JP4529569B2

JP4529569B2 - Car body rear structure

Info

Publication number: JP4529569B2
Application number: JP2004215674A
Authority: JP
Inventors: 弘隆楠; 文夫岡那
Original assignee: Mazda Motor Corp
Current assignee: Mazda Motor Corp
Priority date: 2004-07-23
Filing date: 2004-07-23
Publication date: 2010-08-25
Anticipated expiration: 2024-07-23
Also published as: JP2006035934A

Description

本発明は、自動車の車体後部の構造に関し、特に、車体後部フロアの下面に接合されて車体の捻り剛性を高めるとともに、衝突安全性を向上させるためのクロスメンバーの構造の技術分野に属する。 The present invention relates to a structure of a rear part of a vehicle body of an automobile, and particularly relates to a technical field of a structure of a cross member that is joined to a lower surface of a rear floor of a vehicle body to increase torsional rigidity of the vehicle body and improve collision safety.

従来より、一般的に、自動車の車体後部フロアには、車体の捻れ剛性を高めるとともにフロアパネルの振動を抑制し、さらには側面への衝突（以下、側突という）による車体の変形を抑えて安全性を向上させるためにクロスメンバーが配設されている。このクロスメンバーは、車幅方向に延びていて左右両側のサイドフレーム間に架設されているとともに、上方に向かって開口する（上開きの）ハット状断面を有し、その上端に形成されたフランジ部が車体後部フロアの下面に接合されて閉断面を構成している。 Conventionally, in general, the rear floor of an automobile has increased torsional rigidity of the vehicle body, suppressed vibration of the floor panel, and further suppressed deformation of the vehicle body due to a side collision (hereinafter referred to as a side collision). A cross member is disposed to improve safety. This cross member extends in the vehicle width direction, is installed between the left and right side frames, has a hat-shaped cross section that opens upward (opened upward), and a flange formed at the upper end thereof The part is joined to the lower surface of the rear floor of the vehicle body to form a closed section.

このようなクロスメンバーの構造としては、例えば特許文献１に開示されるように、クロスメンバーの板厚を各部位毎に変更して、それぞれ所要の強度が得られる最低限度の厚みにすることによって、車体の剛性及び強度を維持しながら、その軽量化を図るようにしたものが知られている。 As a structure of such a cross member, for example, as disclosed in Patent Document 1, the thickness of the cross member is changed for each part so as to obtain a minimum thickness for obtaining a required strength. In addition, there has been known one designed to reduce the weight while maintaining the rigidity and strength of the vehicle body.

すなわち、前記特許文献１に開示される自動車のリヤシートクロスメンバーでは、これを車幅方向中間部位のセンタクロスメンバと、その左右両側の延長部材とからなるものとして、側突に対応して相対的に大きな強度が要求される延長部材の板厚をセンタクロスメンバよりも大きくするとともに、さらに大きな強度の必要なタイダウンフックの取付け部にはレインフォース部材を付加している。
特開２００１−２４７０５８号公報 That is, in the rear seat cross member of an automobile disclosed in Patent Document 1, it is assumed that this is composed of a center cross member at an intermediate portion in the vehicle width direction and extension members on both the left and right sides, and relative to the side collision. In addition, the thickness of the extension member, which requires high strength, is made larger than that of the center cross member, and a reinforcement member is added to the attachment portion of the tie-down hook that requires higher strength.
Japanese Patent Laid-Open No. 2001-247058

ところで、一般に、自動車の運動性能向上のためには車体のヨーモーメントを低減することが効果的であることはよく知られており、そのために車体後部フロアについても車軸よりも後側のオーバーハング部を短縮することが考えられる。 By the way, it is well known that it is generally effective to reduce the yaw moment of the vehicle body in order to improve the motion performance of the automobile. For that reason, the overhang portion on the rear side of the vehicle body also on the rear floor of the vehicle body Can be shortened.

しかし、通常、車体後部フロアには車幅方向に延びるリヤクロスメンバーの後方に隣接して、フロアパネルから下方に膨出するようにスペアタイヤの収納部が設けられており、前記のようにオーバーハング部を短縮しようとすれば、その分、スペアタイヤ収納部を車体前側に配置しなくてはならないから、リヤクロスメンバーとの干渉の問題が発生する。 However, usually, the rear floor of the vehicle body is provided with a spare tire storage portion adjacent to the rear of the rear cross member extending in the vehicle width direction so as to bulge downward from the floor panel. If the hang part is to be shortened, the spare tire storage part has to be arranged on the front side of the vehicle body, which causes a problem of interference with the rear cross member.

特に、近年ではデザイン上の要求から自動車のタイヤ・ホイールのサイズは大径化する傾向にあり、その分、前記スペアタイヤ収納部も大きくなるから、前記のクロスメンバーとの干渉の問題が生じやすい。 In particular, in recent years, the size of automobile tires and wheels tends to increase due to design requirements, and the spare tire storage portion also increases accordingly, so that the problem of interference with the cross member is likely to occur. .

この問題に対し、クロスメンバーそのものの位置を車体前側に移動させようとしても、通常、リヤクロスメンバーの前側には隣接して燃料タンクが配置されているから、そこにはリヤクロスメンバーを移動させる余地はない。 In order to solve this problem, even if the position of the cross member itself is moved to the front side of the vehicle body, the fuel tank is usually arranged adjacent to the front side of the rear cross member, so that the rear cross member is moved there. There is no room.

そこで、リヤクロスメンバーの幅を狭めてスペアタイヤ収納部との干渉を避けるとともに、強度や剛性を確保するためにクロスメンバー全体の上下方向の寸法を大きくして、その断面積を維持することや、或いはリヤクロスメンバーを構成する鋼材の板厚を大きくすることも考えられる。 Therefore, while narrowing the width of the rear cross member to avoid interference with the spare tire storage part, to ensure strength and rigidity, the vertical dimension of the entire cross member is increased to maintain its cross-sectional area. Alternatively, it is conceivable to increase the thickness of the steel material constituting the rear cross member.

しかしながら、リヤクロスメンバーの下方には通常、前記燃料タンクへの燃料供給管や排気管などが配管されており、さらに、リヤサスペンションのリンク等との干渉も避けなくてはならないから、上下方向について寸法を拡大する余裕はあまり残されていない。また、単に鋼材の板厚を大きくすればその分、重くなってしまうので、自動車の運動性能向上という所期の目的に反することになってしまう。 However, under the rear cross member, a fuel supply pipe and an exhaust pipe are usually connected to the fuel tank, and interference with the rear suspension link must be avoided. There is not much room left to expand the dimensions. Moreover, if the thickness of the steel material is simply increased, the steel material becomes heavier accordingly, which is contrary to the intended purpose of improving the motor performance of the automobile.

斯かる問題点に鑑み、本発明の目的は、車体の後部フロア下に配設するクロスメンバーの構造に工夫を凝らして、車体のリヤオーバーハングの短縮やスペアタイヤ収納部の大型化に対応しつつ、その車体後部の強度及び剛性を十分に高くすることにある。 In view of such a problem, the object of the present invention is to devise the structure of the cross member arranged under the rear floor of the vehicle body to cope with shortening the rear overhang of the vehicle body and increasing the size of the spare tire storage unit. On the other hand, the strength and rigidity of the rear part of the vehicle body are to be sufficiently increased.

