Vehicle front structure

A vehicle front structure includes: a bumper reinforcement attached to a front end of a side frame in a vehicle front part; and a load transmission member attached at a position offset upward from the center of a side end portion of the bumper reinforcement. The load transmission member is joined to a front face of the side end portion such that a front end portion projects forward in the vehicle front-rear direction from the front face of the side end portion. A plate is provided at a position offset downward from the center of the side end portion in the up-down direction, the position being a position where the plate overlaps the front end portion when the plate is viewed from above in the vehicle up-down direction. The plate projects forward in the vehicle front-rear direction to the same extent as the front end portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2019-088600 filed on May 8, 2019, which is incorporated herein by reference in its entirety including the specification, drawings and abstract.

BACKGROUND

1. Technical Field

The present disclosure relates to a vehicle front structure and more particularly relates to a structure for collision load absorption.

2. Description of Related Art

A front body structure of a vehicle includes a pair of right and left side frames as side frame members, and a bumper reinforcement extending in the vehicle width direction and connected to front ends of the right and left side frames. The right and left side frames are provided in a vehicle front part and extend in the vehicle front-rear direction. The bumper reinforcement includes side end portions projecting outward in the vehicle width direction from the side frames, respectively. There has been proposed a structure provided with a load transmission member extending rearward and inward in the vehicle width direction from a side end portion (e.g., see Japanese Unexamined Patent Application Publication No. 2014-113894 (JP 2014-113894 A)). The load transmission member is configured to transmit a collision load to a side face of a side frame when a small overlap collision occurs, that is, when a collision object collides with the side end portion.

SUMMARY

Incidentally, in some cases, a load transmission member may be attached to a side end portion of a bumper reinforcement at a position offset, in the up-down direction, from the center of the side end portion in the up-down direction such that a front end portion of the load transmission member projects forward from a front face of the bumper reinforcement. In this case, the side end portion of the bumper reinforcement may torsionally deform due to a collision load input into the load transmission member, thereby resulting in that a desired load may not be transmitted to a side frame as a side frame member.

An object of the present disclosure is to efficiently transmit a collision load to a side frame member via a load transmission member, the collision load being applied to a side end portion of a bumper reinforcement.

A vehicle front structure of the present disclosure is a vehicle front structure including a pair of right and left side frame members, a bumper reinforcement, and a load transmission member. The right and left side frame members are provided in a vehicle front part and extend in the vehicle front-rear direction. The bumper reinforcement is attached to front ends of the right and left side frame members. The bumper reinforcement extends in the vehicle width direction. The bumper reinforcement has right and left side end portions projecting outward in the vehicle width direction from the side frame members, respectively. The load transmission member is attached to each of the side end portions of the bumper reinforcement at a position offset, in the up-down direction, from the center of the each of the side end portions in the up-down direction. The load transmission member extends rearward in the vehicle front-rear direction and inward in the vehicle width direction. The load transmission member is configured to abut with the each of the side frame members and transmit a collision load to the each of the side frame members at a time of a collision. The load transmission member is joined to a front face of the each of the side end portions of the bumper reinforcement such that a front end portion of the load transmission member projects forward in the vehicle front-rear direction from the front face of the each of the side end portions. The load transmission member penetrates through the each of the side end portions and extends rearward in the vehicle front-rear direction and inward in the vehicle width direction. The each of the side end portions includes a projecting portion provided at a position offset from the center of the each of the side end portions in the up-down direction to a side opposite, in the up-down direction, from an attachment position of the load transmission member. The position is a position where the projecting portion overlaps the front end portion of the load transmission member when the projecting portion is viewed from above in the vehicle up-down direction. The projecting portion projects forward in the vehicle front-rear direction from the front face of the each of the side end portions to the same extent as the front end portion of the load transmission member.

Hereby, a collision load is input into the front end portion of the load transmission member and the projecting portion at the same time. The front end portion of the load transmission member projects forward in the vehicle front-rear direction from the front face of the side end portion at the position offset, in the up-down direction, from the center of the side end portion in the up-down direction. The projecting portion is provided at the position offset from the center, in the up-down direction, of the side end portion to the side opposite, in the up-down direction, from the attachment position of the load transmission member, the position being a position where the projecting portion overlaps the front end portion when the projecting portion is viewed from above in the vehicle up-down direction. The projecting portion projects forward in the vehicle front-rear direction from the front face of the side end portion to the same extent as the front end portion of the load transmission member. This makes it possible to restrain the side end portion from torsionally deforming due to the collision load and to transmit a desired load to the side frame member.

