JP4184004B2

JP4184004B2 - Cross member structure

Info

Publication number: JP4184004B2
Application number: JP2002243254A
Authority: JP
Inventors: 博行西山
Original assignee: Shinmaywa Industries Ltd
Current assignee: Shinmaywa Industries Ltd
Priority date: 2002-08-23
Filing date: 2002-08-23
Publication date: 2008-11-19
Anticipated expiration: 2022-08-23
Also published as: JP2004082774A

Description

【０００１】
【発明の属する技術分野】
本発明は、自動車等の車両の車体左右両側方を前後方向へ延びるサイドフレーム間に架設されるクロスメンバ構造に関し、特に、ダンプシリンダの基端が接続される接続部を車幅方向中央部に有するものにおいてその接続部から作用する荷重による応力集中を緩和し得るものに係わる。
【０００２】
【従来の技術】
一般に、自動車等の車両の車体左右両側方を前後方向へ延びるサイドフレーム間に架設されるクロスメンバ構造においては、断面略コ字状のクロスメンバが広く採用され、左右のサイドフレームに対しガセットなど補強部材を用いて強固に連結されるようにしている。
【０００３】
【発明が解決しようとする課題】
ところで、ダンプトラックなどの車両にあっては、サイドフレーム上に搭載した荷箱などをダンプさせる上で、ダンプシリンダが取り付けられることがあり、このようなダンプシリンダの基端がクロスメンバに接続されるようになっている。
【０００４】
その場合、ダンプシリンダの基端が接続されるクロスメンバの接続部には、ダンプシリンダの伸縮時に非常に大きな荷重が作用することになり、その構造によっては、クロスメンバの局所に応力が集中的に作用するおそれがある。かかる点から、接続部からの荷重によるクロスメンバの局所への応力集中を緩和させたいという要求がある。
【０００５】
本発明は、かかる点に鑑みてなされたものであり、その目的とするところは、接続部からの荷重によるクロスメンバの局所への応力集中を緩和させことができるクロスメンバ構造を提供することにある。
【０００６】
【課題を解決するための手段】
上記目的を達成するため、請求項１に係わる発明が講じた解決手段は、車両の車幅方向両端下部を車両前後方向に延びる左右一対のサイドフレームの間に架設されるように車幅方向へ延びるクロスメンバ構造を前提とし、上面および車体前後方向一側面を構成するように断面略Ｌ字状に形成された第１メンバパネルと、ダンプシリンダの基端が接続される接続部を車幅方向中央部に有し、車体前後方向他側面を構成するように上記第１メンバパネルの上面他側端に上端が接合された平板状の第２メンバパネルと、下面を構成するように上記第１メンバパネルの車体前後方向一側面下端および第２メンバパネルの下端に前後両端が接合された平板状の第３メンバパネルとを備える。そして、上記第１ないし第３メンバパネルによって閉断面状に形成するとともに、車幅方向左右両外側部の車体前後方向他側面を、車幅方向中央部に対し断面形状を車体前後方向他側方に拡大させるように、車幅方向外方に行くに従い車体前後方向他側に位置付ける構成としたものである。
【０００７】
この特定事項により、左右のサイドフレーム間に架設されたクロスメンバ構造は、第１ないし第３メンバパネルにより閉断面状に形成されているとともに、車幅方向左右両外側部の車体前後方向他側面を車幅方向外方に行くに従い車体前後方向他側に位置付けて断面形状を車体前後方向他側方に拡大させていることにより、クロスメンバ自身の剛性強度が閉断面形状により確保されている上、左右のサイドフレームに対する接合強度も車体前後方向他側方に拡大させた前後方向に長い車幅方向左右両外側部によって十分に確保されることになる。このため、ダンプシリンダ基端の接続部に、ダンプシリンダの伸縮時に非常に大きな荷重が作用しても、局所的な応力集中が緩和されることになる。
【０００８】
特に、局所的な応力集中をより効果的に緩和させ得るものとして、以下の構成が掲げられる。
【０００９】
すなわち、請求項２に係わる発明が講じた解決手段では、第３メンバパネルの車体前後方向他側端を、第２メンバパネルの下端に対し少なくとも肉厚分だけ車体前後方向一側にオフセットするように、第２メンバパネルの下端に接合させている。
【００１０】
この特定事項により、第１ないし第３メンバパネルにより断面矩形状となるクロスメンバ構造において応力集中が危惧される第２メンバパネルの下端部付近から少なくとも肉厚分だけ車体前後方向一側にオフセットさせた位置で第３メンバパネルの車体前後方向他側端が第２メンバパネルに接合されることになり、第３メンバパネルの車体前後方向他側端と第２メンバパネルの下端との接合部位に応力が集中的に作用することがなくなり、第２メンバパネルの下端部付近での局所的な応力集中をより効果的に緩和させることが可能となる。
【００１１】
また、請求項３に係わる発明が講じた解決手段では、車幅方向中央部の車体前後方向他側面と、この車幅方向中央部に対し車体前後方向他側に位置付けられる車幅方向左右両外側部の車体前後方向他側面とを、所定の曲率半径の円弧を介して折曲させている。
【００１２】
この特定事項により、車幅方向左右両外側部の断面形状を車幅方向中央部に対し車体前後方向他側に拡大させるクロスメンバ構造において応力集中が危惧される車幅方向中央部の後面と車幅方向左右両外側部の車体前後方向他側面とを所定の曲率半径の円弧を介して折曲させて連結していることにより、車幅方向中央部の車体前後方向他側面と車幅方向左右両外側部の車体前後方向他側面との連結部位に応力が集中的に作用することなく分散され、車幅方向中央部の車体前後方向他側面と車幅方向左右両外側部の車体前後方向他側面との連結部位での局所的な応力集中をより効果的に緩和させることが可能となる。
