JP2023030757A

JP2023030757A - Vehicle body lower part structure

Info

Publication number: JP2023030757A
Application number: JP2021136068A
Authority: JP
Inventors: 蒼馬園部; Soma Sonobe
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 2021-08-24
Filing date: 2021-08-24
Publication date: 2023-03-08

Abstract

To enhance the yield strength of a cross member against collision load and to improve the energy absorbing performance of a vehicle body lower part structure.SOLUTION: A vehicle body lower part structure 1 includes a floor panel 10, a side sill 20, a cross member 30, and a joining portion 40 of the floor panel 10 and the cross member 30. The side sill 20 has a hollow portion 20a and an impact absorbing portion 23. The impact absorbing portion 23 is connected to an inside wall portion 25 in a vehicle width direction of the side sill 20. The cross member 30 has: a plurality of wall portions including a top wall portion 31; and a plurality of ridge line portions 34. The plurality of ridge line portions 34 has a first ridge line portion A between the joining portion 40 and the top wall portion 31; and a second ridge line portion B. As viewed from the vehicle width direction, the first ridge line portion A and the second ridge line portion B are located in an area overlapping an area R where the impact absorbing portion 23 is disposed.SELECTED DRAWING: Figure 6

Description

本発明は、自動車の車体下部構造に関する。 The present invention relates to a vehicle body underbody structure of an automobile.

近年、世界中で自動車の燃費規制が厳格化され、電気自動車（ＥＶ）の開発が推進されている。電気自動車は床下にバッテリーが配置されることから、衝突時にバッテリーを保護するためには、車体下部の構造によって衝突エネルギーを吸収する必要がある。例えば電柱と車体側面が接触するような衝突形態では、サイドシル、クロスメンバ、バッテリーケース等の車体下部に設けられる部品によって衝突エネルギーが吸収される。一方で、エネルギー吸収性能の向上を図るために、高強度材料を採用することや部品の板厚を増加させることは、大幅な重量増とコスト増を招く。このため、エネルギー吸収性能の向上は、車体下部の構造的な改良によって実現されることが望ましい。 In recent years, fuel consumption regulations for automobiles have been tightened all over the world, and the development of electric vehicles (EVs) has been promoted. Since the battery is placed under the floor of an electric vehicle, it is necessary to absorb the impact energy with the structure of the lower part of the vehicle body in order to protect the battery in the event of a collision. For example, in a collision mode in which a utility pole and the side of the vehicle body come into contact with each other, the collision energy is absorbed by parts provided under the vehicle body, such as side sills, cross members, and battery cases. On the other hand, adopting high-strength materials or increasing the plate thickness of parts in order to improve the energy absorption performance results in a significant increase in weight and cost. Therefore, it is desirable to improve the energy absorption performance by structurally improving the lower portion of the vehicle body.

車体下部構造に関する技術として、特許文献１には、中空状の自動車骨格部材の内方に、凹凸を有する補強部材が配置される構造が開示されている。特許文献２には、一対のロッカ（サイドシル）と複数のクロスメンバを備え、隣り合うクロスメンバの離間距離を、側面衝突時の入力荷重に対するロッカの曲げ反力が入力荷重以上となるように設定することが開示されている。特許文献３には、一対の縦壁を有するハット形状の衝撃吸収部材がサイドシル内部に配置され、上側の縦壁の車幅方向車内側にクロスメンバが、下側の縦壁の車幅方向車内側にバッテリーサイドフレームが配置される構造が開示されている。 As a technique related to the vehicle body lower part structure, Patent Document 1 discloses a structure in which a reinforcing member having unevenness is arranged inside a hollow automobile frame member. In Patent Document 2, a pair of rockers (side sills) and a plurality of cross members are provided, and the distance between adjacent cross members is set so that the bending reaction force of the rockers against the input load at the time of a side collision is greater than or equal to the input load. It is disclosed to In Patent Document 3, a hat-shaped impact absorbing member having a pair of vertical walls is arranged inside a side sill, a cross member is arranged on the vehicle width direction inner side of the upper vertical wall, and a cross member is arranged on the vehicle width direction vehicle of the lower vertical wall. A structure is disclosed in which a battery side frame is arranged inside.

国際公開第２０２０／０８５３８３号WO2020/085383 特開２０１９－０３１２１９号公報JP 2019-031219 A 特許第６７３４７０９号Patent No. 6734709

側面衝突時に衝撃吸収部材のエネルギー吸収性能を最大限引き出すためには、衝撃吸収部材の全体を塑性変形させて圧潰させることが好ましい。しかし、側面衝突時において、衝撃吸収部材が接続されたサイドシルの壁部が早期に座屈すると、サイドシルの面外変形に追従して衝撃吸収部材の姿勢が変化し、衝撃吸収部材に入力される衝突荷重が当初の想定通りに伝達されない可能性がある。この場合、衝撃吸収部材が所望の変形挙動を示さず、衝撃吸収部材の未変形部が残存しやすくなる。したがって、衝撃吸収部材のエネルギー吸収性能を最大限引き出すためには、衝撃吸収部材が接続されたサイドシルの壁部の面外変形を抑えることが好ましい。 In order to maximize the energy absorption performance of the impact absorbing member in a side collision, it is preferable to plastically deform and crush the entire impact absorbing member. However, if the wall of the side sill to which the shock absorbing member is connected buckles early in the event of a side collision, the posture of the shock absorbing member changes following the out-of-plane deformation of the side sill, and the impact is input to the shock absorbing member. Crash loads may not be transferred as originally expected. In this case, the shock absorbing member does not exhibit the desired deformation behavior, and the undeformed portion of the shock absorbing member tends to remain. Therefore, in order to maximize the energy absorption performance of the shock absorbing member, it is preferable to suppress the out-of-plane deformation of the wall portion of the side sill to which the shock absorbing member is connected.

ところで、サイドシルに接続されたクロスメンバに伝達される衝突荷重は、主に衝撃吸収部材を介して伝達される。このため、側面衝突時のクロスメンバには、衝撃吸収部材が配置された領域から局所的に衝突荷重が入力される。そして、このような局所荷重がクロスメンバに入力されると、クロスメンバを構成する平面部が撓み、その平面部に過大な面外変形が生じる場合がある。この場合、クロスメンバが接続されたサイドシルの車内側壁部の面外変形が誘発され、前述のようにサイドシルの面外変形に追従する衝撃吸収部材の姿勢変化が起こり、衝撃吸収部材の未変形部が残存しやすくなる。 By the way, the collision load transmitted to the cross member connected to the side sill is mainly transmitted via the impact absorbing member. Therefore, a collision load is locally input to the cross member at the time of a side collision from the region where the shock absorbing member is arranged. When such a local load is applied to the cross member, the plane portion of the cross member may flex and excessive out-of-plane deformation may occur in the plane portion. In this case, out-of-plane deformation of the side sill to which the cross member is connected is induced, and as described above, the shock absorbing member follows the out-of-plane deformation of the side sill. becomes more likely to remain.