In the vehicle front structure of the present disclosure, the projecting portion may be constituted by a plate attached to the front face of the each of the side end portions.

Hereby, with a simple and easy configuration, it is possible to restrain the side end portion from torsionally deforming and to transmit a desired load to the side frame member.

With the present disclosure, it is possible to efficiently transmit a collision load to a side frame member via a load transmission member, the collision load being applied to a side end portion of a bumper reinforcement.

DETAILED DESCRIPTION OF EMBODIMENTS

With reference to the drawings, the following describes a vehicle front structure100of an embodiment. The following description deals with the vehicle front structure100for a vehicle using a ladder frame12. In the drawings, the orientation of an arrow FR indicates the front side in the vehicle front-rear direction, the orientation of an arrow LH indicates the left side in the vehicle right-left direction (the vehicle width direction), and the orientation of an arrow UP indicates the upper side in the vehicle up-down direction. In the following description, terms indicative of directions and orientations such as front, rear, right, left, up, and down indicate directions and orientations with respect to the vehicle unless otherwise specified. Further, in terms of the right-left direction, a side close to the center line of the vehicle is referred to as inward in the vehicle width direction, and a side far from the center line of the vehicle is referred to as outward in the vehicle width direction.

As illustrated inFIGS. 1, 2, the vehicle front structure100is a front structure for the vehicle including the ladder frame12. The vehicle front structure100includes: a pair of right and left side frames14R,14L as side frame members provided in a vehicle front part and extending in the vehicle front-rear direction; a bumper reinforcement28attached to front ends of the right and left side frames14R,14L and extending in the vehicle width direction; and load transmission members34R,34L attached to right and left side end portions32R,32L of the bumper reinforcement28.

The side frames14R,14L are made of steel and have a hollow rectangular sectional shape. Front end portions of the side frames14R,14L are formed as crash boxes24R,24L having strength lower than that of parts behind the front end portions. At the time of a front collision, the crash boxes24R,24L are crushed to relax impact. Further, the side frames14R,14L are connected to each other in the vehicle width direction via a plurality of crossmembers16,18,20extending in the vehicle width direction.

The bumper reinforcement28includes: a central portion30positioned between the right and left side frames14R,14L; and the side end portions32R,32L projecting outward in the vehicle width direction respectively from right and left end portions of the central portion30such that the side end portions32R,32L are disposed outside the side frames14R,14L in the vehicle width direction, respectively. The bumper reinforcement28has a bending or curved shape projecting forward as illustrated herein. As a result, outer ends of the side end portions32R,32L are inclined to be placed rearward from inner ends of the side end portions32R,32L, the inner ends being connected to the central portion30.

The load transmission members34R,34L attached to the side end portions32R,32L of the bumper reinforcement28are attached to the side end portions32R,32L such that the load transmission members34R,34L extend rearward in the vehicle front-rear direction and inward in the vehicle width direction from the side end portions32R,32L. At the time of a so-called small overlap collision, a corresponding one of the load transmission members34R,34L transmits a collision load caused by the collision to a corresponding one of the side frames14R,14L. The small overlap collision is a collision in which an object collides with an outer part of the vehicle front part in the vehicle width direction, the outer part corresponding to one fourth of the vehicle front part. Details of the load transmission members34R,34L will be described later.

The side frames14R,14L, the crash boxes24R,24L, the side end portions32R,32L, and the load transmission members34R,34L make respective pairs on the right and left sides such that each of the pairs is provided symmetrically in the right-left direction. In the following description, when it is not necessary to distinguish them from each other in terms of right and left, the side frames14R,14L are just referred to as the side frame14, the crash boxes24R,24L are just referred to as the crash box24, the side end portions32R,32L are just referred to as the side end portion32, and the load transmission members34R,34L are just referred to as the load transmission member34.