【００１３】
更に、請求項４に係わる発明が講じた解決手段では、車幅方向中央部に、少なくとも左右一対のリブを設け、この各リブを、車体前後方向へ延びる略円筒状の接続部に対し、その外径よりも内側位置において車幅方向中央部を車幅方向から仕切るように接合させている。
【００１４】
この特定事項により、車幅方向中央部を車体前後方向へ延びる略円筒状の接続部は、接続部の外径よりも内側位置において車幅方向中央部を車幅方向から仕切るリブによって接合されていることにより、ダンプシリンダの伸縮時に接続部に作用する非常に大きな荷重がリブによって効果的に分散され、接続部付近での局所的な応力集中をより効果的に緩和させることが可能となる。
【００１５】
そして、重量の軽量化を図り得るものとして、以下の構成が掲げられる。
【００１６】
つまり、請求項５に係わる発明が講じた解決手段では、接続部に作用する荷重によって作用する応力が所定値未満となる第３メンバパネルの車幅方向左右両外側部に切欠部を設ける構成としたものである。
【００１７】
この特定事項により、所定値未満の応力しか作用しない第３メンバパネルの車幅方向左右両外側部に切欠部が設けられていることにより、クロスメンバ自身の剛性強度を低下させることなく重量が軽量化されることになる。
【００１８】
【発明の実施の形態】
以下、本発明の実施形態を図面に基づいて説明する。
【００１９】
図１ないし図４は本発明の実施形態に係わるクロスメンバ構造を示し、このクロスメンバ構造は、トラックの車体の左右両側部を前後方向に延びるサイドフレームＳ，Ｓの前後方向略中央部間に用いられている。
【００２０】
図１ないし図４において、クロスメンバＡは、上面および車体前後方向一側面としての前面を構成する断面略Ｌ字状の第１メンバパネル１と、車体前後方向他側面としての後面を構成する平板状の第２メンバパネル２と、下面を構成する平板状の第３メンバパネル３とを備えている。この第１ないし第３メンバパネル１〜３は、クロスメンバＡの車幅方向中央部としての中央部分Ａ１と、車幅方向左右両外側部としての左右両側部分Ａ２，Ａ２とによってそれぞれ構成されている。
【００２１】
上記第１メンバパネル１は、図５および図６にも示すように、クロスメンバＡの上面を構成する上面パネル部１１と、前面を構成する前面パネル部１２とを備えている。上記上面パネル部１１の左右両側部分Ａ２，Ａ２は、その中央部分Ａ１に対し後端が車幅方向外方に行くに従い後方に位置付けられるように略直角二等辺三角形状に形成されている。また、上記前面パネル部１２の中央部分Ａ１の車幅方向中央位置には、後述する接続部２１の前端を挿通させて支持する略真円形状の支持孔部１２ａを備えている。更に、上記第１メンバパネル１の前面パネル部１２の中央部分Ａ１下端は、上記支持孔部１２ａとの干渉を回避するように、車幅方向中央位置に向かって左右両側部分Ａ２，Ａ２からそれぞれ下方に傾斜している。
【００２２】
上記第２メンバパネル２は、図７および図８にも示すように、中央部分Ａ１の車幅方向中央位置の下部にダンプシリンダ（図示せず）の基端が接続される接続部２１を備えている。この接続部２１は、車体前後方向へ延びる略円筒状に形成され、第２メンバパネル２を貫通してその前後方向略中央部が第２メンバパネル２に対し溶接により接合されている。上記接続部２１は、クロスメンバＡに対し第２メンバパネル２よりも車体後方に凸設されている。また、上記第２メンバパネル２の左右両側部分Ａ２，Ａ２と中央部分Ａ１とは、所定の曲率半径の円弧部２２を介して略４５°の角度に折曲されている。そして、上記第２メンバパネル２の上端は、上記第１メンバパネル１の上面パネル部１１の下面後端に溶接により接合されている。この場合、第１メンバパネル１の上面パネル部１１の左右両側部分Ａ２，Ａ２後端と中央部分Ａ１後端とは、第２メンバパネル２の左右両側部分Ａ２，Ａ２と中央部分Ａ１との間の円弧部２２と同様の所定の曲率半径の円弧部１１ａを介して折曲され、これによって、第２メンバパネル２の上端が第１メンバパネル１の上面パネル部１１の下面後端に沿って接合されている。
【００２３】
上記第３メンバパネル３は、図９および図１０にも示すように、上記第１メンバパネル１の前面パネル部１２の中央部分Ａ１下端が車幅方向中央位置に向かって左右両側部分Ａ２，Ａ２からそれぞれ下方に傾斜している形状に則して形成されている。また、上記第３メンバパネル３の中央部分Ａ１は、第１メンバパネル１の中央部分Ａ１とほぼ一致する前後寸法に形成されている。一方、第３メンバパネル３の左右両側部分Ａ２，Ａ２は、その前部がそれぞれ略直角二等辺三角形状の切欠部３２，３２によって切り欠かれ、中央部分Ａ１に対し略一定の前後寸法のまま斜め後方に向かって折曲形成されている。そして、上記第３メンバパネル３の中央部分Ａ１後端と左右両側部分Ａ２，Ａ２後端とは、円弧部３１，３１を介して斜め後ろ外方向きに折曲され、これによって、第３メンバパネル３（中央部分Ａ１後端および左右両側部分Ａ２，Ａ２）の後端面が、第２メンバパネル２の前面下端に対し溶接により接合されている。また、上記第３メンバパネル３の前端（各切欠部３２を除く部分）は、その上に上記第１メンバパネル１の前面パネル部１２の下端面の一部（後端側）が載置された状態で、前面パネル部１２の下端に溶接により接合されている。この場合、第３メンバパネル３の左右両側部分Ａ２，Ａ２の前部は、図１１に示すように、ダンプシリンダの伸縮時、特に伸長時に、接続部２１に対し車体後方から入力される約０．０５Ｗｋｇｆ（Ｗは荷台からの負荷荷重）の大きな荷重と上方の荷箱から入力されるＷｋｇｆの大きな荷重とが作用しても、クロスメンバＡに応力が集中し難い部位、つまり所定値未満の応力しか作用しない部位であることから、不要な重量増加を避ける上で、切欠部３２，３２が設けられるようになっている。なお、図１１において、斜線部分が応力の作用する部位であり、その間隔が密になるに従って大きな応力が作用していることを示している。
【００２４】
そして、上記クロスメンバＡは、第１ないし第３メンバパネル１〜３によって車体左右方向に延びる閉断面状に形成されているとともに、左右両外側部分Ａ２，Ａ２の後面は、中央部分Ａ１に対し断面形状を車体後方に拡大させるように、車幅方向外方に行くに従い後方に位置付けられている。
