JP4927516B2 - Shock absorption structure for vehicle frame - Google Patents

Description

  The present invention relates to an impact absorbing structure for a vehicle frame for absorbing impact energy generated during a vehicle collision or the like.

  For example, as shown in FIG. 14, the vehicle casing 1 includes a pair of side members 2 disposed at a predetermined interval in the width direction, and a cross member 3 provided between the side members 2. In the vehicle casing 1 shown in FIG. 14, a large unit such as an engine is disposed on the front side in the vehicle casing 1, and suspensions having different specifications, quantities, etc. are provided on the front side and the rear side outside the vehicle casing 1. Since the wheels and the like are arranged and the vehicle casing 1 is sandwiched between the vehicle body and the axle from the top and bottom, the side member 2 has a changing portion that is bent in the width direction or the vertical direction of the vehicle casing 1. . Therefore, in the vehicle casing 1 shown in FIG. 14, when an impact load is applied to the side member 2 via a bumper or the like, the side member 2 is bent at the changing portion.

  In order to prevent such bending deformation at the changing portion of the side member and absorb impact energy at the time of a vehicle collision or the like, for example, in Patent Document 1, a cylindrical impact absorbing member is provided at the front end portion of the side member. There has been proposed a structure in which a concave or convex wall bead is provided on the wall surface of the shock absorbing member and a concave square bead is provided at a corner formed by two wall surfaces adjacent to each other in the circumferential direction of the shock absorbing member.

  According to Patent Document 1, the impact absorbing member receives an impact load at the time of a vehicle collision, and the impact absorbing member is sequentially crushed from the front end portion by the bead, thereby preventing the side member from being bent, and at the time of the vehicle collision. Can be absorbed.

  By the way, in order to mold the bead described in Patent Document 1, a portion in the vicinity of the bead in the impact absorbing member must be locally stretched, the yield point is low (easily stretched), and necking or the like is performed during press molding. Material costs increase because it is necessary to use high-grade materials that are less likely to cause thickness reduction and cracking. Moreover, since it is not possible to use a high-strength material (high-tensile material) that is difficult to mold, weight reduction due to thinning is restricted.

Japanese Patent Laid-Open No. 3-94137

  The present applicant has previously filed an application for a shock absorbing structure 20 for a vehicle frame as shown in FIGS. 12 and 13 (Japanese Patent Application No. 2006-280149).

  As shown in FIGS. 12 and 13, the shock absorbing structure 20 includes a shock absorbing member 21 provided at the front end portion of the side member 2 of the vehicle casing 1. The shock absorbing member 21 is formed in a rectangular tube shape having a plurality (four in the illustrated example) of outer surface portions 22a and 22b extending in the front-rear direction of the vehicle casing 1.

  The shock absorbing member 21 is provided with an annular bead 23 over the entire circumference. Of the two outer surface portions 22a and 22b adjacent to each other in the circumferential direction of the shock absorbing member 21, the bead 23 has a recess 24a on one outer surface portion 22a, and a protrusion 24b on the other outer surface portion 22b. In the shock absorbing member 21, the circumferential length of the cross section of the bead 23 is substantially equal to the circumferential length of the cross section of the outer surface portions 22a and 22b where the bead 23 is not provided.

  According to the shock absorbing member 21, there is no local material expansion / contraction deformation during the press molding of the shock absorbing member 21 (channel members 25, 26), and a reduction in thickness or cracking such as necking occurs during the press molding. Therefore, it is not necessary to use a high-grade material having a low yield point (easily stretched), and the material cost can be reduced. In addition, a high-strength material (high-tensile material) can be used, and it is possible to reduce the weight by reducing the thickness. If the thickness is not reduced, the amount of impact energy absorbed is increased without increasing the weight. It becomes possible.

  In the meantime, in the impact absorbing member 21 shown in FIGS. 12 and 13, the impact absorbing member 21 has the effect of reducing the initial impact load by buckling the impact absorbing member 21 with the bead 23 as a base point of buckling. There is still room to increase.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a shock absorbing structure for a vehicle frame that has high impact energy absorption efficiency.

