００５６】
参考例は、図１及び図１０に見られるように、サイドメンバ型衝撃吸収体１１２を構成する小管体２０１の拡開した取付先端１２３，１２３間にクロスメンバ１２４を架設して車体メンバ１１１を構成し、このクロスメンバ１２４から各小管体２０１と同軸に突設したバンパ支持型衝撃吸収体１０５でバンパ補強材１１３を支持している。取付先端１２３を拡開するのは、クロスメンバ１２４とサイドメンバ型衝撃吸収体１１２との接合強度を高めるためであり、このほか図１１に見られるように、後部を開放したクロスメンバ１２４に小管体２０１先端をそのまま差し込んで接合してもよい。
【００５７】
本発明は、段差203の大管体の折返縁204から大管体側面205にかけて確実に塑性変形を引き起こすため、段差203は、図12に見られるように、前後する小管体201及び大管体202の両管体側面207,205から連続して形成した円弧角度180度の円弧状断面からなる小管体の折返縁206及び大管体の折返縁204を連結して形成している。
【００５８】
特に、参考例では、大管体の折返縁２０４の円弧状断面の半径を、小管体の折返縁２０６の円弧状断面の半径より約１．７倍大きくしている。この半径比に伴い、図１２から明らかなように、小管体の折返縁２０６は相対的に急峻な折返となり、大管体の折返縁２０４は相対的に緩やかに大管体側面２０５と連続する構造になる。
【００５９】
このような段差２０３を介して小管体２０１及び大管体２０２を連結することで、小管体２０１の外径は大管体２０２の内径よりも小さくなり、図１３に見られるように、サイドメンバ型衝撃吸収体１１２の軸方向に衝撃Ｆが加われば、バンパ支持型衝撃吸収体１０５における衝撃吸収（参考例では塑性変形による衝撃吸収）の後又は略同時に、小管体２０１が大管体２０２へ没入していく。
【００６０】
この小管体の大管体への没入は、主として大管体の折返縁から大管体側面にかけての塑性変形に基づく(図13中太線矢印参照)。これは、直管を拡径して大管体202を形成する(又は直管を縮径して小管体201を形成する)ことで、大管体側面205の厚みは小管体側面207の厚みより小さくなり、相対的に小管体201よりも大管体202を塑性変形しやすくできるからである。この塑性変形は、大管体側面205を内側へ捲り込ませるように連続して生ずるので、安定して高い衝撃エネルギーの吸収を実現できる利点がある。
【００６１】
衝撃Ｆが斜め方向から印加される場合に小管体201の傾倒を防止するには、小管体の折返縁206及び大管体の折返縁204を環状側面208で結ぶ段差203を形成するとよい。図14は小管体側面207及び大管体側面205に平行な円筒状環状側面208で小管体の折返縁206及び大管体の折返縁204を結んだサイドメンバ型衝撃吸収体112の図12相当断面図、図15は斜め方向からの衝撃Ｆを受けて小管体201が少し傾倒した状態を表した図14相当断面図で、図16は更に衝撃Ｆの印加が続き、傾倒を修正しながら小管体201が大管体202に没入していく状態を表した図14相当断面図である。
【００６２】
参考例のサイドメンバ型衝撃吸収体１１２は、図１４に見られるように、相対的に半径の大きな大管体の折返縁２０４から小管体２０１の没入方向へ離隔して小管体の折返縁２０６を形成し、小管体の折返縁２０６及び大管体の折返縁２０４を円筒状環状側面２０８で結んだ段差２０３を形成している。
【００６３】
小管体201は、環状側面208に小管体側面207を密着させていないので、衝撃Ｆがサイドメンバ型衝撃吸収体112の軸方向からずれた斜め方向から印加されると、図15に見られるように、前記小管体側面207は小管体の折返縁206を傾倒軸として環状側面208又は大管体の折返縁204に当接するまで傾倒するが、小管体側面207が環状側面208又は大管体の折返縁204に当接すると、小管体201の傾倒は規制される。
【００６４】
そして、更に衝撃Ｆが印加されると、衝撃Ｆのサイドメンバ型衝撃吸収体112の軸直交方向成分fhは環状側面208に受け止められて小管体201の傾倒を進めることができず、図16に見られるように、衝撃Ｆのサイドメンバ型衝撃吸収体112の軸方向成分fvのみが小管体201を大管体202に没入させる運動に寄与する。
【００６５】
小管体の傾倒は、小管体の折返縁を傾倒軸とするもので、小管体の折返縁から環状側面又は大管体の折返縁の円弧状断面への接線の範囲でしか許されない。よって、小管体201が大管体202に没入していく段階で、小管体201は小管体側面207を環状側面208又は大管体の折返縁204の円弧状断面に摺接しながら傾倒を暫時修正され、衝撃Ｆは段差203から大管体側面205を内側に捲り込ませる塑性変形にのみ寄与させることができる。
【００６６】
上記環状側面208は、小管体側面207又は大管体側面205と平行でなくてもよい。図17は小管体201から大管体202に向けて縮径する円錐台状環状側面209を形成したサイドメンバ型衝撃吸収体112の図12相当断面図であり、図18は衝撃Ｆの印加を受けて小管体201が大管体202に没入していく状態を表した図17相当断面図である。
【００６７】
環状側面は、小管体の傾倒を防止するものであり、直接的には傾倒する小管体側面に接触し、間接的には傾倒軸となる小管体の折返縁の円弧状断面を大管体の折返縁の円弧状断面から離隔して傾倒角度を規制することで、小管体の傾倒を防止する。これから、前記傾倒防止機能を発揮できれば環状側面の形状は自由であり、図17及び図18に見られるように、円錐台状環状側面209でも、妨げられずに小管体201を大管体202へ没入させることができる。
【００６８】
【発明の効果】
本発明の衝撃吸収体は、段差形状の特定や、傾倒防止体の付設により、従来に比べてより大きな角度の軸方向斜めから衝撃が加えられても、なお大管体に対する小管体の没入が確保でき、衝撃エネルギーを塑性変形の変形エネルギーとして吸収する衝撃吸収性能を十分に発揮することができる。
【００６９】
従来は、軸方向斜め約30度を限度として小管体が傾倒していたが、本発明のバンパ支持型衝撃吸収体では、軸直交方向成分fhが軸方向成分fvを超える軸方向斜め45度までの範囲で、大管体に対する小管体の没入が確保できる。傾倒防止体は、小管体の傾倒を簡素な構造で防止又は抑制できる効果がある。
【００７０】
本発明は、車両のバンパ補強材を車体メンバに対して支持する管体からなるバンパ支持型衝撃吸収体や、車両の車体メンバ側部を構成する管体からなるサイドメンバ型衝撃吸収体を提供する。サイドメンバ型衝撃吸収体の場合、段差で屈曲し、車体や燃料タンクに接触する危険性を回避できるようになり、安全性向上の効果を得る。
【図面の簡単な説明】
【図１】バンパ支持型衝撃吸収体及びサイドメンバ型衝撃吸収体の使用態様を表す斜視図である。
【図２】小管体に向けたカーリングの大径環部を形成した傾倒防止体を取り付けたバンパ支持型衝撃吸収体の断面図である。
【図３】同バンパ支持型衝撃吸収体に軸方向の衝撃Ｆが加わり始めた段階を表した図２相当断面図である。
【図４】同バンパ支持型衝撃吸収体に軸方向斜めから衝撃Ｆが加わり始めた段階を表した図２相当断面図である。
【図５】同バンパ支持型衝撃吸収体が軸方向の衝撃Ｆを吸収し終えた段階を表した図２相当断面図である。
【図６】カーリング及び筒状環により大径環部を形成した傾倒防止体を取り付けたバンパ支持型衝撃吸収体の図２相当断面図である。
【図７】同バンパ支持型衝撃吸収体が軸方向の衝撃Ｆを吸収し終えた段階を表した図６相当断面図である。
【図８】小管体の折返縁を拡開して形成した傾倒防止体を設けたバンパ支持型衝撃吸収体の図２相当断面図である。
【図９】同バンパ支持型衝撃吸収体が軸方向の衝撃Ｆを吸収し終えた段階を表した図８相当断面図である。
【図１０】サイドメンバ型衝撃吸収体の軸方向断面図である。
【図１１】別の参考例のサイドメンバ型衝撃吸収体の軸方向断面図である。
【図１２】図１０中Ａ部拡大断面図である。
【図１３】小管体を大管体に没入させる過程を表した図１２相当断面図である。
【図１４】円筒状環状側面で小管体の折返縁及び大管体の折返縁を結んだサイドメンバ型衝撃吸収体の図１２相当断面図である。
【図１５】斜め方向からの衝撃Ｆを受けて小管体が少し傾倒した状態を表した図１４相当断面図である。
【図１６】更に衝撃Ｆの印加が続き、傾倒を修正しながら小管体が大管体に没入していく状態を表した図１４相当断面図である。
【図１７】円錐台状環状側面を形成したサイドメンバ型衝撃吸収体の図１２相当断面図である。
【図１８】衝撃Ｆの印加を受けて小管体が大管体に没入していく状態を表した図１７相当断面図である。[0001]
BACKGROUND OF THE INVENTION
