Vehicle body structure

A vehicle body structure that includes a rear floor side member that extends along a vehicle front-rear direction at a vehicle width direction end portion of a vehicle rear section and that is divided into front and rear portions in the vehicle front-rear direction. The rear floor side member includes a joint section that is provided between a vehicle width direction inner side of a rocker rear, which is provided along the vehicle front-rear direction at a vehicle front-rear direction rear side of a rocker extending along the vehicle front-rear direction at a vehicle side section, and a vehicle front-rear direction front end of an attachment portion of a rear suspension member in vehicle side view, and that joins together a rear floor side member front portion and a rear floor side member rear portion.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2018-230228 filed on Dec. 7, 2018, the disclosure of which is incorporated by reference herein.

BACKGROUND

Technical Field

The present disclosure relates to a vehicle body structure.

Related Art

Japanese Patent Application Laid-Open (JP-A) No. 2001-347966 discloses technology in which a front side member extending along a vehicle front-rear direction and disposed at a vehicle width direction end portion is formed using a cast material such as an aluminum alloy, and a rear side member extending along the vehicle front-rear direction at the vehicle front-rear direction rear side of the front side member is formed using an extrusion-molded material such as an aluminum alloy, and these members are coupled together.

In the above technology, since the front side member and the rear side member are formed using aluminum alloys or the like as described above, although rigidity can be set higher than that of a ferrous member, brittleness is also higher than that of a ferrous member. Thus, in a side-on collision of a vehicle (hereafter referred to as “vehicle side-on collision”), and in particular, in a side-on collision such as a side-on collision with a pole in which collision load is concentrated at a side section of the vehicle, if a side member (hereafter referred to as “rear floor side member”) configured by a front side member and a rear side member were to fail, surrounding vehicle components (such as a fuel tank) might be affected by fragments from the side member.

SUMMARY

An aspect of the disclosure is a vehicle body structure that includes a rear floor side member that extends along a vehicle front-rear direction at a vehicle width direction end portion of a vehicle rear section and that is divided into front and rear portions in the vehicle front-rear direction, the rear floor side member that includes: a rear floor side member front portion that is made of a ferrous metal and that configures a front portion of the rear floor side member; a rear floor side member rear portion that is die-cast and that configures a rear portion of the rear floor side member; and a joint section that is provided between a vehicle width direction inner side of a rocker rear, which is provided along the vehicle front-rear direction at the vehicle front-rear direction rear side of a rocker extending along the vehicle front-rear direction at a vehicle side section, and a vehicle front-rear direction front end of an attachment portion of a rear suspension member in vehicle side view, and that joins together the rear floor side member front portion and the rear floor side member rear portion.

DETAILED DESCRIPTION

Explanation follows regarding a vehicle body (vehicle) applied with a vehicle body structure according to an exemplary embodiment of the present disclosure. Note that in the respective drawings, the arrow FR indicates a vehicle front-rear direction front side, and the arrow UP indicates a vehicle vertical direction upper side, as appropriate. The arrow OUT indicates a vehicle width direction outer side. Unless specifically stated otherwise, in the below explanation, simple reference to front and rear, left and right, and up and down directions refers to front and rear in the vehicle front-rear direction, left and right in the vehicle left-right direction (vehicle width direction), and up and down in the vehicle vertical direction.

Configuration of Vehicle Body Structure

First, explanation is given regarding configuration of the vehicle body structure according to the present exemplary embodiment.

FIG. 1is a plan view illustrating a rear section (hereafter referred to as “vehicle rear section”)14side of a vehicle10at a lower section (hereafter referred to as “vehicle lower section”)12of the vehicle10, which is applied with the vehicle body structure according to the present exemplary embodiment.

As illustrated inFIG. 1, left and right rockers18are provided extending along the vehicle front-rear direction at side sections (hereafter referred to as “vehicle side sections”)16of the vehicle10. A cross-section profile of each of the rockers18when sectioned along directions (the vehicle vertical direction and the vehicle width direction) that are orthogonal to the length direction of the rocker18is a closed cross-section profile, and the left and right rockers18respectively configure parts of framework of the vehicle side sections16.

A floor panel24, configuring a floor surface of a vehicle cabin interior (cabin)22, is provided extending along the vehicle front-rear direction and the vehicle width direction between the left and right rockers18. The two vehicle width direction end portions of the floor panel24are respectively joined to the left and right rockers18. A rocker rear19extends along the vehicle front-rear direction at the vehicle front-rear direction rear side of each of the left and right rockers18, and each of the rockers18is joined together with the corresponding rocker rear19to form a single unit. Note that each of the rockers18may be formed integrally with the corresponding rocker rear19.

A floor cross member28is installed extending along the vehicle width direction between vehicle front-rear direction front end portions19A of the left and right rocker rears19. The floor cross member28is joined to the vehicle front-rear direction front end portions19A above the floor panel24. Vehicle front-rear direction front end portions20A of rear floor side members20that extend along the vehicle front-rear direction are joined to the vehicle width direction inner sides of the respective left and right rocker rears19.