すなわち、側面衝突時に衝撃吸収部材の塑性変形を促進させてエネルギー吸収性能を向上させるためには、サイドシルの車内側壁部の面外変形を抑制する必要があるが、そのためには衝撃吸収部材を介して伝達される衝突荷重に対するクロスメンバの耐力を高める必要がある。 In other words, in order to promote the plastic deformation of the shock absorbing member during a side collision and improve the energy absorption performance, it is necessary to suppress the out-of-plane deformation of the side wall of the side sill. It is necessary to increase the strength of the cross member against the impact load transmitted through the

しかしながら、特許文献１～３には、衝突荷重に対するクロスメンバの耐力を高めるための構造は開示されていない。 However, Patent Documents 1 to 3 do not disclose a structure for increasing the resistance of the cross member to the collision load.

本発明は、上記事情に鑑みてなされたものであり、衝突荷重に対するクロスメンバの耐力を高め、車体下部構造のエネルギー吸収性能を向上させることを目的とする。 SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to increase the resistance of a cross member against a collision load and improve the energy absorption performance of a vehicle body lower structure.

上記課題を解決する本発明は、車体下部構造であって、車体下部に配置されるフロアパネルと、前記フロアパネルの車幅方向端部に設けられた、車長方向に延伸するサイドシルと、前記サイドシルに接続された、車幅方向に延伸するクロスメンバと、前記フロアパネルと前記クロスメンバの接合部と、を備え、前記サイドシルは、車長方向に延伸する中空部と、前記中空部に配置された衝撃吸収部と、を有し、前記衝撃吸収部は、前記サイドシルの車幅方向車内側の壁部に接続され、前記クロスメンバは、天壁部を含む複数の壁部と、各壁部の間に挟まれた、車幅方向に延伸する複数の稜線部と、を有し、前記複数の稜線部は、前記接合部から前記天壁部までの間に第１稜線部と、第２稜線部と、を有し、前記第１稜線部の曲げ中心は、前記クロスメンバの内側に位置し、前記第２稜線部の曲げ中心は、前記クロスメンバの外側に位置し、前記第１稜線部と前記第２稜線部は、車幅方向から見て、前記衝撃吸収部の配置領域と重なる領域に位置していることを特徴としている。 The present invention for solving the above-mentioned problems is a vehicle body lower structure, comprising: a floor panel arranged at the vehicle body lower portion; A cross member extending in the vehicle width direction and connected to a side sill, and a joint portion between the floor panel and the cross member, the side sill having a hollow portion extending in the vehicle length direction and disposed in the hollow portion. a shock absorbing portion connected to a wall portion of the side sill on the inner side in the vehicle width direction, and the cross member includes a plurality of wall portions including a top wall portion; and a plurality of ridgeline portions extending in the vehicle width direction sandwiched between the portions, wherein the plurality of ridgeline portions include a first ridgeline portion and a second ridgeline portion between the joint portion and the top wall portion. a bending center of the first ridge is positioned inside the cross member; a bending center of the second ridge is positioned outside the cross member; The ridgeline portion and the second ridgeline portion are characterized in that they are positioned in a region overlapping with the arrangement region of the shock absorbing portion when viewed in the vehicle width direction.

本発明によれば、衝突荷重に対するクロスメンバの耐力を高め、車体下部構造のエネルギー吸収性能を向上させることができる。 According to the present invention, the resistance of the cross member to the collision load can be increased, and the energy absorption performance of the vehicle body lower structure can be improved.

本発明の一実施形態に係る車体下部構造の概略を示す図である。BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the outline of the vehicle body lower part structure which concerns on one Embodiment of this invention. サイドシルの軸方向（車長方向）に垂直な断面を示す図である。FIG. 4 is a view showing a cross section perpendicular to the axial direction (vehicle length direction) of the side sill; 衝撃吸収部材の形状を示す斜視図である。4 is a perspective view showing the shape of a shock absorbing member; FIG. 図３の衝撃吸収部材を車幅方向から見た図である。FIG. 4 is a view of the shock absorbing member in FIG. 3 as seen from the vehicle width direction; サイドシルの形状例を示す図である。It is a figure which shows the example of a shape of a side sill. クロスメンバの軸方向（車幅方向）に垂直な断面を示す図である。It is a figure which shows the cross section perpendicular|vertical to the axial direction (vehicle width direction) of a cross member. クロスメンバの形状例を示す図である。FIG. 4 is a diagram showing an example of the shape of a cross member; クロスメンバの形状例を示す図である。FIG. 4 is a diagram showing an example of the shape of a cross member; 第１稜線部と第２稜線部を有するクロスメンバの形状例を示す図である。FIG. 5 is a diagram showing a shape example of a cross member having a first ridge line portion and a second ridge line portion; 第１稜線部と第２稜線部の一方または両方を有しないクロスメンバの形状例を示す図である。FIG. 5 is a diagram showing an example shape of a cross member that does not have one or both of a first edge portion and a second edge portion; クロスメンバに補強部材が接合された例を示す図である。FIG. 4 is a diagram showing an example in which a reinforcing member is joined to a cross member; 補強部材の配置例を示す図である。It is a figure which shows the example of arrangement|positioning of a reinforcement member. 中空部を有するクロスメンバの形状例を示す図である。FIG. 4 is a diagram showing an example shape of a cross member having a hollow portion; 中空部を有するクロスメンバに補強部材が接合された例を示す図である。FIG. 10 is a diagram showing an example in which a reinforcing member is joined to a cross member having a hollow portion; ポール側突シミュレーションの解析モデルを示す図である。It is a figure which shows the analysis model of pole side collision simulation. シミュレーション結果を示す図である。It is a figure which shows a simulation result. シミュレーション結果を示す図である。It is a figure which shows a simulation result. シミュレーション結果を示す図である。It is a figure which shows a simulation result.

以下、本発明の一実施形態について、図面を参照しながら説明する。なお、本明細書および図面において、実質的に同一の機能構成を有する要素においては、同一の符号を付することにより重複説明を省略する。 An embodiment of the present invention will be described below with reference to the drawings. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description.

図１は、本発明の一実施形態に係る車体下部構造の概略を示す図である。図２は、サイドシルの軸方向（車長方向）に垂直な断面を示す図である。図３は、衝撃吸収部材の形状を示す斜視図である。図４は、図３の衝撃吸収部材を車幅方向から見た図である。なお、本明細書で参照する図面に示される「Ｘ方向」は車幅方向、「Ｙ方向」は車長方向、「Ｚ方向」は車高方向である。なお、本明細書における部品同士の「接続」には、部品同士が接触している状態の他、部品同士が接合されている状態も含まれる。また、本明細書における部品同士の「接合」には、溶接による接合の他、例えば接着剤による接合も含まれる。 FIG. 1 is a diagram showing an outline of a vehicle body lower portion structure according to one embodiment of the present invention. FIG. 2 is a view showing a cross section perpendicular to the axial direction (vehicle length direction) of the side sill. FIG. 3 is a perspective view showing the shape of the shock absorbing member. FIG. 4 is a view of the impact absorbing member in FIG. 3 as seen from the vehicle width direction. In the drawings referred to in this specification, the "X direction" is the vehicle width direction, the "Y direction" is the vehicle length direction, and the "Z direction" is the vehicle height direction. In this specification, the term "connection" between parts includes not only the state in which the parts are in contact with each other, but also the state in which the parts are joined together. Also, in this specification, "joining" between parts includes joining by, for example, an adhesive in addition to joining by welding.

