JP5104331B2 - Front side member structure - Google Patents

Description

  The present invention relates to a structure of a front side member disposed along a longitudinal direction of a vehicle body at a lower portion of a front portion of a vehicle body.

  Front side members are disposed along the vehicle front-rear direction on the left and right sides in the vehicle width direction at the lower part of the front part of the vehicle body. In such a front side member, when a load is input from the front part of the vehicle body, a bead is generally formed on the side surface of the front side member in order to absorb the energy of the load input by the front side member.

For example, a front side member structure has been proposed in which a triangular bead having a width gradually expanding in the vertical direction of the vehicle body is formed on the side surface of the front side member (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 4-126777

  However, in the above prior art, the front side member is formed in a shape matching the triangular bead, and the front end of the front side member has a tapered shape. Cannot be secured, and the rigidity of the front end portion of the front side member may be too small.

  In addition, since the front side member is formed in a shape that matches the triangular bead, the width of the front side member at the rear end of the front side member is too wide, contrary to the front side member front end, There is a problem that the front side members cannot be laid out freely.

  An object of the present invention is to maintain the rigidity of a front side member at an appropriate size in a front side member having a bead formed on a side surface, and to prevent the front side member shape from being dependent on the bead shape.

In order to solve the above problems, the present invention is, front side members are disposed in the longitudinal direction of the vehicle body, the front side member has a rectangular closed cross section, the side surfaces of the front side member, said front side member The front side member structure is formed with a bead extending continuously in the longitudinal direction of the vehicle body from the front to the rear of the vehicle, wherein the bead protrudes from the inside of the closed cross section of the front side member, and the longitudinal direction of the vehicle body. The width of the front side is large, and the width is gradually narrowed toward the rear side.

  According to the above configuration, the bead is formed so that the width of the front side of the front side member in the front-rear direction of the vehicle body is wide, and the width gradually decreases as it approaches the rear side. That is, the rigidity) is relatively small (not too small) on the front side of the front side member, and gradually increases as it approaches the rear side. When a load is input from the front of the vehicle body, The shaft is crushed sequentially from the front side, and the impact energy due to load input can be absorbed efficiently.

  According to the present invention, in the front side member having a bead formed on the side surface, the rigidity of the front side member can be maintained high, and when a load is input from the front part of the vehicle body, the impact energy by the load input is efficiently obtained. Can be absorbed.

  Further, since the width of the rear side of the front side member is not increased, the front side member shape can be prevented from depending on the bead shape.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is an external perspective view of a front side member according to the present invention. FIG. 1 shows a front side member arranged on the right side of the vehicle body, and the front side member arranged on the left side of the vehicle body is symmetrical with respect to the front side member of FIG. It has become a shape. In FIG. 1, FR indicates the vehicle body front side, IN indicates the vehicle width direction inner side, and UP indicates the vehicle body upper side.

  The front side member 1 includes a front side member inner 2 having a hat-shaped cross section and a front side member outer 3 having a hat-shaped cross section.

  The front side member inner 2 is provided with a convex portion 4 having a U-shaped cross section provided at the center in the vertical direction of the vehicle body, an upper flange portion 5 formed by bending the upper end of the convex portion 4 upward, The lower end portion of the portion 4 has a lower flange portion 6 formed by bending downward. The convex portion 4 is provided so as to protrude inward in the vehicle width direction, and is formed of a vertical wall 4A, an upper wall 4B above the vertical wall 4A, and a lower wall 4C below the vertical wall 4A.

  The front side member outer 3 is provided with a convex portion 7 having a U-shaped cross section provided at the center in the vertical direction of the vehicle body, an upper flange portion 8 formed by bending the upper end portion of the convex portion 7 upward, The lower end portion of the portion 7 has a lower flange portion 9 formed by bending downward. The convex portion 7 is provided so as to protrude outward in the vehicle width direction, and is formed of a vertical wall 7A, an upper wall 7B above the vertical wall 7A, and a lower wall 7C below the vertical wall 7A.

  The upper flange portion 5 of the front side member inner 2 and the upper flange portion 8 of the front side member outer 3 are joined to each other by spot welding or the like. Further, the lower flange portion 6 of the front side member inner 2 and the lower flange portion 9 of the front side member outer 3 are also joined to each other by spot welding or the like. Thereby, the front side member 1 forms the rectangular closed cross section.

  In the present embodiment, a bead 10 that extends continuously in the longitudinal direction of the vehicle body from the front portion to the rear portion of the front side member 1 is formed on the vertical wall 4A of the convex portion 4 of the front side member inner 2, which is the side surface of the front side member 1. Is formed. A bead 11 is formed on the vertical wall 7A of the convex portion 7 of the front side member outer 3, which is the side surface of the front side member 1, and extends continuously in the longitudinal direction of the vehicle body from the front to the rear of the front side member 1. Yes. The bead 10 and the bead 11 are formed to protrude toward the inside of the closed cross section of the front side member 1. That is, when the front side member 1 is viewed from the outside, the bead 10 is recessed in the surface of the vertical wall 4A of the front side member inner 2, and the bead 11 is the surface of the vertical wall 7A of the front side member outer 3. Observed as a dent.