【００２５】
また、クロスメンバＡ（第１ないし第３メンバパネル１〜３）の中央部分Ａ１には、左右一対のリブ４，４が設けられている。この各リブ４は、第１メンバパネル１の上面パネル部１１の中央部分Ａ１下面より下方に突設され、第２メンバパネル２の中央部分Ａ１の車幅方向中央位置下部を車体前後方向へ延びる略円筒形状の接続部２１に対し、その外径よりも若干内側位置においてクロスメンバＡの中央部分Ａ１を左右方向（車幅方向）から仕切るように接合されている。
【００２６】
更に、第１ないし第３メンバパネル１〜３の左右両外側部分Ａ２，Ａ２の外端には、サイドフレームＳ，Ｓの内端面に対し接合される前後方向に長い支持プレート５，５が溶接により接合されている。この場合、第３メンバパネル３の左右両外側部分Ａ２，Ａ２の外端部は、後方に延設されてサイドフレームＳ，Ｓに対する前後方向への支持点間距離を確保し、第３メンバパネル３に作用した応力がサイドフレームＳ，Ｓに対し支持プレート５，５を介して円滑に伝達されるようになっている。
【００２７】
したがって、上記実施形態では、左右のサイドフレームＳ，Ｓ間に架設されたクロスメンバＡは、第１ないし第３メンバパネル１〜３により閉断面状に形成されているとともに、左右両外側部分Ａ２，Ａ２の後面を車幅方向外方に行くに従い後方に位置付けて断面形状を車体後方に拡大させているので、クロスメンバＡ自身の剛性強度が閉断面形状により確保されている上、左右のサイドフレームＳ，Ｓに対する接合強度も後方に拡大させた前後方向に長い左右両外側部分Ａ２，Ａ２によって十分に確保されることになる。このため、ダンプシリンダ基端の接続部２１に、ダンプシリンダの伸縮時に車体後方および上方から非常に大きな荷重が作用しても、クロスメンバＡの局所に応力を集中させることなく緩和させることができる。
【００２８】
その上、第３メンバパネル３（中央部分Ａ１後端および左右両側部分Ａ２，Ａ２）の後端面が、第２メンバパネル２の前面下端に対し溶接により接合されているので、第１ないし第３メンバパネル１〜３により断面矩形状となるクロスメンバＡにおいて応力集中が危惧される第２メンバパネル２後面下端付近から前方へ肉厚分だけオフセットさせた前面下端位置で、第３メンバパネル３の後端面に対し接合されることになる。このため、第３メンバパネル３の後端面と第２メンバパネル２の前面下端との接合部位に応力が集中的に作用することがなくなり、第２メンバパネル２下端の後面下端位置付近での局所的な応力集中をより効果的に緩和させることができる。
【００２９】
また、第１メンバパネル１の上面パネル部１１の中央部分Ａ１後端と左右両側部分Ａ２，Ａ２後端は、第２メンバパネル２の左右両側部分Ａ２，Ａ２と中央部分Ａ１との間の円弧部２２と同様の所定の曲率半径の円弧部１１ａを介して折曲されているので、左右両側部分Ａ２，Ａ２の断面形状を中央部分Ａ１に対し車体後方に拡大させるクロスメンバ構造において応力集中が危惧される中央部分Ａ１の後面と左右両側部分Ａ２，Ａ２の後面とを所定の曲率半径の円弧部１１ａ，２２を介して折曲させて連結していることにより、中央部分Ａ１の後面と左右両側部分Ａ２，Ａ２の後面との連結部位に応力が集中的に作用することなく分散され、中央部分Ａ１の後面と左右両側部分Ａ２，Ａ２の後面との連結部位での局所的な応力集中をより効果的に緩和させることができる。
【００３０】
更に、クロスメンバＡ（第１ないし第３メンバパネル１〜３）の中央部分Ａ１において第１メンバパネル１の上面パネル部１１の中央部分Ａ１下面より下方に突設された左右一対のリブ４，４が、第２メンバパネル２の中央部分Ａ１の略円筒形状の接続部２１に対しその外径よりも若干内側位置でクロスメンバＡの中央部分Ａ１を左右方向（車幅方向）から仕切るように接合されているので、ダンプシリンダの伸縮時に接続部２１に車体後方および上方から作用する非常に大きな荷重が各リブ４によって効果的に分散され、接続部２１付近での局所的な応力集中をより効果的に緩和させることができる。
【００３１】
しかも、ダンプシリンダの伸長時に、接続部２１に対し車体後方および上方から大きな荷重が作用しても、クロスメンバＡに応力が集中し難い部位、つまり所定値未満の応力しか作用しない部位となる第３メンバパネル３の左右両側部Ａ２，Ａ２の前部に切欠部３２，３２が設けられているので、クロスメンバＡ自身の剛性強度を低下させることなく重量を軽量化させることができる。
【００３２】
なお、本発明は、上記実施形態に限定されるものではなく、その他種々の変形例を包含している。例えば、上記実施形態では、第２メンバパネル２の前面下端に第３メンバパネル３の後端面を接合したが、第２メンバパネルの下端を前方に折曲し、その折曲部から肉厚分以上前方にオフセットさせた先端位置で、第３メンバパネルの後端面が溶接により接合されるようにしてもよく、要するに、第３メンバパネルの後端面が、第２メンバパネルの下端に対し肉厚分以上前方にオフセットさせた状態で、第２メンバパネルの前面下端に接合されていればよい。
【００３３】
また、上記実施形態では、クロスメンバＡの中央部分Ａ１を左右方向から仕切る左右一対のリブ４，４により接続部２１を接合したが、３つ以上のリブによって接続部を接合してクロスメンバの中央部分が左右方向から仕切られていてもよい。
【００３４】
更に、上記実施形態では、上面および前面を構成する断面略Ｌ字状の第１メンバパネル１と、後面を構成する平板状の第２メンバパネル２と、下面を構成する平板状の第３メンバパネル３とでクロスメンバＡを構成したが、上面および車体前後方向一側面としての後面を構成する断面略Ｌ字状の第１メンバパネルと、車体前後方向他側面としての前面を構成する平板状の第２メンバパネルと、下面を構成する平板状の第３メンバパネルとでクロスメンバが構成されていてもよい。この場合、第２メンバパネルの中央部分の車幅方向中央位置の下部にダンプシリンダの基端を接続する接続部が前方に凸設されることになる。
【００３５】
【発明の効果】