The present invention provides an impact absorber that absorbs impact energy as deformation energy of plastic deformation, for example, a side member that constitutes a vehicle body member side portion of a vehicle such as an automobile, or absorbs impact energy applied to a bumper of an automobile or the like. The present invention relates to an impact absorber that can be used as a bumper-supporting impact absorber that prevents or suppresses transmission of the impact energy to a vehicle body member.
[0002]
[Prior art]
In vehicles such as automobiles, impact absorbers that absorb impact energy as deformation energy of plastic deformation are used in various places in order to protect the occupant from impact during a collision. For example, a shock absorber (hereinafter referred to as a bumper-supporting shock absorber) is used as a bumper-supporting shock absorber made of a tubular body that supports a vehicle bumper reinforcing material with respect to a vehicle body member.
[0003]
The bumper-supporting type shock absorber used as the shock absorber is received from the axial direction (the arrangement direction of the small and large tubes, and the normal vehicle longitudinal direction), as seen in Patent Document 1 and Patent Document 2. By pushing the small tubular body into the large tubular body by the impact energy, the plastic deformation is caused, and the impact energy is absorbed as the deformation energy of the plastic deformation. Bumper-supported shock absorbers that use shock absorbers are excellent in impact energy absorption performance while being simple in structure, and also have the advantage that the design can be flexibly changed according to the difference in vehicle weight.
[0004]
Further, as the vehicle body member that holds the passenger compartment, the shock absorber (hereinafter referred to as a side member type shock absorber) is used for a side member formed of a tubular body that constitutes a vehicle body member side portion of the vehicle. Patent Documents 3 to 7 are known as prior arts using an impact absorber for a side member.
[0005]
In Patent Document 3, the ends of two cylindrical members are coaxially attached to each other, and the impact is absorbed by plastic deformation (see FIG. 1 of Patent Document 3) that falls inward from the ends of both cylindrical members. In Patent Document 4, the strength against impact is changed in the length direction by a plurality of holes arranged in two upper and lower stages, and the range of plastic deformation is adjusted according to the degree of impact. Patent Document 5 is made of a material with relatively low rigidity, and brackets are intermittently installed inside. Patent document 6 has joined the mirror-symmetric multistage cylinder. And patent document 7 interposes the impact-absorbing member provided with the elongate hole or space | gap as a part of structure of a side member.
[0006]
[Patent Document 1]
Japanese Examined Patent Publication No. 47-045986 (pages 2-6, FIGS. 1-4)
[Patent Document 2]
JP 2001-138841 A (2-5 pages, FIG. 2)
[Patent Document 3]
JP 2001-241478 A (2-5 pages, FIG. 2)
[Patent Document 4]
Japanese Patent No. 2984434 (2-3 pages, FIG. 2)
[Patent Document 5]
Japanese Examined Patent Publication No. 51-021850 (1-4 pages, FIGS. 4-8)
[Patent Document 6]
US Pat. No. 3,998,485 (pages 3-4, FIG. 2)
[Patent Document 7]
US Pat. No. 6,312,028 (pages 6-7, FIGS. 1-2)
[0007]
[Problems to be solved by the invention]
Each impact absorber found in each of the above prior arts has a function of causing plastic deformation by impact and absorbing impact energy as deformation energy. This function is basically the same regardless of whether the bumper support type shock absorber or the side member type shock absorber. From this, it is desirable that the shock absorber be stably plastically deformed. In particular, it is necessary that the shock absorber does not bend even when an unbalanced load is applied, and the plastic deformation is generated correctly.