前記の目的を達成するために、本願の第１の解決手段は、車体の後部フロア下に配設するクロスメンバーを、その後側のスペアタイヤ収納部との干渉を避けるように平面視で中細りの形状にするとともに、その結果として断面積の小さくなるクロスメンバーの中間部位を高張力鋼により形成するものとした。 In order to achieve the above object, the first solving means of the present application is to thin the cross member disposed below the rear floor of the vehicle body in plan view so as to avoid interference with the spare tire storage portion on the rear side. As a result, the intermediate portion of the cross member having a reduced cross-sectional area is formed of high-tensile steel.

具体的に、請求項１の発明では、車体後部フロアの下面の左右両側にそれぞれ前後方向に延びるサイドフレームが接合されているとともに、そのフロアから下方に膨出するスペアタイヤ収納部の前方で左右に延びるクロスメンバーの両端部がそれぞれ前記各サイドフレームに結合されており、且つ、該クロスメンバーが上開きのハット状断面を有していて、その上端に形成されたフランジ部が前記フロア下面に接合されている車体後部の構造を前提とする。 Specifically, in the first aspect of the present invention, side frames extending in the front-rear direction are joined to the left and right sides of the lower surface of the rear floor of the vehicle body, and left and right in front of the spare tire storage portion bulging downward from the floor. Both end portions of the cross member extending to the side frame are coupled to the side frames, respectively, and the cross member has a hat-shaped cross section with an open top, and a flange portion formed at an upper end of the cross member is formed on the lower surface of the floor. It is assumed that the structure of the rear part of the vehicle body is joined.

そして、前記クロスメンバーの前方に隣接して燃料タンクが配設されているとともに、平面視で、前記クロスメンバーと各サイドフレームとの各結合部位におけるフランジ部を含めた車体後端部位同士を結んだ仮想線が、前記スペアタイヤ収納部と交差している場合に、前記クロスメンバーを、前記スペアタイヤ収納部の前側に隣接する部位の車両前後方向の寸法が、前記各サイドフレームとの各結合部位に比べて小さい、中細りの形状とし、当該スペアタイヤ収納部の前側に隣接する部位を、高張力鋼により形成されて略直線的に左右に延びる中間部材によって構成する一方、該中間部材の左右両端部から前記左右の各サイドフレームまで延びる部位は、それぞれ、前記中間部材よりも破壊強度の低い鋼材により形成されて、前記中間部材に連結される車体内方の端部から前記各サイドフレームに接続される車体外方の端部に向かって断面積が徐々に大きくなる左側及び右側部材によって構成する。 A fuel tank is disposed adjacent to the front of the cross member, and connects the rear end parts of the vehicle body including the flanges at the joint parts of the cross member and the side frames in plan view. When the imaginary line intersects the spare tire storage portion, the cross member has a dimension in the vehicle front-rear direction of a portion adjacent to the front side of the spare tire storage portion, and each coupling with the side frames. A portion that is small compared to the portion and has a thin shape, and a portion adjacent to the front side of the spare tire storage portion is formed by an intermediate member that is formed of high-strength steel and extends substantially linearly to the left and right. The portions extending from the left and right ends to the left and right side frames are each formed of a steel material having a lower breaking strength than the intermediate member, and the intermediate member Sectional area toward the end of the outside of the vehicle body from the vehicle body inner end are connected to the respective side frames are connected to constitute the gradually increases left and right members.

前記の構成によれば、車体後部フロアの下面に接合されるリヤクロスメンバーが左右方向の中間部位において相対的に断面積の小さくなる中細りの形状とされ、そうして幅（車両前後方向の寸法）の狭くなっている中間部位に後側から隣接するようにしてスペアタイヤ収納部が配置されているので、そのスペアタイヤ収納部が比較的大きくても、クロスメンバーとの干渉を回避しながら比較的車体前側寄りに配置することができる。 According to the above configuration, the rear cross member joined to the lower surface of the rear floor of the vehicle body is formed into a thin shape with a relatively small cross-sectional area at the intermediate portion in the left-right direction, and thus the width (in the vehicle front-rear direction). The spare tire storage part is arranged so as to be adjacent from the rear side to the intermediate part where the dimension) is narrow, so even if the spare tire storage part is relatively large, while avoiding interference with the cross member It can be disposed relatively closer to the front side of the vehicle body.

しかも、そのように相対的に断面積の小さな中間部位を別部材（中間部材）として、これを相対的に破壊強度の高い高張力鋼により形成したことで、前記の如くクロスメンバーが中細りの形状になっていても、そのことによる車体剛性の低下を抑制することができ、また、側突時の安全性を十分に確保することも可能になる。加えて、前記中間部材を略直線的な形状としたことで、高張力鋼であっても比較的容易に成形することができる。 Moreover, the intermediate member having a relatively small cross-sectional area is formed as a separate member (intermediate member) and is formed of high tensile steel having a relatively high breaking strength, so that the cross member is thinned as described above. Even if it is in a shape, it is possible to suppress a decrease in the rigidity of the vehicle body due to this, and it is also possible to sufficiently ensure the safety at the time of a side collision. In addition, since the intermediate member has a substantially linear shape, even high-tensile steel can be formed relatively easily.

従って、自動車の車体におけるリヤオーバーハングの短縮やスペアタイヤ収納部の大型化に対応しつつ、リヤクロスメンバーによって車体の強度及び剛性を十分に確保することができる。 Therefore, the strength and rigidity of the vehicle body can be sufficiently ensured by the rear cross member while corresponding to the shortening of the rear overhang in the vehicle body and the enlargement of the spare tire storage portion.

前記の構成において好ましいのは、前記クロスメンバーの左側及び右側部材のそれぞれにおいて、中間部材に結合される端部のハット状断面を閉塞するように当該各部材の前面部、後面部及び底面部に亘るリブを一体成形することである（請求項２の発明）。 In the above-described configuration, preferably, in each of the left and right members of the cross member, the front surface portion, the rear surface portion, and the bottom surface portion of each member are closed so as to close the hat-shaped cross section of the end portion coupled to the intermediate member. The extending rib is integrally formed (invention of claim 2).

こうすれば、例えば軟鋼材などにより形成される左側及び右側部材において、その断面積が中間部材と同様に小さくなってしまう端部の閉断面が、当該部材の前面部、後面部及び底面部に亘る一体成形のリブによって補強されることから、この閉断面の変形を効果的に抑えて、その剛性を十分に高めることができる。尚、そのリブを車体フロア下に接合するためのフランジ部も一体成形すれば、より好ましい。 In this way, in the left and right members formed of, for example, mild steel, the closed cross-sections of the end portions whose cross-sectional areas become the same as those of the intermediate member are formed on the front surface portion, the rear surface portion, and the bottom surface portion of the member. Since it is reinforced by the integrally formed rib, it is possible to effectively suppress the deformation of the closed cross section and sufficiently increase its rigidity. In addition, it is more preferable if the flange part for joining the rib under the vehicle body floor is also integrally formed .