  The center line L1 of the bead 10 coincides with the center line L2 of the front side member inner 2, and the bead 10 is formed symmetrically in the vehicle body vertical direction about the center line L1. Further, both end portions 10A and 10B in the vertical direction of the bead 10 are formed in a linear shape.

  The center line L3 of the bead 11 coincides with the center line L4 of the front side member outer 3, and the bead 11 is formed symmetrically with respect to the vertical direction of the vehicle body about the center line L3. Further, both end portions 11A and 11B in the vertical direction of the bead 11 are linearly formed.

  The bead 10 has a width W that is wide on the front side of the front side member inner 2 and is gradually narrowed toward the rear side. Similarly, the bead 11 is also formed so that the width W is wide at the front side of the front side member outer 3 and gradually becomes narrower as it approaches the rear side. In FIG. 1, the width W of the bead 11 is omitted, but the contour shape of the bead 11 is the same as that of the bead 10.

  The width W1 of the front end portion of the bead 10 is set to be 3% or more wider than the width W2 of the rear end portion of the bead 10. Similarly, the width (reference numeral omitted) of the front end portion of the bead 11 is set to be 3% or more wider than the width (reference numeral omitted) of the rear end portion of the bead 11.

  Next, the operation of this embodiment will be described.

  Since the width W of the beads 10 and 11 is wide on the front side of the front side member 1 and the width W of the beads 10 and 11 is gradually narrowed toward the rear side of the front side member 1, the front side member 1 The yield strength in each cross section of the front side member 1 is relatively small (not too small) on the front side of the front side member 1, and gradually increases as it approaches the rear side. The reason will be described with reference to FIGS.

  2A is a sectional view taken along the line SA-SA in FIG. 1, FIG. 3A is a sectional view taken along the line SB-SB in FIG. 1, and the section shown in FIG. The front part side is shown along the vehicle body front-back direction rather than the cross section shown to Fig.3 (a). 2B shows the distribution of the proof stress of the front side member 1 in the cross-sectional shape of FIG. 2A, and FIG. 3B shows the proof strength of the front side member 1 in the cross-sectional shape of FIG. Each distribution is shown.

  As shown in FIGS. 2B and 3B, the distribution of the proof stress in the front side member 1 is large at the upper and lower portions of the front side member 1 and is small at the center in the vertical direction. Moreover, the proof stress in the center part of the front side member 1 is comparatively small in FIG.2 (b), and larger than the case of FIG.2 (b) in FIG.3 (b).

  Therefore, it can be said that the proof stress in each cross section of the front side member 1 is relatively small (not too small) on the front side of the front side member 1 and gradually increases as it approaches the rear side.

  According to the front side member structure having the above configuration, when a load is input from the front part of the vehicle body, the shaft side is sequentially crushed from the front part side of the front side member 1, and impact energy due to the load input can be efficiently absorbed.

  Further, since the beads 10 and 11 are formed so that the width W gradually becomes narrower as they approach the rear side of the front side member 1, it is possible to avoid the width of the rear side of the front side member 1 from increasing. The layout of the front side member 1 will not be hindered.

  The front side member outer 3 may not be provided with a bead, and the front side member inner 2 may be provided with a bead 10. Conversely, the front side member inner 2 may not be provided with a bead and the front side member inner 2 may be provided with a front side member. The bead 11 may be provided only on the outer 3.

  Here, the effect of the front side member structure according to the present embodiment will be described in comparison with the conventional example.

  6 and 7 show a front side member according to a conventional example. The front side member 101 in FIG. 6 includes a front side member inner 102 having a hat-shaped cross section and a front side member outer 103 having a hat shape. However, no bead is formed along the longitudinal direction of the vehicle body on the vertical wall 102A of the front side member inner 102 or the vertical wall 103A of the front side member outer 103.

  Further, the front side member 111 shown in FIG. 7 includes a front side member inner 112 having a hat-shaped cross section and a front side member outer 113 having a hat-shaped cross section. Further, a bead is attached to the vertical wall 112A of the front side member inner 112. 114, the bead 115 is formed in the longitudinal wall 113A of the front side member outer 113 along the vehicle body front-rear direction.

  However, in the front side member 111 shown in FIG. 7, the beads 114 and 115 have a constant width W5 along the vertical direction of the vehicle body, and are wide on the front side of the front side member as in this embodiment, and on the rear side. It is not configured to gradually narrow as it approaches.

