JP2007283875A - Vehicle body front structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle body front structure which controls a buckling mode while making a front side member thinner. <P>SOLUTION: By a diagonal joint structure 32 between a thin steel plate portion 22 and a thick steel plate portion 26 diagonally joined in a vehicle body fore-and-aft direction, in the state where a front side member front portion 20 receives a front collision foal F, an input load to an inside ridgeline 27 of a front side member rear portion 24 is made to be larger than an input load to an outside ridgeline 28 of a front side member rear portion 24. Even if a folding bead is not set on the front side member rear portion 24, therefore, the inside ridgeline 27 side can be buckled before buckling the outside ridgeline 28 side of the front side member rear portion 24. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle body front structure in which a front side member has a differential thickness steel plate structure.

  In the front part of the vehicle body, the front side member is made of a differential thickness steel plate structure and the thickness of the rear part of the front side member is set in front of the front side member in order to axially deform the front side member from the front during a front collision (front collision). In some cases, the thickness is larger than the plate thickness of the portion (see, for example, Non-Patent Document 1). In such a difference thickness steel plate structure, in order to control the buckling mode, there is a structure in which a bead is set at a ridge line on the inner side in the vehicle width direction, for example, at the rear part of the front side member.

However, in this conventional vehicle body front structure, since the bending proof strength against the collision load is lowered by setting the bead, it is difficult to reduce the thickness of the front side member.
Japan Society for Invention and Innovation Technical Report, Technical Number 93-32866

  In view of the above fact, an object of the present invention is to provide a vehicle body front part structure capable of controlling the buckling mode while reducing the thickness of the front side member.

  The vehicle body front structure according to the first aspect of the present invention includes a front bumper reinforcement extending in the vehicle width direction on the front end side of the vehicle body, and both sides of the front bumper reinforcement on the vehicle body rear side along the vehicle body longitudinal direction. A pair of left and right front side member front portions provided with the disposed thin steel plate portions, and disposed along the vehicle front-rear direction on the vehicle body rear side of the front side member front portion and joined to the rear end portion of the thin steel plate portions. When the front side member rear portion including a pair of left and right front side members having a thick steel plate portion thicker than the thin steel plate portion and the front side member front portion receive a front impact load, the front side in the vehicle front view Load control means for increasing the input load to the first ridge line on one side of the rear part of the member as compared with the input load to the second ridge line on the other side of the member; That.

  According to the vehicle body front part structure of the present invention described in claim 1, the thickness of the thick steel plate part at the rear part of the front side member is larger than the thickness of the thin steel plate part at the front part of the front side member. When a load greater than or equal to a predetermined value is input to the front side member front portion via the front bumper reinforcement, the front side member front portion is axially compressed and deformed before the front side member rear portion to absorb collision energy. Here, when the front side member front part receives a front impact load, the load control means applies the input load to the first ridge line on one side of the rear side of the front side member in the front view of the vehicle on the other side. Since it is larger than the input load to the ridgeline, the input load to the first ridgeline on one side of the rear side of the front side member through the front part of the front side member and the input load to the second ridgeline on the other side You can control the magnitude relationship with. Accordingly, the first ridge line side that is one side can be buckled before the second ridge line side that is the other side of the rear part of the front side member is buckled without setting the bent bead.

  The vehicle body front part structure according to a second aspect of the present invention is the structure according to the first aspect, wherein the joining portion between the rear end portion of the thin steel plate portion and the front end portion of the thick steel plate portion is in a vehicle front view. Compared with the joining position on one side, the joining position on the other side is the rear side in the longitudinal direction of the vehicle body.

  According to the vehicle body front part structure of the present invention described in claim 2, the joining portion between the rear end portion of the thin steel plate portion and the front end portion of the thick steel plate portion is different from the joining position on one side in the vehicle front view. Because the joint position on the side is the rear side in the longitudinal direction of the vehicle body, even if one side of the front side member front part in front view of the vehicle is crushed and cannot absorb the collision energy at the time of front collision, the front side member front There is a remaining crushing margin on the other side of the portion, and the collision energy can be absorbed by the remaining crushing margin. Thereby, the input load to the first ridge line on one side of the rear part of the front side member in the vehicle front view can be made larger than the input load to the second ridge line on the other side.