車体下部構造１は、自動車の車体下部に配置されるフロアパネル１０と、サイドシル２０と、クロスメンバ３０を備えている。車体下部構造１は、ハイブリットカーや電気自動車の他、例えば内燃機関を動力源とする他の自動車など、フロアパネル、サイドシルおよびクロスメンバを有した車体下部構造を備える自動車に適用することができる。 A vehicle body lower structure 1 includes a floor panel 10, a side sill 20, and a cross member 30, which are arranged under the vehicle body of an automobile. The vehicle body lower structure 1 can be applied to vehicles having a vehicle body lower structure having floor panels, side sills and cross members, such as hybrid cars, electric vehicles, and other vehicles powered by an internal combustion engine.

サイドシル２０は、車長方向（Ｙ方向）に延伸する中空部２０ａを有した部材であり、フロアパネル１０の車幅方向（Ｘ方向）の端部に配置されている。 The side sill 20 is a member having a hollow portion 20a extending in the vehicle length direction (Y direction), and is arranged at the end of the floor panel 10 in the vehicle width direction (X direction).

サイドシル２０は、アウター部品２１と、インナー部品２２と、衝撃吸収部２３を有している。なお、図１では衝撃吸収部２３の形状を模式的に示し、図２～図４において具体的な形状を示している。 The side sill 20 has an outer component 21 , an inner component 22 and a shock absorbing portion 23 . 1 schematically shows the shape of the impact absorbing portion 23, and FIGS. 2 to 4 show specific shapes.

アウター部品２１とインナー部品２２は、それぞれハット形状の部品であり、アウター部品２１のフランジとインナー部品２２のフランジが互いに接合されることによって、サイドシル２０は中空状に形成される。サイドシル２０の車幅方向車外側の壁部（以下、「車外側壁部２４」）には、側面衝突時に衝突荷重が入力される。また、サイドシル２０の車幅方向車内側の壁部（以下、「車内側壁部２５」）には、前述のフロアパネル１０が接続される。 The outer component 21 and the inner component 22 are hat-shaped components, respectively, and the side sill 20 is formed in a hollow shape by joining the flanges of the outer component 21 and the inner component 22 to each other. A collision load is input to a wall portion of the side sill 20 on the outer side in the vehicle width direction (hereinafter referred to as the "outer side wall portion 24") at the time of a side collision. Further, the above-described floor panel 10 is connected to a wall portion of the side sill 20 on the inner side of the vehicle in the vehicle width direction (hereinafter referred to as "inner side wall portion 25").

衝撃吸収部２３は、衝突時に自身の塑性変形により衝突エネルギーを吸収する部材であり、サイドシル２０の車長方向（Ｙ方向）に延伸している。本実施形態における衝撃吸収部２３は、アウター部品２１およびインナー部品２２の車高方向（Ｚ方向）の中央部において、車外側壁部２４と車内側壁部２５の間に架設されるようにして両壁部２４、２５の内面に接続されている。 The shock absorbing portion 23 is a member that absorbs collision energy by plastic deformation of itself at the time of collision, and extends in the vehicle length direction (Y direction) of the side sill 20 . The impact absorbing portion 23 in the present embodiment is constructed between the vehicle outer side wall portion 24 and the vehicle inner side wall portion 25 at the central portion of the outer component 21 and the inner component 22 in the vehicle height direction (Z direction). It is connected to the inner surfaces of the walls 24 , 25 .

図２～図４に示すように、衝撃吸収部２３は、複数の底面部２３ａと、その底面部２３ａを間に挟む２つの側面部２３ｂと、各側面部２３ｂの上端部に接続される天面部２３ｃを有している。各面２３ａ～２３ｃの間にある稜線部２３ｄは、それぞれ車幅方向（Ｘ方向）に延びている。衝撃吸収部２３は、このような底面部２３ａ、２つの側面部２３ｂおよび天面部２３ｃが車長方向（Ｙ方向）に沿って連続して設けられている。このため、衝撃吸収部２３の形状は、車長方向に沿って連続する凹凸を有した波形状となっている。 As shown in FIGS. 2 to 4, the shock absorbing portion 23 includes a plurality of bottom surface portions 23a, two side surface portions 23b sandwiching the bottom surface portions 23a, and a ceiling portion connected to the upper end of each side surface portion 23b. It has a surface portion 23c. A ridgeline portion 23d between the surfaces 23a to 23c extends in the vehicle width direction (X direction). The impact absorbing portion 23 has such a bottom surface portion 23a, two side surface portions 23b, and a top surface portion 23c that are continuously provided along the vehicle length direction (Y direction). Therefore, the shape of the impact absorbing portion 23 is a wave shape having unevenness that is continuous along the vehicle length direction.

なお、本明細書では、車幅方向（Ｘ方向）から見た際の衝撃吸収部２３が配置された領域を「衝撃吸収部２３の配置領域Ｒ」と称す。例えば図４に示す衝撃吸収部２３においては、底面部２３ａから天面部２３ｃまでの領域が衝撃吸収部２３の配置領域Ｒである。 In this specification, the region where the shock absorbing portion 23 is arranged when viewed from the vehicle width direction (X direction) is referred to as the "arrangement region R of the shock absorbing portion 23". For example, in the impact absorbing portion 23 shown in FIG. 4, the area from the bottom surface portion 23a to the top surface portion 23c is the arrangement area R of the impact absorbing portion 23. As shown in FIG.

サイドシル２０の概略構成の説明は以上の通りであるが、サイドシル２０の構成は特に限定されず、公知の構成を適用してもよい。また、図５に示すように、サイドシル２０は、例えば押出成形によって、中空部２０ａと、衝撃吸収部２３を有する構成であってもよい。なお、図５の例における衝撃吸収部２３の配置領域Ｒは、衝撃吸収部２３の下面と上面の間の領域である。 Although the schematic configuration of the side sill 20 has been described above, the configuration of the side sill 20 is not particularly limited, and a known configuration may be applied. Further, as shown in FIG. 5, the side sill 20 may be configured to have a hollow portion 20a and a shock absorbing portion 23 by extrusion molding, for example. Note that the arrangement region R of the shock absorbing portion 23 in the example of FIG. 5 is a region between the lower surface and the upper surface of the shock absorbing portion 23 .

クロスメンバ３０は、車幅方向（Ｘ方向）に延伸する部材である。本実施形態におけるクロスメンバ３０は、車長方向（Ｙ方向）に延伸する一対のサイドシル２０に架設されるように延伸し、クロスメンバ３０の車幅方向における両端部がサイドシル２０の車内側壁部２５に接続されている。なお、クロスメンバ３０は例えば車幅方向における一端部がサイドシル２０の車内側壁部２５に接続され、他端部がフロアトンネル（図示せず）に接続されてもよい。また、クロスメンバ３０の数は特に限定されず、クロスメンバ３０は、車長方向（Ｙ方向）に間隔をおいて複数設けられてもよい。 The cross member 30 is a member extending in the vehicle width direction (X direction). The cross member 30 in this embodiment extends so as to be mounted on a pair of side sills 20 extending in the vehicle length direction (Y direction). It is connected to the. For example, the cross member 30 may have one end in the vehicle width direction connected to the vehicle interior side wall portion 25 of the side sill 20 and the other end connected to a floor tunnel (not shown). The number of cross members 30 is not particularly limited, and a plurality of cross members 30 may be provided at intervals in the vehicle length direction (Y direction).