A central floor panel26, configuring the floor surface at a rear section side of the vehicle cabin interior22, is provided between the left and right rear floor side members20. The central floor panel26extends along the vehicle front-rear direction and the vehicle width direction, and is positioned at the vehicle front-rear direction rear side of the floor panel24. The left and right rear floor side members20are respectively joined to the two vehicle width direction end portions of the central floor panel26.

A floor cross member30is installed extending along the vehicle width direction between the left and right rear floor side members20at vehicle front-rear direction center portions20B of the left and right rear floor side members20. The floor cross member30is joined to the vehicle front-rear direction center portions20B of the rear floor side members20above the central floor panel26.

A floor cross member32is installed extending along the vehicle width direction between the left and right rear floor side members20at vehicle front-rear direction rear end portions20C of the rear floor side members20. Similarly to the floor cross member30described above, the floor cross member32is joined to the vehicle front-rear direction rear end portions20C above the central floor panel26.

Note that a fuel tank34is installed at the lower side of the central floor panel26between vehicle front-rear direction front portion sides of the left and right rear floor side members20, namely, between the floor cross member28and the floor cross member30. Moreover, suspension towers (attachment portions for rear suspension members)36, to which shock absorbers or the like are attached, are respectively provided at the vehicle width direction outer sides of the left and right rear floor side members20.

Rear floor side member rears38respectively extend along the vehicle front-rear direction at the vehicle front-rear direction rear side of the left and right rear floor side members20. A rear floor panel42, configuring a floor surface of a luggage compartment interior41, is provided extending along the vehicle front-rear direction and the vehicle width direction at the vehicle front-rear direction rear side of the central floor panel26.

Rear floor side panels44are respectively provided extending along the vehicle front-rear direction and the vehicle width direction at the two vehicle width direction outer sides of the rear floor panel42. The left and right rear floor side member rears38are respectively joined to the rear floor side panels44.

FIG. 2illustrates a cross-section profile of a joint section45between one of the rocker rears19and the corresponding rear floor side member20at a position sectioned along line2-2inFIG. 1.

As illustrated inFIG. 2, in the present exemplary embodiment, a cross-section profile of the rocker rear19when sectioned along the vehicle vertical direction and the vehicle width direction is formed with a closed cross-section area46(described later). The rocker rear19is configured including a plate shaped rocker rear inner48configuring the vehicle width direction inner side of the rocker rear19, and a plate shaped rocker rear outer50configuring the vehicle width direction outer side of the rocker rear19.

The rocker rear inner48and the rocker rear outer50are joined together by welding or the like to form a single unit, and the vehicle front-rear direction front end portion20A of the corresponding rear floor side member20is joined to the rocker rear inner48. Note that the rocker rear19does not necessarily have to be configured including the rocker rear inner48and the rocker rear outer50, and may be formed such that the rocker rear inner48and the rocker rear outer50are integrated together.

A side member outer52, configuring a styling face of the corresponding vehicle side section16, is provided at the vehicle width direction outer side of the rocker rear19. Although the closed cross-section area46is formed between the side member outer52and the rocker rear inner48inFIG. 2, at other vehicle front-rear direction positions, the closed cross-section area46is formed between the rocker rear inner48and the rocker rear outer50.

Rocker Rear Inner

Explanation follows regarding the rocker rear inner48.

As illustrated inFIG. 2, a cross-section profile of the rocker rear inner48when sectioned along the vehicle vertical direction and the vehicle width direction is a substantially hat shaped profile open toward the vehicle width direction outer side. An upright wall (first upright wall)54, formed running along the vehicle front-rear direction and the vehicle vertical direction, is provided at a vehicle vertical direction center portion of the rocker rear inner48.

An upper wall (first upper wall)56that is linked to the upright wall54is provided extending along the vehicle front-rear direction and the vehicle width direction at the vehicle vertical direction upper side of the upright wall54. A lower wall (first lower wall)58that is linked to the upright wall54is provided extending along the vehicle front-rear direction and the vehicle width direction at the vehicle vertical direction lower side of the upright wall54so as to oppose the upper wall56.

An upper flange60extends toward the vehicle vertical direction upper side from a vehicle width direction outer end56A of the upper wall56, and a lower flange62extends toward the vehicle vertical direction lower side from a vehicle width direction outer end58A of the lower wall58.

Rocker Rear Outer

Explanation follows regarding the rocker rear outer50.

A cross-section profile of the rocker rear outer50when sectioned along the vehicle vertical direction and the vehicle width direction is a substantially hat shaped profile open toward the vehicle width direction inner side. The rocker rear outer50is formed with an upright wall64running along the vehicle front-rear direction and the vehicle vertical direction and provided so as to oppose the upright wall54of the rocker rear inner48.

