Vehicle body framework structure

A vehicle body framework structure includes an elongated hollow framework member and a reinforcement member disposed within the hollow framework member, the reinforcement member including a first contact portion that contacts a first internal face of an opposing pair of internal faces of the framework member, a second contact portion that contacts a second internal face of the opposing pair of internal faces, and a coupling portion that couples the first contact portion to the second contact portion. At least one slit is formed in at least the second contact portion and the coupling portion of the reinforcement member, the slit extending from an end portion on the second internal face side of the reinforcement member toward the first internal face side of the reinforcement member and having a depth that is greater than or equal to one fourth of a spacing between the pair of internal faces.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2015-180633, filed on Sep. 14, 2015, the entire contents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein are related to a vehicle body framework structure.

BACKGROUND

Japanese Patent Application Laid-Open (JP-A) No, 2008-24019 describes a structure in which a reinforcement member is built into a hollow shaped elongated bumper member (hollow framework member).

However, in cases in which the above known structure is applied to a bumper member made of carbon-fiber reinforced plastic (CFRP) or a bumper member made of aluminum alloy, it is conceivable that the bumper member breaks or yields at a portion located at an end of the inbuilt reinforcement member.

In consideration of the above circumstances, in a vehicle body framework structure in which a reinforcement member is built into a hollow framework member, an object of the embodiments is to provide a vehicle body framework structure in which breaking or yielding of the framework member is suppressed.

SUMMARY

A vehicle body framework structure according to a first aspect includes an elongated hollow framework member, and a reinforcement member disposed within the hollow framework member, the reinforcement member including a first contact portion that contacts a first internal face of an opposing pair of internal faces of the hollow framework member, a second contact portion that contacts a second internal face of the opposing pair of internal faces, and a coupling portion that couples the first contact portion to the second contact portion. At least one slit is formed in at least the second contact portion and the coupling portion of the reinforcement member, the at least one slit extending from an end portion on the second internal face side of the reinforcement member toward the first internal face side of the reinforcement member, and the slit having a depth that is greater than or equal to one fourth of a spacing between the pair of internal faces.

The vehicle body framework structure according to the first aspect includes the reinforcement member including the first contact portion, the second contact portion, and the coupling portion. The first contact portion contacts the first internal face of the opposing pair of internal faces of the hollow framework member and the second contact portion contacts the second internal face of the opposing pair of internal faces. The coupling portion couples the first contact portion to the second contact portion. The strength of the vehicle body framework structure is thereby improved with respect to compression force applied in the direction that the pair of internal faces oppose each other.

The at least one slit is formed in at least the second contact portion and the coupling portion of the reinforcement member, the slit extending from an end portion on the second internal face side of the reinforcement member toward the first internal face side of the reinforcement member and having a depth that is greater than or equal to one fourth of a spacing between the pair of internal faces. In this manner, the slit extending from the end portion on the second internal face side toward the first internal face side is formed in the reinforcement member such that the bending rigidity of the vehicle body framework structure at a portion where the slit is formed is reduced compared to a case in which the slit is not formed. Strain on the framework member can thereby be dispersed not only at the end portion of the reinforcement member in the framework member, but also at the portion of the framework member where the slit is formed in the reinforcement member. As a result, when load is input to the framework member in the direction that the pair of internal faces oppose each other and the framework member undergoes bending deformation, breaking or yielding of the framework member is suppressed, while maintaining the strength of the vehicle body framework structure with respect to compression force in the direction that the pair of internal faces oppose each other.

In the vehicle body framework structure according to a second aspect, the hollow framework member is a bumper reinforcement attached to front ends of a pair of front-rear direction members extending along a vehicle front-rear direction at both vehicle width direction sides of a vehicle front section, the bumper reinforcement extending along a vehicle width direction. A pair of the reinforcement members are provided such that, in each of the reinforcement members, the first contact portion faces a vehicle front direction and the second contact portion faces a vehicle rear direction, and each of the reinforcement members includes a portion present at one of the two respective vehicle width direction ends of the bumper reinforcement and facing toward a front end of the respective front-rear direction member. The at least one slit of each of the reinforcement members is formed further toward a vehicle width direction inner side than each of the respective portions facing toward front ends of the front-rear direction members.