以上の如く、本発明の請求項１に係わるクロスメンバ構造によれば、第１ないし第３メンバパネルによって車幅方向に延びる閉断面状に形成するとともに、車幅方向左右両外側部の車体前後方向他側面を車幅方向外方に行くに従い車体前後方向他側に位置付けて断面形状を車体前後方向他側方に拡大させることで、クロスメンバ自身の剛性強度を閉断面形状により確保する上、左右のサイドフレームに対する接合強度も十分に確保し、ダンプシリンダの伸縮時にダンプシリンダ基端の接続部に非常に大きな荷重が作用した際の局所的な応力集中を緩和させることができる。
【００３６】
そして、本発明の請求項２に係わるクロスメンバ構造によれば、応力集中が危惧される第２メンバパネルの下端部付近から少なくとも肉厚分だけ車体前後方向一側にオフセットさせた位置で第３メンバパネルの車体前後方向他側端を第２メンバパネルに接合することで、第３メンバパネルの車体前後方向他側端と第２メンバパネルの下端との接合部位への応力集中を防止し、第２メンバパネル下端部付近での局所的な応力集中をより効果的に緩和させることができる。
【００３７】
また、本発明の請求項３に係わるクロスメンバ構造によれば、応力集中が危惧される車幅方向中央部の車体前後方向他側面と車幅方向左右両外側部の車体前後方向他側面とを所定の曲率半径の円弧を介して折曲させて連結することで、車幅方向中央部と車幅方向左右両外側部との車体前後方向他側端同士の連結部位への応力集中を分散し、車幅方向中央部と車幅方向左右両外側部との車体前後方向他側端同士の連結部位での局所的な応力集中をより効果的に緩和させることができる。
【００３８】
更に、本発明の請求項４に係わるクロスメンバ構造によれば、車幅方向中央部を車体前後方向へ延びる略円筒状の接続部を、その外径よりも内側位置において車幅方向中央部を車幅方向から仕切るリブによって接合することで、ダンプシリンダの伸縮時に接続部に作用する非常に大きな荷重をリブによって効果的に分散し、接続部付近での局所的な応力集中をより効果的に緩和させることができる。
【００３９】
しかも、本発明の請求項５に係わるクロスメンバ構造によれば、所定値未満の応力しか作用しない第３メンバパネルの車幅方向左右両外側部に切欠部を設けることで、クロスメンバ自身の剛性強度を低下させることなく重量を軽量化することができる。
【図面の簡単な説明】
【図１】本発明の実施形態に係るクロスメンバ構造を斜め下方から見た斜視図である。
【図２】クロスメンバ構造を車体下方から見た底面図である。
【図３】クロスメンバ構造を車体後方から見た背面図である。
【図４】図３のＸ−Ｘ線において切断した断面図である。
【図５】第１メンバパネルを車体前方から見た正面図である。
【図６】第１メンバパネルを車体下方から見た底面図である。
【図７】第２メンバパネルを車体後方から見た背面図である。
【図８】第２メンバパネルを車体下方から見た底面図である。
【図９】第３メンバパネルを車体後方から見た背面図である。
【図１０】第３メンバパネルを車体下方から見た底面図である。
【図１１】ダンプシリンダ伸縮時における支持部への荷重によりクロスメンバに作用する応力の分布状況を示す図である。
【符号の説明】
１第１メンバパネル
１１上面パネル部（クロスメンバの上面）
１１ａ円弧部（円弧）
１２前面パネル部（クロスメンバの前面）
２第２メンバパネル
２１接続部
２２円弧部（円弧）
３第３メンバパネルと
３２切欠部
４リブ
Ａクロスメンバ
Ａ１中央部分（車幅方向中央部）
Ａ２左右両側部分（車幅方向左右両外側部）
Ｓサイドフレーム[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cross member structure constructed between side frames extending in the front-rear direction on both the left and right sides of a vehicle such as an automobile, and in particular, a connecting portion to which a base end of a dump cylinder is connected is provided at a vehicle width direction central portion. The present invention relates to a structure that can relieve stress concentration due to a load acting from the connecting portion.
[0002]
[Prior art]
In general, in a cross member structure installed between side frames extending in the front-rear direction on both the left and right sides of a vehicle such as an automobile, a cross member having a substantially U-shaped cross section is widely used, and gussets are used for the left and right side frames. It is made to be firmly connected using a reinforcing member.
[0003]
[Problems to be solved by the invention]
By the way, in a vehicle such as a dump truck, a dump cylinder may be attached when dumping a packing box mounted on a side frame, and the base end of such a dump cylinder is connected to a cross member. It has become so.