An upper wall66that is linked to the upright wall64is provided extending along the vehicle front-rear direction and the vehicle width direction at the vehicle vertical direction upper side of the upright wall64. A lower wall68that is linked to the upright wall64is provided extending along the vehicle front-rear direction and the vehicle width direction at the vehicle vertical direction lower side of the upright wall64so as to oppose the upper wall66.

An upper flange70extends toward the vehicle vertical direction upper side from a vehicle width direction inner end66A of the upper wall66, and a lower flange72extends toward the vehicle vertical direction lower side from a vehicle width direction inner end68A of the lower wall68. Note that lower flange72is overlapped and joined together with the lower flange62of the rocker rear inner48.

Side Member Outer

Explanation follows regarding the side member outer52.

A cross-section profile of the side member outer52when sectioned along the vehicle vertical direction and the vehicle width direction is a substantially hat shaped profile open toward the vehicle width direction inner side. An upright wall74that overlaps the upright wall64of the rocker rear outer50is formed running along the vehicle front-rear direction and the vehicle vertical direction.

An upper wall76that is linked to the upright wall74is formed running along the vehicle front-rear direction and the vehicle width direction at the vehicle vertical direction upper side of the upright wall74. A lower wall78that is linked to the upright wall74is formed running along the vehicle front-rear direction and the vehicle width direction at the vehicle vertical direction lower side of the upright wall74so as to oppose the upper wall76. Note that the lower wall78is overlapped and joined together with the lower wall68of the rocker rear outer50.

An upper flange80extends toward the vehicle vertical direction upper side from a vehicle width direction inner end76A of the upper wall76, and the upper flange80is overlapped and joined together with the upper flange60of the rocker rear inner48. Note that as described above, the lower wall78of the side member outer52is overlapped and joined together with the lower wall68of the rocker rear outer50, and so there is no lower flange formed thereto.

Rear Floor Side Member

Explanation follows regarding the rear floor side member20.

As illustrated inFIG. 1, each of the rear floor side members20is curved so as to project toward the vehicle width direction inner side in plan view, and curved so as to project toward the vehicle vertical direction upper side in side view. The vehicle front-rear direction front end portion20A of each of the rear floor side members20is joined to the rocker rear inner48configuring the vehicle width direction inner side of the corresponding rocker rear19(at a joint section29), and the vehicle front-rear direction rear end portion20C of each of the rear floor side members20is joined to a vehicle front-rear direction front end portion38A of the corresponding rear floor side member rear38(at a joint section40).

FIG. 3is a perspective view illustrating one of the rear floor side members20viewed from the vehicle front-rear direction front side and the vehicle width direction inner side, andFIG. 4is an exploded perspective view illustrating a state in which the rear floor side member20has been divided into front and rear in the vehicle front-rear direction.

As illustrated inFIG. 3andFIG. 4, in the present exemplary embodiment, the rear floor side member20is divided into front and rear in the vehicle front-rear direction, and the two portions are joined together through the joint section45. More precisely, the rear floor side member20is configured including a rear floor side member front portion82configuring a front portion21of the rear floor side member20, and a rear floor side member rear portion84configuring a rear portion23of the rear floor side member20.

As illustrated inFIG. 1, the rear floor side member20is set such that in vehicle side view the joint section45is provided spanning between the vehicle front-rear direction front end portion20A of the rear floor side member20(the vehicle width direction inner side of the corresponding rocker rear19) and a vehicle front-rear direction front end36A of the corresponding suspension tower36.

Namely, in the present exemplary embodiment, the rear floor side member20is divided into the rear floor side member front portion82and the rear floor side member rear portion84, and the rear floor side member front portion82and the rear floor side member rear portion84are joined together through the joint section45.

Rear Floor Side Member Rear Portion

Explanation follows regarding the rear floor side member rear portion84.

The rear floor side member rear portion84illustrated inFIG. 3andFIG. 4is, for example, formed of die-cast aluminum using a mold that is opened along the vehicle width direction of the rear floor side member20. Note that the rear floor side member rear portion84is not limited to being formed of aluminum, and may be a die-cast article formed of an alloy of zinc, magnesium, copper, or the like, or may be a cast article formed using a sand mold.

As illustrated inFIG. 2, a cross-section profile of the rear floor side member rear portion84when sectioned along the vehicle vertical direction and the vehicle width direction has a substantially U shape open toward the vehicle width direction outer side.

The rear floor side member rear portion84is formed with an upright wall (second upright wall)86running along the vehicle front-rear direction and the vehicle vertical direction at a vehicle vertical direction center portion of the rear floor side member rear portion84. The upright wall86is provided opposing the upright wall54of the rocker rear inner48.

An upper wall (second upper wall)88that is linked to the upright wall86is provided extending along the vehicle front-rear direction and the vehicle width direction at the vehicle vertical direction upper side of the upright wall86. The upper wall88is disposed in a state in which a gap t1is provided between the upper wall88and the upright wall54of the rocker rear inner48, and is provided at a position overlapping the upright wall54in vehicle side view.