As illustrated inFIGS. 3, 4, the side end portion32of the bumper reinforcement28has a hollow square sectional shape and includes an upper wall36corresponding to an upper side of the square of the section, a lower wall38corresponding to a lower side of the square, a front wall40corresponding to a front side of the square in the vehicle front-rear direction, and a rear wall42corresponding to a rear side of the square in the vehicle front-rear direction. The square as the sectional shape of the side end portion32can be a rectangular shape, for example. In this case, the upper wall36and the lower wall38may be placed horizontally, and the front wall40and the rear wall42may be placed vertically. Further, the side end portion32includes a reinforcing wall44between the upper wall36and the lower wall38. The reinforcing wall44is placed so as to connect the front wall40to the rear wall42. The reinforcing wall44can be provided over the overall length of the side end portion32and also can be placed horizontally. The reinforcing wall44is provided so as to achieve necessary strength and rigidity of the side end portion32. The number of reinforcing walls44is not limited to one, and a plurality of reinforcing walls44may be provided as necessary. When the side end portion32has sufficient strength, the reinforcing wall44may not be provided. The front wall40and the rear wall42have openings46,48configured to receive the load transmission member34, and the openings46,48are provided at positions between the upper wall36and the reinforcing wall44. The side end portion32is made of metal, e.g., aluminum. The central portion30of the bumper reinforcement28also has the same configuration as the side end portion32. By use of a material such as aluminum that is suitable for extrusion, the bumper reinforcement28can be manufactured by forming the central portion30and the side end portion32by extrusion.

The load transmission member34has an angular tubular shape having a hollow square section. The load transmission member34includes an upper wall50corresponding to an upper side of the square of the section, a lower wall52corresponding to a lower side of the square, an outer wall54corresponding to an outer side of the square in the vehicle width direction, and an inner wall56corresponding to an inner side of the square in the vehicle width direction. The square as the sectional shape of the load transmission member34can be a rectangular shape, for example. In this case, the upper wall50and the lower wall52may be placed horizontally, and the outer wall54and the inner wall56may be placed vertically. The walls50,52,54,56have the same thickness or may have different thicknesses. More specifically, the thickness of the inner wall56can be thicker than those of the other walls, and for example, the thickness of the inner wall56can be 1.3 times or more or 1.5 times thicker than those of the other walls. The load transmission member34is made of metal, and for example, by use of a material such as aluminum that is suitable for extrusion, the load transmission member34can be manufactured by extrusion.

The load transmission member34penetrates through the side end portion32of the bumper reinforcement28such that the load transmission member34crosses the side end portion32between the upper wall36and the reinforcing wall44of the side end portion32. The load transmission member34is connected to the front wall40and the rear wall42. Thus, the load transmission member34is attached at a position that is offset upward from a center32cof the side end portion32in the up-down direction. The load transmission member34penetrates through the side end portion32from a front face32aof the side end portion32and further extends rearward in the vehicle front-rear direction and inward in the vehicle width direction such that the load transmission member34extends diagonally to the center line of the vehicle.

The load transmission member34is joined to the front wall40and the rear wall42of the side end portion32by arc-welding performed along peripheries of the openings46,48formed in the front wall40and the rear wall42. In order to join the load transmission member34by arc-welding, a front end portion34aof the load transmission member34projects forward in the vehicle front-rear direction from the front face32aof the side end portion32only by a length d. Fillet welding is performed between an outer periphery of the front end portion34athus projecting and the periphery of the opening46of the front face32aof the side end portion32. In terms of a rear-side part of the load transmission member34, fillet welding is performed between a part projecting from a rear face32bof the side end portion32and the periphery of the opening48. Fillet welding may be performed on the whole peripheries of the openings46,48or may be performed on only parts of the peripheries, e.g., only along the upper sides and the lower sides of the openings46,48.

The upper wall50of the load transmission member34and the upper wall36of the side end portion32of the bumper reinforcement28are placed in parallel to each other and adjacent to each other. Instead of this or in addition to this, the lower wall52of the load transmission member34and the reinforcing wall44of the bumper reinforcement28are placed in parallel to each other and adjacent to each other.

A rear end of the load transmission member34is distanced from the side frame14. Further, a rear end face58of the load transmission member34is placed such that a plane defined by the rear end face58intersects with the side frame14. In the load transmission member34of the present embodiment, the rear end face58is perpendicular to the center line of the load transmission member34having the angular tubular shape. An inner margin60on the inner side of the rear end face58in the vehicle width direction forms a corner facing a side face of the side frame14. This corner may be chamfered into a round surface.

A square plate70formed in a flat-plate shape and having a thickness d that is equal to a projection length d of the front end portion34ais attached to the front face32abetween the reinforcing wall44and the lower wall38in each of the right and left side end portions32R,32L. The plate70constitutes a projecting portion. As illustrated inFIG. 4, the plate70is placed right under the load transmission member34. That is, the plate70is placed at a position that is offset downward from the center32cof the side end portion32in the up-down direction reversely to the load transmission member34. Note that, like a range C illustrated inFIG. 4, the plate70may be placed at a position deviating from the load transmission member34in the right-left direction instead of a position right under the load transmission member34, provided that the plate70is placed at a position where the plate70overlaps the front end portion34awhen the plate70is viewed from above in the vehicle up-down direction. Further, the plate70may be constituted by a circular plate instead of the square plate.