以下、クロスメンバ３０の形状について説明する。図６は、クロスメンバ３０の軸方向（車幅方向）に垂直な断面を示す図である。図７および図８は、クロスメンバ３０の形状例を示す図である。 The shape of the cross member 30 will be described below. FIG. 6 is a diagram showing a cross section perpendicular to the axial direction (vehicle width direction) of the cross member 30. As shown in FIG. 7 and 8 are diagrams showing examples of the shape of the cross member 30. FIG.

図６に示すように、クロスメンバ３０は、天壁部３１と、２つの縦壁部３２と、２つのフランジ部３３を含む複数の壁部を有している。 As shown in FIG. 6 , the cross member 30 has a plurality of wall portions including a top wall portion 31 , two vertical wall portions 32 and two flange portions 33 .

縦壁部３２の上端は、天壁部３１の車長方向（Ｙ方向）の端部に接続されている。縦壁部３２の下端は、フランジ部３３に接続されている。天壁部３１、縦壁部３２およびフランジ部３３の各壁部の間に挟まれた稜線部３４は、車幅方向（Ｘ方向）に延伸している。このような形状のクロスメンバ３０は、フランジ部３３がフロアパネル１０に接合されることによって、車幅方向に延伸する中空部３０ａが形成されている。なお、本明細書で参照する図面中の黒丸部は、隣り合う２部品の接合部４０を示している。 The upper end of the vertical wall portion 32 is connected to the end portion of the ceiling wall portion 31 in the vehicle length direction (Y direction). A lower end of the vertical wall portion 32 is connected to the flange portion 33 . A ridgeline portion 34 sandwiched between the wall portions of the top wall portion 31, the vertical wall portion 32, and the flange portion 33 extends in the vehicle width direction (X direction). The cross member 30 having such a shape has a hollow portion 30 a extending in the vehicle width direction by joining the flange portion 33 to the floor panel 10 . Note that black circles in the drawings referred to in this specification indicate joints 40 of two adjacent parts.

縦壁部３２は、第１壁部３２ａと、第２壁部３２ｂと、第３壁部３２ｃを有している。第１壁部３２ａと第３壁部３２ｃはそれぞれ車高方向（Ｚ方向）に延伸し、第２壁部３２ｂは、第１壁部３２ａの上端と第３壁部３２ｃの下端に接続されている。各壁部３２ａ～３２ｃの間に挟まれた各稜線部３４は、車幅方向（Ｘ方向）に延伸している。第１壁部３２ａと第２壁部３２ｂに挟まれた稜線部３４は、曲げ中心がクロスメンバ３０の内側（中空部３０ａの内側）に位置している。第２壁部３２ｂと第３壁部３２ｃに挟まれた稜線部３４は、曲げ中心がクロスメンバ３０の外側（中空部３０ａの外側）に位置している。 The vertical wall portion 32 has a first wall portion 32a, a second wall portion 32b, and a third wall portion 32c. The first wall portion 32a and the third wall portion 32c each extend in the vehicle height direction (Z direction), and the second wall portion 32b is connected to the upper end of the first wall portion 32a and the lower end of the third wall portion 32c. there is Each ridge portion 34 sandwiched between the wall portions 32a to 32c extends in the vehicle width direction (X direction). The center of bending of the ridgeline portion 34 sandwiched between the first wall portion 32a and the second wall portion 32b is positioned inside the cross member 30 (inside the hollow portion 30a). The center of bending of the ridgeline portion 34 sandwiched between the second wall portion 32b and the third wall portion 32c is located outside the cross member 30 (outside the hollow portion 30a).

縦壁部３２は、上記の構成を有していることにより段状に形成されている。そして、第１壁部３２ａと第２壁部３２ｂに挟まれた稜線部３４と、第２壁部３２ｂと第３壁部３２ｃに挟まれた稜線部３４は、車幅方向（Ｘ方向）から見て、衝撃吸収部２３の配置領域Ｒと重なる位置に存在している。 The vertical wall portion 32 is formed in a stepped shape due to the above configuration. The ridgeline portion 34 sandwiched between the first wall portion 32a and the second wall portion 32b and the ridgeline portion 34 sandwiched between the second wall portion 32b and the third wall portion 32c are separated from the vehicle width direction (X direction). When viewed, it exists at a position overlapping the arrangement region R of the shock absorbing portion 23 .

以降の説明では、フロアパネル１０との接合部４０から天壁部３１までに存在する複数の稜線部３４のうち、曲げ中心がクロスメンバ３０の内側（中空部３０ａの内側）に位置し、かつ、車幅方向（Ｘ方向）から見て衝撃吸収部２３の配置領域Ｒと重なる領域に位置する稜線部３４を「第１稜線部Ａ」と称す場合がある。また、曲げ中心がクロスメンバ３０の外側（中空部３０ａの外側）に位置し、かつ、車幅方向から見て衝撃吸収部２３の配置領域Ｒと重なる領域に位置する稜線部３４を「第２稜線部Ｂ」と称す場合がある。例えば図６に示すクロスメンバ３０においては、第１壁部３２ａと第２壁部３２ｂの間の稜線部３４が第１稜線部Ａであり、第２壁部３２ｂと第３壁部３２ｃの間の稜線部３４が第２稜線部Ｂである。 In the following description, among the plurality of ridge line portions 34 existing from the joint portion 40 with the floor panel 10 to the top wall portion 31, the bending center is located inside the cross member 30 (inside the hollow portion 30a), and , the ridgeline portion 34 located in the region overlapping with the arrangement region R of the shock absorbing portion 23 when viewed in the vehicle width direction (X direction) may be referred to as a "first ridgeline portion A". In addition, the ridgeline portion 34 whose bending center is located outside the cross member 30 (outside the hollow portion 30a) and located in a region overlapping with the arrangement region R of the impact absorbing portion 23 when viewed from the vehicle width direction is defined as the "second It may be referred to as a ridge portion B”. For example, in the cross member 30 shown in FIG. 6, the ridgeline portion 34 between the first wall portion 32a and the second wall portion 32b is the first ridgeline portion A, and the ridgeline portion A is between the second wall portion 32b and the third wall portion 32c. is the second edge line portion B.