In order to achieve the above object, the present invention provides a shock absorbing structure for a vehicle frame including a rectangular tube-shaped shock absorbing member extending in the front-rear direction of the vehicle frame, and is provided on an outer surface portion of the shock absorbing member. In the shock absorbing structure for a vehicle frame, in which a plurality of projecting surface portions each having an arcuate longitudinal section projecting outward from the shock absorbing member are provided in the longitudinal direction of the shock absorbing member, the circumferential direction of the shock absorbing member The circumferential length of the cross section of the overhanging surface portion of the shock absorbing member is equal to the circumferential length of the cross section of the node between the overhanging surface portions adjacent to the longitudinal direction of the shock absorbing member. In order to be equal, a concave surface portion having a circular cross section that is recessed inside the shock absorbing member is provided .

  According to the present invention, it is possible to provide an excellent effect that it is possible to provide an impact absorbing structure with high impact energy absorption efficiency.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a perspective view of a vehicle frame to which an impact absorbing structure according to an embodiment of the present invention is applied. FIG. 2 is a perspective view of an impact absorbing member according to an embodiment of the present invention. FIG. 3: shows the impact-absorbing member which concerns on one Embodiment of this invention, (a) is a top view, (b) is a front view, (c) is a side view. 4A is a sectional view taken along the line IVa-IVa in FIG. 3C, and FIG. 4B is a sectional view taken along the line IVb-IVb in FIG.

  As shown in FIG. 1, the shock absorbing structure 10 according to the present embodiment includes a shock absorbing member 11 provided at the front end portion of the side member 2 of the vehicle casing 1. The impact absorbing member 11 receives an impact load at the time of a vehicle collision or the like and is crushed by the impact load. In the present embodiment, the shock absorbing member 11 is provided integrally with the side member 2.

  As shown in FIGS. 2 and 3, the shock absorbing member 11 is formed in a rectangular tube shape having a plurality (four in this embodiment) of outer surface portions 12 a extending in the front-rear direction of the vehicle casing 1. Yes.

  On the outer surface portion 12 a of the shock absorbing member 11, a projecting surface portion 13 having a substantially arched vertical cross section (see FIGS. 3A and 3C) projecting outside the shock absorbing member 11 is provided. A plurality of (three in the present embodiment) are continuously provided in the longitudinal direction (the longitudinal direction of the vehicle casing 1). The number of the projecting surface portions 13 provided continuously in the longitudinal direction of the shock absorbing member 11 is determined so as to obtain a desired amount of collision energy absorption according to the cross-sectional shape, thickness, material, etc. of the vehicle casing 1. Is done.

  Each overhanging surface portion 13 is provided on the impact absorbing member 11 with a predetermined length L in the longitudinal direction (the longitudinal direction of the vehicle casing 1). The length L is determined so as to obtain a desired amount of collision energy absorption according to the cross-sectional shape, thickness, material, and the like of the vehicle casing 1.

  In the present embodiment, the corner portion 12 b formed by the overhanging surface portion 13 adjacent in the circumferential direction of the shock absorbing member 11 has a circumferential length of the cross section of the overhanging surface portion 13 between the overhanging surface portions 13 adjacent in the longitudinal direction of the shock absorbing member 11. The longitudinal section of the shock absorbing member 11 is substantially arcuate (FIGS. 3A and 3C) so as to be substantially equal to the circumferential length of the cross section at other portions such as the node 14 and the end of the The concave surface portion 15 is provided.

  That is, in the present embodiment, the shock absorbing member 11 has substantially the same circumferential length in the cross section of the projecting surface portion 13 and the concave surface portion 15 and the circumferential length of the cross section in other portions such as the node portion 14 and the end portion. (See FIG. 4).