A lower wall (second lower wall)90that is linked to the upright wall86is provided extending along the vehicle front-rear direction and the vehicle width direction at the vehicle vertical direction lower side of the upright wall86so as to oppose the upper wall88. The lower wall90is disposed in a state in which a gap t2is provided between the lower wall90and the upright wall54of the rocker rear inner48, and is provided at a position overlapping the upright wall54in vehicle side view. Note that the gap t1and the gap t2need not necessarily have the same dimensions.

Rear Floor Side Member Front Portion

Explanation follows regarding the rear floor side member front portion82.

The rear floor side member front portion82illustrated inFIG. 3andFIG. 4is made of a ferrous metal. As previously described, in the present exemplary embodiment the rear floor side member front portion82and the rear floor side member rear portion84are joined together through the joint section45. The rear floor side member front portion82abuts and is joined together with the outer side of the rear floor side member rear portion84at the joint section45.

As illustrated inFIG. 2, a cross-section profile of the rear floor side member front portion82when sectioned along the vehicle vertical direction and the vehicle width direction has a substantially U shape open toward the vehicle width direction outer side.

The rear floor side member front portion82is formed with an upright wall (third upright wall)98running along the vehicle front-rear direction and the vehicle vertical direction at a vehicle vertical direction center portion of the rear floor side member front portion82. The upright wall98is provided opposing the upright wall54of the rocker rear inner48. The upright wall98abuts and is joined to the upright wall86of the rear floor side member rear portion84(at spot joins A).

An upper wall (third upper wall)100that is linked to the upright wall98is provided extending along the vehicle front-rear direction and the vehicle width direction at the vehicle vertical direction upper side of the upright wall98. The upper wall100abuts and is joined to the upper wall88of the rear floor side member rear portion84(at spot joins B). The upper wall100also abuts and is joined to the upper wall56of the rocker rear inner48(at spot joins C).

A lower wall (third lower wall)102that is linked to the upright wall98is provided extending along the vehicle front-rear direction and the vehicle width direction at the vehicle vertical direction lower side of the upright wall98so as to oppose the upper wall100. The lower wall102abuts and is joined to the lower wall90of the rear floor side member rear portion84(at spot joins D). The lower wall102also abuts and is joined to the lower wall58of the rocker rear inner48(at spot joins E). A closed cross-section area85is formed between the rear floor side member front portion82and the rocker rear inner48.

Note that the rear floor side member front portion82is joined to the rear floor side member rear portion84from the vehicle width direction inner side (at the spot joins A, B, D) at the joint section45, either by joining at one side using flow drill screws (FDS) or the like, or by joining at both sides using self-piercing rivets (SPR) or the like. The rear floor side member front portion82is also joined to the rocker rear inner48from the vehicle width direction inner side (at the spot joins C, E).

As illustrated inFIG. 3andFIG. 4, recess shaped bead portions92,94,96that project toward the vehicle width direction inner side are formed to the rear floor side member front portion82so as to run along the vehicle front-rear direction in side view. The bead portions92,94,96are disposed in a row along the vehicle vertical direction.

The spot joins A between the upright wall98of the rear floor side member front portion82and the upright wall86of the rear floor side member rear portion84are provided on extension lines of the bead portions92,94,96. Note that although the recess shaped bead portions92,94,96are formed projecting toward the vehicle width direction inner side in the present exemplary embodiment, protruding shaped bead portions may be formed projecting toward the vehicle width direction outer side.

Operation and Effects of Vehicle Body Structure

Explanation follows regarding operation and effects of the vehicle body structure according to the present exemplary embodiment.

In the present exemplary embodiment, the rear floor side members20, which extend along the vehicle front-rear direction at vehicle width direction end portions of the vehicle rear section14illustrated inFIG. 1, are each divided into front and rear in the vehicle front-rear direction. More precisely, each of the rear floor side members20is configured including the ferrous rear floor side member front portion82configuring the front portion21of the rear floor side member20, and the die-cast rear floor side member rear portion84configuring the rear portion23of the rear floor side member20.

The rear floor side member20is also provided with the joint section45that joins the rear floor side member front portion82and the rear floor side member rear portion84together and spans in vehicle side view between the vehicle front-rear direction front end portion20A of the rear floor side member20and the vehicle front-rear direction front end36A of the corresponding suspension tower36.

Although members formed by die-casting generally allow a high degree of freedom for design, such that high rigidity may be obtained by locally increasing the thickness or providing reinforcing ribs, die-cast members are also more brittle than ferrous members.

As illustrated inFIG. 1, a battery, the fuel tank34and so on are installed at the vehicle width direction inner side of the rocker rears19, and so there is a need to suppress failure of the rear floor side members20located at the vehicle width direction inner sides of the rocker rears19. Thus ductility, as well as rigidity, is demanded of the rear floor side members20. Meanwhile, steering stability of the vehicle10is demanded of the suspension towers36. High rigidity is therefore demanded of the rear floor side members20.