[0004]
In that case, a very large load acts on the connecting part of the cross member to which the base end of the dump cylinder is connected when the dump cylinder expands and contracts, and depending on the structure, stress is concentrated locally on the cross member. May affect From such a point, there is a demand for relaxing stress concentration on the cross member locally due to the load from the connecting portion.
[0005]
The present invention has been made in view of such points, and an object of the present invention is to provide a cross member structure that can alleviate stress concentration on the cross member due to a load from a connecting portion. is there.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the solution provided by the invention according to claim 1 is the vehicle width direction so as to be installed between a pair of left and right side frames extending in the vehicle front-rear direction at both lower ends in the vehicle width direction. Assuming an extending cross member structure, the first member panel formed in a substantially L-shaped cross section so as to constitute the upper surface and one side surface in the longitudinal direction of the vehicle body and a connecting portion to which the base end of the dump cylinder is connected are arranged in the vehicle width direction. A flat plate-like second member panel having an upper end joined to the other side end of the upper surface of the first member panel so as to constitute the other side surface in the longitudinal direction of the vehicle body and the first side so as to constitute the lower surface. And a flat plate-like third member panel having both front and rear ends joined to the lower end of one side surface of the member panel in the vehicle longitudinal direction and the lower end of the second member panel. The first to third member panels are formed in a closed cross-sectional shape, and the vehicle body front-rear direction other side surfaces of the left and right outer sides in the vehicle width direction are cross-sectionally shaped in the vehicle width direction center side. Thus, the vehicle is positioned on the other side in the vehicle longitudinal direction as it goes outward in the vehicle width direction.
[0007]
Due to this specific matter, the cross member structure erected between the left and right side frames is formed in a closed cross-sectional shape by the first to third member panels, and the other side surface in the vehicle longitudinal direction at both the left and right outer portions in the vehicle width direction. As the cross section is positioned on the other side in the longitudinal direction of the vehicle as it goes outward in the vehicle width direction, the cross-sectional shape is expanded to the other side in the longitudinal direction of the vehicle, so that the rigidity strength of the cross member itself is secured by the closed cross-sectional shape. Also, the bonding strength to the left and right side frames is sufficiently ensured by the left and right outer portions in the vehicle width direction that are long in the front-rear direction and expanded in the front-rear direction of the vehicle body. For this reason, even if a very large load acts on the connecting portion of the dump cylinder base end during expansion and contraction of the dump cylinder, local stress concentration is alleviated.
[0008]
In particular, the following configurations are listed as those that can relieve local stress concentration more effectively.
[0009]
That is, in the solution provided by the invention according to claim 2, the other end of the third member panel in the longitudinal direction of the vehicle body is offset to one side in the longitudinal direction of the vehicle body by at least the wall thickness with respect to the lower end of the second member panel. And joined to the lower end of the second member panel.
[0010]
Due to this specific matter, the cross-member structure having a rectangular cross section by the first to third member panels is offset from the vicinity of the lower end portion of the second member panel, which is concerned about stress concentration, to at least one wall thickness in the longitudinal direction of the vehicle body. The other end of the third member panel in the longitudinal direction of the vehicle body is joined to the second member panel at the position, and stress is applied to the joint portion between the other side of the third member panel in the longitudinal direction of the vehicle body and the lower end of the second member panel. Does not act intensively, and local stress concentration in the vicinity of the lower end of the second member panel can be more effectively mitigated.
[0011]
Further, in the solution provided by the invention according to claim 3, the vehicle body longitudinal direction other side surface at the vehicle width direction central portion and the vehicle width direction left and right outer sides positioned on the vehicle body longitudinal direction other side with respect to the vehicle width direction central portion The other side surface of the vehicle body in the front-rear direction is bent through an arc having a predetermined radius of curvature.
[0012]
Due to this specific matter, the rear surface of the vehicle width direction center and the vehicle width in the cross member structure that expands the cross-sectional shape of the left and right outer sides in the vehicle width direction to the other side in the vehicle longitudinal direction relative to the vehicle width direction center. The other side of the vehicle body in the longitudinal direction of the vehicle body is connected to the other side surface in the longitudinal direction of the vehicle body by bending it through an arc having a predetermined radius of curvature, thereby Stress is distributed without intensively acting on the connecting part of the outer part with the other side surface in the longitudinal direction of the vehicle body, and the other side surface in the longitudinal direction of the vehicle body in the central part in the vehicle width direction and the other side surface in the longitudinal direction in the vehicle width direction. It is possible to more effectively alleviate local stress concentration at the connection site.
[0013]
Further, in the solution means taken by the invention according to claim 4, at least a pair of left and right ribs are provided at the center in the vehicle width direction, and each of these ribs is connected to a substantially cylindrical connecting portion extending in the longitudinal direction of the vehicle body. The central part in the vehicle width direction is joined so as to be partitioned from the vehicle width direction at a position inside the outer diameter.
[0014]
Due to this specific matter, the substantially cylindrical connecting portion extending in the vehicle width direction center portion in the vehicle width direction is joined by ribs that partition the vehicle width direction center portion from the vehicle width direction at a position inside the outer diameter of the connection portion. As a result, a very large load acting on the connecting portion when the dump cylinder expands and contracts is effectively dispersed by the rib, and the local stress concentration in the vicinity of the connecting portion can be more effectively mitigated.
[0015]
And as the thing which can achieve weight reduction, the following structures are hung up.
[0016]
In other words, in the solution provided by the invention according to claim 5, the configuration is such that the notch portions are provided on both the left and right outer sides in the vehicle width direction of the third member panel where the stress acting on the connecting portion is less than a predetermined value. It is a thing.
[0017]
Due to this specific matter, the cut-out portions are provided on the left and right outer side portions in the vehicle width direction of the third member panel where only a stress of less than a predetermined value acts, thereby reducing the weight without reducing the rigidity strength of the cross member itself. Will be converted.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0019]
1 to 4 show a cross member structure according to an embodiment of the present invention. This cross member structure is formed between the left and right side portions of the truck body in the front and rear direction and between the front and rear direction substantially central portions of the side frames S and S. It is used.