In the vehicle body framework structure according to the second aspect, the pair of reinforcement members each include a portion that is present at one of the two vehicle width direction ends of the bumper reinforcement and that faces toward a front end of the respective front-rear direction member. Each reinforcement member is provided with the first contact portion facing in the vehicle front direction and the second contact portion facing in the vehicle rear direction. Thus, for example, in cases in which a vehicle is in an offset collision, cross-sectional collapse of the bumper reinforcement can be suppressed at both ends of the bumper reinforcement, and collision load can be efficiently transmitted to the respective front-rear direction member.

In the vehicle body framework structure, the at least one slit of each of the reinforcement members is positioned further to the vehicle width direction inner side than the portions facing respective front ends of the front-rear direction members. Thus, for example, in cases in which the vehicle is in an offset collision and the bumper reinforcement bends, strain occurring in the bumper reinforcement can be dispersed not only at the vehicle width direction inside end portions of the reinforcement member of the bumper reinforcement, but also at the portions of the bumper reinforcement where the slits are provided, so as to suppress the bumper reinforcement from breaking or yielding.

As explained above, the vehicle body framework structure according to the first aspect is capable of suppressing the breaking or yielding of a hollow framework member in a vehicle body framework structure in which a reinforcement member is built into the framework member.

The vehicle body framework structure according to the second aspect is capable of suppressing the bumper reinforcement from breaking or yielding and is capable of efficiently transmitting collision load toward the front-rear direction member.

DESCRIPTION OF EMBODIMENTS

First Exemplary Embodiment

Explanation follows regarding a first exemplary embodiment, with reference toFIGS. 1 to 4B. Note that in the following explanation, for ease of explanation, a ease will be described in which a length direction of a framework member12is in a left-right direction. The arrow UP indicates the up direction, the arrow FR indicates the front direction (for example, relative to a vehicle having the framework member), the arrow RH indicates the right direction, and he arrow LH indicates the left direction in each of the drawings.

Overall Configuration

FIG. 1illustrates a vehicle body framework structure S1of the first exemplary embodiment. As illustrated inFIG. 1, the vehicle body framework structure S1includes a hollow framework member12and reinforcement members14provided inside the framework member12. The material of both the framework member12and the reinforcement members14is a carbon-fiber reinforced plastic (referred to hereafter as “CFRP”).

Framework Member

The framework member12is an elongated member that has a substantially rectangular cross-section profile and includes an interior space.FIG. 3illustrates a state in which the framework member12has been cut away along a horizontal direction at an up-down direction intermediate portion. As illustrated inFIG. 3, an internal front face20(one internal face or a first internal face) and an internal rear face22(another internal face or a second internal face) of the framework member12oppose each other in the front-rear direction. In the following explanation of the reinforcement member14, the front direction side refers to the front face20side, and the rear direction side refers to the rear face22side.

Reinforcement Member

As illustrated inFIG. 1, the reinforcement members14are provided at internal portions of the framework member12, at both length direction end portions of the framework member12.FIG. 2illustrates an enlarged reinforcement member14. As illustrated inFIG. 2, each reinforcement member14has what is referred to as a hat shape. Namely, each reinforcement member14includes a sheet shaped first contact portion14F disposed extending in the up-down direction and the left-right direction, a pair of sheet shaped coupling portions14M respectively provided extending from both up-down direction end portions of the first contact portion14F toward the rear side, and disposed extending in the front-rear direction and the left-right direction, and a pair of sheet shaped second contact portions14R provided extending from respective rear side end portions of the pair of coupling portions14M toward the upper direction and the lower direction, and disposed extending in the up-down direction and the left-right direction.

As illustrated inFIG. 3, the first contact portion14F (the face on the front side thereof) makes contact with the internal front face20of the framework member12. The second contact portions14R (the faces on the rear side thereof) make contact with the internal rear face22of the framework member12. In the present exemplary embodiment, the framework member12and the reinforcement member14are joined using vibration welding.

Moreover, slits16are formed in the reinforcement member14. The slits16are formed in the reinforcement member14from an end portion on the rear face22side toward the internal front face20side. Namely, base ends16A of the slits16are formed in the second contact portions14R of the reinforcement member14, and the slits16face toward the first contact portion14F side. Leading ends16B of the slits16reach as far as a boundary portion (ridge lines18) between the coupling portion14M and the first contact portion14F.