次に、請求項３の発明では、前記請求項１の発明と同じ前提構成の車体後部構造を対象として、これと同様に、平面視で、前記クロスメンバーと各サイドフレームとの各結合部位におけるフランジ部を含めた車体後端部位同士を結んだ仮想線が、前記スペアタイヤ収納部と交差するようにする。そして、前記クロスメンバーが、高張力鋼により形成され、前記スペアタイヤ収納部の前側に隣接して略直線的に左右に延びるとともに、そのスペアタイヤ収納部の前端側を平面視で囲むように後側のフランジ部が切り欠かれた第１部材と、当該第１部材よりも破壊強度の低い鋼材によって、該第１部材の左右両端部から前記左右の各サイドフレームまでそれぞれ延びる左側並びに右側部、及びそれらを連結するブリッジ部が一体成形された第２部材と、を備え、該ブリッジ部が、前記第１部材によって下方から覆われているとともに、この第１部材の後側フランジ部に前記切り欠きの形成されている車幅方向範囲において車体後部フロアの下面に接合されている構成とする。 In the following, the invention of claim 3, the target vehicle rear body structure in the same premise construction as invention of claim 1, Similarly, in plan view, in each binding site with the cross member and the side frames A virtual line connecting the rear end portions of the vehicle body including the flange portion intersects the spare tire storage portion. The cross member is made of high-strength steel, and extends substantially linearly to the left and right adjacent to the front side of the spare tire storage unit, and surrounds the front end side of the spare tire storage unit in plan view. A left member and a right member extending from the left and right ends of the first member to the left and right side frames, respectively, by a first member in which the side flange portion is cut out and a steel material having a lower breaking strength than the first member; And a second member integrally formed with a bridge portion for connecting them, and the bridge portion is covered by the first member from below, and the rear flange portion of the first member is cut with the cut portion. It is assumed that the vehicle body is joined to the lower surface of the rear floor in the vehicle width direction range where the notches are formed.

前記の構成により、リヤクロスメンバーの左右方向の中間部位においてフランジ部が、後側に隣接するスペアタイヤ収納部の前端側を平面視で囲むように切り欠かれているので、そのスペアタイヤ収納部が比較的大きくても、クロスメンバー（この場合はフランジ部）との干渉を回避しながら比較的車体前側寄りに配置することができる。 With the above configuration, the flange portion is cut out so as to surround the front end side of the spare tire storage portion adjacent to the rear side in a plan view in the left-right intermediate portion of the rear cross member. Even if is relatively large, it can be disposed relatively closer to the front of the vehicle body while avoiding interference with the cross member (in this case, the flange portion).

しかも、そのようにフランジ部が切り欠かれている中間部を別部材（第１部材）として、これを相対的に破壊強度の高い高張力鋼により形成したことで、フランジ部の切り欠き形成に伴う剛性や強度の低下を抑制することができる。加えて、前記第１部材を略直線的な形状としたことで、高張力鋼であっても比較的容易に成形することができる。 Moreover, by forming the intermediate part in which the flange part is cut out as a separate member (first member) and using high-tensile steel with relatively high breaking strength, it is possible to form a notch in the flange part. The accompanying reduction in rigidity and strength can be suppressed. In addition, since the first member has a substantially linear shape, even high-tensile steel can be formed relatively easily.

さらに、前記第１部材のフランジ部に切り欠きの形成されている車幅方向範囲において左右両側部材を繋ぐブリッジ部が車体後部フロアの下面に接合されているので、前記切り欠かきの形成によるクロスメンバーとリヤフロアとの接合強度の低下を補完して、十分な強度を得ることができる。 Furthermore, since the bridge portion that connects the left and right side members in the vehicle width direction range in which the notch is formed in the flange portion of the first member is joined to the lower surface of the vehicle body rear floor, the crossing due to the formation of the notch A sufficient strength can be obtained by complementing the decrease in the bonding strength between the member and the rear floor.

従って、請求項３の発明でも、請求項１の発明と同じく、自動車の車体におけるリヤオーバーハングの短縮やスペアタイヤ収納部の大型化に対応しつつ、リヤクロスメンバーによって車体の強度及び剛性を十分に確保することができる。 Therefore, in the invention of claim 3, as in the invention of claim 1, the strength and rigidity of the vehicle body are sufficiently increased by the rear cross member while the rear overhang in the vehicle body is shortened and the spare tire storage portion is enlarged. Can be secured.

以上のように、請求項１又は２の発明に係る車体後部構造によると、リヤクロスメンバーを中細りの形状としたことで、その後側に隣接するスペアタイヤ収納部を比較的車体前側寄りに配置することができるとともに、その中細りとなるクロスメンバーの中間部分を高張力鋼により形成したことなどによって剛性及び強度の低下を防止することができる。これにより、自動車のリヤオーバーハングの短縮やスペアタイヤ収納部の大型化に対応しつつ、車体の強度及び剛性を十分に確保することができる。 As described above, according to the vehicle body rear structure according to the first or second aspect of the invention, the rear cross member is formed in a thin shape, so that the spare tire storage portion adjacent to the rear side is disposed relatively closer to the vehicle front side. In addition, it is possible to prevent a decrease in rigidity and strength by forming an intermediate portion of the cross member that is thinned with high-strength steel. Thereby, the strength and rigidity of the vehicle body can be sufficiently ensured while corresponding to the reduction of the rear overhang of the automobile and the enlargement of the spare tire storage portion.

また、請求項３の発明に係る車体後部構造によると、リヤクロスメンバーの後側フランジ部を切り欠いたことで、その後側に隣接するスペアタイヤ収納部を比較的車体前側寄りに配置することができるとともに、その切り欠きの形成されている車幅方向範囲において車体後部フロアに接合する部位（ブリッジ部）を新たに設けたことで、フランジ部の切り欠きによる接合強度の低下を補完して、十分な強度及び剛性を確保することができる。 According to the vehicle body rear structure according to the third aspect of the present invention, the rear flange member of the rear cross member is notched so that the spare tire storage portion adjacent to the rear side can be disposed relatively closer to the vehicle front side. As well as being able to compensate for the decrease in joint strength due to the notch of the flange part by newly providing a part (bridge part) to be joined to the vehicle body rear floor in the vehicle width direction range where the notch is formed, Sufficient strength and rigidity can be ensured.

以下、本発明の実施形態を図面に基づいて詳細に説明する。尚、以下の好ましい実施形態の説明は、本質的に例示に過ぎず、本発明、その適用物或いはその用途を制限することを意図するものではない。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

（実施形態１）
図１〜３には、本発明の実施形態に係る自動車の車体後部フロアの構造（車体後部構造）Ａを示し、図１に示すように自動車の車体後部においては、車室の床部分を構成するフロントフロアパネル１の後端から立ち上がるようにキックアップ部２（センタフロアパネル）が配設され、このキックアップ部２のの後側に連続してリヤフロアパネル３が配設されて、車体後部フロアを構成している。また、前記キックアップ部２からリヤフロアパネル３に掛けてのフロア下面の左右両側には、それぞれ、車体前後方向に延びるリヤサイドフレーム４，４が配設されているとともに、これらのリヤサイドフレーム４，４の間にはリヤクロスメンバー５が架設されている。 (Embodiment 1)
1 to 3 show a vehicle body rear floor structure (vehicle body rear structure) A according to an embodiment of the present invention. As shown in FIG. 1, the vehicle body rear portion constitutes a floor portion of a passenger compartment. A kick-up portion 2 (center floor panel) is disposed so as to rise from the rear end of the front floor panel 1 to be operated, and a rear floor panel 3 is continuously disposed on the rear side of the kick-up portion 2 so that the rear portion of the vehicle body It constitutes the floor. In addition, rear side frames 4, 4 extending in the longitudinal direction of the vehicle body are disposed on the left and right sides of the floor lower surface from the kick-up portion 2 to the rear floor panel 3, and these rear side frames 4, 4 are disposed. A rear cross member 5 is installed between the two.