[0008]
The bumper-support-type shock absorber disclosed in Patent Document 1 can exhibit necessary and sufficient absorption performance when an impact is applied from the axial direction in which the small tube body and the large tube body are arranged. However, since the step that becomes the boundary between the small tube body and the large tube body is easily plastically deformed, for example, when an impact is applied to the small tube from obliquely in the axial direction, the small tube body is tilted by the axially orthogonal component fh of the impact. There is a problem that plastic deformation due to immersion of the small tubular body into the large tubular body does not occur, and impact energy cannot be absorbed.
[0009]
The bumper-supporting shock absorber disclosed in Patent Document 2 prevents or suppresses the tilting of the small tube by the three-stage bumper-supporting shock absorber including the small tube, the middle tube, and the large tube. However, the effect of preventing or suppressing the tilting of the small tube by the middle tube is limited (up to about 30 degrees in the axial direction), and still prevents the tilting of the small tube against an impact from a larger angle in the axial direction. Cannot be achieved sufficiently.
[0010]
Further, in the side member type shock absorber of Patent Document 3, the end of the small-diameter cylindrical member is brought into contact with the step plane provided at the end of the large-diameter cylindrical member. If an impact is applied, it is possible to cause plastic deformation to the end edges of both cylindrical members through the step plane. However, in the case of an unbalanced load, there is a problem that the small-diameter cylindrical member tilts and bends on the step plane.
[0011]
In addition, the side member type shock absorbers shown in Patent Document 4, Patent Document 5 and Patent Document 7 are difficult to obtain a stable shock absorbing performance (in particular, refer to the load characteristics of FIG. 4 in Patent Document 4). The side member-type shock absorber shown in FIG.
[0012]
Therefore, even if a shock is applied to the bumper support type shock absorber or side member type shock absorber from an oblique angle in the axial direction at a larger angle, the immersion of the small tube body with respect to the large tube body is ensured, and the impact due to plastic deformation is ensured. We examined the problem of energy absorption.
[0013]
[Means for Solving the Problems]
As a result of the study, small pipes and large pipes that are connected through a step by partially reducing or expanding the diameter of a straight pipe that can be plastically formed are formed.AndThe folded edge of the small tube connected through the step and the folded edge of the large tube are both arc-shaped cross sections having an arc angle of more than 90 degrees, and the step is an S-shape connecting the folded edge of the small tube and the folded edge of the large tube. In cross sectionTheShock absorberThe small tubular body is formed integrally with an anti-tilt body that suppresses or prevents tilting of the small tubular body when the small tubular body is immersed, with the folding edge of the small tubular body being expanded toward the inner surface of the large tubular body. The anti-tilt body is configured to return the small tubular body at the step of the S-shaped cross section in which the radius of the circular section of the folded edge of the small tubular body is relatively smaller than the radius of the circular section of the folded edge of the large tubular body. Formed by expanding the edge toward the inner surface of the large tubeDeveloped a shock absorber.
[0014]
The term “greater than 90 degrees” as used in the present invention refers to the angular range of the arc portion of the folded edge of the small tube that is bent from the side surface of the small tube to the step, or the folding of the small tube that is bent from the side surface of the large tube to the step. It means that the angle range of the arc part of the edge is not 90 degrees (right angle).
[0015]
Here, when the straight pipe that supports the bumper reinforcement of the vehicle with respect to the vehicle body member is partially reduced in diameter or expanded to form a small pipe and a large pipe connected through a step, the bumper reinforcement is supported. An impact absorber that can also serve as a structural element (hereinafter referred to as a bumper-supported impact absorber) is obtained. In addition, if a small pipe and a large pipe are formed by partially reducing or expanding the diameter of a straight pipe constituting a vehicle body member side portion through a step, an impact that becomes a structural element constituting the vehicle body member itself It becomes an absorber (hereinafter referred to as a side member type shock absorber).
[0016]
The shock absorber of the present invention can be applied to a multistage tube having one or more steps, but a two-stage tube composed of a small tube and a large tube, or a three-stage tube composed of a small tube, a medium tube and a large tube. The body is preferred. Here, in the three-stage tube, the relationship between the small tube and the medium tube, the relationship between the medium tube and the large tube respectively corresponds to the relationship between the small tube and the large tube of the two-stage tube, and the shock absorber as a whole It is a connected configuration.
[0017]
Since the shock absorber of the present invention forms a small tube or a large tube by partially reducing or expanding a straight pipe that can be plastically processed, the wall of the large tube is thinner than the small tube, Large pipes are more likely to be plastically deformed. Further, the step interposed between the small tube body and the large tube body has an S-shaped cross section in which the small tube body is slightly immersed in the large tube body, and the step is indented inwardly. Easy to immerse your body.
[0018]
From this, the shock absorber according to the present invention causes plastic deformation in which the small tubular body is immersed in the large tubular body as it is, and indented inward from the step to the side of the large tubular body, and the impact energy is absorbed as deformation energy of the plastic deformation. To do.
[0019]
The arc angle of each arcuate section of the folded edge of the small tube and the folded edge of the large tube is considered to be in the range of more than 90 degrees and less than 360 degrees. Specifically, the arc angle is (1) the difference between the outer diameter of the small tube and the inner diameter of the large tube, and (2) the arc-shaped cross section of the folded edge of the small tube and the arc-shaped cross section of the folded edge of the large tube. This is determined by the difference in radius (the definition of the radius will be described later). More specifically, each arc angle of the arc-shaped cross section at both side edges is preferably around 180 degrees.
[0020]
In order to reliably cause plastic deformation in which the small pipe is immersed in the large pipe as it is and indented inward from the step to the side of the large pipe, the radius of the arcuate section of the folded edge of the small pipe is set to the large pipe. The step of the S-shaped cross section is made relatively smaller than the radius of the arc-shaped cross section of the folded edge. Here, the small tube side surface and the small tube folding edge and the large tube folding edge continuous to the side surfaces of the small tube body having different thicknesses are curved while changing the thickness. Is the radius of the center line of the plate thickness.
