CROSS-REFERENCE TO RELATED APPLICATION

Priority is claimed on Japanese Patent Application No. 2019-223921, filed on Dec. 11, 2019, the contents of which are incorporated herein by reference.

BACKGROUND

Field of the Invention

The present invention relates to a vehicle body front part structure.

Background

Most vehicles include an upper member that extends from a front pillar to a vehicle body front side. The front pillar forms a closed cross-section that extends in a vehicle body vertical direction, and the upper member forms a closed cross-section that extends in a vehicle body front-to-rear direction. When an impact load is input from a vehicle frontward direction to a position offset to a right or left of the vehicle, the upper member transmits the input load to a vehicle body rear part through the front pillar while being plastically deformed. In this case, it is essential to reliably transmit the input load to the front pillar side when a base of the upper member is plastically deformed to some degree. A vehicle body front part structure that is intended to achieve this has been proposed (refer to Japanese Patent No. 4996707).

In the vehicle body front part structure described in Japanese Patent No. 4996707, a reinforcement member is attached to an inside of the closed section of the upper member. A rear end part of the reinforcement member faces a front wall of the front pillar with a gap. When an impact load is input to the upper member from a vehicle body frontward direction, the upper member plastically deforms, and the rear end part of the reinforcement member comes into contact with the front wall of the front pillar when the upper member is plastically deformed to some degree. As a result, the impact load input to the upper member is transmitted to the front wall of the front pillar via the reinforcement member.

SUMMARY

However, the vehicle body front part structure described in Japanese Patent No. 4996707 has a structure in which a rear part of the upper member is simply joined to a front surface or a side surface in a vehicle width direction of the front pillar. Therefore, depending on an input position, angle, or the like of the impact load input from the vehicle body frontward direction, there is a concern that the upper member will fall outward in the vehicle width direction from a connection part of the rear part of the upper member connected to the front pillar as a starting point. In this case, a load transmission amount to the front pillar from the upper member is decreased due to the falling of the upper member, and it becomes difficult to increase an absorption amount of impact energy.

An aspect of the present invention provides a vehicle body front part structure capable of preventing an upper member from falling outward in a vehicle width direction when an impact load is input from a vehicle body frontward direction and efficiently transmitting the impact load from the upper member to a front pillar.

A vehicle body front part structure according to an aspect of the present invention includes: a front pillar that forms a closed cross-section extending in a vehicle body vertical direction; and an upper member that extends from the front pillar to a vehicle body frontward direction, wherein the upper member includes: a side wall on an outside in a vehicle width direction; and an stiffener that is joined to an inner surface of the side wall, that has a rear end part facing a front surface of the front pillar, and that forms a closed cross-section extending substantially in a vehicle body front-to-rear direction together with the side wall, and the side wall of the upper member includes: a pillar fixation part that is arranged in a rearward extension area extending in a vehicle body rearward direction further than the rear end part of the stiffener and that is fixed to a side wall on an outside in the vehicle width direction of the front pillar; and a bead shape part that convexly projects outward in the vehicle width direction and that extends to a vicinity of the pillar fixation part from a frontward position further than the rear end part of the stiffener.

In the configuration described above, when an impact load is input from a frontward direction of the upper member, a rear part of the upper member collapses and deforms, and the rear end part of the stiffener of the upper member comes into contact with a front wall of the front pillar. Thereby, the impact load input to the upper member is transmitted through the front pillar to the vehicle body rear. At this time, in the side wall of the upper member, the bead shape part that convexly projects outward in the vehicle width direction extends from a further frontward position than the rear end part of the stiffener to the vicinity of the pillar fixation part in the rearward extension area. Therefore, the rearward extension area of the side wall of the upper member does not easily fall and deform outward in the vehicle width direction. Accordingly, the upper member can efficiently transmit the impact load to the front pillar without falling outward in the vehicle width direction when the impact load is input from the vehicle body frontward direction.

Further, since the bead shape part of the side wall of the upper member convexly projects outward in the vehicle width direction, it is possible to enlarge a cross-sectional area of the closed cross-section formed of the upper member and the stiffener. Accordingly, the input load from the vehicle frontward direction can be stably transmitted to the front pillar side.

A circumference edge bend part that is bent outward in the vehicle width direction may be formed on a circumference edge portion of the pillar fixation part in the rearward extension area, and a ridge line on a root of the circumference edge bend part may continue to a ridge line on a root of the bead shape part.

In this case, since the ridge line on the root of the circumference edge bend part continues to the ridge line on the root of the bead shape part, it is possible to efficiently enhance a stiffness in the rearward extension area of the side wall from the bead shape part to the circumference edge portion of the pillar fixation part. Accordingly, in a case where the present configuration is employed, when an impact load is input to the upper member from the vehicle body frontward direction, it is possible to further prevent the falling deformation of the rearward extension area of the upper member, and it is possible to efficiently transmit the impact load to the vehicle body rearward direction through the rearward extension area of the upper member.

The bead shape part may have a vertical cross-section formed in a substantially trapezoidal shape, and a part of the bead shape part that is a top surface of the trapezoidal shape may be a flat surface.

In this case, the part of the bead shape part that becomes the top surface of the trapezoidal shape is a flat surface, and thereby, a ridge line is formed not only on the root of the bead shape part but also on a part corresponding to the top of the trapezoidal shape.

Therefore, the impact load input to the upper member from the vehicle body frontward direction can be further efficiently transmitted to the vehicle body rearward direction.

A ridge line may be formed on each of root positions of an upper side portion and a lower side portion of the bead shape part, and a spacing between the ridge lines of the upper side portion and the lower side portion may be increased toward a rearward direction from a frontward direction in a vehicle body front-to-rear direction.