前記リヤクロスメンバー５は、その構造について詳しくは後述するが、図２や図３(a)に示すようにリヤフロアパネル３などを取り除いて見ると、左右（車幅方向）の中央付近で幅（前後方向の寸法）の細くなる中細りの形状とされ、リヤフロアパネル３の下方に膨出するスペアタイヤパン３ａ（スペアタイヤ収納部）の前側を迂回するように左右に延びていて、その左右両端部がそれぞれ左右の各リヤサイドフレーム４，４に接合されている。また、リヤサイドフレーム４，４及びリヤクロスメンバー５は、いずれも上開きのハット状断面を有し、その上端に形成されたフランジ部４ａ，５ａがリヤフロアパネル３の下面に接合されることによって、それぞれ閉断面を構成するようになっている。 Although the structure of the rear cross member 5 will be described in detail later, when the rear floor panel 3 is removed as shown in FIGS. 2 and 3 (a), the rear cross member 5 has a width ( The front and rear dimensions of the spare tire pan 3a (spare tire storage part) bulges downward from the rear floor panel 3 so as to bypass the front side and extend to the left and right. The portions are joined to the left and right rear side frames 4 and 4, respectively. The rear side frames 4 and 4 and the rear cross member 5 both have a hat-shaped cross section that opens upward, and flange portions 4a and 5a formed at the upper ends thereof are joined to the lower surface of the rear floor panel 3, Each has a closed cross section.

前記キックアップ部２からリヤフロアパネル３の前側に掛けてフロントフロアパネル１から一段、高くなった車体フロアの下方には、図２や図３に示すように燃料タンク１０が配設されており、この燃料タンク１０へ燃料を給油するためのフィラーパイプ１１（燃料供給管）や蒸発燃料の通路となるブリーザパイプ１２がいずれも車体の左側（図１，２の手前側）に配管されて、前記リヤクロスメンバー５の下方を前後方向に延びている。一方、車体右側においては該リヤクロスメンバー５の下方を排気管１３が通っている。 A fuel tank 10 is disposed below the body floor which is hung from the kick-up portion 2 to the front side of the rear floor panel 3 and raised from the front floor panel 1 as shown in FIG. 2 and FIG. A filler pipe 11 (fuel supply pipe) for supplying fuel to the fuel tank 10 and a breather pipe 12 serving as an evaporative fuel passage are both provided on the left side (front side of FIGS. 1 and 2) of the vehicle body. A lower part of the rear cross member 5 extends in the front-rear direction. On the other hand, on the right side of the vehicle body, an exhaust pipe 13 passes under the rear cross member 5.

また、この実施形態では、自動車のリヤサスペンションはいわゆるトーションビームアクスル式のものであり、丸パイプからなる左右のトレーリングアーム１５（図１、２に車体左側のみ示す）同士を連結する略Ｕ字状断面のトーションビーム１６が、図２や図３に示すように前記リヤクロスメンバー５の下方に重なるようにして、所定間隔（サスペンションのフルボトム時にもトーションビーム１６がリヤクロスメンバー５と接触しないような間隔）を空けて配置されている。尚、図１の符号１７，１７は、それぞれ下端部が前記トレーリングアーム１５に連結されているショックアブソーバを示す。 In this embodiment, the rear suspension of the automobile is of a so-called torsion beam axle type, and is substantially U-shaped that connects the left and right trailing arms 15 (shown only on the left side of the vehicle body in FIGS. 1 and 2) made of round pipes. As shown in FIGS. 2 and 3, the cross-sectional torsion beam 16 overlaps below the rear cross member 5 and has a predetermined interval (an interval at which the torsion beam 16 does not contact the rear cross member 5 even at the full bottom of the suspension). It is arranged with a gap. Reference numerals 17 and 17 in FIG. 1 denote shock absorbers whose lower ends are connected to the trailing arm 15, respectively.

この実施形態に係る車体後部構造Ａの特徴は、前記の如く中細り形状とされたリヤクロスメンバー５の構造にある。すなわち、この実施形態に係る自動車は、その運動性能の向上のために車体のリヤオーバーハングを短縮してヨーモーメントを低減するようにしており、これに伴い車体前方寄りに配置されるスペアタイヤパン３ａとの干渉を避けるべく、概ね該スペアタイヤパン３ａの車幅方向範囲に相当する部位において、リヤクロスメンバー５の車体後側が隣接するスペアタイヤパン３ａの前端側を取り囲むように凹陥されている。 The vehicle body rear part structure A according to this embodiment is characterized by the structure of the rear cross member 5 having a slender shape as described above. That is, in the vehicle according to this embodiment, in order to improve the motion performance, the rear overhang of the vehicle body is shortened to reduce the yaw moment, and accordingly, the spare tire pan disposed closer to the front of the vehicle body In order to avoid interference with the spare tire pan 3a, the rear side of the rear cross member 5 is recessed so as to surround the front end side of the adjacent spare tire pan 3a in a portion corresponding to the range of the spare tire pan 3a in the vehicle width direction. .

言い換えると、図３(a)に示すように車体フロアを上方から見て、リヤクロスメンバー５は、その中間部位がスペアタイヤパン３ａの前端部に隣接して略直線的に車体左右に延びていて、その両端部から車体左右の各リヤサイドフレーム４，４に向かって徐々に幅が拡大するような形状とされている。このことで、リヤクロスメンバー５と各リヤサイドフレーム４，４との結合部位においてそれぞれフランジ部５ａを含めた車体後端部位同士を直線（仮想線）で結ぶと、この仮想線Ｌは前記スペアタイヤパン３ａと交差することになる。 In other words, as shown in FIG. 3 (a), when the vehicle body floor is viewed from above, the rear cross member 5 has an intermediate portion extending substantially linearly to the left and right of the vehicle adjacent to the front end of the spare tire pan 3a. Thus, the width gradually increases from both ends toward the rear side frames 4 and 4 on the left and right sides of the vehicle body. As a result, when the rear end portions of the vehicle body including the flange portion 5a are connected by straight lines (virtual lines) at the connecting portions of the rear cross member 5 and the rear side frames 4 and 4, the virtual lines L indicate the spare tires. It will cross the bread 3a.

ところで、一般に、自動車のフロアにおいて左右のサイドメンバー同士を連結するクロスメンバーは、操縦安定性に影響の大きい車体捻り剛性の確保に大きく寄与するものであり、特にリヤクロスメンバーはリヤサスペンションからの入力を直接的に受けることから、操縦安定性及び乗り心地への影響が極めて強い。また、リヤクロスメンバーは、車体側面への衝突時に車室の変形を抑えて乗員のための空間を確保するという極めて重要な役割も担っている。 By the way, in general, the cross member that connects the left and right side members on the floor of an automobile greatly contributes to securing the torsional rigidity of the vehicle body, which has a great influence on the steering stability. In particular, the rear cross member is input from the rear suspension. Because it is directly affected, the influence on the handling stability and ride comfort is extremely strong. In addition, the rear cross member plays an extremely important role of securing a space for the occupant by suppressing deformation of the passenger compartment at the time of a collision with the side of the vehicle body.