  The vehicle body front part structure according to a third aspect of the present invention is the structure according to the second aspect, wherein the rear end portion of the thin steel plate portion and the front end portion of the thick steel plate portion are joined together by welding. The portion forms an oblique joining line with respect to the longitudinal direction of the vehicle body.

  According to the vehicle body front portion structure of the present invention described in claim 3, the rear end portion of the thin steel plate portion and the front end portion of the thick steel plate portion so that the joint portion forms an oblique joining line with respect to the vehicle body longitudinal direction. Are joined by welding, and joining is easy, and by easy processing, the input load to the first ridge line that is one side of the rear side of the front side member at the time of the front collision and the second ridge line that is the other side The magnitude relationship with the input load can be controlled.

  The vehicle body front part structure according to a fourth aspect of the present invention is the structure according to any one of the first to third aspects, wherein the first ridge line is a ridge line on the inner side in the vehicle width direction of the rear part of the front side member. The second ridge line is a ridge line on the outer side in the vehicle width direction of the rear portion of the front side member.

  According to the vehicle body front part structure of the present invention described in claim 4, the first ridge line is a ridge line on the inner side in the vehicle width direction of the rear part of the front side member, and the second ridge line is a ridge line on the outer side in the vehicle width direction of the rear part of the front side member. Therefore, it is possible to control the magnitude relationship between the input load to the ridge line on the inner side in the vehicle width direction and the input load to the ridge line on the outer side in the vehicle width direction through the front part of the front side member. Accordingly, the ridge line side on the inner side in the vehicle width direction can be buckled before buckling the ridge line side on the outer side in the vehicle width direction of the rear part of the front side member without setting the bend bead.

  As described above, according to the vehicle body front portion structure according to the first aspect of the present invention, the front ridge to the first ridge line on one side of the front side member rear portion via the front side member front portion at the time of a front collision. By controlling the magnitude relationship between the input load and the input load applied to the second ridge line on the other side, the buckling mode can be controlled while making the front side member thinner without the need for a fold bead. It has an excellent effect.

  According to the vehicle body front part structure of the second aspect, there is an excellent effect that the buckling mode can be easily controlled while making the front side member thin by eliminating the need for a folding bead.

  According to the vehicle body front part structure according to claim 3, it has an excellent effect that the buckling mode can be controlled by thinning the front side member without using a folding bead by easy processing. .

  According to the vehicle body front structure according to the fourth aspect, the front side member can be reliably buckled outward in the vehicle width direction at the time of a front collision while eliminating the need for a fold bead and reducing the thickness of the front side member. It has an excellent effect.

  An embodiment of a vehicle body front structure in the present invention will be described with reference to the drawings. In the figure, arrow UP indicates the upward direction of the vehicle body, arrow FR indicates the forward direction of the vehicle body, arrow W indicates the vehicle width direction, and arrow OUT indicates the vehicle width direction outside.

(Configuration of the embodiment)
As shown in the front part of the vehicle body in FIG. 1, a front bumper reinforcement 12 extends in the vehicle width direction (arrow W direction) on the front end side of the vehicle body 10, and the front bumper reinforcement 12 has a closed cross-sectional structure. Or it is set as the open cross-section structure. On both sides of the front bumper reinforcement 12 on the rear side of the vehicle body, a pair of left and right front side members 14 that are skeleton members are disposed along the longitudinal direction of the vehicle body.

  As shown in FIGS. 2 and 3, the front side member 14 includes a bent plate-shaped front side member inner 16 having a substantially U-shaped cross section, and a cross section having an approximately L cross-section for closing the opening portion of the front side member inner 16. A closed plate structure (box-shaped cross-sectional structure) is configured by two components, a bent plate-shaped front side member outer 18 that is shaped like a letter.