Thus, in each of the rear floor side members20in the present exemplary embodiment, the rear floor side member front portion82disposed on the rocker rear19side is formed of ferrous metal, and the rear floor side member rear portion84disposed on the suspension tower36side is formed by die-casting.

Thus, in the present exemplary embodiment, the rigidity and ductility that are necessary in a side-on collision of the vehicle10are obtained on the rear floor side member front portion82side, and the rigidity that is necessary while the vehicle10is traveling is obtained on the rear floor side member rear portion84side. Moreover, since the rigidity and ductility that are necessary in a side-on collision of the vehicle10are obtained on the rear floor side member front portion82side as described above, failure of the rear floor side member20can be suppressed, even if the vehicle10is involved in a side-on collision such as a side-on collision with a pole.

As illustrated inFIG. 2, in the present exemplary embodiment, the upright wall86of the rear floor side member rear portion84is provided opposing the upright wall54of the rocker rear inner48. The upper wall88and lower wall90of the rear floor side member rear portion84are disposed in a state in which the gaps t1, t2are respectively provided between the upper wall88and lower wall90and the upright wall54of the rocker rear inner48, and are provided at positions overlapping the upright wall54in vehicle side view.

In the present exemplary embodiment, the closed cross-section area85is formed between the rear floor side member front portion82and the rocker rear inner48, and the upright wall98of the rear floor side member front portion82is joined to the upright wall86of the rear floor side member rear portion84(at the spot joins A). The upper wall100of the rear floor side member front portion82is joined to the upper wall88of the rear floor side member rear portion84(at the spot joins B), and is also joined to the upper wall56of the rocker rear inner48(at the spot joins C). The lower wall102of the rear floor side member front portion82is joined to the lower wall90of the rear floor side member rear portion84(at the spot joins D), and is also joined to the lower wall58of the rocker rear inner48(at the spot joins E).

As described above, in the present exemplary embodiment, the rear floor side member front portion82is joined to the rocker rear inner48, and the closed cross-section area85is formed between the rear floor side member front portion82and the rocker rear inner48. This enables the rigidity of the rear floor side member front portion82itself to be increased.

In the present exemplary embodiment, the gaps t1, t2are respectively provided between the upper wall88and lower wall90, configuring parts of the die-cast rear floor side member rear portion84, and the upright wall54of the ferrous rocker rear inner48. Thus, collision load input to the rocker rear inner48in a side-on collision of the vehicle10is not directly transmitted toward the rear floor side member rear portion84side.

Thus, in the present exemplary embodiment, collision load input to the rocker rear inner48in a side-on collision of the vehicle10is first transmitted toward the rear floor side member front portion82. Since the rear floor side member front portion82is made of a ferrous metal, the rear floor side member front portion82undergoes plastic deformation when input with impact load, enabling impact energy to be absorbed.

The upper wall88and lower wall90of the rear floor side member rear portion84are provided at positions overlapping the upright wall54of the rocker rear inner48in vehicle side view. This enables collision load to be transmitted from the upright wall54of the rocker rear inner48to the rear floor side member rear portion84through the upper wall88and lower wall90in a side-on collision of the vehicle10.

Collision load can also be transmitted from the upper wall88and lower wall90of the rear floor side member rear portion84to the rocker rear inner48through the upright wall54in a rear collision of the vehicle10.

Furthermore, in the present exemplary embodiment, the upper wall100and lower wall102of the rear floor side member front portion82are respectively joined to the upper wall56and the lower wall58of the rocker rear inner48, thereby increasing the join strength between the rear floor side member front portion82and the rocker rear inner48.

As illustrated inFIG. 3, in the present exemplary embodiment, the shaped bead portions92,94,96that project so as to have a recess shape in the vehicle width direction are formed to the rear floor side member front portion82so as to run along the vehicle front-rear direction. The spot joins A between the rear floor side member front portion82and the rear floor side member rear portion84are provided on extension lines of the bead portions92,94,96.

Forming the bead portions92,94,96to the rear floor side member front portion82enables the rigidity of the rear floor side member front portion82to be increased. Moreover the spot joins A between the rear floor side member front portion82and the rear floor side member rear portion84have higher rigidity than other locations. Namely, this enables deformation of the rear floor side member front portion82to be suppressed.

Respective ridge lines P, Q, R are formed by forming the bead portions92,94,96to the rear floor side member front portion82, thereby enabling collision load to be effectively transmitted from the rear floor side member front portion82to the rocker rear inner48in a rear collision of the vehicle10.

As illustrated inFIG. 2, in the present exemplary embodiment, the rear floor side member front portion82abuts and is joined together with the outer side of the rear floor side member rear portion84(at the spot joins A, B, D).

