JP2008094309A - Shock absorbing structure for vehicle frame - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shock absorbing structure for a vehicle frame having excellent press moldability and a small initial impact load. <P>SOLUTION: The shock absorbing structure for the vehicle frame includes a square rod-shaped shock absorbing member 11 having a plurality of plane parts 12a, 12b extended to the longitudinal direction of the vehicle frame 1. The shock absorbing structure is provided with annular beads 13 formed over the perimeter of the shock absorbing member 11 and forming recesses 14a on the plane part 12a out of the two plane parts 12a, 12b adjacent in the circumferential direction of the shock absorbing member 11 and projections 14b on the other plane part 12b. In the shock absorbing member 11, the peripheral length of the cross sections in the beads 3 is set approximately equal to the peripheral length of a cross sections in a portion having no bead 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

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. 9, 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. 9, a large unit such as an engine is disposed on the front side in the vehicle casing 1, and suspensions having different specifications and quantities 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. 9, 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 2 and absorb impact energy at the time of a vehicle collision or the like, for example, in Patent Document 1, as shown in FIG. The shock absorbing member 21 is provided, a concave or convex wall bead 23 is provided on the flat surface portion (wall surface) 22 of the shock absorbing member 21, and two flat surface portions 22 adjacent to each other in the circumferential direction of the shock absorbing member 21 are provided. The thing which provided the concave corner bead 25 in the corner | angular part 24 to make is proposed.

  Further, in Patent Document 2, as shown in FIG. 11, a cylindrical impact absorbing member 31 is provided at the front end of the side member 2, and the two planar portions 32 of the impact absorbing member 31 facing each other are arranged on the side member 2. A first bead 33 that alternately repeats the concave portion 33a and the convex portion 33b along the longitudinal direction is provided, and is formed over the entire circumference at a position in front of the first bead 33 in the shock absorbing member 31. One of the two flat portions 32 adjacent to the first flat portion 32 has a concave line 34a, and the other flat surface portion 32 is provided with a second bead 34 forming a convex line 34b.

  According to these patent documents 1 and 2, the impact absorbing members 21 and 31 receive an impact load at the time of a vehicle collision, and the impact absorbing members 21 and 31 are sequentially crushed from the front end by the beads 23, 25, 33 and 34. By doing so, it is possible to prevent the side member 2 from being bent and to absorb impact energy at the time of a vehicle collision.

Japanese Patent Laid-Open No. 3-94137 JP-A-8-324454

  By the way, in order to press-mold the impact absorbing members 21 and 31 shown in FIGS. 10 and 11, the portions near the beads 23, 25, 33 and 34 in the impact absorbing members 21 and 31 must be locally extended. In addition, since it is necessary to use a high-grade material that has a low yield point (easily stretched) and is less likely to cause a reduction in thickness or cracking such as necking during press molding, the material cost increases. In addition, since it is impossible to use a high-strength material (high-tensile material) that is difficult to press-mold, weight reduction due to thinning is restricted.

  In addition, after the shock absorbing members 21 and 31 are press-molded, tensile stress remains in the beads 23, 25, 33, and 34 of the shock absorbing members 21 and 31, and the peripheral portions of the beads 23, 25, 33, and 34 are left. Since compression stress remains, a springback occurs in which the shape of the shock absorbing members 21 and 31 after press molding changes with respect to the shape of the mold, and the expected amount of this springback needs to be reflected in the mold. Resulting in increased mold costs. Further, since it becomes necessary to add a re-striking process for removing the stress (residual stress) remaining in the beads 23, 25, 33, 34 of the shock absorbing members 21, 31 or the periphery thereof, the cost of the molding process increases. To do.

  Further, the impact absorbing members 21 and 31 are sequentially crushed from the front end portion at the time of a vehicle collision or the like, but in the impact absorbing member 21 shown in FIG. Is not provided over the entire circumference of the shock absorbing member 21, and a portion where the beads 23 and 25 are not provided is less likely to be crushed than a portion where the beads 23 and 25 are provided. Therefore, in the impact absorbing member 21 shown in FIG. 10, the impact absorbing member 21 is prevented from being crushed by the portions where the beads 23 and 25 are not provided, and the impact absorbing member 21 is more easily crushed, thereby further increasing the initial impact load. There remains room for reduction.