  FIG. 4 shows a comparison between the front side member (shown in FIG. 7) in which a bead having a constant width is formed and the front side member according to the present invention with respect to the absorption rate of the input load at the time of load input.

  In FIG. 4, (a) shows a case where a bead with a constant width is formed on the front side member inner and the front side member outer (shown in FIG. 7), and (b) shows on the front side of the front side member. The case where the bead which becomes narrow gradually as it approaches the rear side is formed in the front side member inner and the front side member outer is shown (shown in FIG. 1).

  (C) shows a case where a bead with a constant width is formed only on the front side member outer, and (d) shows a bead that is wide at the front side of the front side member and gradually narrows as it approaches the rear side. The case where it forms only in the side member outer is shown.

  Further, (e) shows a case where a bead having a constant width is formed only on the front side member inner, and (f) is a wide bead on the front side of the front side member, and a bead that gradually narrows as it approaches the rear side. The case where it forms only in the side member inner is shown.

  In FIG. 4, when (A) and (B) are compared, the absorption rate of the input load is higher in the case of (B) than in the case of (A). Further, when (c) and (d) are compared, the absorption rate of the input load is higher in the case of (d) than in the case of (c). Furthermore, when (e) and (f) are compared, the absorption rate of the input load is higher in the case of (f) than in the case of (e).

  Therefore, according to the front side member structure of the present invention, when a load input is applied to the front portion of the vehicle body, the input load is efficiently absorbed compared to the case where a bead having a constant width is formed as in the prior art. Is possible.

  FIG. 5 shows the reaction force generated in the entire front side member when the front side member is subjected to axial crush due to a load input at the front of the vehicle body, and the front side member of the present invention shown in FIG. This is a comparison with the conventional front side member shown in FIG. In FIG. 5, the solid line represents the data for the front side member shown in FIG. 1, the broken line represents the data for the front side member shown in FIG. 6, and the dotted line represents the data for the front side member shown in FIG. Yes.

  As can be seen from FIG. 5, the front side member structure of the present invention indicated by a solid line is compared with the conventional front side member structure indicated by a broken line or a dotted line in the latter half portion (A High reaction force can be maintained even in the case of

  According to the present embodiment, the front side member 1 has a rectangular closed cross section, and the beads 10 and 11 are formed on the front side member inner 2 and the front side member outer 3 facing each other in the closed cross section. Therefore, the front side member 1 does not bend when a load is input, and stable shaft crushing is possible.

  Further, according to the present embodiment, the center line L1 of the bead 10 and the center line L2 of the front side member inner 2 are matched, and the bead 10 is formed symmetrically in the vehicle body vertical direction about the center line L1. Further, the center line L3 of the bead 11 and the center line L4 of the front side member outer 3 coincide with each other, and the bead 11 is formed symmetrically in the vehicle body vertical direction about the center line L3. The amount of impact energy absorbed can be increased.

  In addition, according to the present embodiment, both the upper and lower end portions 10A and 10B of the bead 10 and the upper and lower end portions 11A and 11B of the bead 11 are formed in a straight line, so that the processing of the beads 10 and 11 is easy. In addition, the impact energy at the time of load input can be stably absorbed.

  Furthermore, according to the present embodiment, the bead 10 and the bead 11 are formed so as to protrude to the inside of the closed cross section of the front side member 1, so that the degree of freedom when other parts are arranged around the front side member 1. Will improve.

  8 to 10 show modifications of the bead.

In FIG. 8, a bead 20 is provided on the front side member inner 2. Although not shown in the drawing, a bead 20 is also provided on the front side member outer 3 (see FIG. 1). These beads 20 have a wide width W3 along the vertical direction of the vehicle body on the front side of the front side member, and the width W3 is gradually narrowed toward the rear side of the front side member. Further, both end portions 20 </ b> A and 20 </ b> B in the vertical direction of the bead 20 are formed in a convex arc shape inside the bead 20. The bead 20 is formed so as to protrude to the inside of the closed cross section of the front side member.
Even when configured as described above, when a load is input from the front part of the vehicle body, the shafts are sequentially crushed from the front part side of the front side member, and impact energy due to the load input can be efficiently absorbed. Further, according to the above-described configuration, the both ends 20A and 20B in the vertical direction of the bead 20 are formed in an arc shape, so that the processing of the bead 20 is easy and the impact energy at the time of load input is stably absorbed. can do.