  In the present embodiment, the shock absorbing member 11 has a substantially octagonal cross section connecting the center of the overhanging surface portion 13 and the center of the concave surface portion 15 (see FIG. 4B). The surface has a substantially rectangular shape (see FIG. 4A).

  Further, by forming the corner 12b to be recessed inside the shock absorbing member 11, two ridge lines of the corner 12b are formed in the circumferential direction of the shock absorbing member 11, and the ridge line of the corner 12b is It is formed in a substantially chain shape (or ∞ shape).

  In the present embodiment, all the heights H of the projecting surface portions 13 provided continuously in the longitudinal direction of the shock absorbing member 11 (the longitudinal direction of the vehicle casing 1) are substantially equal. The height H is determined according to the cross-sectional shape, thickness, material, etc. of the vehicle casing 1 so that a desired amount of collision energy absorption can be obtained.

  In this embodiment, the shock absorbing member 11 is formed by facing a pair of channel members 16 and 17 to each other and joining the flange portions of the channel members 16 and 17 by welding, rivets, bolts, nuts, or the like. .

  In the present embodiment, the web width on the inner side of one groove-shaped member 16 of the pair of groove-shaped members 16, 17 is substantially equal to the web width on the outer side of the other groove-shaped member 17. One channel member 16 is superimposed on the outside of the other channel member 17.

  Here, in this embodiment, the groove-shaped members 16 and 17 constituting the impact absorbing member 11 are formed by press-molding a metal plate, and the circumferential lengths of the cross sections of the overhanging surface portion 13 and the concave surface portion 15 are the same as those before the press-molding. It is substantially equal to the circumferential length of the cross section (the width of the metal plate). That is, the groove-shaped members 16 and 17 constituting the shock absorbing member 11 are not accompanied by local expansion / contraction deformation of the material during press molding.

  Next, the operation of this embodiment will be described.

  When an impact load F (see FIG. 2) acts on the impact absorbing member 11 from the front to the rear in the front-rear direction of the vehicle casing 1 via a bumper (not shown) or the like, first, the impact absorbing member 11 The portions of the protruding surface portion 13 and the concave surface portion 15 on the rear side are crushed toward the rear in the front-rear direction of the vehicle casing 1. The portion of the projecting surface portion 13 (and the concave surface portion 15) on the rearmost side in the shock absorbing member 11 is deformed so that the length L decreases and the height H increases due to crushing.

  If the portions of the rearmost projecting surface portion 13 and the concave surface portion 15 in the shock absorbing member 11 are crushed, then the front projecting surface portion 13 (and the concave surface portion 15 of the rearmost projecting surface portion 13 in the shock absorbing member 11). ) Is crushed sequentially. As a whole, the shock absorbing member 11 is crushed in a bellows shape toward the front sequentially from the rearmost protruding surface portion 13 as a base point.

  Here, in the conventional side member 2 as shown in FIG. 14, when the side member 2 undergoes buckling deformation at the time of a vehicle collision or the like, as shown in FIG. When one (upper and lower surfaces in the illustrated example) bulges outward, the other (left and right side surfaces in the illustrated example) dents toward the inner side with less deformation resistance. Therefore, during the buckling of the side member 2, the sectional area and the section modulus are reduced.

  On the other hand, in the present embodiment, each of the outer surface portions 12a of the shock absorbing member 11 is provided with a projecting surface portion 13 having a substantially arched longitudinal section projecting to the outside of the shock absorbing member 11. In other words, in the present embodiment, all the upper and lower surfaces and the left and right side surfaces (the overhanging surface portion 13) except for the corner portion 12b of the shock absorbing member 11 are expected to bulge outward, so that the shock absorbing member 11 collides with the vehicle. When buckling deformation occurs at times or the like, as shown in FIG. 11B, all of the upper and lower surfaces and the left and right side surfaces (the overhanging surface portion 13) excluding the corner portion 12b bulge outward, and the shock absorbing member 11 as a whole. Is deformed so as to generate a transverse section circumferential length difference (deformation resistance), so that the cross-sectional area and the section modulus do not decrease in the overhanging surface portion 13 during buckling of the shock absorbing member 11. Therefore, according to the present embodiment, it is possible to improve the absorption efficiency of impact energy by crushing the impact absorbing member 11 with appropriate deformation resistance.