Flow drill screws (FDS), for example, are generally employed when joining a die-cast member to a ferrous member. In such cases, the FDS are inserted into the high rigidity die-cast member from the ferrous member side. Thus, in the present exemplary embodiment, since the ferrous rear floor side member front portion82abuts and is joined together with the outer side of the die-cast rear floor side member rear portion84, heterogeneous members can be joined using FDS, rivets, or the like.

When joining using rivets, the joined members press-contact each other in their thickness directions similarly to in spot welding, thus rendering joining equipment such as a brazing torch unnecessary. Thus, in the present exemplary embodiment, the rear floor side member front portion82that is a ferrous member and the rear floor side member rear portion84that is a die-cast member are joined together by joining using rivets.

Namely, although the rear floor side member front portion82and the rear floor side member rear portion84are heterogeneous members, during assembly of the vehicle10illustrated inFIG. 1, in a rear-under assembly process in which the vehicle rear section14side of the vehicle lower section12is assembled, joining together of the rear floor side member front portion82and the rear floor side member rear portion84is completed by joining using rivets. This enables body structures made using ferrous members and body structures made using die-cast members to be jointly manufactured.

Modified Examples of Present Exemplary Embodiment

As illustrated inFIG. 2, in the present exemplary embodiment, the rear floor side member front portion82abuts and is joined to the outer side of the rear floor side member rear portion84at the joint section45between the rear floor side member front portion82and the rear floor side member rear portion84. However, there is no limitation thereto.

For example, as illustrated inFIG. 5, the rear floor side member rear portion84may abut and be joined to the outer side of the rear floor side member front portion82at the joint section45between the rear floor side member front portion82and the rear floor side member rear portion84.

Moreover, as illustrated inFIG. 2, in the present exemplary embodiment, the upright wall98of the rear floor side member front portion82abuts and is joined to the upright wall86of the rear floor side member rear portion84. However, there is no limitation thereto. As illustrated inFIG. 5, setting may be made such that a closed cross-section area104is formed between the rear floor side member front portion82and the rear floor side member rear portion84.

As illustrated inFIG. 4, in the present exemplary embodiment, a dividing plane X of the rear floor side member20is formed running along the vehicle vertical direction and the vehicle front-rear direction. However, since it is sufficient that the rear floor side member20be divided into front and rear in the vehicle front-rear direction, there is no limitation thereto. For example, a dividing plane may be formed as a plane running along the vehicle front-rear direction and the vehicle width direction.

Note that in such cases, the rear floor side member front portion82and the rear floor side member rear portion84would be divided in the vertical direction at the joint section45between the rear floor side member front portion82and the rear floor side member rear portion84. Since it is sufficient that the rear floor side member20can be divided into a front side and a rear side when viewed as a whole, there is no particular limitation to the dividing plane at the joint section45.

An example of an exemplary embodiment has been given above. However, exemplary embodiments are not limited to the above description, and the exemplary embodiment and various modified examples may be employed in appropriate combinations, and various configurations may be implemented within a range not departing from the spirit of the present disclosure.

An object of the present disclosure is to provide a vehicle body structure capable of suppressing failure of a side member, even in a vehicle side-on collision such as a side-on collision with a pole.

A first aspect of the disclosure is a vehicle body structure that includes a rear floor side member that extends along a vehicle front-rear direction at a vehicle width direction end portion of a vehicle rear section and that is divided into front and rear portions in the vehicle front-rear direction, the rear floor side member that includes: a rear floor side member front portion that is made of a ferrous metal and that configures a front portion of the rear floor side member; a rear floor side member rear portion that is die-cast and that configures a rear portion of the rear floor side member; and a joint section that is provided between a vehicle width direction inner side of a rocker rear, which is provided along the vehicle front-rear direction at the vehicle front-rear direction rear side of a rocker extending along the vehicle front-rear direction at a vehicle side section, and a vehicle front-rear direction front end of an attachment portion of a rear suspension member in vehicle side view, and that joins together the rear floor side member front portion and the rear floor side member rear portion.

In the vehicle body structure of the first aspect, the rear floor side member extends along the vehicle front-rear direction at the vehicle width direction end portion of the vehicle rear section. The rear floor side member is divided into front and rear in the vehicle front-rear direction, and is configured including the rear floor side member front portion that is made of a ferrous metal and that configures the front portion of the rear floor side member, and the rear floor side member rear portion that is made by die-casting and that configures the rear portion of the rear floor side member.

The rocker rear is provided running along the vehicle front-rear direction at the vehicle front-rear direction rear side of the rocker extending along the vehicle front-rear direction at the vehicle side section. The joint section that joins the rear floor side member front portion and the rear floor side member rear portion together is provided to the rear floor side member so as to span in vehicle side view between the vehicle width direction inner side of the rocker rear and the vehicle front-rear direction front end of the attachment portion of the rear suspension member.

Although members formed by die-casting generally allow a high degree of freedom for design, such that high rigidity may be obtained by locally increasing the thickness or providing reinforcing ribs, die-cast members are also more brittle than ferrous members.