従って、前記のようにリヤクロスメンバー５を中間部の細い中細りの形状とした場合、その中間部位における閉断面積の減少によってクロスメンバー５自体の曲げ・捻り剛性が低下し、これにより車体の捻り剛性が低下してしまい、操縦安定性や乗り心地が損なわれるとともに、そのように細くなっている中間部位で座屈耐力が低下することから、側突時にクロスメンバー５が折れ曲がり易くなって、安全性も低下する虞れがある。 Therefore, when the rear cross member 5 is formed in a thin and thin shape at the middle part as described above, the bending / twisting rigidity of the cross member 5 itself is reduced due to the reduction in the closed cross-sectional area at the middle part, thereby Torsional rigidity is reduced, steering stability and ride comfort are impaired, and buckling strength is reduced at the thinned intermediate part, so that the cross member 5 is easily bent during a side collision, There is also a possibility that safety will also fall.

このような問題に対して、クロスメンバー５の断面の寸法を上下方向に大きくして、これにより強度や剛性を確保することも考えられるが、この実施形態では、上述したようにリヤクロスメンバー５の下方には車体の左右両側にてそれぞれ燃料系統の配管１１，１２及び排気管１３がレイアウトされており、さらに、リヤサスペンションのトーションビーム１６との干渉も避けなくてはならないから、リヤクロスメンバー５の寸法を上下方向に拡大する余裕は殆どない。 To deal with such a problem, it is conceivable to increase the cross-sectional dimension of the cross member 5 in the vertical direction, thereby ensuring strength and rigidity. In this embodiment, as described above, the rear cross member 5 is used. Since the pipes 11 and 12 and the exhaust pipe 13 of the fuel system are laid out on the left and right sides of the vehicle body, and further, interference with the torsion beam 16 of the rear suspension must be avoided. There is almost no margin for expanding the size of the above in the vertical direction.

また、単純にリヤクロスメンバー５の鋼板の厚みを大きくすることも考えられなくはないが、この場合には、板厚を大きくした分、リヤクロスメンバー５が重くなってしまい、自動車の運動性能向上という所期の目的との間に矛盾を生じることになる。 In addition, simply increasing the thickness of the steel plate of the rear cross member 5 is not considered, but in this case, the rear cross member 5 becomes heavier as the plate thickness is increased, and the motor performance of the car is increased. There will be a contradiction between the intended purpose of improvement.

そこで、この実施形態では、前記のように中細りの形状となるリヤクロスメンバー５の構造に工夫を凝らして、重量の増大を殆ど招くことなく、その剛性や強度を確保するようにした。すなわち、図４に示すように、前記リヤクロスメンバー５は、スペアタイヤパン３ａの前端部に対応して車幅方向の中央部寄りに位置する中間部材５１と、その左右両端部からそれぞれ車体左右の各リヤサイドフレーム４，４まで延びる左側及び右側部材５２，５３との３つに分割されている。 Therefore, in this embodiment, the structure of the rear cross member 5 having a thin shape as described above is devised to ensure the rigidity and strength without incurring a substantial increase in weight. That is, as shown in FIG. 4, the rear cross member 5 includes an intermediate member 51 located near the center in the vehicle width direction corresponding to the front end of the spare tire pan 3a, and the left and right ends of the vehicle. The left and right members 52, 53 extending to the rear side frames 4, 4 are divided into three parts.

前記中間部材５１は、高張力鋼板をプレス成形したもので、それぞれ車幅方向に延びる前面部５１ａ、後面部５１ｂ及び底面部５１ｃの３つの壁部を備えて、上方に開口するハット状の略一定の断面形状を有しており、その前面部５１ａ及び後面部５１ｂの上端からそれぞれ前側及び後側に折り曲げられて、スポット溶接などによりリヤフロアパネル３に接合されるフランジ部５１ｄ，５１ｄ（リヤクロスメンバー５のフランジ部５ａの一部を構成する）が形成されている。この中間部材５１は、リヤクロスメンバー５の中では最も幅が狭く、スペアタイヤパン３ａの前端部に隣接して左右に略直線的に延びるように配置される。 The intermediate member 51 is formed by press-forming a high-tensile steel plate, and includes a front wall portion 51a, a rear surface portion 51b, and a bottom surface portion 51c that extend in the vehicle width direction, and has a hat-like shape that opens upward. Flange portions 51d and 51d (rear crossings) which have a constant cross-sectional shape, are bent from the upper ends of the front surface portion 51a and the rear surface portion 51b to the front side and the rear side, respectively, and joined to the rear floor panel 3 by spot welding or the like. A part of the flange portion 5a of the member 5 is formed. The intermediate member 51 has the narrowest width in the rear cross member 5 and is disposed so as to extend substantially linearly to the left and right adjacent to the front end portion of the spare tire pan 3a.

そのように高張力鋼板によって形成したことで、前記中間部材５１は、通常の軟鋼材などにより形成したものに比べて大幅に破壊強度が高くなり、また重量増を招くことなく剛性も高くすることができるから、中細りのリヤクロスメンバー５の中央部位における剛性の低下を抑えることができるとともに、その座屈耐力を高めて側突時の車室の変形をリヤクロスメンバー５により十分に抑制することができる。しかも、略直線的に延びる形状としたことで、高張力鋼板であっても比較的容易にプレス成形することができる。 By forming the intermediate member 51 in such a manner, the intermediate member 51 has significantly higher fracture strength than that formed by a normal mild steel material, and also increases rigidity without causing an increase in weight. Therefore, it is possible to suppress a decrease in rigidity at the central portion of the middle thin rear cross member 5 and to increase the buckling resistance to sufficiently suppress the deformation of the vehicle compartment at the time of a side collision by the rear cross member 5. be able to. Moreover, since the shape extends substantially linearly, even a high-strength steel plate can be press-formed relatively easily.

一方、前記左側部材５２及び右側部材５３は、いずれも前記中間部材５１よりも成形の容易な例えば軟鋼板などをプレス成形してなり、それぞれ車幅方向に延びる前面部５２ａ，５３ａ、後面部５２ｂ，５３ｂ及び底面部５２ｃ，５３ｃの３つの壁部を備えて上方に開口するハット状の断面形状を有するものであるが、その断面積は、前記中間部材５１ａの左右両端部に接続される車体内方の端部から左右の各リヤサイドフレーム４，４，に接続される車体外方の端部に向かって徐々に大きくなっている。 On the other hand, each of the left side member 52 and the right side member 53 is formed by press-molding, for example, a mild steel plate, which is easier to form than the intermediate member 51, and extends in the vehicle width direction. , 53b and bottom wall portions 52c, 53c, and has a hat-like cross-sectional shape opening upward, the cross-sectional area of which is a vehicle connected to both left and right end portions of the intermediate member 51a. It gradually increases from the end portion on the inside of the body toward the end portion on the outer side of the vehicle body connected to the left and right rear side frames 4, 4.

また、前記中間部材５１の左右両端部に各々接続される左側部材５２及び右側部材５３の車体内方端には、該各部材５２，５３の前面部５２ａ，５３ａ、後面部５２ｂ，５３ｂ及び底面部５２ｃ，５３ｃに亘って、ハット状断面を閉塞するようにリブ５２ｅ，５３ｅが一体成形されている。このことで、断面積が前記中間部材５１と同様に小さくなってしまう左側及び右側部材５２，５３の車体内方の端部断面が、そこに一体成形されたリブ５２ｅ，５３ｅによって塞がれて効果的に補強される。 Further, on the vehicle body inner ends of the left member 52 and the right member 53 respectively connected to the left and right ends of the intermediate member 51, front surface portions 52a, 53a, rear surface portions 52b, 53b and bottom surfaces of the members 52, 53 are provided. Ribs 52e and 53e are integrally formed so as to block the hat-shaped cross section over the portions 52c and 53c. As a result, the cross-sectional area of the left and right members 52 and 53 that are smaller in cross-sectional area than the intermediate member 51 is blocked by the ribs 52e and 53e formed integrally therewith. Effectively reinforced.