  Further, by providing a plurality of overhanging surface portions 13 in the longitudinal direction of the shock absorbing member 11, the overhanging surface portions 13 are sequentially crushed, and buckling due to plastic buckling such as load loss during buckling of the shock absorbing member 11. It is possible to increase the impact energy absorption efficiency by suppressing a decrease in load (yield strength).

  Next, another embodiment will be described.

  FIG. 6 is a perspective view of a vehicle frame to which an impact absorbing structure according to another embodiment is applied. FIG. 7 is a perspective view of an impact absorbing member according to another embodiment. FIG. 8 shows an impact absorbing member according to another embodiment, wherein (a) is a plan view, (b) is a front view, and (c) is a side view. 9A is a cross-sectional view taken along line IXa-IXa in FIG. 8C, and FIG. 9B is a cross-sectional view taken along line IXb-IXb in FIG. 8C.

  The same components as those in the embodiment of FIG.

  On the outer surface portion 12 a of the shock absorbing member 11, a projecting surface portion 13 having a substantially arched shape (see FIGS. 8A and 8C) projecting outside the shock absorbing member 11 is provided. Are continuously provided in the longitudinal direction (the front-rear direction of the vehicle casing 1).

  In the embodiment of FIG. 1, the end of the shock absorbing member 11 is formed in a substantially square shape in cross section, but in the embodiment of FIG. 6, the end of the shock absorbing member 11 is formed in a substantially octagonal shape in cross section. ing.

  According to this embodiment, the same effect as that of the embodiment of FIG. 1 can be obtained.

  By the way, in the above-mentioned embodiment, each groove-shaped member 16 and 17 which comprises the impact-absorbing member 11 press-molds a metal plate, and the circumferential length of the cross section in the overhang | projection surface part 13 and the concave surface part 15 is before press molding. Is substantially equal to the circumferential length of the cross section. Therefore, when the channel-shaped members 16 and 17 constituting the shock absorbing member 11 are press-molded, there is no local material expansion / contraction deformation.

  Therefore, according to the above-described embodiment, it is not necessary to use a high-grade material having a low yield point (easily stretched), because it is difficult to cause a reduction in thickness or cracking such as necking during press molding, thereby reducing material costs. It becomes possible. In addition, a high-strength material (high-tensile material) can be used, and it is possible to reduce the weight by reducing the thickness. If the thickness is not reduced, the amount of impact energy absorbed is increased without increasing the weight. It becomes possible.

  Moreover, since the spring back at the time of press molding can be suppressed to a very small amount, it is not necessary to reflect the expected amount of spring back on the mold, and the mold cost can be reduced. In addition, it is not necessary to add a restorative process after press molding, and the molding processing cost can be reduced.

  In addition, if there is a local expansion / contraction deformation of the material during press molding, the end portions of the channel members 16, 17 will vary, and the trim cut that trims the ends of the channel members 16, 17 after press molding will occur. Where it is necessary to add a process, in the above-described embodiment, it is difficult for the end portions of the groove-shaped members 16 and 17 to occur during press molding, so there is no need to add a trim process after press molding, It is possible to improve material yield and reduce material cost.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and various other embodiments can be adopted.

  For example, only a specific overhanging surface portion 13 among the overhanging surface portions 13 provided in the front-rear direction of the vehicle casing 1 may have a height H higher than that of the other overhanging surface portions 13. By doing so, it is possible to reduce the initial impact load and control the location where the impact absorbing member 11 starts to collapse. The other overhanging surface portion 13 in the shock absorbing member 11 is less likely to be crushed than the specific overhanging surface portion 13, but the other overhanging surface portion 13 is easily crushed due to the collapse of the specific overhanging surface portion 13. That is, the other overhanging surface portion 13 that is crushed after the second is made to have a moderately small height H, thereby minimizing the influence of the deformation of the specific overhanging surface portion 13 that has been crushed earlier, Since an excessive decrease in deformation resistance can be suppressed, impact energy can be effectively absorbed.