すなわち、本実施形態におけるクロスメンバ３０は、車幅方向（Ｘ方向）から見て、第１稜線部Ａ、第２稜線部Ｂ、および第１稜線部Ａと第２稜線部Ｂの間の第２壁部３２ｂが、衝撃吸収部２３の配置領域Ｒと重なる領域に位置している。また、第１稜線部Ａから下方に延びる第１壁部３２ａの一部が配置領域Ｒ内に位置し、残部は配置領域Ｒ外に位置している。また、第２稜線部Ｂから上方に延びる第３壁部３２ｃの一部が配置領域Ｒ内に位置し、残部は配置領域Ｒ外に位置している。 That is, the cross member 30 in this embodiment includes a first ridgeline portion A, a second ridgeline portion B, and a second ridgeline portion between the first ridgeline portion A and the second ridgeline portion B when viewed from the vehicle width direction (X direction). The second wall portion 32b is located in a region overlapping with the arrangement region R of the shock absorbing portion 23. As shown in FIG. A part of the first wall portion 32a extending downward from the first ridgeline portion A is located within the arrangement region R, and the remaining portion is located outside the arrangement region R. As shown in FIG. Further, a portion of the third wall portion 32c extending upward from the second ridgeline portion B is positioned within the arrangement region R, and the remaining portion is positioned outside the arrangement region R. As shown in FIG.

車体下部構造１が備えるフロアパネル１０、サイドシル２０およびクロスメンバ３０の概略構成の説明は以上の通りである。なお、フロアパネル１０、サイドシル２０、クロスメンバ３０は、例えば引張強さが４４０～２５００ＭＰａの鋼材やアルミニウム合金部材、マグネシウム合金部材等の金属材料で形成される。 The schematic configurations of the floor panel 10, the side sill 20, and the cross member 30 included in the vehicle body lower structure 1 are as described above. The floor panel 10, the side sills 20, and the cross members 30 are made of metal materials such as steel, aluminum alloy members, and magnesium alloy members having a tensile strength of 440 to 2500 MPa.

本実施形態に係る車体下部構造１によれば、クロスメンバ３０の縦壁部３２が複数の壁部３２ａ～３２ｃで構成されていることによって縦壁部３２の面剛性が向上する。詳述すると、本実施形態における縦壁部３２は、縦壁部全体の高さ（車高方向長さ）が単一の壁部で構成される従前の縦壁部と同一の高さであっても、縦壁部３２を構成する一つあたりの壁部の高さが低いため、各壁部の面剛性が高まる。その結果、縦壁部３２全体の面剛性も高まるため、縦壁部３２の面外変形が抑制され、衝突荷重に対するクロスメンバ３０の耐力が向上する。 According to the vehicle body lower portion structure 1 according to the present embodiment, the vertical wall portion 32 of the cross member 30 is configured by the plurality of wall portions 32a to 32c, so that the surface rigidity of the vertical wall portion 32 is improved. More specifically, the vertical wall portion 32 in this embodiment has the same overall height (vehicle height direction length) as the conventional vertical wall portion constituted by a single wall portion. However, since the height of each wall constituting the vertical wall 32 is low, the surface rigidity of each wall increases. As a result, the surface rigidity of the vertical wall portion 32 as a whole is increased, so that the out-of-plane deformation of the vertical wall portion 32 is suppressed, and the resistance of the cross member 30 to the collision load is improved.

また、クロスメンバ３０に入力される衝突荷重は、衝撃吸収部２３の配置領域Ｒから主に伝達されるが、本実施形態におけるクロスメンバ３０においては、第１稜線部Ａと第２稜線部Ｂが、車幅方向（Ｘ方向）から見て、衝撃吸収部２３の配置領域Ｒと重なる位置にある。このため、配置領域Ｒから伝達される衝突荷重を第１稜線部Ａと第２稜線部Ｂで受けることができるため、衝突荷重に対するクロスメンバ３０の耐力が向上する。 In addition, the collision load input to the cross member 30 is mainly transmitted from the arrangement region R of the shock absorbing portion 23. is positioned so as to overlap with the arrangement region R of the impact absorbing portion 23 when viewed from the vehicle width direction (X direction). Therefore, since the collision load transmitted from the arrangement region R can be received by the first ridge line portion A and the second ridge line portion B, the resistance of the cross member 30 to the collision load is improved.

したがって、本実施形態に係る車体下部構造１によれば、側面衝突時の衝突荷重に対するクロスメンバ３０の耐力を高めることができ、クロスメンバ３０の縦壁部３２の面外変形を抑制することができる。その結果、クロスメンバが接続されたサイドシル２０の車内側壁部の面外変形も抑制することができ、衝撃吸収部２３の塑性変形を促進させることが可能となる。これにより、後述の実施例でも示すように、車体下部構造１のエネルギー吸収性能を向上させることができる。 Therefore, according to the vehicle body lower structure 1 according to the present embodiment, the resistance of the cross member 30 to the collision load at the time of side collision can be increased, and the out-of-plane deformation of the vertical wall portion 32 of the cross member 30 can be suppressed. can. As a result, out-of-plane deformation of the side wall portion of the side sill 20 to which the cross member is connected can be suppressed, and plastic deformation of the impact absorbing portion 23 can be promoted. As a result, the energy absorption performance of the vehicle body lower structure 1 can be improved, as will be shown in the examples described later.

なお、段状に形成された縦壁部３２の段数が過度に多くなって各段の壁部の高さが過度に低くなると、各段の境界が曖昧となり、衝突時における縦壁部３２の変形挙動が、縦壁部が一つの壁部で構成されている場合と同様の変形挙動となる可能性がある。縦壁部３２の段数としての好ましい上限は、クロスメンバ３０の形状や衝撃吸収部２３の配置領域Ｒの大きさに応じて異なるが、縦壁部３２の面剛性向上の効果を高めるためには、縦壁部３２の段数は例えば２～３段であることが好ましい。 If the number of steps of the vertical wall portion 32 formed in a stepped manner becomes excessively large and the height of each stepped wall portion becomes excessively low, the boundaries between the steps become ambiguous, and the vertical wall portion 32 at the time of a collision becomes obscure. The deformation behavior may be similar to that in the case where the vertical wall is composed of one wall. A preferred upper limit for the number of steps of the vertical wall portion 32 varies depending on the shape of the cross member 30 and the size of the arrangement region R of the shock absorbing portion 23. , the number of stages of the vertical wall portion 32 is preferably 2 to 3, for example.

図７に示すように、クロスメンバ３０の天壁部３１は、車幅方向（Ｘ方向）から見て、衝撃吸収部２３の配置領域Ｒと重なる領域に位置してもよい。この場合、第１壁部３２ａと第２壁部３２ｂの間の稜線部３４に加え、天壁部３１と第３壁部３２ｃの間の稜線部３４も第１稜線部Ａとなり、衝撃吸収部２３の配置領域Ｒから伝達される衝突荷重を受ける稜線部の数が増加する。これにより、衝突荷重に対するクロスメンバ３０の耐力を効果的に高めることができる。 As shown in FIG. 7 , the top wall portion 31 of the cross member 30 may be located in a region overlapping the arrangement region R of the impact absorbing portion 23 when viewed from the vehicle width direction (X direction). In this case, in addition to the ridgeline portion 34 between the first wall portion 32a and the second wall portion 32b, the ridgeline portion 34 between the top wall portion 31 and the third wall portion 32c also serves as the first ridgeline portion A, which acts as a shock absorbing portion. The number of ridges that receive the impact load transmitted from the placement area R of 23 increases. As a result, the resistance of the cross member 30 to the collision load can be effectively increased.