さらに、前記左側部材５２及び右側部材５３には、各々、前面部５２ａ，５３ａ及び後面部５２ｂ，５３ｂの上端からそれぞれ前側及び後側に折り曲げられて、リヤフロアパネル３に接合されるフランジ部５２ｄ，５２ｄ，５３ｄ，５３ｄ（リヤクロスメンバー５のフランジ部５ａの一部を構成する）が形成されるとともに、前記リブ５２ｅ，５３ｅの上端から車体内方に折り曲げられてそれぞれ前記中間部材５１に覆われた状態でリヤフロアパネル３に接合されるインナーフランジ部５２ｆ，５３ｆが設けられている。 Further, the left side member 52 and the right side member 53 are respectively bent to front and rear sides from the upper ends of the front surface parts 52a and 53a and the rear surface parts 52b and 53b, and are joined to the rear floor panel 3 by flange parts 52d and 52d, respectively. 52d, 53d, 53d (which constitutes a part of the flange portion 5a of the rear cross member 5) are formed, and the ribs 52e, 53e are bent inwardly of the vehicle body and covered with the intermediate member 51, respectively. Inner flange portions 52f and 53f are provided to be joined to the rear floor panel 3 in a state of being attached.

そして、そのようにインナーフランジ部５２ｆ，５３ｆがリヤフロアパネル３に接合されることにより、前記の如くリブ５２ｅ，５３ｅによって効果的に補強された左側及び右側部材５２，５３の車体内方の端部における車体フロアとの接合強度も高くなり、前記リブ５２ｅ，５３ｅによる補強とも相俟って、断面積の小さな車体内方の端部における左側及び右側部材５２，５３の剛性及び強度が十分に高くなる。 Then, the inner flange portions 52f and 53f are joined to the rear floor panel 3 as described above, so that the end portions of the left and right members 52 and 53 inside the vehicle body effectively reinforced by the ribs 52e and 53e as described above. The strength of the left and right members 52 and 53 at the inner end of the vehicle body having a small cross-sectional area is sufficiently high in combination with the reinforcement by the ribs 52e and 53e. Become.

したがって、上述の如き構造のリヤクロスメンバー５を用いた、この実施形態の車体後部構造Ａによると、リヤフロアパネル３の下面に接合させるリヤクロスメンバー５をその中央付近において幅の狭い中細りの形状とし、その幅狭の部分に後側から隣接するようにしてスペアタイヤパン３ａをレイアウトしたことで、このスペアタイヤパン３ａが比較的大きな場合でも、これを車体前側寄りにレイアウトして、車体のリヤオーバーハングを短縮することができる。 Therefore, according to the vehicle body rear structure A of this embodiment using the rear cross member 5 having the structure as described above, the rear cross member 5 to be joined to the lower surface of the rear floor panel 3 has a narrow and narrow shape near the center. Since the spare tire pan 3a is laid out so as to be adjacent to the narrow portion from the rear side, even if the spare tire pan 3a is relatively large, the spare tire pan 3a is laid out toward the front side of the vehicle body. Rear overhang can be shortened.

また、そのように中細りとなって断面積の小さくなるリヤクロスメンバー５の中央付近を別部材（中間部材５１）として、これを高張力鋼により形成したことで、リヤクロスメンバー５中細り形状に起因する車体剛性の低下を抑制するとともに、側突時の安全性を十分に確保することができる。 Further, by forming the rear cross member 5 near the center of the rear cross member 5 having a small cross-sectional area as a separate member (intermediate member 51) by using high tensile steel, the rear cross member 5 has a medium thin shape. It is possible to suppress the decrease in the vehicle body rigidity caused by the above and to sufficiently ensure the safety at the time of a side collision.

こうして自動車の車体リヤオーバーハングの短縮やタイヤ・ホイールの大径化に対応しつつ、車体の強度及び剛性を十分に確保することができる。 Thus, the strength and rigidity of the vehicle body can be sufficiently ensured while corresponding to shortening of the vehicle body rear overhang and increasing the diameter of the tire and wheel.

（実施形態２）
図５は、本発明の実施形態２に係るリヤクロスメンバー６の概略構造を示す。この実施形態２の車体後部構造Ａは、前記リヤクロスメンバー６の構造以外は前記実施形態１のものと同じなので、以下、同一部材には同一の符号を付してその説明は省略する。そして、この実施形態２のものでは、前記実施形態１のリヤクロスメンバー５のようにスペアタイヤパン３ａとの隣接部位で幅を狭めるのではなく、長手方向に略一定の幅としながら、スペアタイヤパン３ａの前側に隣接するフランジ部を、平面視で該スペアタイヤパン３ａの前端側を取り囲むように切り欠いたものである。 (Embodiment 2)
FIG. 5 shows a schematic structure of the rear cross member 6 according to the second embodiment of the present invention. Since the vehicle body rear structure A of the second embodiment is the same as that of the first embodiment except for the structure of the rear cross member 6, hereinafter, the same members are denoted by the same reference numerals and description thereof is omitted. In the second embodiment, the width of the spare tire is not narrowed at the adjacent portion to the spare tire pan 3a as in the rear cross member 5 of the first embodiment, but the width of the spare tire is kept constant in the longitudinal direction. A flange portion adjacent to the front side of the pan 3a is cut out so as to surround the front end side of the spare tire pan 3a in plan view.

この結果として、図示しないが、この実施形態２においても前記実施形態１と同様に、平面視でリヤクロスメンバー６と各リヤサイドフレーム４，４との結合部位においてそれぞれフランジ部を含めた車体後端部位同士を結んだ仮想線は、スペアタイヤパン３ａと交差することになる。 As a result, although not shown, the rear end of the vehicle body including the flange portion in the coupling portion between the rear cross member 6 and each of the rear side frames 4 and 4 in plan view as well as in the first embodiment. An imaginary line connecting the parts intersects the spare tire pan 3a.

より具体的に、同図に示すように、この実施形態のリヤクロスメンバー６は、前記実施形態１のものとは異なり長手方向に略一定の断面形状を有する一方、実施形態１のものと同様に左右方向の中間部６１とその左右両側の左側部６２及び右側部６３とに分かれており、その中間部６１が高張力鋼板のプレス加工により形成されて単独で第１部材６１を構成し、また、左側部６２及び右側部６３は両者を繋ぐブリッジ部６４とともに例えば軟鋼板のプレス加工により一体成型されて、第２部材６５を構成している。 More specifically, as shown in the figure, the rear cross member 6 of this embodiment has a substantially constant cross-sectional shape in the longitudinal direction, unlike the one of the first embodiment, while the same as that of the first embodiment. Are divided into a left-right intermediate portion 61 and left and right left-side portions 62 and 63 on the right and left sides, and the intermediate portion 61 is formed by pressing a high-tensile steel plate to constitute the first member 61 alone. Further, the left side portion 62 and the right side portion 63 are integrally formed together with a bridge portion 64 that connects them, for example, by press working of a mild steel plate, thereby constituting a second member 65.