[0021]
The step in the cross-sectional structure suppresses the squeezing of the side surface of the small tube through the folded edge of the small tube that becomes a relatively sharp turn, and conversely the folded edge of the large tube that makes a relatively gentle turn. Invite the side of the large tube that falls through. As a result, the small tubular body can be immersed in the large tubular body as it is, and plastic deformation can be realized in which the small tubular body is drawn inward from the folded edge of the large tubular body to the side surface of the large tubular body.
[0022]
As described above, the present invention realizes the plastic deformation that always immerses the small tubular body toward the large tubular body by devising the structure of the step. However, when an impact (biased load) from an oblique direction is applied to the small tubular body, the small tubular body is tilted with respect to the large tubular body, and the side surface of the small tubular body hits the folded edge of the large tubular body, thereby blocking the above-mentioned immersion of the small tubular body. There is also a risk of being.
[0023]
Therefore, the step is preferably an S-shaped cross section in which the folded edge of the small tubular body and the folded edge of the large tubular body are connected by an annular side surface. The radius of each arcuate section of the folded edge of the small tube and the folded edge of the large tube may be the same or different. That is, as described above, even when the radius of the arcuate cross section of the folded edge of the small tubular body is relatively smaller than the radius of the arcuate cross section of the folded edge of the large tubular body, the inhibiting element that causes the annular side surface to stagnate. It will not be.
[0024]
The annular side surface is parallel to the side surface of the small tubular body and the side surface of the large tubular body when a step of an S-shaped cross section that connects the folded edge of the small tubular body and the folded edge of the large tubular body both having an arc angle of 180 degrees is formed. However, by changing the radius of each arc-shaped cross section of the folded edge of the small tube and the folded edge of the large tube, the side surface of the frustum gradually decreases or expands from the small tube to the large tube. It is preferable. More preferably, a step having an S-shaped cross section is formed in which the radius of the arcuate cross section of the folded edge of the small tubular body is relatively smaller than the radius of the arcuate cross section of the folded edge of the large tubular body, and opens toward the small tubular body. It has an inverted frustum-shaped annular side surface.
[0025]
When the small tubular body is tilted due to an impact from an oblique direction, the annular side surface connecting the folded edge of the small tubular body and the folded edge of the large tubular body should be kept away from the folded edge of the large tubular body. Therefore, the side surface of the small tubular body is brought into contact with the folded edge or the annular side surface of the large tubular body at an early stage to prevent the small tubular body from being largely inclined. Then, at the stage where the small tube starts to be immersed in the large tube, the tilt is corrected while sliding the side surface of the small tube against the folded edge or the annular side surface of the large tube, and the reliable small tube is immersed in the large tube. Guarantee.
[0026]
In order to prevent the small tubular body from tilting more positively, an anti-tilting body that suppresses or prevents the small tubular body from tilting when immersed in the large tubular body may be fixed to the inner surface of the small tubular body. This tilt prevention body is composed of a small-diameter ring portion having an outer diameter equal to the inner diameter of the small tube body and a large-diameter ring portion having an outer diameter equal to the inner diameter of the large tube body, and the small-diameter ring portion is fixed to the inner surface of the small tube body, Projecting from the small tube body to the large tube over the step, the large-diameter ring portion is added to the small tube body obliquely in the axial direction by contacting the inner surface of the large tube body at a position where the small-diameter ring portion exceeds the step. The tilt prevention body integrated with the small tubular body counteracts the applied impact on the basis of the inner surface of the large tubular body, and prevents or suppresses the tilting of the small tubular body.
[0027]
Here, “contacts the inner surface of the large tube” means that when the small tube is immersed in the large tube, the large diameter ring portion is continuously or intermittently on the inner surface of the large tube. Including case of point contact, line contact or surface contact. In addition, the large-diameter ring portion does not need to be in contact with the whole, and if it is a point contact, it suffices if there are multiple point contact points in the direction in which it is desired to prevent the small ring from tilting. You can contact intermittently.
[0028]
In order for the tilt prevention body to exhibit the function of suppressing or preventing the tilt of the small ring itself that immerses in the large tube, the small tube needs to smoothly immerse in the large tube. From this, along with the application of the tilt prevention body, the step of the S-shaped cross section in which the radius of the arcuate section of the folded edge of the small tubular body is made relatively smaller than the radius of the arcuate section of the folded edge of the large tubular body can be formed. desirable.
[0029]
The small-diameter ring portion and the large-diameter ring portion that constitute the tilt prevention body may be configured by separate members, respectively, or, like the stepped tube body that constitutes the shock absorber, an annular body that can be plastically deformed. It may be partly reduced in diameter or increased in diameter and integrally formed through a step. In this case, the small-diameter ring portion corresponds to the small tube body, and the large-diameter ring portion corresponds to the large tube body, but since the tilt prevention body does not require an impact absorbing action due to plastic deformation, a step connecting the small-diameter ring portion and the large-diameter ring portion. Does not require the structural limitations described above.
[0030]
An anti-tilt body in which a plastically deformable ring is partially reduced in diameter or expanded and integrally formed through a step, a small diameter ring projecting from the small tube to the large tube contacts the inner surface of the large tube. The diameter may be expanded to a large diameter ring portion. That is, the small-diameter ring portion is formed in a relatively long tubular shape, and the diameter of the small-diameter ring portion is increased until the end edge of the small-diameter ring portion contacts the inner surface of the large tube body.
[0031]
In addition, the tilt prevention body expands the diameter of the small-diameter ring protruding from the small tube to the large tube until it contacts the inner surface of the large tube, and forms a large-diameter ring as a curling folded toward the small tube. The large-diameter ring part may be formed as a curling that expands the small-diameter ring part protruding from the small pipe body to the inner surface of the large pipe body so as to abut on the inner surface of the large pipe body. Thus, by forming the large-diameter ring portion by curling, it is possible to give the large-diameter ring portion structural strength that resists an impact applied obliquely in the axial direction.
[0032]
Further, the tilt prevention body may be provided with a cylindrical ring in contact with the inner surface of the large tube body in the large diameter ring portion. The cylindrical ring that contacts the inner surface of the large tube over a large area reduces the pressure (impact force / contact surface area) due to the impact applied obliquely in the axial direction, preventing or suppressing the tilting of the small tube Strengthen the work of Since this cylindrical ring is in contact with the inner surface of the large tubular body, it basically has a similar shape to the large tubular body. The curling may be formed on the edge of the cylindrical ring.