Specifically, plural (six in the present exemplary embodiment) of the slits16are formed such that there are three slits16respectively formed in both the second contact portion14R and the coupling portion14M at the upper side, and in the second contact portion14R and the coupling portion14M at the lower side. As illustrated inFIG. 3, the slits16at the lower side and the slits16at the upper side are formed at positions that overlap with each other as viewed from above. The extension direction of the slits16is parallel to the front-rear direction (a direction in which the front face20and the rear face22oppose each other).

As illustrated inFIG. 2, the reinforcement member14has a shape with a cross-section profile that is opened in a hat shape at one end portion (a left side end portion) out of the two length direction end portions of the reinforcement member14. An inclined portion24that is inclined toward the right side on progression from the front direction toward the rear direction is provided to another end portion (the right side end portion) out of the two length direction end portions of the reinforcement member14. As illustrated inFIG. 3, the reinforcement member14thus has a shape that moves away from the front face20of the framework member12at the inclined portion24. Note that configuration may be made in which the inclined portion24is not provided.

Operation and Advantageous Effects

Next, explanation follows regarding operation and advantageous effects of the present exemplary embodiment.

The vehicle body framework structure S1of the present exemplary embodiment includes the reinforcement member14configured including the first contact portion14F, the second contact portions14R, and the coupling portions14M. As illustrated inFIG. 3, out of these, the first contact portion14F makes contact with the one internal face (the front face20) out of the opposing pair of internal faces of the framework member12, and the second contact portions14R make contact with the other internal face (the rear face22) out of the opposing pair of internal faces. The coupling portions14M couple the first contact portion14F and the second contact portions14R together. The strength of the vehicle body framework structure S1with respect to compression force acting in the direction that the pair of internal faces (front face20, rear face22) oppose each other (the front-rear direction) is thereby improved. In other words, cross-sectional collapse of the framework member12is suppressed.

The slits16are formed in the reinforcement member14, extending from the end portion on the other internal face (the rear face22) side toward the one internal face (the front face20) side and having a depth substantially the same as that of the spacing at which the pair of internal faces (front face20, rear face22) oppose each other. By forming the slits16extending from the end portion on the other internal face side toward the one internal face side in the reinforcement member14in this manner, the bending rigidity of the vehicle body framework structure S1at portions where the slits16are formed is reduced compared to a case in which the slits16are not fainted. Strain on the framework member12illustrated by the arrows C inFIG. 4AandFIG. 4Bcan thereby be dispersed not only at the end portion of the reinforcement member14in the framework member12, but also at the portions of the framework member12where the slits are formed in the reinforcement member14. As a result, breaking or yielding of the framework member12is suppressed when load is input to the framework member in the direction that the pair of internal faces (front face20, rear face22) oppose each other, and the framework member undergoes bending deformation.

In the vehicle body framework structure S1of the present exemplary embodiment, the leading ends16B of the slits16reach as far as the boundary portion (the ridge lines18) between the coupling portions14M and the first contact portion14F. At the portions of the reinforcement member14where the slits16are formed, the reinforcement member14is thereby configured by the first contact portion14F alone. In this manner, the bending rigidity of the vehicle body framework structure S1is efficiently reduced due to the reinforcement member14being configured, where the slits16are formed, by the first contact portion14F alone that makes contact with the front face20of the framework member12.

Second Exemplary Embodiment

Explanation follows regarding a second exemplary embodiment, with reference toFIG. 5. Note that a vehicle body framework structure S2of the second exemplary embodiment differs from that of the first exemplary embodiment only in the structure of a reinforcement member34. Explanation is therefore only given regarding the structure of the reinforcement member34, and other explanation is omitted.

The reinforcement member34of the second exemplary embodiment has a rectangular cross-section profile. Namely, the reinforcement member34includes a sheet shaped first contact portion34F disposed extending in the up-down direction and the left-right direction, a pair of sheet shaped coupling portions34M provided extending from both up-down direction end portions of the first contact portion34F toward the rear side, and disposed extending in the front-rear direction and the left-right direction, and a sheet shaped second contact portion34R that joins rear side end portions of the pair of coupling portions34M together in the up-down direction and that is disposed extending in the up-down direction and the left-right direction.