  The front side member inner 16 includes a pair of wall portions 16A and 16B facing each other, and the front end side of one wall portion 16A is folded back into a flange shape to form a first mating portion 16C. The other wall portion 16B of the front side member inner 16 has a larger amount of extension from the bottom portion 16D than the one wall portion 16A, and the tip portion thereof is a second mating portion 16E. The front side member outer 18 includes a strip plate portion 18A that forms a general surface, and a folded portion 18B that is folded substantially perpendicularly from the strip plate portion 18A. As shown in FIG. The end portion of the shape portion 18A and the first mating portion 16C of the front side member inner 16 are spot welded, and the folded portion 18B and the second mating portion 16E of the front side member inner 16 are spot welded. That is, the front side member inner 16 and the front side member outer 18 are joined by spot welding.

  The front side member inner 16 is formed of a differential thickness steel plate (tailored blank material), and a thin steel plate portion 22 disposed on the front side of the vehicle body, and a thick steel plate disposed on the rear side of the thin steel plate portion 22 in the vehicle body. Part 26. In the present embodiment, the thin steel plate portion 22 and the thick steel plate portion 26 are formed of the same type of material, but the thickness of the thick steel plate portion 26 is thicker than the thickness of the thin steel plate portion 22. The proof stress (strength) with respect to the axial compressive load of the steel plate portion 26 is higher than the proof strength (strength) with respect to the axial compressive load of the thin steel plate portion 22. The rear end portion 22A of the thin steel plate portion 22 and the front end portion 26A of the thick steel plate portion 26 are joined by laser welding or the like. The front side member inner 16 is formed by bending a differential thickness steel plate having a thin steel plate portion 22 and a thick steel plate portion 26 by press forming.

  As shown in FIG. 1, the front side member 14 configured as described above has a front side member front portion 20 provided with a thin steel plate portion 22 on the front side of the vehicle body, and the vehicle rear side of the front side member front portion 20 is thick. The front side member rear portion 24 includes a steel plate portion 26. That is, the pair of left and right front side members front portion 20 includes thin steel plate portions 22 disposed along the vehicle body longitudinal direction on both sides of the front bumper reinforcement 12 on the vehicle body rear side, and the pair of left and right front side members. The rear portion 24 includes a thick steel plate portion 26 that is disposed along the vehicle front-rear direction on the vehicle body rear side of the front side member front portion 20 and joined to the rear end portion 22A of the thin steel plate portion 22.

  The joint portion 30 between the rear end portion 22A of the thin steel plate portion 22 and the front end portion 26A of the thick steel plate portion 26 is compared with the joint position P on the inner side in the vehicle width direction, which is one side in the vehicle front view. The joint position Q on the outer side in the vehicle width direction, which is the other side, is the rear side in the longitudinal direction of the vehicle body (the side opposite to the arrow FR direction), and is a diagonally linear joining line in plan view with respect to the longitudinal direction of the vehicle body. (Differential thickness line) is formed.

  The diagonally joined structure 32 of the thin steel plate portion 22 and the thick steel plate portion 26 that are joined obliquely with respect to the longitudinal direction of the vehicle body is the load control means in the present embodiment, and is the front side member front portion shown in FIG. In a state in which 20 receives a front collision load, an input load to the inner ridge line 27 as a first ridge line (ridge line on the inner side in the vehicle width direction) on one side of the front side member rear portion 24 in the front view of the vehicle is It is set larger than the input load to the outer ridge line 28 as the second ridge line (the ridge line on the outer side in the vehicle width direction) on the other side of the member rear portion 24.

  In the present embodiment, the inner ridge line 27 and the outer ridge line 28 in the rear portion 24 of the front side member have the same proof strength against a collision load.

(Operation and effect of the embodiment)
Next, the operation and effect of the above embodiment will be described.

  Since the thickness of the thick steel plate portion 26 of the front side member rear portion 24 shown in FIG. 1 is thicker than the thickness of the thin steel plate portion 22 of the front side member front portion 20, the front bumper reinforcement 12 from the collision body 34 at the time of the front collision. When a front impact load F of a predetermined value or more is input to the front side member front part 20 via the front side member front part 20, the front side member front part 20 is axially deformed in a bellows shape before the front side member rear part 24, resulting in collision energy. To absorb.