[0033]
The anti-tilt body of the present invention only needs to be able to counteract the large tube against the tilt of the small tube. From now on, the small tube body is an anti-tilt body that suppresses or prevents the small tube body from tilting when immersing into the large tube body.TheSpread the folded edge of the small tube toward the inner surface of the large tubeTogetherFormThe
[0034]
The anti-tilt body has a folding edge of the small tubular body having a step of an S-shaped cross section in which the radius of the arcuate cross section of the folding edge of the small tubular body is relatively smaller than the radius of the arcuate cross section of the folding edge of the large tubular body. The small tube folded edge of the S-shaped cross section formed by expanding toward the inner surface of the large tube, or connecting the folded edge of the small tube and the folded edge of the large tube with an annular side surface, It is formed to expand toward the inner surface of the tube body. Each anti-tilt body can be brought into sliding contact with the inner surface of the large tube body as the anti-tilt body while the small tube body is surely immersed in the large tube body.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a bumper support type shock absorber will be described with reference to the drawings. FIG. 1 shows the present invention.Is appliedBumper support type shock absorber 105 and side member type shock absorber 112Reference exampleFIG. 2 is a cross-sectional view of a bumper-support-type shock absorber 105 having a two-stage tubular structure to which a tilt prevention body 104 in which a large-diameter ring portion 103 is formed by a curling 102 folded back toward the small tubular body 101 is attached. 3 is a cross-sectional view corresponding to FIG. 2 showing a stage where an axial impact F starts to be applied to the bumper-supporting shock absorber 105, and FIG. FIG. 5 is a cross-sectional view corresponding to FIG. 2 showing a stage at which the bumper support type shock absorber 105 has absorbed the impact F in the axial direction.
[0036]
referenceAs shown in FIG. 2, the bumper-supporting shock absorber 105 of the example includes a small tube body 101 and a large tube body 106 that are partially reduced in diameter or expanded through a straight tube that can be plastically processed. It consists of a formed two-stage tube.referenceIn the example, the small tubular body 101 and the large tubular body 106 are contracted in the axial direction (see the alternate long and short dash line in FIG. 2, the same applies hereinafter), and the folded edge 107 of the small tubular body with the small curvature radius section and the large tubular body with the large curvature radius section. A step 110 having an S-shaped cross section is formed by connecting the folded edge 108 with an annular side surface 109. As shown in FIG. 1, the bumper-supporting shock absorber 105 has a large pipe 106 connected to each front end of the side member-type shock absorber 112 that constitutes the vehicle body member 111, and the small pipes 101 and 101 are bumpered. The reinforcing material 113 is used in an erected manner.
[0037]
referenceThe tilt prevention body 104 in the example includes a small-diameter ring portion 114 having an outer diameter equal to the inner diameter of the small tube body 101 and a large-diameter ring portion 103 having an outer diameter equal to the inner diameter of the large tube body 106. The large-diameter ring portion 103 is a curling 102 in which the small-diameter ring portion 114 protruding from the small tube body 101 to the large tube body 106 is expanded in diameter until it comes into contact with the inner surface of the large tube body 106, and is turned back toward the small tube body 101. The edge of the curling 102 is brought into contact with the inner surface of the large tubular body 106 at a position beyond the step 110. The tilt prevention body 104 is fixed to the inner surface of the small tube body 101 by spot welding (spot welding marks 115 shown in FIG. 2).
[0038]
When an axial impact F (white arrow in FIG. 3) is applied to the small tubular body 101, the small tubular body 101 enters the large tubular body 106 as shown in FIG. While extending the annular side surface 109, the large tube body 106 is pushed inward by the small tube body 101 through the step 110 (plastic deformation: black arrow in FIG. 3), and the impact energy of the impact F is deformed by the large tube body 106. Absorb as energy. Here, the annular side surface 109 and the large tubular body 106 are each accompanied by plastic deformation (ductility), but most of the plastic deformation occurs in such a manner that the annular side surface 109 extends in accordance with the amount by which the large tubular body 106 is swollen. .
[0039]
referenceIn the case of the example, the folded edge 107 of the small tube sandwiching the step 110 has an arc-shaped cross section having a relatively small radius, and the folded edge 108 of the large tube has an arc-shaped cross section having a relatively large radius. The folded edge 108 of the large tube is easily plastically deformed, and only the large tube 106 is unilaterally swollen without the small tube 101 being rolled. In this way, the plastic deformation that absorbs the impact energy of the impact F is achieved exclusively by the encroachment of the large tubular body 106 having a large diameter, so that it is absorbed compared to the same-type bumper-supported impact absorber in which the small tubular body 101 is encroached. The total amount of impact energy that can be produced is large.
[0040]
Also,referenceIn the example, since a step 110 is formed by connecting the folded edge 107 of the small tube body and the folded edge 108 of the large tube body with the annular side surface 109, the annular body extends in the process of immersing the small tube body 101 into the large tube body 106. The side surface 109 is interposed between the small tube body 101 and the large tube body 106. The annular side surface 109 interposed between the small tube body 101 and the large tube body 106 has a function of preventing or suppressing the tilting of the small tube body 101, and as shown in FIG. There is no possibility that the small tubular body 101 tilts at the stage where it is immersed.
[0041]
The problem is when the impact F is applied from the beginning obliquely in the axial direction. As shown in FIG. 4, the impact F applied obliquely in the axial direction tilts the small tubular body 101 with an axial component fv (downward solid arrow in FIG. 4) that pushes the small tubular body 101 into the large tubular body 106. It can be decomposed into the axis orthogonal component fh (solid arrow pointing to the right in FIG. 4).
[0042]
The tilt prevention body 104 is opposed to the small tubular body 101 that is inclined to receive the axial orthogonal component fh, and the folding edge 107 of the small tubular body approaches the inner surface of the large tubular body 106 on the upstream side of the axial orthogonal component fh. (Refer to the solid line arrow and broken line arrow on the right side in FIG. 4), and on the downstream side of the axial orthogonal component fh, it is countered that the folded edge 107 of the small tube is separated from the inner surface of the large tube 106 (solid line on the left side in FIG. 4). (See arrows and dashed arrows).