Slits16are formed from the second contact portion34R toward the first contact portion34F as viewed from above. Namely, slits16are formed in the second contact portion34R so as to extend in the up-down direction, with the length of the slits16spanning across the entire up-down direction region of the second contact portion34R. The slits16extending in the front-rear direction in the pair of coupling portions34M are formed so as to be continuous with the respective slits16in the second contact portion34R. Leading ends of the slits16reach as far as a boundary portion (ridge lines18) between the coupling portions34M and the first contact portion34F.

Operation and Advantageous Effects

The vehicle body framework structure S2that includes the reinforcement member34of the second exemplary embodiment configured in this manner exhibits advantageous effects similar to those of the first exemplary embodiment. Namely, breaking or yielding of the framework member12is suppressed when load is input to the framework member in the direction that the pair of internal faces (front face20, rear face22) oppose each other, and the framework member undergoes bending deformation.

Third Exemplary Embodiment

Explanation follows regarding a third exemplary embodiment, with reference toFIGS. 6A to 6C.FIG. 6Aillustrates a vehicle body framework structure S3of the third exemplary embodiment. As illustrated inFIG. 6A, in the third exemplary embodiment, the vehicle body framework structure S3is applied with bumper reinforcement40provided at a vehicle front section and extending along a vehicle width direction. Note that the arrow FR and the arrow LH illustrated inFIGS. 6A to 6Crespectively indicate the vehicle front direction and the vehicle left direction.

The bumper reinforcement40is a framework member provided extending along the vehicle width direction, and is disposed toward a vehicle rear of a front bumper (not illustrated in the drawings) of a vehicle. A pair of left and right crash boxes42are attached at the vehicle rear of the bumper reinforcement40. The crash boxes42are disposed with their axes oriented substantially along the vehicle front-rear direction. Rear sections of the crash boxes42are connected to front side members (not illustrated in the drawings), these being framework members provided extending along substantially the vehicle front-rear direction. Vehicle front-rear direction rear sections of the front side members are connected to a portion of the vehicle body structure configuring a vehicle cabin. The crash boxes42and the front side members taken together may be viewed as being front-rear direction members provided extending along the vehicle front-rear direction on both vehicle width direction sides of a vehicle front section. The crash boxes42and the front side members in the present exemplary embodiment correspond to “front-rear direction members.”

A pair of left and right reinforcement members14are provided at internal portions of the bumper reinforcement40, disposed at both vehicle width direction ends thereof. The length of each of the reinforcement members14in the vehicle width direction is approximately one third of the length of the bumper reinforcement40. The bumper reinforcement40has a shape inclined toward the vehicle rear side at both vehicle width direction end portions. The reinforcement members14are accordingly formed matching the inclined shape of the bumper reinforcement40. The reinforcement members14are disposed so as to include both end positions of the bumper reinforcement40. Cross-sectional collapse of both ends of the bumper reinforcement40is thereby suppressed by the reinforcement members14.

Each of the reinforcement members14is disposed so as to include a portion (framework facing portions40A) of the bumper reinforcement40facing a front end of the crash box42. The slits16of the reinforcement members14are positioned further to the vehicle width direction inner side than the framework facing portions40A.

Operation and Advantageous Effects

Next, explanation follows regarding operation and advantageous effects of the third exemplary embodiment.

In the third exemplary embodiment, in cases in which an offset collision with a collision body W has occurred, the bumper reinforcement40deforms as illustrated inFIG. 6AtoFIG. 6C. As illustrated inFIG. 6AtoFIG. 6C, in cases in which the collision body W collides with a left side section of a vehicle, a left side section of the bumper reinforcement40extending in the left-right direction (vehicle width direction) deforms toward the vehicle rear direction, and the bumper reinforcement40bends.

Cross-sectional collapse of the bumper reinforcement40is suppressed at the sections of the bumper reinforcement40provided with the reinforcement members14. Collision load can thereby be efficiently transmitted to the crash boxes42and the front side members such that collision energy can be absorbed by the crash boxes42and the front side members.