  In FIG. 9, two beads 21 and 22 are provided on the front side member inner 2 along the vertical direction of the vehicle body. Although not shown in the figure, the front side member outer 3 (see FIG. 1) is also provided with beads 21 and 22. These beads 21 and 22 have wide widths W4 and W5 along the vertical direction of the vehicle body on the front side of the front side member, and the widths W4 and W5 are gradually narrowed toward the rear side of the front side member. And the bead 21 has the up-and-down direction both ends 21A and 21B formed linearly, and the whole has comprised the triangle, respectively. Also, the bead 22 has both end portions 22A and 22B in the vertical direction formed in a straight line, and the whole forms a triangle. The beads 21 and 22 are formed so as to protrude to the inside of the closed cross section of the front side member.

  Even when configured as described above, when a load is input from the front part of the vehicle body, the shafts are sequentially crushed from the front part side of the front side member, and impact energy due to the load input can be efficiently absorbed. Note that the number of beads is not limited to two and may be three or more. In addition, two or more beads each having an arc shape at both ends in the vertical direction shown in FIG. 8 may be provided.

In FIG. 10, a bead 23 is provided on the front side member inner 2. Although not shown in the figure, a bead 23 is also provided on the front side member outer 3 (see FIG. 1). The bead 23 has an upper side end portion including an inclined portion 23A, a horizontal portion 23B, and an inclined portion 23C, and a lower side end portion including an inclined portion 23D, a horizontal portion 23E, and an inclined portion 23F. The portions formed by the inclined portions 23A and 23D are gradually narrowed as the width W6 approaches the rear side, and the portions formed by the horizontal portions 23B and 23E have a constant width W7 (<W6). The portions formed by 23C and 23F are gradually narrowed as the width W8 (<W7) approaches the rear side. The bead 23 is formed so as to protrude to the inside of the closed cross section of the front side member .

  Even when configured as described above, when a load is input from the front part of the vehicle body, the shafts are sequentially crushed from the front part side of the front side member, and impact energy due to the load input can be efficiently absorbed.

  8 to 10, the front side member outer 3 may not be provided with beads but only the front side member inner 2 may be provided. Conversely, the front side member inner 2 may be provided with beads. Each bead may be provided only on the front side member outer 3.

  As mentioned above, although the Example of this invention has been explained in full detail with drawing, the said Example is only the illustration of this invention, and this invention is not limited only to the structure of the said Example. Needless to say, changes in design and the like within the scope of the present invention are included in the present invention.

  For example, the beads 10 and 11 shown in FIG. 1, the beads 20 shown in FIG. 8, the beads 21 and 22 shown in FIG. 9, and the beads 23 shown in FIG. 10 protrude outward from the closed cross section of the front side member. May be formed.

It is an external appearance perspective view of the front side member in this invention. (A) is sectional drawing along the SA-SA line of FIG. 1, (b) is a figure which shows distribution of the yield strength of the front side member in the sectional shape of (a). (A) is sectional drawing along the SB-SB line | wire of FIG. 1, (b) is a figure which shows distribution of the yield strength of the front side member in the sectional shape of (a). It is the figure which compared the front side member in which the bead of a fixed width | variety was formed, and the front side member by this invention about the absorption factor of the input load at the time of load input. It is the figure which compared the front side member of this invention, and the conventional front side member about the reaction force which arises in the whole front side member when there exists load input in a vehicle body front and a front side member is axially collapsed. . It is an external appearance perspective view of the front side member by a prior art example. It is an external appearance perspective view of the front side member by another prior art example. It is a figure which shows the modification of a bead. It is a figure which shows the other modification of a bead. It is a figure which shows the other modification of a bead.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Front side member 2 Front side member inner 3 Front side member outer 10, 11 Beads 10A, 10B Both ends of the upper and lower direction of the bead 10 11A, 11B Both ends of the upper and lower direction of the bead 11

Claims (7)

A front side member is arranged in the longitudinal direction of the vehicle body, the front side member has a rectangular closed cross section,
Wherein the side surface of the front side member, a front side member structure body longitudinal direction extending continuously bead is formed from the front toward the rear of the front side members,
The bead is provided to protrude to the inside of the closed cross section of the front side member, and has a wide width on the front side in the front-rear direction of the vehicle body , and is gradually narrowed toward the rear side. Front side member structure. The front side member, the front side member structure according to claim 1, wherein the bead is formed on the two surfaces facing each of the closed cross section. The center line of the bead coincides with the center line of the side surface of the front side member on which the bead is formed, and the bead is formed vertically or horizontally symmetrically about the center line of the bead. The front side member structure according to claim 1 or 2. The front side member structure according to claim 1, 2 or 3, wherein both ends of the bead in the vertical direction are linear. 4. The front side member structure according to claim 1, wherein both end portions in the vertical direction of the bead have a circular arc shape convex toward the inside of the bead. The front side member structure according to any one of claims 1 to 5, wherein a width of a front end portion of the bead is set to be 3% or more wider than a width of a rear end portion of the bead. The front side member structure according to any one of claims 1, 2, 4, 5, and 6, wherein a plurality of the beads are formed .

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