[0043]
Each of the above countermeasures is realized by the large-diameter ring portion 103 being in contact with the inner surface of the large tubular body 106 and the tilt prevention body 104 being limited in freedom with respect to the tilting direction of the small tubular body 101. That is, in order for the small tube body 101 to tilt, a load sufficient to break the restriction of freedom = an impact sufficient to deform the entire tilt preventing body 104 must be applied. The tilt prevention body 104 has the small-diameter ring portion 114 fixed to the small tube body 101 so that the curling 102 constituting the large-diameter ring portion 103 is in contact with the large tube body 106. The deformation of the tilt prevention body 104 requires the entire deformation.
[0044]
Furthermore,referenceSince the tilt prevention body 104 in the example has a substantially cylindrical shape, the load necessary for the deformation of the tilt prevention body 104 can be equal regardless of the direction in which the axis orthogonal component fh with respect to the small tube body 101 is applied. In this manner, the small diameter ring portion 114 is fixed to the inner surface of the small tube body 101, and the tilt prevention body 104 that makes the large diameter ring portion 103 abut on the inner surface of the large tube body 106 is provided. It is possible to prevent a tilt in the initial stage when the impact F starts to be applied.
[0045]
As described above, if the small tubular body 101 is immersed in the large tubular body 106 to some extent, the annular side surface 109 can prevent the small tubular body 101 from being tilted. Even if an axially oblique impact F is applied, the small tubular body 101 can be surely immersed in the large tubular body 106 without tilting, and the impact energy of the impact F can be absorbed.
[0046]
As shown in FIG. 5, the small tubular body 101 that is prevented from being tilted has a curling 102 that constitutes the large-diameter ring portion 103 of the tilt preventing body 104 as a front end of the side member-type shock absorber 112 (see FIG. 1, The large tube body 106 can be immersed until it contacts the edge of the body 106). How much impact energy of shock F can be absorbed as a bumper support type shock absorber is determined by the amount of immersing of the small tubular body. For example, an immersive hole or the like that allows the tilt prevention body to immerse is opened at the front end of the side member. If this is done, it is possible to further immerse the small tubular body. In this case, since there is no basis on which the large-diameter ring portion comes into contact, it is preferable to provide a guide that can contact the large-diameter ring portion continuously with the immersion hole.
[0047]
FIG. 6 shows another example in which the large-diameter ring portion 103 is formed by a curling 116 that is turned back inward in the radius of the large tube body 106 and a cylindrical ring 117 that is in contact with the inner surface of the large tube body 106.ReferenceFIG. 7 is a cross-sectional view corresponding to FIG. 2 of a bumper-supporting type shock absorber 119 having a two-stage tubular structure to which an anti-tilt body 118 is attached, and FIG. FIG. 7 is a cross-sectional view corresponding to FIG. 6 showing a stage where energy has been absorbed.
[0048]
The tilt prevention body may have a structure having a large-diameter ring portion that can counter the axially orthogonal component fh of the impact F on the basis of the inner surface of the large tube body in order to counter the tilt of the small tube body.Another referenceAs shown in FIG. 6, the large diameter ring portion 103 of the example expands the diameter of the small diameter ring portion 114 protruding from the small tube body 101 to the large tube body 106 until it abuts against the inner surface of the large tube body 106. In this structure, a cylindrical ring 117 that is in contact with the inner surface of 106 is formed, and then a curling 116 that is folded back inward in the radius of the large tubular body 106 is formed.
[0049]
Another referenceThe function of the example large-diameter ring portion 103 to prevent the small tubular body 101 from tilting is described above.referenceIt is no different from the example (see Fig. 2 and below). The cylindrical ring 117 that is in wide contact with the inner surface of the large tubular body 106 has a function of strengthening the resistance against the tilting of the small tubular body 101.Another referenceIn the example, since the curling 116 inward in the radial direction of the large tubular body 106 is formed subsequent to the cylindrical ring 117, the structural strength of the large diameter annular portion 103 is high, and the tilting of the small tubular body can be prevented better. .
[0050]
Here, the large-diameter annular portion 103 having a width in the axial direction including the cylindrical ring 117 restricts the displacement of the folding edge 107 of the small tubular body 101 of the small tubular body 101 that is immersed in the large tubular body 106, as shown in FIG. As a result, the amount of immersion of the small tubular body 101 is reduced. In this case, by omitting the curling that follows the cylindrical ring, leaving a room where the large-diameter ring plane leading to the cylindrical ring can be plastically deformed, for example, by crushing the large-diameter ring part 103 at the folded edge of the small tube, You can also earn immersive amount of small tubes.
[0051]
FIG. 8 shows that the folded edge of the small tubular body of the step 120 connecting the folded edge 107 of the small tubular body and the folded edge 108 of the large tubular body is expanded toward the inner surface of the large tubular body 106.Example of the embodiment of the present invention (this example)FIG. 9 is a cross-sectional view corresponding to FIG. 2 of a bumper-supporting type shock absorber 122 having a two-stage tube structure provided with the anti-tilt body 121, and FIG. 9 shows the impact energy of an impact F in the axial direction of the bumper-supporting shock absorber 122. FIG. 9 is a cross-sectional view corresponding to FIG.
[0052]
The anti-tilt body separate from the bumper-supporting shock absorber is preferable because of its high degree of freedom in design and manufacture, but requires an assembly process in which the small-diameter ring portion integrated with the large-diameter ring portion is fixed to the small tube body. On the other hand, the tilt prevention body 121 shown in FIG. 8 has an advantage that only the large-diameter ring portion 103 is formed integrally with the small tube body 101, and therefore an assembly process for fixing the small-diameter ring portion to the small tube body is not required. .
[0053]
The tilt prevention body 121 of this example creates a step 120 that connects the folded edge 107 of the small tubular body with a small radius of curvature and the folded edge 108 of the large tubular body with a large radius of curvature. The large tube body 106 is expanded toward the inner surface and is in contact with the inner surface of the large tube body 106. Each of the abovereferenceAlthough it is not an open shape as seen in the example, the annular side surface connecting the folded edge 107 of the small tubular body and the folded edge 108 of the large tubular body corresponds to the annular side surface 109, and the tilt formed integrally with the small tubular body 101 It is possible to prevent the small tubular body 101 from being tilted together with the preventing body 121.