In this case, the load input to the bead shape part of the upper member from the vehicle body frontward direction is easily distributed and transmitted to a wide range in a vertical direction of the front pillar.

The front pillar may have an inner portion of the closed cross-section that extends in a vehicle body vertical direction to which a bulk head that extends in a direction intersecting an extension direction of the closed cross-section is joined, and the bulk head may be arranged at a position that intersects the ridge line on the root of the circumference edge bend part in the rearward extension area.

In this case, the impact load transmitted to the rearward extension area of the upper member from the vehicle body frontward direction is efficiently transmitted to a reinforcement portion by the bulk head of the front pillar. Accordingly, when the present configuration is employed, the impact load transmitted to the rearward extension area of the upper member can be further efficiently transmitted to the vehicle body rearward direction.

The bulk head may include a connection flange joined to the sidewall of the front pillar, and a connection part of the connection flange may be arranged at a position at substantially the same height as a fixed part of the front pillar to which the pillar fixation part is fixed.

In this case, the impact load transmitted to the rearward extension area of the upper member from the vehicle body frontward direction is efficiently transmitted to the fixed part of the front pillar from the pillar fixation part of the rearward extension area at substantially the same height as the direct reinforcement part by the connection flange of the bulk head. When the present configuration is employed, the impact load transmitted to the rearward extension area of the upper member can be further efficiently transmitted to the front pillar at a height position where the stiffness is enhanced by the bulk head.

The bulk head may be arranged at a vertical position aligned in the vehicle body front-to-rear direction with a lower wall of a rear part of the upper member.

In this case, the load transmitted from the vehicle body frontward direction to the lower wall on the rear part of the upper member can be stably supported by the bulk head inside the front pillar.

The upper member may include an upper member inner part and an upper member outer part that are joined together in a vertical direction and that form a closed cross-section extending in a vehicle body front-to-rear direction, the upper member inner part and the upper member outer part may include an inner upper flange and an outer upper flange that stand upward and that are joined together, the inner upper flange and the outer upper flange may include a tilt area in which a standing position changes from an inside to an outside in a vehicle width direction toward a vehicle body rearward direction from a vehicle body frontward direction, and the stiffener may include a joint piece that is provided between the tilt areas of the inner upper flange and the outer upper flange and that is joined to the inner upper flange and the outer upper flange.

In this case, when an impact load input from a vehicle body frontward direction to a front part of the upper member is transmitted through outer corner portions of the upper member inner part and the upper member outer part to the tilt areas of the inner upper flange and the outer upper flange, the impact load is efficiently transmitted to an upper wall of the upper member inner part via the joint piece of the stiffener provided between the tilt areas of the inner upper flange and the outer upper flange. Therefore, it is possible to reduce the load transmitted to the pillar fixation part at the rear part of the side wall on the outside in the vehicle width direction of the upper member. Accordingly, when the present configuration is employed, it is possible to further prevent the upper member from falling outward in the vehicle width direction when the impact load is input from the vehicle body frontward direction.

The inner upper flange and the outer upper flange may have a rear extension region that is arranged at a rear end of the tilt area and that extends via a bend part to a vehicle body rearward direction, and the joint piece of the stiffener may be joined to the tilt area and the rear extension region so as to interpose the bend part.

In this case, an impact load transmitted from a vehicle frontward direction to the tilt area of the outer upper flange is also efficiently transmitted to a rear tilt area and the bend part of the inner upper flange via the joint piece of the stiffener. Accordingly, when the present configuration is employed, it is possible to increase the load transmitted to the upper wall of the upper member inner part.

The front pillar may include a pillar inner part and a pillar outer part that are joined together and that form the closed cross-section extending in the vehicle body vertical direction, the upper member inner part may include a side wall on an inside in the vehicle width direction and an upper wall that is bent outward in the vehicle width direction from an upper part of the side wall and that is connected to the inner upper flange, the pillar inner part may include a front extension part extending in a vehicle body frontward direction further than the pillar outer part from a joint part on a vehicle body frontward side with the pillar outer part, and a rear part of the side wall on the inside in the vehicle width direction of the upper member inner part may be joined to the front extension part of the pillar inner part.

In this case, an impact load transmitted from a vehicle frontward direction to the side wall on the inside in the vehicle width direction of the upper member inner part is transmitted to the closed cross-section of the front pillar via the front extension part of the pillar inner part. Accordingly, in a case where the present configuration is employed, the impact load that is input from the vehicle body frontward direction to the upper member can be transmitted to the front pillar through a wide area of the rear part of the upper member.

The upper wall of the upper member inner part and the inner upper flange of the upper member inner part may be joined to a front wall of the pillar outer part via a patch member, the patch member may include a patch upper wall joined to the upper wall of the upper member inner part and a patch flange joined to the inner upper flange of the upper member inner part, and a bend ridge line between the patch flange and the patch upper wall of the patch member may continue in the vehicle body front-to-rear direction to a bend ridge line between the inner upper flange and the upper wall of the upper member inner part.

In this case, an impact load transmitted from a vehicle frontward direction to the inner upper flange or the upper wall of the upper member inner part is efficiently transmitted to the front wall of the pillar outer part through the bend ridge line of the patch member and the bend ridge line of the upper member inner part. Accordingly, in a case where the present configuration is employed, it is possible to further prevent the upper member from falling outward in the vehicle width direction when an impact load is input.

According to the aspect of the present invention, by the bead shape part formed on the side wall of the upper member, an impact load input to the upper member from a vehicle body frontward direction can be efficiently transmitted to the front pillar via the stiffener while preventing the upper member from falling outward in the vehicle width direction.