  In the above-described embodiment, the shock absorbing member 11 is provided integrally with the side member 2 of the vehicle casing 1. However, the present invention is not limited to this, and the shock absorbing member 11 is attached to the side of the vehicle casing 1. It may be formed separately from the member 2 and attached to the side member 2 by welding, rivets or bolts / nuts. In this case, the method of forming the impact absorbing member 11 is not limited to press forming, and roll forming, hydroforming, or the like can be applied.

  In the above-described embodiment, the shock absorbing member 11 is formed by superposing a pair of groove-shaped members 16 and 17 having different web widths. However, the present invention is not limited to this, and FIGS. As shown in (a), the impact absorbing member 11 may be formed by stacking a pair of channel-shaped members 16 and 17 having the same web width, as shown in FIGS. 5 (b) and 10 (b), The shock absorbing member 11 may be formed by abutting a pair of channel-shaped members 16 and 17 having the same web width. As shown in FIGS. It may consist of the cylindrical member 18.

  Furthermore, in the above-described embodiment, the shock absorbing member 11 is provided at the front end portion of the side member 2 of the vehicle casing 1. However, the present invention is not limited to this, and the shock absorbing member 11 is provided on the vehicle casing 1. You may provide in the rear-end part of the side member 2. FIG.

1 is a perspective view of a vehicle frame to which a shock absorbing structure according to an embodiment of the present invention is applied. It is a perspective view of the impact-absorbing member which concerns on one Embodiment of this invention. The impact-absorbing member which concerns on one Embodiment of this invention is shown, (a) is a top view, (b) is a front view, (c) is a side view. (A) is the IVa-IVa arrow directional cross-sectional view of FIG.3 (c), (b) is the IVb-IVba arrow directional cross-sectional view of FIG.3 (c). (A) to (c) is a front view of an impact absorbing member according to a modification. It is a perspective view of the vehicle frame which applied the impact-absorbing structure which concerns on other embodiment. It is a perspective view of the impact-absorbing member which concerns on other embodiment. The impact-absorbing member which concerns on other embodiment is shown, (a) is a top view, (b) is a front view, (c) is a side view. (A) is the IXa-IXa arrow directional cross-sectional view of FIG.8 (c), (b) is the IXb-IXb arrow directional cross-sectional view of FIG.8 (c). (A) to (c) is a front view of an impact absorbing member according to a modification. It is a figure for demonstrating the deformation | transformation state at the time of impact load input. It is a perspective view of a vehicle frame. It is a perspective view of an impact-absorbing member. It is a perspective view of the conventional vehicle frame.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle frame 10 Shock absorption structure 11 Shock absorption member 12a Outer surface part 12b Corner | angular part 13 Overhang | projection surface part 15 Concave surface part

Claims (1)

A shock absorbing structure for a vehicle frame including a rectangular tube-shaped shock absorbing member extending in the front-rear direction of the vehicle frame, and projecting outward of the shock absorbing member on an outer surface portion of the shock absorbing member, respectively. In the shock absorbing structure for a vehicle frame provided with a plurality of arc- shaped projecting surface portions in the longitudinal direction of the shock absorbing member .
In the corner portion formed by the projecting surface portion adjacent to the circumferential direction of the shock absorbing member, the circumferential length of the cross section of the projecting surface portion of the shock absorbing member is a node between the projecting surface portions adjacent to the longitudinal direction of the shock absorbing member. A shock absorbing structure for a vehicle vehicle frame, wherein a concave surface portion having a circular cross section that is recessed inside the shock absorbing member is provided so as to be equal to a circumferential length of the cross section .

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