  Here, the joint portion 30 between the rear end portion 22A of the thin steel plate portion 22 and the front end portion 26A of the thick steel plate portion 26 is in the vehicle width direction compared to the joint position P on the inner side in the vehicle width direction (one side in the vehicle front view). Since the outer side (the other side) joining position Q is the rear side in the longitudinal direction of the vehicle body, as shown in FIG. 4, the inner side in the vehicle width direction (one side) of the front side member front portion 20 is crushed as shown in FIG. In other words, even if the crushing portion reaches the vehicle width direction inner side portion (bonding position P) of the joint portion 30 and cannot absorb the collision energy, the front side member front portion 20 outside the vehicle width direction (the other side) ) Has a crush remaining allowance 21, and the crush energy can be absorbed by the crush remaining allowance 21. By such an oblique joint structure 32, the input load F1 applied to the inner ridge line 27 on the inner side in the vehicle width direction (one side) of the rear portion 24 of the front side member is changed to the outer ridge line 28 on the outer side in the vehicle width direction (the other side). The load can be made larger than the input load F2. Thus, even without setting a bead as in the conventional structure, before buckling the outer ridge line 28 side, which is the outer side in the vehicle width direction (the other side) of the front side member rear portion 24, the inner side in the vehicle width direction ( It is possible to buckle the inner ridge line 27 side (one side) (buckling timing control).

  As a result, the front side member 14 is reliably buckled outwardly in the vehicle width direction (in the outward convex folding mode) at the time of a frontal collision while reducing the thickness (lightening) of the front side member 14, that is, buckling. The mode can be controlled easily. In addition, the front side member 14 is buckled outward in the vehicle width direction at the time of a front collision, so that, for example, entry of the toe board portion into the cabin can be suppressed.

  Here, to supplement the thinning of the front side member 14, when the bending bead is set at the rear part of the front side member as in the conventional structure to reduce the bending strength against the collision load, the folding bead is not set. A certain amount of plate thickness is required for the portion, and bending deformation is performed without using 100% of the proof strength of the portion where the bead is not set. In other words, the plate thickness required for the rear part of the front side member to obtain a predetermined bending strength with respect to the collision load can be made thinner when the folding bead is not set than when the folding bead is set. In this embodiment, the front side member rear part 24 is not set with a fold bead, and the strength of the member of the front side member rear part 24 is 100%, so the front side member rear part 24 is made thinner than the conventional structure. (Weight reduction) can be achieved.

  Further, the rear end portion 22A of the thin steel plate portion 22 and the front end portion 26A of the thick steel plate portion 26 are joined by welding so that the joining portion 30 forms an oblique joining line with respect to the vehicle body longitudinal direction. Therefore, it is easy to move the laser welding machine during welding, joining is easy, and the buckling mode can be controlled by low-cost and easy processing.

(Supplementary explanation of the embodiment)
In the above-described embodiment, when the front side member front portion 20 receives the front collision load F, the input load F1 to the inner ridge line 27 on the vehicle width direction inner side of the front side member rear portion 24 is applied to the outer side in the vehicle width direction. Although it is larger than the input load F2 to the ridge line 28, for example, in a state where the front side member front part receives a front impact load, the lower ridge line on the vehicle body lower side on the rear side of the front side member (in the vehicle front view). Even if the input load to the first ridge line on one side) is set to be larger than the input load to the upper ridge line on the upper side of the vehicle body (second ridge line on the other side in the vehicle front view). Good. In this case, for example, the joining portion of the rear end portion of the thin steel plate portion and the front end portion of the thick steel plate portion is on the vehicle body upper side (the other side) compared to the joint position on the vehicle body lower side (one side in the vehicle front view). The joining position may be the rear side in the vehicle longitudinal direction.