[0054]
The small tubular body 101 receives the impact F from the axial direction and immerses into the large tubular body 106 while pushing the folded edge 107 of the small tubular body outward in the radial direction of the large tubular body 106. The folding edge 107 always comes into sliding contact with the inner surface of the large tube body 106 in the process of the small tube body 101 being immersed in the large tube body 106. Since the tilt prevention body 121 of this example expands with a gentle curvature from the small tube body 101 to the folded edge 107 of the small tube body, the small tube body 101 has the lower end at the front end of the side member type shock absorber 112 (see FIG. 1). 9 (which coincides with the end edge of the large tubular body 106), as shown in FIG. 9, the plastic tube deforms from the folded edge 107 of the small tubular body to the small tubular body 101 and spreads slightly to stop the immersion.
[0055]
next,The present inventionSide member type shock absorberReference example applied toWill be described with reference to the drawings. FIG. 10 is an axial sectional view of the side member type shock absorber 112, and FIG.Reference12 is an axial sectional view of an example side member type shock absorber 112, FIG. 12 is an enlarged sectional view of a portion A in FIG. 10, and FIG. 13 is a sectional view corresponding to FIG. FIG.
[0056]
referenceIn the example, as shown in FIGS. 1 and 10, the vehicle body member 111 is constructed by laying a cross member 124 between the expanded mounting tips 123, 123 of the small tube body 201 constituting the side member type shock absorber 112. The bumper reinforcing material 113 is supported by a bumper support type shock absorber 105 protruding from the cross member 124 coaxially with each small tube body 201. The reason why the mounting tip 123 is expanded is to increase the bonding strength between the cross member 124 and the side member type shock absorber 112. In addition, as shown in FIG. The tip of the body 201 may be inserted as it is and joined.
[0057]
Since the present invention surely causes plastic deformation from the folded edge 204 of the large tubular body of the step 203 to the side surface 205 of the large tubular body, as shown in FIG. The folded edge 206 of the small tubular body and the folded edge 204 of the large tubular body are formed by connecting the side surfaces 207 and 205 of the tubular body 202 with a circular cross section having an arc angle of 180 degrees.
[0058]
In particular,referenceIn the example, the radius of the arcuate section of the folded edge 204 of the large tubular body is about 1.7 times larger than the radius of the arcuate section of the folded edge 206 of the small tubular body. With this radius ratio, as is apparent from FIG. 12, the folded edge 206 of the small tubular body becomes a relatively steep fold, and the folded edge 204 of the large tubular body continues relatively gently with the side surface 205 of the large tubular body. Become a structure.
[0059]
By connecting the small tube body 201 and the large tube body 202 through such a step 203, the outer diameter of the small tube body 201 becomes smaller than the inner diameter of the large tube body 202, and as shown in FIG. If an impact F is applied in the axial direction of the mold shock absorber 112, the shock absorption (referenceIn the example, the small tubular body 201 is immersed in the large tubular body 202 after or substantially simultaneously with the impact absorption by plastic deformation.
[0060]
The immersion of the small tubular body into the large tubular body is mainly based on plastic deformation from the folded edge of the large tubular body to the side surface of the large tubular body (see thick line arrow in FIG. 13). This is because the diameter of the straight pipe is expanded to form the large pipe body 202 (or the diameter of the straight pipe is reduced to form the small pipe body 201). This is because the size can be reduced and the large tube 202 can be more easily plastically deformed than the small tube 201. This plastic deformation continuously occurs so that the large tubular body side surface 205 is sunk inward, so that there is an advantage that high impact energy can be stably absorbed.
[0061]
In order to prevent the small tube body 201 from tilting when the impact F is applied from an oblique direction, a step 203 connecting the folded edge 206 of the small tube body and the folded edge 204 of the large tube body with the annular side surface 208 may be formed. FIG. 14 is equivalent to FIG. 12 of the side member type shock absorber 112 in which the folded edge 206 of the small tube and the folded edge 204 of the large tube are connected by the cylindrical annular side surface 208 parallel to the small tube side surface 207 and the large tube side surface 205. FIG. 15 is a cross-sectional view corresponding to FIG. 14 showing a state where the small tube body 201 is slightly tilted in response to the shock F from the oblique direction. FIG. 16 is a cross-sectional view of the small tube while correcting the tilt. FIG. 15 is a cross-sectional view corresponding to FIG. 14, illustrating a state in which the body 201 is immersed in the large tubular body 202.
[0062]
referenceAs shown in FIG. 14, the side member type shock absorber 112 of the example has a small tube folding edge 206 that is spaced apart from the large tube folding edge 204 having a relatively large radius in the direction in which the small tube 201 is immersed. The step 203 is formed by connecting the folded edge 206 of the small tubular body and the folded edge 204 of the large tubular body by the cylindrical annular side surface 208.
[0063]
Since the small tubular body 201 does not have the small tubular body side surface 207 in close contact with the annular side surface 208, when the impact F is applied from an oblique direction shifted from the axial direction of the side member type shock absorber 112, it can be seen in FIG. Further, the side surface 207 of the small tubular body tilts with the folding edge 206 of the small tubular body as the tilting axis until it contacts the annular side surface 208 or the folding edge 204 of the large tubular body. When contacting the folding edge 204, the tilt of the small tubular body 201 is restricted.
[0064]
Further, when the impact F is further applied, the axially orthogonal component fh of the side member type shock absorber 112 of the impact F is received by the annular side surface 208, and the inclination of the small tubular body 201 cannot be advanced, and FIG. As can be seen, only the axial component fv of the side member type shock absorber 112 of the impact F contributes to the movement of immersing the small tube body 201 into the large tube body 202.
[0065]
The tilting of the small tubular body takes the folding edge of the small tubular body as the tilting axis, and is allowed only in the range of the tangent line from the folding edge of the small tubular body to the circular side surface or the arcuate section of the folding edge of the large tubular body. Therefore, at the stage where the small tubular body 201 is immersed in the large tubular body 202, the small tubular body 201 temporarily corrects the tilt while sliding the small tubular body side surface 207 against the circular side surface 208 or the arcuate section of the folded edge 204 of the large tubular body. Thus, the impact F can only contribute to plastic deformation that causes the large tubular body side surface 205 to be sunk inward from the step 203.
[0066]
The annular side surface 208 may not be parallel to the small tubular body side surface 207 or the large tubular body side surface 205. FIG. 17 is a cross-sectional view corresponding to FIG. 12 of a side member type shock absorber 112 having a truncated cone-shaped annular side surface 209 whose diameter decreases from the small tube body 201 toward the large tube body 202. FIG. FIG. 18 is a cross-sectional view corresponding to FIG. 17, illustrating a state in which the small tubular body 201 is immersed in the large tubular body 202.