A battery, a fuel tank, and so on are installed at the vehicle width direction inner side of the rocker rear, and so there is a need to suppress failure of the rear floor side member at the vehicle width direction inner side of the rocker rear. Thus, ductility, as well as rigidity, is demanded of the rear floor side member. Meanwhile, vehicle steering stability is demanded of the attachment portion of the rear suspension member. High rigidity is therefore required of the rear floor side member.

Thus, in the rear floor side member in the present disclosure, the rear floor side member front portion disposed on the rocker rear side is formed of ferrous metal, and the rear floor side member rear portion disposed on the side of the attachment portion of the rear suspension member is formed by die-casting. Thus, in the present disclosure, the rigidity and ductility that are necessary in a vehicle side-on collision are obtained on the rear floor side member front portion side, and the rigidity that is necessary while the vehicle is traveling is obtained on the rear floor side member rear portion side. Note that in the present disclosure, “ferrous metals” include sheet steel.

A second aspect of the disclosure is the first aspect of the vehicle body structure, wherein the rear floor side member front portion abuts and is joined together with an outer side of the rear floor side member rear portion.

Flow drill screws (FDS), for example, are generally employed when joining a die-cast member to a ferrous member. In such cases, the FDS are inserted into the high rigidity die-cast member from the ferrous member side. Thus, in the vehicle body structure of the second aspect, since the ferrous rear floor side member front portion abuts and is joined together with the outer side of the die-cast rear floor side member rear portion, heterogeneous members can be joined using FDS, rivets, or the like.

A third aspect of the disclosure is the second aspect of the vehicle body structure, wherein: a cross-section profile of a rocker rear inner configuring a vehicle width direction inner side of the rocker rear, when sectioned along a vehicle vertical direction and the vehicle width direction, is an open cross-section profile that opens toward a vehicle width direction outer side; the rocker rear inner includes: a first upright wall that is provided at a vehicle vertical direction center portion of the rocker rear inner and that extends along the vehicle vertical direction and the vehicle front-rear direction, a first upper wall that is provided at a vehicle vertical direction upper side of the first upright wall, and that is linked to the first upright wall by extending along the vehicle front-rear direction and the vehicle width direction, and a first lower wall that is provided at a vehicle vertical direction lower side of the first upright wall so as to oppose the first upper wall, and that is linked to the first upright wall by extending along the vehicle front-rear direction and the vehicle width direction; and the rear floor side member rear portion includes: a second upright wall that is provided at a vehicle vertical direction center portion of the rear floor side member rear portion so as to oppose the first upright wall and that extends along the vehicle vertical direction and the vehicle front-rear direction, a second upper wall that is provided at a vehicle vertical direction upper side of the second upright wall, that is linked to the second upright wall by extending along the vehicle front-rear direction and the vehicle width direction, that is disposed in a state in which a gap is provided between the second upper wall and the first upright wall, and that is provided at a position that overlaps with the first upright wall in vehicle side view, and a second lower wall that is provided at a vehicle vertical direction lower side of the second upright wall so as to oppose the second upper wall, that is linked to the second upright wall by extending along the vehicle front-rear direction and the vehicle width direction, that is disposed in a state in which a gap is provided between the second lower wall and the first upright wall, and that is provided at a position that overlaps with the first upright wall in vehicle side view.

In the vehicle body structure of the third aspect, the cross-section profile of the rocker rear inner configuring the vehicle width direction inner side of the rocker rear when sectioned along the vehicle vertical direction and the vehicle width direction is an open cross-section profile open toward the vehicle width direction outer side.

The rocker rear inner is configured including the first upright wall, the first upper wall, and the first lower wall. The first upright wall is provided extending along the vehicle vertical direction and the vehicle front-rear direction at the vehicle vertical direction center portion of the rocker rear inner. The first upper wall is provided extending along the vehicle front-rear direction and the vehicle width direction at the vehicle vertical direction upper side of the first upright wall, and is linked to the first upright wall. The first lower wall is provided extending along the vehicle front-rear direction and the vehicle width direction at the vehicle vertical direction lower side of the first upright wall so as to oppose the first upper wall, and is linked to the first upright wall.

The rear floor side member rear portion is configured including the second upright wall, the second upper wall, and the second lower wall. The second upright wall is provided extending along the vehicle vertical direction and the vehicle front-rear direction at the vehicle vertical direction center portion of the rear floor side member rear portion so as to oppose the first upright wall of the rocker rear inner. The second upper wall is provided extending along the vehicle front-rear direction and the vehicle width direction at the vehicle vertical direction upper side of the second upright wall, and is formed linked to the second upright wall. Moreover, the second upper wall is disposed in a state in which a gap is provided between the second upper wall and the first upright wall of the rocker rear inner, and is provided at a position overlapping the first upright wall in vehicle side view. The second lower wall is provided extending along the vehicle front-rear direction and the vehicle width direction at the vehicle vertical direction lower side of the second upright wall so as to oppose the second upper wall, and is formed linked to the second upright wall. The second lower wall is disposed in a state in which a gap is provided between the second lower wall and the first upright wall of the rocker rear inner, and is provided at a position overlapping the first upright wall in vehicle side view.