The slits16of the reinforcement members14are positioned further to the vehicle width direction inner side than the framework facing portions40A such that strain can be dispersed not only at vehicle width direction inside end portions of the reinforcement members14of the bumper reinforcement40, but also at the portions of the bumper reinforcement40where the slits16are provided. As a result, the bumper reinforcement40is suppressed from breaking. Cross-sectional collapse occurs at a vehicle width direction central portion of the bumper reinforcement40due to compression in the front-rear direction, which also suppresses strain.

In the vehicle body framework structure S3of the third exemplary embodiment as described above, the bumper reinforcement40can be suppressed from breaking, and collision load can be efficiently transmitted to the crash boxes42and the front side members.

Supplemental Explanation of the Exemplary Embodiments Above

In each of the exemplary embodiments described above, the cross-section profile of the framework member12is a rectangular shape. However, the embodiments are not limited thereto. The framework member may be formed in any hollow, elongated shape. For example, the cross-section profile of the framework member may be substantially hexagonal. Moreover, the framework member may be formed by two sheet members joined together. The material of the framework member or the reinforcement member is not limited to CFRP, and, for example, may be glass-fiber reinforced plastic (GFRP) or an aluminum alloy. The framework member and the reinforcement member may be configured by materials that are different from each other.

In each of the exemplary embodiments described above, the reinforcement members14and the framework member12are joined together using vibration welding. However, the embodiments are not limited thereto. For example, the reinforcement members and the framework member may be joined together using an adhesive. The reinforcement members and the framework member may also be joined together using welding or rivets.

In the third exemplary embodiment, explanation has been given in which an embodiment is applied to the (front) bumper reinforcement40. However, the embodiments may be applied to various other vehicle body framework members such as rear bumper reinforcement, front pillars, center pillars, rear pillars, rockers (side sills), and roof side rails.

In the exemplary embodiments above, the reinforcement members14are provided at positions at both length direction end portions of the framework member12. However, the embodiments are not limited thereto. That is to say, the reinforcement members14may be provided at positions not at the end sections of the framework member12, as long as the reinforcement members14are provided at internal sections of the framework member12. The positions where slits are formed in the reinforcement members are also not particularly limited. However, from the viewpoint of suppressing a concentration of stress toward the framework members at the end portions of the reinforcement members, and from the viewpoint of suppressing cross-sectional collapse, this being a basic function of the reinforcement members, is it preferable that the slits are formed in the vicinity of the end portions of the reinforcement members.

In the exemplary embodiments above, the shape of the reinforcement members14,34have rectangular cross-sections or hat shaped cross-sections. However, the embodiments are not limited thereto, as long as the reinforcement member is configured including a first contact portion making contact with one internal face out of the opposing pair of internal faces of the framework member, a second contact portion making contact with another internal face out of the opposing pair of internal faces, and a coupling portion that couples the first contact portion and the second contact portion.

In the exemplary embodiments above, the leading ends16B of the slits16reach as far as the boundary between the first contact portion14F and the coupling portions14M. However, the embodiments are not limited thereto. The leading ends of the slits may be positioned in the coupling portions without reaching as far as the first contact portion. In other words, the slits may be formed in at least the second contact portions and the coupling portions of the reinforcement member. This is due to the fact that in cases in which the depth of the slits is smaller (thinner) than the spacing at which the pair of internal faces oppose each other, the slits16obtain operation to disperse stress during bending deformation. Note that the depth of the slits is a dimension measured in the direction that the pair of internal faces oppose each other. In this case, each slit16extends from an end portion on the other internal face side toward the one internal face side, and it is preferable that the slits16have a depth that is greater than or equal to one fourth of the spacing at which the pair of internal faces oppose each other. Due to the depth of the slits16being made to be greater than or equal to one fourth of the spacing at which the pair of internal faces oppose each other, the bending rigidity of the vehicle body framework structure at a portion where the slits are formed is more effectively reduced.

In the exemplary embodiments above, the slits16are parallel to each other in the front-rear direction (the direction that the front face20and the rear face22oppose each other). However, the embodiments are not limited thereto. The slits may be inclined with respect to the direction that the pair of internal faces oppose each other.