[0067]
The annular side surface prevents the small tubular body from tilting, and is in direct contact with the tilting side surface of the small tubular body, and indirectly, the arcuate cross section of the folded edge of the small tubular body serving as the tilting axis is By restricting the tilt angle away from the arcuate section of the folded edge, the small tube body is prevented from tilting. From this, the shape of the annular side surface is free as long as the tilt prevention function can be exhibited. As shown in FIGS. 17 and 18, the small tubular body 201 is moved to the large tubular body 202 without being obstructed even by the truncated cone-shaped annular side surface 209. I can immerse myself.
[0068]
【The invention's effect】
The impact absorber of the present invention can prevent the small tubular body from being immersed in the large tubular body even if an impact is applied from an oblique angle in the axial direction with a larger angle compared to the prior art by specifying the step shape and attaching the tilt preventing body. It can be ensured, and the shock absorbing performance for absorbing the impact energy as the deformation energy of plastic deformation can be sufficiently exhibited.
[0069]
Conventionally, the small tube body tilted about 30 degrees in the axial direction, but in the bumper-supporting shock absorber of the present invention, the axial orthogonal direction component fh exceeds the axial direction component fv up to 45 degrees in the axial direction. In this range, it is possible to secure the immersion of the small tube body with respect to the large tube body. The tilt prevention body has an effect of preventing or suppressing the tilting of the small tubular body with a simple structure.
[0070]
The present invention provides a bumper-supporting type shock absorber made of a tube that supports a vehicle bumper reinforcing member with respect to a vehicle body member, and a side member type shock absorber made of a tube that constitutes a vehicle body member side portion of the vehicle. To do. In the case of the side member type shock absorber, it is possible to avoid the risk of bending at a step and coming into contact with the vehicle body or the fuel tank, and the effect of improving safety is obtained.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a usage mode of a bumper support type shock absorber and a side member type shock absorber.
FIG. 2 is a cross-sectional view of a bumper-supporting shock absorber to which an anti-tilt body that forms a large-diameter ring of curling facing a small tubular body is attached.
FIG. 3 is a cross-sectional view corresponding to FIG. 2 showing a stage where an axial impact F has started to be applied to the bumper-supporting impact absorber.
4 is a cross-sectional view corresponding to FIG. 2, illustrating a stage where an impact F starts to be applied to the bumper-supporting shock absorber obliquely in the axial direction.
5 is a cross-sectional view corresponding to FIG. 2 showing a stage where the bumper-supporting shock absorber has finished absorbing an impact F in the axial direction.
6 is a cross-sectional view corresponding to FIG. 2 of a bumper-supporting shock absorber to which a tilt prevention body having a large-diameter ring portion formed by curling and a cylindrical ring is attached.
7 is a cross-sectional view corresponding to FIG. 6 showing a stage where the bumper-supporting shock absorber has finished absorbing the shock F in the axial direction.
FIG. 8 is a cross-sectional view corresponding to FIG. 2 of a bumper-supporting shock absorber provided with a tilt prevention body formed by expanding a folded edge of a small tubular body.
FIG. 9 is a cross-sectional view corresponding to FIG. 8 showing a stage where the bumper-supporting shock absorber has finished absorbing the shock F in the axial direction.
FIG. 10 is an axial sectional view of a side member type shock absorber.
[Fig. 11] AnotherReferenceIt is an axial sectional view of an example side member type shock absorber.
12 is an enlarged cross-sectional view of a portion A in FIG.
13 is a cross-sectional view corresponding to FIG. 12 showing a process of immersing a small tubular body into a large tubular body.
14 is a cross-sectional view corresponding to FIG. 12 of a side member type shock absorber in which a folded edge of a small tubular body and a folded edge of a large tubular body are connected by a cylindrical annular side surface.
15 is a cross-sectional view corresponding to FIG. 14 showing a state where the small tubular body is slightly tilted in response to an impact F from an oblique direction.
16 is a cross-sectional view corresponding to FIG. 14 showing a state in which the small tube is immersed in the large tube while the application of the impact F continues and the tilt is corrected.
17 is a cross-sectional view corresponding to FIG. 12 of a side member type shock absorber having a truncated cone-shaped annular side surface.
18 is a cross-sectional view corresponding to FIG. 17 illustrating a state in which a small tubular body is immersed in a large tubular body under application of an impact F. FIG.

Claims

Small pipes and large pipes that are connected through a step by partially reducing or expanding the diameter of a straight pipe that can be plastically processed, and the folding edge of the small pipe and the folding edge of the large pipe connected through the step are Both of the shock absorbers have an arcuate cross section with an arc angle of more than 90 degrees, and the step is an S-shaped cross section connecting the folded edge of the small tube and the folded edge of the large tube .
The small tubular body is formed integrally with an anti-tilt body that suppresses or prevents tilting of the small tubular body when immersing into the large tubular body, with the folded edge of the small tubular body being expanded toward the inner surface of the large tubular body. ,
The anti-tilt body has a folding edge of the small tubular body having a step in an S-shaped cross section in which the radius of the arcuate cross section of the folding edge of the small tubular body is relatively smaller than the radius of the arcuate cross section of the folding edge of the large tubular body. An impact absorber formed by expanding toward the inner surface of a large tube .

Small pipes and large pipes that are connected through a step by partially reducing or expanding the diameter of a straight pipe that can be plastically processed, and the folding edge of the small pipe and the folding edge of the large pipe connected through the step are Both of the shock absorbers have an arcuate cross section with an arc angle of more than 90 degrees, and the step is an S-shaped cross section connecting the folded edge of the small tube and the folded edge of the large tube.
The small tubular body is formed integrally with an anti-tilt body that suppresses or prevents tilting of the small tubular body when immersing into the large tubular body, with the folded edge of the small tubular body being expanded toward the inner surface of the large tubular body. ,
The tilt prevention body is formed by expanding the folded edge of the small tubular body at the step of the S-shaped section obtained by connecting the folded edge of the small tubular body and the folded edge of the large tubular body with an annular side surface toward the inner surface of the large tubular body. A shock absorber characterized by that.