前記第１部材６１は、前記実施形態１の中間部材５１と同様にそれぞれ車幅方向に延びる前面部６１ａ、後面部６１ｂ及び底面部６１ｃの３つの壁部を備えて、上方に開口する略一定のハット状断面を有しており、その前面部６１ａ及び後面部６１ｂの上端からそれぞれ前側及び後側に折り曲げられて、リヤフロアパネル３に接合されるフランジ部６１ｄ，６１ｄが形成されている。この第１部材６１の後側のフランジ部６１ｄには、隣接するスペアタイヤパン３ａの前端側（図には仮想線で示す）を平面視で取り囲むようにして、切り欠き６１ｅが形成されている。 The first member 61 includes three wall portions including a front surface portion 61a, a rear surface portion 61b, and a bottom surface portion 61c that extend in the vehicle width direction, like the intermediate member 51 of the first embodiment, and is substantially constant and opens upward. The flange portions 61d and 61d are formed to be bent from the upper ends of the front surface portion 61a and the rear surface portion 61b to the front side and the rear side, respectively, and joined to the rear floor panel 3. A notch 61e is formed in the flange portion 61d on the rear side of the first member 61 so as to surround the front end side (indicated by a virtual line in the drawing) of the adjacent spare tire pan 3a in plan view. .

そのようにフランジ部６１ｄを切り欠いたことで、その分、スペアタイヤパン３ａを車体前側寄りに配置することができる。また、第１部材６１を高張力鋼板により形成したことで、切り欠かき６１ｅの形成に起因する剛性や強度の低下を抑制することができ、しかも、略直線的に延びる形状としたことで、高張力鋼板であっても比較的容易にプレス成形することができる。 By notching the flange portion 61d in this way, the spare tire pan 3a can be disposed closer to the front side of the vehicle body. In addition, by forming the first member 61 with a high-tensile steel plate, it is possible to suppress a decrease in rigidity and strength due to the formation of the notch 61e, and in addition, a shape that extends substantially linearly, Even a high-strength steel plate can be press-formed relatively easily.

一方、前記第２部材６５の左側部６２及び右側部６３は、いずれも前記第１部材６１と同様に前面部６２ａ，６３ａ、後面部６２ｂ，６３ｂ及び底面部６２ｃ，６３ｃの３つの壁部を備え、その前面部６２ａ，６３ａ及び後面部６２ｂ，６３ｂの上端がそれぞれ前側及び後側に折り曲げられて、リヤフロアパネル３に接合されるフランジ部６２ｄ，５２ｄ，６３ｄ，６３ｄが形成されている。 On the other hand, each of the left side portion 62 and the right side portion 63 of the second member 65 has three wall portions of the front surface portions 62a and 63a, the rear surface portions 62b and 63b, and the bottom surface portions 62c and 63c, similarly to the first member 61. The upper ends of the front surface portions 62a, 63a and the rear surface portions 62b, 63b are bent to the front side and the rear side, respectively, to form flange portions 62d, 52d, 63d, 63d joined to the rear floor panel 3.

また、前記左側部６２及び右側部６３の各底面部６２ｃ，６３ｃにおける車体内方の端部には前記ブリッジ部６４の左右両端部が連続していて、このブリッジ部６４は、前記左側部６２及び右側部６３と連続する部位からそれぞれ車体内方の斜め上方に向かって延びる左右一対の傾斜面部６４ａ，６４ａと、この各傾斜面部６４ａ，６４ａの上端同士を連繋するように左右に延びる上面部６４ｂとからなる。 The left and right ends of the bridge portion 64 are connected to the inner ends of the vehicle body at the bottom surface portions 62c and 63c of the left side portion 62 and the right side portion 63. The bridge portion 64 is connected to the left side portion 62. And a pair of left and right inclined surface portions 64a and 64a extending obliquely upward inward of the vehicle body from a portion continuous with the right side portion 63, and an upper surface portion extending left and right so as to connect the upper ends of the inclined surface portions 64a and 64a. 64b.

そして、前記第２部材６５の左右両側部６２，６３の各フランジ部６２ｄ，６３ｄがそれぞれリヤフロアパネル３の下面の左右両側部位にスポット溶接などにより接合されるとともに、それらの中間の部位ではブリッジ部６４の上面部６４ｂも接合され、これにより前記第２部材６５がリヤフロアパネル３に取り付けられる。また、そのブリッジ部６４を下方から覆うようにして前記第１部材６１がリヤフロアパネル３に下方から取り付けられる。この際、図示の如く、第１部材６１のフランジ部６１ｄは全体としてリヤフロアパネル３の下面に接合されるとともに、特に左右両端部においては前記第２部材６５の左右両側部６２，６３のフランジ部６２ｄ，６３ｄに下方から重ね合わされて接合される。 The flange portions 62d and 63d of the left and right side portions 62 and 63 of the second member 65 are joined to the left and right side portions of the lower surface of the rear floor panel 3 by spot welding or the like. The upper surface portion 64b of 64 is also joined, whereby the second member 65 is attached to the rear floor panel 3. The first member 61 is attached to the rear floor panel 3 from below so as to cover the bridge portion 64 from below. At this time, as shown in the drawing, the flange portion 61d of the first member 61 is joined to the lower surface of the rear floor panel 3 as a whole, and the flange portions of the left and right side portions 62 and 63 of the second member 65 are particularly connected to the left and right ends. Overlaid and joined to 62d and 63d from below.

ここで、前記第１部材６１の後側フランジ部６１ｄには切り欠き６１ｅが形成されていて、この切り欠き６１ｅの形成部位ではリヤフロアパネル３との接合強度は得られないことになるが、その第１部材６１と一体になる第２部材６５のブリッジ部６４が、ちょうど前記切り欠き６１ｅの形成されている車幅方向範囲においてリヤフロアパネル３に接合されており、このことで、当該切り欠き６１ｅの形成による接合強度の低下を補完することができる。 Here, a notch 61e is formed in the rear flange portion 61d of the first member 61, and the joining strength with the rear floor panel 3 cannot be obtained at the portion where the notch 61e is formed. The bridge portion 64 of the second member 65 that is integrated with the first member 61 is joined to the rear floor panel 3 in the vehicle width direction range where the notch 61e is formed, and thus the notch 61e. The decrease in bonding strength due to the formation of can be supplemented.

したがって、この実施形態２によれば、リヤクロスメンバー６の左右方向中間部位を構成する第１部材６１の後側フランジ部６１ｄを、スペアタイヤパン３ａの前端側を取り囲むように切り欠いたことで、前記実施形態１と同様にスペアタイヤパン３ａを車体前側寄りに配置することができ、これによりリヤオーバーハングの短縮が可能になる。 Therefore, according to the second embodiment, the rear flange portion 61d of the first member 61 constituting the intermediate portion in the left-right direction of the rear cross member 6 is cut out so as to surround the front end side of the spare tire pan 3a. As in the first embodiment, the spare tire pan 3a can be disposed closer to the front side of the vehicle body, which makes it possible to shorten the rear overhang.