  Moreover, in the said embodiment, the load control means is made into the diagonal joining structure 32, and the junction part 30 of 22 A of rear end parts 22A of the thin steel plate part 22 and 26 A of front end parts of the thick steel plate part 26 is vehicle width direction inner side (vehicle front The joint position Q on the outer side in the vehicle width direction (the other side) compared to the joint position P on the one side in view is the rear side in the longitudinal direction of the vehicle body. For example, the rear end portion of the thin steel plate portion and the thick steel plate portion The front end portion of the front side member is joined to the front end of the vehicle at the same position in the vehicle longitudinal direction on the one side and the other side in the front view of the vehicle. It may be set to be low on one side, and such a structure may be applied as another load control means.

  Moreover, in the said embodiment, although the junction part 30 forms the diagonally linear joining line with respect to the vehicle body front-back direction, a junction part forms the diagonal arc-shaped joining line with respect to the vehicle body longitudinal direction, for example Alternatively, a step-like joining line may be formed.

  Furthermore, in the said embodiment, although the thin steel plate part 22 and the thick steel plate part 26 are formed with the same kind of material, for example, a normal steel plate is applied to a thin steel plate part, and a high-tensile steel plate is used for a thick steel plate part. Different types of materials may be applied to the thin steel plate portion and the thick steel plate portion, respectively.

  Furthermore, in the above embodiment, the front side member outer 18 has the same thickness over the entire length. For example, a difference thickness steel plate is applied to the front side member outer as in the case of the front side member inner. The thin steel plate portion of the front side member outer may be disposed at the front portion of the side member, and the thick steel plate portion of the front side member outer may be disposed at the rear portion of the front side member.

  In the above embodiment, the rear end portion 22A of the thin steel plate portion 22 and the front end portion 26A of the thick steel plate portion 26 are joined by welding, but the rear end portion 22A of the thin steel plate portion 22 and the thick steel plate portion 26 are connected. The front end portion 26A may be joined by other joining means.

It is a top view which shows the vehicle body front part structure which concerns on embodiment of this invention. It is a perspective view which shows the principal part of the front side member in embodiment of this invention. It is a disassembled perspective view which shows the principal part of the front side member in embodiment of this invention. It is a perspective view which shows the state which the front side member front part in embodiment of this invention deformed axially.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Car body 12 Front bumper reinforcement 20 Front side member front part 22 Thin steel plate part 22A Rear end part 24 Front side member rear part 26 Thick steel plate part 26A Front end part 27 Inner edge line (1st edge line)
28 Outside ridgeline (second ridgeline)
30 joints 32 oblique joint structure (load control means)
OUT Vehicle width direction outside P Joint position inside vehicle width direction (joint position on one side)
Q Joint position on the outside in the vehicle width direction (joint position on the other side)
W Vehicle width direction

Claims (4)

Front bumper reinforcement extending in the vehicle width direction on the front end side of the vehicle body,
A pair of left and right front side members provided with thin steel plate portions disposed along the longitudinal direction of the vehicle body on both sides of the vehicle body rear side of the front bumper reinforcement;
Left and right provided with a thick steel plate portion disposed along the vehicle front-rear direction on the rear side of the front side member front portion and joined to the rear end portion of the thin steel plate portion and thicker than the thin steel plate portion A pair of front side member rear parts,
In a state in which the front part of the front side member has received a frontal impact load, an input load to the first ridge line on one side of the rear part of the front side member in a front view of the vehicle is input to the second ridge line on the other side. A load control means for making the load larger than the load;
The vehicle body front part structure characterized by having.   The joining portion between the rear end portion of the thin steel plate portion and the front end portion of the thick steel plate portion has a joining position on the other side as a rear side in the longitudinal direction of the vehicle body as compared with a joining position on one side in a vehicle front view. The vehicle body front part structure according to claim 1.   3. The rear end portion of the thin steel plate portion and the front end portion of the thick steel plate portion are joined by welding, and the joining portion forms an oblique joining line with respect to the vehicle body longitudinal direction. Vehicle body front structure as described.   The first ridge line is a ridge line on the inner side in the vehicle width direction of the rear portion of the front side member, and the second ridge line is a ridge line on the outer side of the front side member in the vehicle width direction. The vehicle body front part structure as described in any one of these.

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