[0020]
1 to 4, a cross member A includes a first member panel 1 having a substantially L-shaped cross section that constitutes an upper surface and a front surface as one side surface in the vehicle longitudinal direction, and a flat plate that constitutes a rear surface as the other side surface in the vehicle longitudinal direction. Second member panel 2 and a flat plate-like third member panel 3 constituting the lower surface. The first to third member panels 1 to 3 are respectively constituted by a center portion A1 as a center portion in the vehicle width direction of the cross member A and left and right side portions A2 and A2 as left and right outer portions in the vehicle width direction. Yes.
[0021]
As shown in FIGS. 5 and 6, the first member panel 1 includes an upper panel portion 11 constituting the upper surface of the cross member A and a front panel portion 12 constituting the front surface. The left and right side portions A2, A2 of the upper panel portion 11 are formed in a substantially right-angled isosceles triangle shape so that the rear end thereof is positioned rearward as it goes outward in the vehicle width direction with respect to the center portion A1. Further, at the center position in the vehicle width direction of the center portion A1 of the front panel portion 12, there is provided a substantially circular support hole portion 12a for inserting and supporting the front end of the connecting portion 21 described later. Further, the lower end of the center portion A1 of the front panel portion 12 of the first member panel 1 is respectively separated from the left and right side portions A2 and A2 toward the center position in the vehicle width direction so as to avoid interference with the support hole portion 12a. Inclined downward.
[0022]
As shown in FIGS. 7 and 8, the second member panel 2 includes a connection portion 21 to which a base end of a dump cylinder (not shown) is connected to a lower portion of the center portion A1 in the vehicle width direction center position. ing. The connecting portion 21 is formed in a substantially cylindrical shape extending in the longitudinal direction of the vehicle body, penetrates through the second member panel 2 and is joined to the second member panel 2 by welding at a substantially central portion in the longitudinal direction. The connecting portion 21 protrudes rearward of the cross member A from the second member panel 2 relative to the vehicle body. Further, the left and right side portions A2, A2 and the central portion A1 of the second member panel 2 are bent at an angle of about 45 ° via an arc portion 22 having a predetermined radius of curvature. The upper end of the second member panel 2 is joined to the lower rear end of the upper panel portion 11 of the first member panel 1 by welding. In this case, the rear left and right side portions A2 and A2 and the rear end of the center portion A1 of the upper panel portion 11 of the first member panel 1 are between the left and right side portions A2 and A2 of the second member panel 2 and the central portion A1. The upper end of the second member panel 2 is bent along the lower rear end of the upper panel portion 11 of the first member panel 1 by being bent through an arc portion 11a having a predetermined radius of curvature similar to the arc portion 22 of the first member panel 1. It is joined.
[0023]
As shown in FIGS. 9 and 10, the third member panel 3 has both the left and right side portions A2, A2 at the lower end of the center portion A1 of the front panel portion 12 of the first member panel 1 toward the center position in the vehicle width direction. Are formed in accordance with the shape inclined downward. Further, the central portion A1 of the third member panel 3 is formed to have a front-rear dimension that substantially coincides with the central portion A1 of the first member panel 1. On the other hand, the left and right side portions A2 and A2 of the third member panel 3 are cut out at the front portions thereof by cutout portions 32 and 32 having substantially right-angled isosceles triangles, respectively, and the front and rear dimensions are substantially constant with respect to the central portion A1. It bends diagonally backward. The rear end of the center portion A1 and the left and right side portions A2 and A2 of the third member panel 3 are bent obliquely rearward and outward via the arc portions 31 and 31, thereby the third member. The rear end surface of the panel 3 (the rear end of the central portion A1 and the left and right side portions A2, A2) is joined to the lower end of the front surface of the second member panel 2 by welding. Further, a part of the lower end surface (rear end side) of the front panel portion 12 of the first member panel 1 is placed on the front end of the third member panel 3 (excluding the notches 32). In this state, it is joined to the lower end of the front panel portion 12 by welding. In this case, as shown in FIG. 11, the front portions of the left and right side portions A2 and A2 of the third member panel 3 are about 0 inputted from the rear of the vehicle body to the connecting portion 21 when the dump cylinder is extended and contracted, particularly when extended. .05 Wkgf (W is the load applied from the loading platform) and a portion where stress is difficult to concentrate on the cross member A even if a large load of Wkgf input from the upper packing box is applied, that is, less than a predetermined value Since it is a site where only stress acts, notches 32 are provided in order to avoid an unnecessary increase in weight. In FIG. 11, the shaded portion is a portion where stress acts, and shows that a large stress is acting as the interval becomes dense.
[0024]
The cross member A is formed in a closed cross section extending in the left-right direction of the vehicle body by the first to third member panels 1 to 3, and the rear surfaces of the left and right outer portions A2 and A2 are located with respect to the center portion A1. It is positioned rearward as it goes outward in the vehicle width direction so as to expand the cross-sectional shape rearward of the vehicle body.
[0025]
In addition, a pair of left and right ribs 4 and 4 are provided in the central portion A1 of the cross member A (first to third member panels 1 to 3). The ribs 4 project downward from the lower surface of the central portion A1 of the upper surface panel portion 11 of the first member panel 1 and extend in the vehicle width direction central position lower portion of the central portion A1 of the second member panel 2 in the vehicle longitudinal direction. It joins with respect to the connection part 21 of a substantially cylindrical shape so that the center part A1 of the cross member A may be partitioned from the left-right direction (vehicle width direction) at a position slightly inside the outer diameter.