また、前記第１部材６１を高張力鋼により形成して剛性及び強度を高めることができるとともに、この第１部材６１のフランジ部６１ｄが切り欠かれている範囲に対応付けて、第２部材６５のブリッジ部６４をリヤフロアパン３の下面に接合したので、フランジ部６１ｄを切り欠いたことによるリヤクロスメンバー６とリヤフロアパネル３との接合強度の低下を補完して、車体の剛性や強度を十分に確保することができる。 Further, the first member 61 can be made of high-tensile steel to increase the rigidity and strength, and the second member 65 is associated with the range where the flange portion 61d of the first member 61 is cut away. Since the bridge portion 64 is joined to the lower surface of the rear floor pan 3, the lowering of the joining strength between the rear cross member 6 and the rear floor panel 3 due to the notch of the flange portion 61d is complemented, and the rigidity and strength of the vehicle body are sufficient. Can be secured.

（他の実施形態）
本発明の構成は、前記実施形態１、２のものに限定されることはなく、その他の種々の構成をも包含するものである。すなわち、例えば前記実施形態１のリヤクロスメンバー５においては、中細りの形状とすることでスペアタイヤパン３ａとの干渉を回避するようにしており、その代わりにフランジ部５ａは切り欠かないでリヤフロアパネル３との間の接合強度を確保するようにしているが、これに限らず、例えば前記実施形態２のもののようにリヤクロスメンバー５の中間部材５１の後側フランジ部５１ｄを切り欠くようにしてもよい。 (Other embodiments)
The configuration of the present invention is not limited to those of the first and second embodiments, and includes other various configurations. That is, for example, in the rear cross member 5 of the first embodiment, it is made thin so as to avoid interference with the spare tire pan 3a. Instead, the flange portion 5a is not cut out and the rear floor member 5 is not cut out. However, the present invention is not limited to this. For example, the rear flange portion 51d of the intermediate member 51 of the rear cross member 5 is cut out as in the second embodiment. May be.

こうすれば、フランジ部５１ｄの切り欠きによってもスペアタイヤパン３ａとの干渉を避けることができるので、その分は中間部材５１の幅を広げて（断面積を大きくして）、剛性や強度を高めることができる。但し、フランジ部５１ｄを切り欠けば、その分、リヤフロアパネル３との間の接合強度は低下することになるので、その点については前記実施形態２と同様に補強する必要がある。 In this way, interference with the spare tire pan 3a can be avoided even by the notch of the flange portion 51d. Therefore, the width of the intermediate member 51 is increased (the cross-sectional area is increased) to increase the rigidity and strength. Can be increased. However, if the flange portion 51d is cut out, the joint strength with the rear floor panel 3 is reduced accordingly, so that it is necessary to reinforce that point as in the second embodiment .

本発明の実施形態１に係る自動車の車体後部フロアの概略構造を示す斜視図。The perspective view which shows schematic structure of the vehicle body rear floor of the motor vehicle based on Embodiment 1 of this invention. リヤフロアパネルを取り除いてリヤクロスメンバーの配置を示す図１相当図。FIG. 1 is a view corresponding to FIG. 1 showing the arrangement of a rear cross member with the rear floor panel removed. リヤフロアパネルを取り除いてリヤクロスメンバーの配置を示す上面図(a)、及び側面図(b)。The top view (a) which shows the arrangement | positioning of a rear cross member by removing a rear floor panel, and a side view (b). リヤクロスメンバーの構造を示す斜視図。The perspective view which shows the structure of a rear cross member. 実施形態２に係る図４相当図。FIG. 4 is a diagram corresponding to FIG. 4 according to the second embodiment.

Ａ車体後部構造
３リヤフロアパネル（車体後部フロア）
３ａスペアタイヤパン（スペアタイヤ収納部）
４リヤサイドフレーム
５リヤクロスメンバー
５ａフランジ部
５１中間部材
５１ｄフランジ部
５２左側部材
５２ａ前面部
５２ｂ後面部
５２ｃ底面部
５２ｄフランジ部
５２ｅリブ
５３右側部材
５３ａ前面部
５３ｂ後面部
５３ｃ底面部
５３ｄフランジ部
５３ｅリブ
６リヤクロスメンバー
６１第１部材
６１ｄフランジ部
６１ｅ切り欠き
６２第２部材の左側部
６３右側部
６４ブリッジ部
６５第２部材
Ｌ仮想線 A Car body rear structure 3 Rear floor panel (car body rear floor)
3a Spare tire pan (spare tire storage)
4 Rear side frame 5 Rear cross member 5a Flange part 51 Intermediate member 51d Flange part 52 Left side member 52a Front part 52b Rear part 52c Bottom part 52d Flange part 52e Rib 53 Right member 53a Front part 53b Rear part 53c Bottom part 53d Flange part 53e Rib 6 Rear cross member 61 First member 61d Flange portion 61e Notch 62 Left side portion 63 of second member Right side portion 64 Bridge portion 65 Second member L Virtual line

Claims

Side frames extending in the front-rear direction are joined to both the left and right sides of the lower surface of the rear floor of the vehicle body, and both end portions of the cross member extending left and right in front of the spare tire storage portion bulging downward from the floor are respectively A structure of a rear part of a vehicle body that is coupled to a side frame, the cross member has a top-opening hat-shaped cross section, and a flange portion formed at an upper end thereof is joined to the lower surface of the floor. ,
A fuel tank is disposed adjacent to the front of the cross member,
In a plan view, an imaginary line connecting the rear end parts of the vehicle body including the flange part in each joint part of the cross member and each side frame intersects the spare tire storage part,
The cross member is
The dimension in the vehicle front-rear direction of the portion adjacent to the front side of the spare tire storage portion is smaller than each coupling portion with each side frame, and is a thin shape.
While the part adjacent to the front side of the spare tire storage part is formed of an intermediate member formed of high-strength steel and extending substantially linearly to the left and right,
Sites extending from the left and right end portions of the intermediate member to the left and right side frames are each formed of a steel material having a lower breaking strength than the intermediate member, and each of the portions from the inner end of the vehicle body connected to the intermediate member. A vehicle body rear structure characterized by comprising left and right members whose cross-sectional areas gradually increase toward the outer end of the vehicle connected to the side frame.

In the vehicle body rear structure according to claim 1,
On the left and right members of the cross member, ribs are integrally formed across the front, rear and bottom surfaces of each member so as to close the hat-shaped cross section of the end portion coupled to the intermediate member. A vehicle body rear structure characterized by that.

Side frames extending in the front-rear direction are joined to both the left and right sides of the lower surface of the rear floor of the vehicle body, and both end portions of the cross member extending left and right in front of the spare tire storage portion bulging downward from the floor are respectively A structure of a rear part of a vehicle body that is coupled to a side frame, the cross member has a top-opening hat-shaped cross section, and a flange portion formed at an upper end thereof is joined to the lower surface of the floor. ,
In a plan view, an imaginary line connecting the rear end parts of the vehicle body including the flange part in each joint part of the cross member and each side frame intersects the spare tire storage part, and the cross member is
It is made of high-strength steel and extends substantially linearly to the left and right adjacent to the front side of the spare tire storage part, and the rear flange part is cut away so as to surround the front end side of the spare tire storage part in plan view. The first member
A steel material having a fracture strength lower than that of the first member is formed by integrally forming a left side and a right side extending from the left and right ends of the first member to the left and right side frames, and a bridge portion connecting them. Two members,
The bridge portion is covered with the first member from below, and is joined to the lower surface of the rear floor of the vehicle body in the vehicle width direction range where the notch is formed in the rear flange portion of the first member. A vehicle body rear structure characterized by