図８に示すように、クロスメンバ３０の天壁部３１には、凹部３５が形成されてもよい。図８に示す凹部３５は、底壁部３５ａと、側壁部３５ｂを有している。側壁部３５ｂは、底壁部３５ａと天壁部３１の間にある壁部であり、底壁部３５ａと側壁部３５ｂに挟まれた稜線部３４は車幅方向（Ｙ方向）に延伸している。このような凹部３５が天壁部３１に形成されていることにより、衝突荷重を受ける稜線部の数が増加し、クロスメンバ３０の耐力を高めることができる。 As shown in FIG. 8 , the top wall portion 31 of the cross member 30 may be formed with a recess 35 . The concave portion 35 shown in FIG. 8 has a bottom wall portion 35a and a side wall portion 35b. The side wall portion 35b is a wall portion between the bottom wall portion 35a and the top wall portion 31, and the ridge portion 34 sandwiched between the bottom wall portion 35a and the side wall portion 35b extends in the vehicle width direction (Y direction). there is By forming such a concave portion 35 in the ceiling wall portion 31, the number of ridge line portions that receive a collision load increases, and the strength of the cross member 30 can be increased.

また、クロスメンバ３０は、図８のように複数の部品で構成されてもよい。図８に示す例では、クロスメンバ３０が第１の部品３６と第２の部品３７で構成されている。第１の部品３６と第２の部品３７は、それぞれ第１稜線部Ａと第２稜線部Ｂを有していて、凹部３５の底壁部３５ａにおいて両部品が接合されている。 Also, the cross member 30 may be composed of a plurality of parts as shown in FIG. In the example shown in FIG. 8, the cross member 30 is composed of a first part 36 and a second part 37 . The first part 36 and the second part 37 have a first ridge A and a second ridge B, respectively, and are joined together at the bottom wall 35 a of the recess 35 .

クロスメンバ３０の形状は以上で説明した形状に限定されず、例えば図９に示す形状であってもよい。図９（ａ）は、２つの縦壁部３２のうちの一方の縦壁部３２のみが段状に形成された例である。図９（ｂ）は、凹部３５の底壁部３５ａがフロアパネル１０に接していない例である。図９（ｃ）は、凹部３５の底壁部３５ａが衝撃吸収部２３の配置領域Ｒ内に位置する例である。図９（ｄ）は、縦壁部３２の段数が４段の例である。図９（ｅ）は、縦壁部３２が傾斜部を有している例である。 The shape of the cross member 30 is not limited to the shape described above, and may be the shape shown in FIG. 9, for example. FIG. 9A shows an example in which only one of the two vertical wall portions 32 is stepped. FIG. 9B shows an example in which the bottom wall portion 35a of the recess 35 is not in contact with the floor panel 10. FIG. FIG. 9C shows an example in which the bottom wall portion 35a of the recess portion 35 is positioned within the arrangement region R of the impact absorbing portion 23. FIG. FIG. 9(d) shows an example in which the number of steps of the vertical wall portion 32 is four. FIG. 9(e) shows an example in which the vertical wall portion 32 has an inclined portion.

図９（ｆ）は、縦壁部３２が段状に形成されていないが、凹部３５の側壁部３５ｂが段状に形成された例である。この例では、凹部３５の底壁部３５ａとフロアパネル１０が接合され、その接合部４０から天壁部３１までの間に第１稜線部Ａと第２稜線部Ｂが存在している。このため、側壁部３５ｂの面剛性が高まり、衝突荷重に対するクロスメンバ３０の耐力を高めることができる。すなわち、段状に形成される壁部は、縦壁部３２に限定されず、フロアパネル１０との接合部４０から天壁部３１までの間にある壁部であればよい。 FIG. 9F shows an example in which the vertical wall portion 32 is not stepped, but the side wall portion 35b of the recess 35 is stepped. In this example, the bottom wall portion 35a of the recess 35 and the floor panel 10 are joined, and a first ridgeline portion A and a second ridgeline portion B are present between the joint portion 40 and the ceiling wall portion 31. As shown in FIG. Therefore, the surface rigidity of the side wall portion 35b is increased, and the resistance of the cross member 30 to the collision load can be increased. That is, the stepped wall portion is not limited to the vertical wall portion 32 , and may be any wall portion between the joint portion 40 with the floor panel 10 and the ceiling wall portion 31 .

図１０は、第１稜線部Ａと第２稜線部Ｂの一方または両方を有しないクロスメンバ３０の形状例を示す図である。図１０（ａ）は、一般的なハット形状のクロスメンバ３０を示す例である。図１０（ｂ）は、天壁部３１が衝撃吸収部２３の配置領域Ｒと重なる領域に位置していることにより第１稜線部が存在するが、第２稜線部Ｂが存在しない例である。図１０（ｃ）は、縦壁部３２が段状に形成されているが、各壁部の稜線部３４が衝撃吸収部２３の配置領域Ｒ外に位置する例である。図１０（ｄ）は、天壁部３１に凹部３５が形成されているが、第１稜線部Ａと第２稜線部Ｂが存在しない例である。 FIG. 10 is a diagram showing a shape example of the cross member 30 that does not have one or both of the first ridgeline portion A and the second ridgeline portion B. FIG. FIG. 10(a) is an example showing a general hat-shaped cross member 30. FIG. FIG. 10(b) shows an example in which the top wall portion 31 is positioned in a region overlapping the arrangement region R of the shock absorbing portion 23, so that the first ridge line portion exists, but the second ridge line portion B does not exist. . FIG. 10C shows an example in which the vertical wall portion 32 is formed stepwise, but the ridge line portion 34 of each wall portion is positioned outside the arrangement region R of the impact absorbing portion 23 . FIG. 10(d) shows an example in which the top wall portion 31 is formed with the recessed portion 35, but the first ridgeline portion A and the second ridgeline portion B are not present.

図１０（ｅ）は、図９（ｆ）に示すクロスメンバ３０と同一の形状であるが、凹部３５の底壁部３５ａとフロアパネル１０が接合されていない例である。このクロスメンバ３０においては、凹部３５の側壁部３５ｂが段状に形成されているが、底壁部３５ａがフロアパネル１０に接合されていないために、クロスメンバ３０の耐力向上への寄与度が低い。 FIG. 10(e) shows an example in which the cross member 30 has the same shape as the cross member 30 shown in FIG. 9(f), but the bottom wall portion 35a of the recess 35 and the floor panel 10 are not joined. In this cross member 30, the side wall portion 35b of the concave portion 35 is formed in a stepped shape, but since the bottom wall portion 35a is not joined to the floor panel 10, the degree of contribution to the improvement of the strength of the cross member 30 is small. low.