With reference toFIGS. 5 to 7, the following describes deformation of the vehicle front structure at the time of a small overlap collision. As illustrated inFIG. 5, the small overlap collision is a collision mode in which an object collides with an outer part of the vehicle front part in the vehicle width direction, the outer part corresponding to one fourth of the vehicle front part. In a collision test, the vehicle collides with a barrier80. The barrier80collides with a part of the vehicle, the part being positioned outward from the side frame14in the vehicle width direction. Accordingly, the side frame14may not receive a collision load sufficiently. In the vehicle front structure100, the collision load is transmitted to the side frame14via the load transmission member34penetrating through the side end portion32of the bumper reinforcement28.

As illustrated inFIGS. 5, 6, in an initial stage of the small overlap collision, the barrier80collides with the front end portion34aof the load transmission member34and a front face of the plate70, the load transmission member34and the plate70being provided in the side end portion32. Hereby, due to a collision load indicated by a reference sign F inFIG. 6, the center32c, in the up-down direction, of the side end portion32is moved rearward in the vehicle front-rear direction. Then, as illustrated inFIG. 7, the collision load is transmitted to the crash box24of the side frame14, so that the crash box24is crushed. Further, at the same time, the central portion30and the side end portion32of the bumper reinforcement28move rearward and bend, so that the rear end of the load transmission member34faces more inward in the vehicle width direction and moves inward in the vehicle width direction. As a result, in a later stage of the small overlap collision, the inner margin60of the rear end face58of the load transmission member34abuts with the side face of the side frame14, so that the collision load is transmitted to the side frame14. Hereby, the side frame14bends inward in the vehicle width direction, so that collision energy is absorbed. At this time, the load transmission member34directly transmits the collision load to the side frame14, so that the side frame14can be bent efficiently. Further, the load transmission member34supports the side end portion32of the bumper reinforcement28, thereby making it possible to restrain further entry of the barrier80.

In the meantime, like a vehicle front structure200as a comparative example illustrated inFIG. 8, in a case where the plate70is not attached to the side end portion32, a collision load from the barrier80is input into the front end portion34aof the load transmission member34placed above the center32c, in the up-down direction, of the side end portion32. Due to the collision load, a rotational moment M is caused around the center32c, in the up-down direction, of the side end portion32, so that the rear end face58of the load transmission member34rotates downward due to the rotational moment M as indicated by an arrow91. This causes the height of the rear end face58of the load transmission member34to be lower than the height of the side frame14, thereby resulting in that the collision load cannot be sufficiently transmitted to the side frame14.

In the vehicle front structure100of the present embodiment, the plate70having the thickness d equal to the projection length d of the front end portion34ais provided at the position where the plate70overlaps the front end portion34awhen the plate70is viewed from above in the vehicle up-down direction. The position is on a side opposite, in the up-down direction, from an attachment position of the front end portion34aof the load transmission member34. As a result, a collision load is input into the front end portion34aof the load transmission member34and the plate70at the same time, thereby making it possible to restrain the side end portion32from torsionally deforming due to the collision load and to transmit a desired load to the side frame14.

The above description deals with a case where the thickness of the plate70is equal to the projection length d of the front end portion34aof the load transmission member34from the front face32aof the side end portion32. However, the thickness of the plate70may not be equal to the projection length d of the front end portion34a, provided that the thickness of the plate70is generally equal to the projection length d of the front end portion34a. Further, the above description deals with a case where the load transmission member34is placed above the center32cof the side end portion32in the up-down direction, and the plate70is placed below the center32c. However, the present disclosure is not limited to this. The load transmission member34may be placed below the center32c, e.g., in a part between the reinforcing wall44and the lower wall38, and the plate70may be placed above the center32c.

Further, instead of attaching the plate70to the front face32aof the side end portion32, a projection having a height d equal to the projection length d of the front end portion34aof the load transmission member34may be provided on the front face32aof the side end portion32. Further, respective load transmission members34having the same configuration may be attached between the upper wall36and the reinforcing wall44in the side end portion32and between the reinforcing wall44and the lower wall38, and respective projection lengths of the front end portions34aof the load transmission members34may be set to the same length d.

The above embodiment deals with the vehicle front structure100for the vehicle including the ladder frame12. However, the present disclosure is not limited to this, and this disclosure can be also applied to a vehicle including a monocoque frame. In the case of a monocoque frame, a front side member serves as a side frame member.