Thus, in the present disclosure, the gaps are respectively provided between the second upper wall and second lower wall, configuring parts of the die-cast rear floor side member rear portion, and the first upright wall of the rocker rear inner. Thus, collision load input to the rocker rear inner in a vehicle side-on collision is not directly transmitted toward the rear floor side member rear portion side.

Moreover, the second upper wall and second lower wall of the rear floor side member rear portion are provided at positions overlapping the first upright wall of the rocker rear inner in vehicle side view. This enables collision load to be transmitted from the first upright wall of the rocker rear inner to the rear floor side member rear portion through the second upper wall and second lower wall in a vehicle side-on collision. Collision load can also be transmitted from the second upper wall and second lower wall of the rear floor side member rear portion to the rocker rear inner through the first upright wall in a vehicle rear collision.

A fourth aspect of the vehicle body structure is the third aspect of the vehicle body structure, wherein the rear floor side member front portion further includes: a third upright wall that is provided at a vehicle vertical direction center portion of the rear floor side member front portion, that extends along the vehicle vertical direction and the vehicle front-rear direction, and that abuts and is joined to the second upright wall; a third upper wall that is provided at a vehicle vertical direction upper side of the third upright wall, that is linked to the third upright wall by extending along the vehicle front-rear direction and the vehicle width direction, and that abuts and is joined to the first upper wall; and a third lower wall that is provided at a vehicle vertical direction lower side of the third upright wall so as to be able to oppose the third upper wall, that is linked to the third upright wall by extending along the vehicle front-rear direction and the vehicle width direction, and that abuts and is joined to the first lower wall.

In the vehicle body structure of the fourth aspect, the rear floor side member front portion is configured including the third upright wall, the third upper wall, and the third lower wall. The third upright wall is provided extending along the vehicle vertical direction and the vehicle front-rear direction at the vehicle vertical direction center portion of the rear floor side member front portion, and abuts and is joined to the second upright wall of the rear floor side member rear portion. The third upper wall is provided extending along the vehicle front-rear direction and the vehicle width direction at the vehicle vertical direction upper side of the third upright wall, is linked to the third upright wall, and abuts and is joined to the first upper wall of the rocker rear inner. The third lower wall is provided extending along the vehicle front-rear direction and the vehicle width direction at the vehicle vertical direction lower side of the third upright wall at a position capable of opposing the third upper wall, is linked to the third upright wall, and abuts and is joined to the first lower wall of the rocker rear inner.

In the present disclosure, the rear floor side member front portion is joined to the rocker rear inner. As described above, in the third aspect, the rear floor side member rear portion is joined to the rear floor side member front portion in a state in which the gaps are provided between the rear floor side member rear portion and the rocker rear inner.

Thus, in the present disclosure, collision load input to the rocker rear inner in a vehicle side-on collision is first transmitted toward the rear floor side member front portion. Since the rear floor side member front portion is made of a ferrous metal, the rear floor side member front portion undergoes plastic deformation when input with impact load, enabling impact energy to be absorbed.

A fifth aspect of the vehicle body structure of the fourth aspect of the vehicle body structure that further includes: a bead portion that is formed at the rear floor side member front portion along the vehicle front-rear direction, and that projects so as to have a recessed shape or a protruding shape in the vehicle width direction; and a spot join between the rear floor side member front portion and the rear floor side member rear portion that is provided at an extension line of the bead portion.

In the vehicle body structure of the fifth aspect, the bead portion that projects so as to have a recess shape or a protruding shape in the vehicle width direction is formed to the rear floor side member front portion so as to run along the vehicle front-rear direction. The spot join between the rear floor side member front portion and the rear floor side member rear portion is provided on an extension line of the bead portion.

Forming the bead portion to the rear floor side member front portion enables the rigidity of the rear floor side member front portion to be increased. Moreover the spot join between the rear floor side member front portion and the rear floor side member rear portion has a higher rigidity than other locations. Namely, this enables deformation of the rear floor side member front portion to be suppressed. Moreover, a ridge line is formed by forming the bead portion to the rear floor side member front portion, thereby enabling collision load to be effectively transmitted from the rear floor side member front portion to the rocker rear inner in a rear collision of the vehicle.

The first aspect enables failure of the rear floor side member to be suppressed, even in a vehicle side-on collision such as a side-on collision with a pole.

The second aspect enables heterogeneous members to be joined using rivets.

The third aspect enables deformation on the rear floor side member rear portion side to be suppressed.

The fourth aspect enables impact energy to be absorbed by plastic deformation of the rear floor side member front portion when input with impact load.

The fifth aspect enables deformation of the rear floor side member front portion to be suppressed, and enables collision load to be effectively transmitted from the rear floor side member front portion to the rocker rear inner in a rear collision of the vehicle.