以上、クロスメンバ３０の形状について説明したが、図１１に示すように、クロスメンバ３０に補強部材５０が接合されてもよい。この補強部材５０は、軸方向（Ｘ方向）の断面がコ字状となるように形成されていて、底面部５１と、その底面部５１を間に挟む２つの側面部５２を有している。図１１に示す例では、補強部材５０の底面部５１がクロスメンバ３０の天壁部３１の外面に接合され、補強部材５０の側面部５２がクロスメンバ３０の第１壁部３２ａの外面に接合されている。このような補強部材５０が設けられることによって、クロスメンバ３０と補強部材５０で囲まれる閉断面が形成され、クロスメンバ３０の各壁部の面剛性を向上させることができる。なお、補強部材５０の底面部５１は、クロスメンバ３０の天壁部３１に接してなくてもよい。 Although the shape of the cross member 30 has been described above, a reinforcing member 50 may be joined to the cross member 30 as shown in FIG. 11 . The reinforcing member 50 is formed to have a U-shaped cross section in the axial direction (X direction), and has a bottom surface portion 51 and two side surface portions 52 sandwiching the bottom surface portion 51 therebetween. . In the example shown in FIG. 11, the bottom surface portion 51 of the reinforcing member 50 is joined to the outer surface of the top wall portion 31 of the cross member 30, and the side surface portion 52 of the reinforcing member 50 is joined to the outer surface of the first wall portion 32a of the cross member 30. It is By providing such a reinforcing member 50, a closed cross section surrounded by the cross member 30 and the reinforcing member 50 is formed, and the surface rigidity of each wall portion of the cross member 30 can be improved. Note that the bottom surface portion 51 of the reinforcing member 50 does not have to be in contact with the top wall portion 31 of the cross member 30 .

補強部材５０は、クロスメンバ３０の全長にわたって延伸する形状であってもよいが、図１２に示すように、複数の補強部材５０が車幅方向（Ｘ方向）に沿って間隔をおいて配置されてもよい。 Although the reinforcing member 50 may have a shape extending over the entire length of the cross member 30, as shown in FIG. may

また、以上の説明では、クロスメンバ３０がフロアパネル１０に接合されることで、車幅方向（Ｘ方向）に延伸する中空部３０ａが形成されていたが、図１３に示すように、クロスメンバ３０は、例えば押出成形によって中空状に形成されてもよい。このクロスメンバ３０は、天壁部３１と、２つの縦壁部３２と、２つの縦壁部３２の間に挟まれた底壁部３８を有していて、２つの縦壁部３２とフロアパネル１０は例えば隅肉溶接によって接合されている。この例においても、フロアパネル１０との接合部４０から天壁部３１までの間に、衝撃吸収部２３の配置領域Ｒと重なる領域に位置する第１稜線部Ａと第２稜線部Ｂが存在している。これにより縦壁部３２が複数の壁部で構成され、縦壁部３２の面剛性が向上する。 In the above description, the cross member 30 is joined to the floor panel 10 to form the hollow portion 30a extending in the vehicle width direction (X direction). 30 may be formed hollow, for example by extrusion. The cross member 30 has a top wall portion 31, two vertical wall portions 32, and a bottom wall portion 38 sandwiched between the two vertical wall portions 32. The two vertical wall portions 32 and the floor The panels 10 are joined by fillet welds, for example. Also in this example, a first ridgeline portion A and a second ridgeline portion B located in a region overlapping with the arrangement region R of the shock absorbing portion 23 exist between the joint portion 40 with the floor panel 10 and the ceiling wall portion 31. are doing. As a result, the vertical wall portion 32 is composed of a plurality of wall portions, and the surface rigidity of the vertical wall portion 32 is improved.

なお、図１４に示すように、中空部２０ａを有するクロスメンバ３０に前述の補強部材５０が設けられてもよい。また、図１４に示す補強部材５０とクロスメンバ３０が例えば押出成形によって一体成形されてもよい。 Incidentally, as shown in FIG. 14, the reinforcing member 50 described above may be provided on the cross member 30 having the hollow portion 20a. Also, the reinforcing member 50 and the cross member 30 shown in FIG. 14 may be integrally formed by, for example, extrusion molding.

以上、本発明の実施形態の一例について説明したが、本発明はかかる例に限定されない。当業者であれば、特許請求の範囲に記載された技術的思想の範疇内において、各種の変更例または修正例に想到しうることは明らかであり、それらについても当然に本発明の技術的範囲に属するものと了解される。 Although one example of the embodiment of the present invention has been described above, the present invention is not limited to this example. It is obvious that a person skilled in the art can conceive various modifications or modifications within the scope of the technical idea described in the claims, and these are also within the technical scope of the present invention. be understood to belong to

図１５に示す車体下部構造の解析モデルを用いて、側面衝突を模擬したポール側突シミュレーションを実施した。 Using the analytical model of the vehicle body lower structure shown in FIG. 15, a pole side collision simulation was performed to simulate a side collision.

この解析モデルのサイドシル２０は、２つのハット形状部品がフランジ部で互いに接合された構成である。衝撃吸収部２３は、直方体形状であって、サイドシル２０の中空部において、サイドシル２０の車外側壁部と車内側壁部の内面に接続されている。フロアパネル１０は、サイドシル２０の車内側壁部に接続されている。クロスメンバ３０は、車長方向（Ｙ方向）に間隔をおいて２つ配置されている。各部品の材料には引張強さが１１８０ＭＰａの鋼板が設定されている。 The side sill 20 of this analysis model has a configuration in which two hat-shaped parts are joined to each other at a flange portion. The impact absorbing portion 23 has a rectangular parallelepiped shape, and is connected to the inner surfaces of the vehicle outer side wall portion and the vehicle inner side wall portion of the side sill 20 in the hollow portion of the side sill 20 . The floor panel 10 is connected to the inner side wall of the side sill 20 . Two cross members 30 are arranged with an interval in the vehicle length direction (Y direction). A steel plate with a tensile strength of 1180 MPa is set as the material for each part.

本シミュレーションでは、半径１２７ｍｍのポールをサイドシル２０の車外側壁部に当接させ、１ｍ／ｓの速度でポールを車内側に侵入させた。車長方向（Ｙ方向）におけるポールの当接位置は、２つのクロスメンバ３０の間の位置である。また、フロアパネル１０とクロスメンバ３０の車内側端面と、サイドシル２０の軸方向端面には拘束面を設定している。具体的には、フロアパネル１０とクロスメンバ３０の車内側端面を剛体面として完全拘束し、サイドシル２０の軸方向端面については軸方向（Ｙ方向）の変形のみを拘束している。 In this simulation, a pole with a radius of 127 mm was brought into contact with the outer side wall of the side sill 20, and the pole was moved into the inner side of the vehicle at a speed of 1 m/s. The contact position of the pawl in the vehicle length direction (Y direction) is the position between the two cross members 30 . In addition, restraint surfaces are provided on the vehicle interior end surfaces of the floor panel 10 and the cross member 30 and on the axial end surfaces of the side sills 20 . Specifically, the vehicle-interior end faces of the floor panel 10 and the cross member 30 are completely constrained as rigid surfaces, and only axial (Y-direction) deformation of the axial end face of the side sill 20 is constrained.