[0026]
Furthermore, long support plates 5 and 5 which are joined to the inner end surfaces of the side frames S and S are welded to the outer ends of the left and right outer portions A2 and A2 of the first to third member panels 1 to 3, respectively. It is joined by. In this case, the outer end portions of the left and right outer portions A2, A2 of the third member panel 3 are extended rearward to ensure the distance between the support points in the front-rear direction with respect to the side frames S, S, and the third member panel 3 is transmitted smoothly to the side frames S, S via the support plates 5, 5.
[0027]
Therefore, in the above embodiment, the cross member A installed between the left and right side frames S, S is formed in a closed cross-sectional shape by the first to third member panels 1 to 3, and the left and right outer portions A2. , The rear surface of A2 is positioned rearward as it goes outward in the vehicle width direction, and the cross-sectional shape is enlarged to the rear of the vehicle body, so that the rigidity strength of the cross member A itself is ensured by the closed cross-sectional shape, and the left and right sides The joint strength with respect to the frames S and S is sufficiently secured by the left and right outer portions A2 and A2 which are extended rearward and long in the front-rear direction. For this reason, even if a very large load acts on the connecting portion 21 at the base end of the dump cylinder from the rear and the upper side of the vehicle body when the dump cylinder is expanded and contracted, it can be relaxed without concentrating stress locally on the cross member A. .
[0028]
In addition, the rear end surfaces of the third member panel 3 (the rear end of the central portion A1 and the left and right side portions A2, A2) are joined to the lower end of the front surface of the second member panel 2 by welding. The rear end of the third member panel 3 is shifted from the vicinity of the lower end of the rear surface of the second member panel 2 where the stress concentration is a concern in the cross member A having a rectangular cross section by the member panels 1 to 3 to the front. It will be joined to the end face. For this reason, the stress does not concentrate on the joining portion between the rear end surface of the third member panel 3 and the lower end of the front surface of the second member panel 2, and the local area near the rear lower end position of the lower end of the second member panel 2 is prevented. The effective stress concentration can be alleviated more effectively.
[0029]
The rear end of the center portion A1 and the left and right side portions A2 and A2 of the top panel portion 11 of the first member panel 1 are arcs between the left and right side portions A2 and A2 of the second member panel 2 and the center portion A1. Since it is bent through an arc portion 11a having a predetermined radius of curvature similar to that of the portion 22, stress concentration is concentrated in the cross member structure in which the cross-sectional shapes of the left and right side portions A2 and A2 are expanded rearward of the center portion A1. The rear surface of the central portion A1 and the rear surfaces of the left and right side portions A2 and A2 are bent and connected via the arc portions 11a and 22 having a predetermined radius of curvature, so that the rear surface of the central portion A1 is connected to the left and right sides. The stress is distributed without concentrating on the connecting portion with the rear surface of the portions A2 and A2, and the local stress concentration at the connecting portion between the rear surface of the central portion A1 and the rear surfaces of the left and right side portions A2 and A2 is further increased. effect It can be relaxed.
[0030]
Further, a pair of left and right ribs 4 projecting downward from the lower surface of the central portion A1 of the upper panel portion 11 of the first member panel 1 at the central portion A1 of the cross member A (first to third member panels 1 to 3). 4 divides the central portion A1 of the cross member A from the left and right direction (vehicle width direction) at a position slightly inside the outer diameter with respect to the substantially cylindrical connecting portion 21 of the central portion A1 of the second member panel 2. Since they are joined, a very large load acting on the connecting portion 21 from behind and above the vehicle body is effectively dispersed by the ribs 4 when the dump cylinder is expanded and contracted, and the local stress concentration in the vicinity of the connecting portion 21 is further increased. Can be effectively mitigated.
[0031]
In addition, when the dump cylinder is extended, even if a large load is applied to the connection portion 21 from the rear and upper side of the vehicle body, the portion where stress is difficult to concentrate on the cross member A, that is, the portion where only the stress less than a predetermined value acts. Since the notches 32 and 32 are provided in front of the left and right side portions A2 and A2 of the three-member panel 3, the weight can be reduced without reducing the rigidity strength of the cross member A itself.
[0032]
In addition, this invention is not limited to the said embodiment, The other various modifications are included. For example, in the above embodiment, the rear end surface of the third member panel 3 is joined to the lower end of the front surface of the second member panel 2, but the lower end of the second member panel is bent forward, and the thickness of the bent portion is increased. The rear end surface of the third member panel may be joined by welding at the front end position offset forward as described above. In short, the rear end surface of the third member panel is thicker than the lower end of the second member panel. What is necessary is just to join to the front lower end of the 2nd member panel in the state offset by more than a minute.
[0033]
Moreover, in the said embodiment, although the connection part 21 was joined by the left-right paired ribs 4 and 4 which partition the center part A1 of the cross member A from the left-right direction, a connection part is joined by three or more ribs, and cross member's The central part may be partitioned from the left-right direction.
[0034]
Furthermore, in the said embodiment, the 1st member panel 1 of the substantially L-shaped cross section which comprises an upper surface and a front surface, the flat plate-like 2nd member panel 2 which comprises a rear surface, and the flat plate-like 3rd member which comprises a lower surface. The cross member A is constituted by the panel 3, but the first member panel having a substantially L-shaped cross section constituting the upper surface and the rear surface as one side surface in the vehicle longitudinal direction and the flat plate shape constituting the front surface as the other side surface in the vehicle longitudinal direction. The cross member may be comprised by the 2nd member panel of this, and the flat 3rd member panel which comprises a lower surface. In this case, a connecting portion for connecting the base end of the dump cylinder is projected forward from the lower portion of the center portion of the second member panel in the vehicle width direction.
[0035]
【The invention's effect】
As described above, according to the cross member structure of the first aspect of the present invention, the first to third member panels are formed in a closed cross section extending in the vehicle width direction, and the front and rear sides of the vehicle body at the left and right outer portions in the vehicle width direction are formed. As the other side of the direction goes to the outside in the vehicle width direction, the cross-sectional shape is expanded to the other side in the vehicle front-rear direction by positioning it on the other side in the vehicle front-rear direction. Bonding strength to the left and right side frames is sufficiently secured, and local stress concentration when a very large load is applied to the connecting portion of the dump cylinder base end when the dump cylinder is expanded or contracted can be reduced.