以上の条件でシミュレーションを行い、ポールが８５ｍｍ侵入したときのエネルギー吸収効率（衝撃吸収部のエネルギー吸収量／クロスメンバの質量）を算出した。この結果を図１６～図１８に示す。なお、本シミュレーションは、クロスメンバの形状や補強部材の有無が異なる複数のモデルで実施されている。各モデルを作成する際には、車体下部構造の総質量が互いに等しくなるようにクロスメンバの板厚ｔの値を変更している。 A simulation was performed under the above conditions, and the energy absorption efficiency (the amount of energy absorbed by the impact absorbing portion/mass of the cross member) when the pole penetrated by 85 mm was calculated. The results are shown in FIGS. 16-18. This simulation was carried out using a plurality of models with different shapes of cross members and the presence or absence of reinforcing members. When creating each model, the value of the plate thickness t of the cross member is changed so that the total mass of the vehicle body lower structure becomes equal to each other.

図１６に示すように、実施例１のモデルは、クロスメンバの縦壁部が段状に形成され、かつ、衝撃吸収部の配置領域に重なる第１稜線部Ａと第２稜線部Ｂが存在するモデルである。この実施例１のモデルは、第１稜線部Ａと第２稜線部Ｂが存在しない比較例１および比較例２のモデルよりもエネルギー吸収効率に優れている。 As shown in FIG. 16, in the model of Example 1, the vertical wall portion of the cross member is formed stepwise, and there are a first ridgeline portion A and a second ridgeline portion B that overlap the arrangement area of the shock absorbing portion. It is a model that The model of Example 1 is superior in energy absorption efficiency to the models of Comparative Examples 1 and 2 in which the first ridgeline portion A and the second ridgeline portion B do not exist.

図１７に示すように、実施例２と比較例３のモデルは、図１６に示すモデルとは異なり、補強部材を有しないモデルである。このように補強部材が設けられていない場合であっても、第１稜線部Ａと第２稜線部Ｂが存在する実施例２のモデルは、第１稜線部Ａと第２稜線部Ｂが存在しない比較例３のモデルよりもエネルギー吸収効率に優れている。特に、実施例２のモデルは、比較例３のモデルよりもクロスメンバの板厚が薄いにも関わらず、エネルギー吸収効率が上昇していることから、第１稜線部Ａと第２稜線部Ｂが存在することによる面剛性の向上効果が大きいことがわかる。 As shown in FIG. 17, the models of Example 2 and Comparative Example 3 are models that do not have reinforcing members, unlike the model shown in FIG. In the model of Example 2, in which the first ridgeline portion A and the second ridgeline portion B exist, the first ridgeline portion A and the second ridgeline portion B exist even in the case where the reinforcing member is not provided as described above. It is superior to the model of Comparative Example 3 in energy absorption efficiency. In particular, in the model of Example 2, the cross member has a thinner plate thickness than the model of Comparative Example 3, but the energy absorption efficiency is increased. It can be seen that the effect of improving surface rigidity due to the presence of is large.

図１８に示すように、いずれの実施例のモデルにおいても、第１稜線部Ａと第２稜線部Ｂが存在しない比較例２（図１６）のモデルよりもエネルギー吸収効率が優れている。 As shown in FIG. 18, the models of any of the examples are superior in energy absorption efficiency to the model of Comparative Example 2 (FIG. 16) in which the first ridgeline portion A and the second ridgeline portion B are not present.

本発明は、自動車の車体下部構造に適用することができる。 INDUSTRIAL APPLICABILITY The present invention can be applied to the underbody structure of automobiles.

１車体下部構造
１０フロアパネル
２０サイドシル
２０ａ中空部
２１アウター部品
２２インナー部品
２３衝撃吸収部
２３ａ底面部
２３ｂ側面部
２３ｃ天面部
２３ｄ稜線部
２４車外側壁部
２５車内側壁部
３０クロスメンバ
３０ａ中空部
３１天壁部
３２縦壁部
３２ａ第１壁部
３２ｂ第２壁部
３２ｃ第３壁部
３３フランジ部
３４稜線部
３５凹部
３５ａ底壁部
３５ｂ側壁部
３６第１の部品
３７第２の部品
３８底壁部
４０接合部
５０補強部材
５１底面部
５２側面部
Ａ第１稜線部
Ｂ第２稜線部
Ｒ衝撃吸収部の配置領域
ｔ板厚 1 Vehicle lower structure 10 Floor panel 20 Side sill 20a Hollow part 21 Outer part 22 Inner part 23 Impact absorbing part 23a Bottom part 23b Side part 23c Top part 23d Ridge part 24 Outer wall part 25 Inner wall part 30 Cross member 30a Hollow part 31 Top wall 32 Vertical wall 32a First wall 32b Second wall 32c Third wall 33 Flange 34 Ridge 35 Recess 35a Bottom wall 35b Side wall 36 First part 37 Second part 38 Bottom wall Part 40 Joining part 50 Reinforcing member 51 Bottom part 52 Side part A First ridgeline part B Second ridgeline part R Arrangement area t of shock absorbing part Plate thickness

Claims

A floor panel placed at the bottom of the vehicle body,
a side sill extending in the vehicle length direction provided at the vehicle width direction end of the floor panel;
a cross member extending in the vehicle width direction and connected to the side sill;
a junction between the floor panel and the cross member;
The side sill is
a hollow portion extending in the vehicle length direction;
a shock absorbing portion disposed in the hollow portion;
The shock absorbing portion is connected to a wall portion of the side sill on the inner side in the vehicle width direction,
The cross member is
a plurality of walls including a ceiling wall;
a plurality of ridges sandwiched between the walls and extending in the vehicle width direction;
The plurality of ridgeline portions have a first ridgeline portion and a second ridgeline portion between the joint portion and the top wall portion,
a bending center of the first ridge portion is positioned inside the cross member;
the bending center of the second ridge portion is positioned outside the cross member;
The vehicle body lower portion structure, wherein the first ridgeline portion and the second ridgeline portion are positioned in an area overlapping with an arrangement area of the impact absorbing portion when viewed in the vehicle width direction.

A concave portion is formed in the ceiling wall portion,
the recess has a bottom wall and two side walls,
the bottom wall portion is located between the two side wall portions;
2. The vehicle body lower portion structure according to claim 1, wherein a ridge portion sandwiched between said bottom wall portion and said two side wall portions extends in the vehicle width direction.

the cross member having a first part and a second part;
The first part and the second part each have the first ridge and the second ridge,
3. The underbody structure according to claim 2, wherein said first part and said second part are connected to each other at said bottom wall portion.

The vehicle body lower structure according to any one of claims 1 to 3, wherein the ceiling wall portion is positioned in a region overlapping with the arrangement region of the shock absorbing portion when viewed in the vehicle width direction.

a reinforcing member that reinforces the cross member;
The reinforcing member has a bottom portion and two side portions,
The bottom portion is located between the two side portions,
The ridge portion sandwiched between the bottom surface portion and the two side surface portions extends in the vehicle width direction,
The bottom portion is positioned above the top wall portion of the cross member,
The vehicle body lower structure according to any one of claims 1 to 4, wherein the two side portions are respectively joined to wall portions of the cross member other than the top wall portion.

6. The vehicle body lower portion structure according to claim 5, wherein a plurality of said reinforcing members are provided at intervals in the vehicle width direction.