[0036]
According to the cross member structure according to claim 2 of the present invention, the third member is at a position offset from the vicinity of the lower end portion of the second member panel, where the stress concentration is a concern, to at least one wall thickness in the longitudinal direction of the vehicle body. By joining the other side end of the panel in the front-rear direction of the vehicle body to the second member panel, stress concentration on the joint portion between the other side end of the third member panel in the front-rear direction of the vehicle body and the lower end of the second member panel is prevented. The local stress concentration in the vicinity of the lower end of the two-member panel can be alleviated more effectively.
[0037]
According to the cross member structure according to claim 3 of the present invention, the vehicle body front-rear direction other side surface in the vehicle width direction central portion where stress concentration is a concern and the vehicle body front-rear direction other side surface in the vehicle width direction left and right outer portions are predetermined. By bending and connecting via an arc with a radius of curvature, the stress concentration on the connecting part between the other ends of the vehicle body in the vehicle width direction at the vehicle width direction center and the vehicle width direction left and right outer portions is dispersed, It is possible to more effectively alleviate the local stress concentration at the connecting portion between the other ends in the vehicle longitudinal direction of the vehicle width direction central portion and the vehicle width direction left and right outer portions.
[0038]
Further, according to the cross member structure according to claim 4 of the present invention, the substantially cylindrical connecting portion extending in the vehicle longitudinal direction in the vehicle width direction central portion is arranged at the vehicle width direction central portion at a position inside the outer diameter. By joining with ribs partitioning from the vehicle width direction, very large load acting on the connection part when the dump cylinder expands and contracts is effectively dispersed by the rib, and local stress concentration near the connection part is more effectively Can be relaxed.
[0039]
In addition, according to the cross member structure according to claim 5 of the present invention, the notch portions are provided on the left and right outer side portions in the vehicle width direction of the third member panel that only exerts a stress less than a predetermined value, whereby the rigidity of the cross member itself is increased. The weight can be reduced without reducing the strength.
[Brief description of the drawings]
FIG. 1 is a perspective view of a cross member structure according to an embodiment of the present invention viewed obliquely from below.
FIG. 2 is a bottom view of the cross member structure as viewed from below the vehicle body.
FIG. 3 is a rear view of the cross member structure as viewed from the rear of the vehicle body.
4 is a cross-sectional view taken along line XX of FIG.
FIG. 5 is a front view of the first member panel as viewed from the front of the vehicle body.
FIG. 6 is a bottom view of the first member panel as viewed from below the vehicle body.
FIG. 7 is a rear view of the second member panel as viewed from the rear of the vehicle body.
FIG. 8 is a bottom view of the second member panel as viewed from below the vehicle body.
FIG. 9 is a rear view of the third member panel as viewed from the rear of the vehicle body.
FIG. 10 is a bottom view of the third member panel as viewed from below the vehicle body.
FIG. 11 is a diagram illustrating a distribution state of stress acting on the cross member due to a load on the support portion when the dump cylinder is extended and contracted.
[Explanation of symbols]
1 First member panel 11 Upper panel (upper surface of cross member)
11a Arc part (arc)
12 Front panel (front of cross member)
2 Second member panel 21 Connection portion 22 Arc portion (arc)
3 Third member panel and 32 Notch part 4 Rib A Cross member A1 Center part (vehicle width direction center part)
A2 Left and right side parts (vehicle width direction left and right outer parts)
S side frame

Claims

A cross member structure extending in the vehicle width direction so as to be installed between a pair of left and right side frames extending in the vehicle longitudinal direction at both lower ends in the vehicle width direction of the vehicle,
A first member panel formed in a substantially L-shaped cross section so as to constitute the upper surface and one side surface in the longitudinal direction of the vehicle body;
A flat plate having a connecting portion to which the base end of the dump cylinder is connected at the center in the vehicle width direction and having an upper end joined to the other end of the upper surface of the first member panel so as to constitute the other side surface in the vehicle longitudinal direction. A second member panel;
A flat plate-like third member panel having front and rear ends joined to the lower end of one side of the first member panel in the vehicle longitudinal direction and the lower end of the second member panel so as to constitute a lower surface;
The first to third member panels are formed in a closed cross-sectional shape,
The other side of the vehicle longitudinal direction at the left and right outer sides of the vehicle width direction is the other side of the vehicle longitudinal direction as it goes outward in the vehicle width direction so as to expand the cross-sectional shape to the other side of the vehicle longitudinal direction with respect to the central portion of the vehicle width direction. Cross member structure characterized by being positioned in

In the cross member structure according to claim 1,
The other end of the third member panel in the front-rear direction of the vehicle body is joined to the lower end of the second member panel so as to be offset to one side of the front-rear direction of the vehicle body by at least a thickness relative to the lower end of the second member panel. Cross member structure characterized by

In the cross member structure according to claim 1,
The vehicle body longitudinal direction other side surface at the vehicle width direction central portion and the vehicle body longitudinal direction other side surfaces of the vehicle width direction left and right outer portions positioned with respect to the vehicle width direction central portion have a predetermined curvature radius. A cross member structure characterized by being bent through an arc.

In the cross member structure according to claim 1,
At least a pair of left and right ribs are provided in the vehicle width direction center,
Each of the ribs is joined to a substantially cylindrical connecting portion extending in the longitudinal direction of the vehicle body so as to partition the central portion in the vehicle width direction from the vehicle width direction at a position inside the outer diameter. Member structure.

In the cross member structure according to claim 1,
A cross member structure characterized in that notches are provided on both the left and right outer sides in the vehicle width direction of the third member panel where the stress acting on the connecting portion is less than a predetermined value.