  On the other hand, in the impact absorbing member 31 shown in FIG. 11, since the second bead 34 on the foremost side of the impact absorbing member 31 is provided over the entire circumference of the impact absorbing member 31, there is a portion that is not easily crushed in the circumferential direction. not exist. Therefore, although the impact absorbing member 31 shown in FIG. 11 is easily crushed and reduces the initial impact load as compared with the impact absorbing member 21 shown in FIG. 10, the spring due to the bead formability and the residual stress accompanying the bead forming described above. There remains room to improve the impact of the back.

  Accordingly, an object of the present invention is to provide a shock absorbing structure for a vehicle frame that has excellent press formability and a small initial impact load.

  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 having a plurality of flat portions extending in the front-rear direction of the vehicle frame. One of the two planar portions adjacent to the circumferential direction of the shock absorbing member that is formed over the entire circumference of the absorbing member is provided with an annular bead that forms a concave line on the other side and a convex line on the other side. In the absorbent member, the circumference of the cross section of the bead is substantially equal to the circumference of the cross section of the portion where the bead is not provided.

  Here, the shock absorbing member may be formed by joining a pair of channel members facing each other.

  Further, the bead may be one in which the depth of one concave stripe and the height of the other convex stripe are approximately equal among two plane portions adjacent to each other in the circumferential direction of the shock absorbing member.

  The bead may be such that the width of one concave stripe and the width of the other convex stripe are approximately equal to each other among two plane portions adjacent to each other in the circumferential direction of the shock absorbing member.

  In addition, a plurality of the beads are provided on the shock absorbing member at a predetermined interval in the front-rear direction of the vehicle frame, and the depth of the ridges and the height of the ridges of at least one of the plurality of beads are provided. However, it may be larger than the depth of the ridges and the height of the ridges of the other beads.

  Further, a plurality of the beads are provided on the shock absorbing member at a predetermined interval in the front-rear direction of the vehicle frame, and at least one of the plurality of beads is wider than the width of the other beads. It can be large.

  According to the present invention, it is possible to provide an excellent effect of providing a shock absorbing structure for a vehicle vehicle frame that is excellent in press moldability and has a small initial impact load.

  Hereinafter, a preferred embodiment 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 the embodiment of FIG. FIG. 3 shows an impact absorbing member according to the embodiment of FIG. 1, (a) is a plan view, (b) is a front view, and (c) is a side view. 4 is a cross-sectional view taken along the line IV-IV in FIG.

  As shown in FIG. 1, a vehicle casing 1 is arranged at a predetermined interval in the width direction, and is provided between a pair of side members 2 that extend in the front-rear direction and the side members 2, and extends in the width direction. And a cross member 3 extending to the center.

  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 flat portions 12 a and 12 b extending in the front-rear direction of the vehicle casing 1. Has been.

  The shock absorbing member 11 is provided with an annular bead 13 over the entire circumference. The bead 13 has a groove 14a on one flat surface 12a of the two flat surfaces 12a and 12b adjacent to each other in the circumferential direction of the shock absorbing member 11, and a protrusion 14b on the other flat surface 12b. In the present embodiment, the bead 13 has a ridge 14 b on the flat surface 12 b that is the upper and lower surfaces of the shock absorbing member 11, and a concave 14 a on the flat surface 12 a that is the side surface of the shock absorbing member 11. Moreover, in this embodiment, the bead 13 is formed in the cross-sectional substantially triangular shape (refer FIG. 4).

  In the present embodiment, in the impact absorbing member 11, the circumferential length of the cross section of the bead 13 is substantially equal to the circumferential length of the cross section of the flat portions 12a and 12b where the bead 13 is not provided.

  A plurality of beads 13 are provided in the shock absorbing member 11 at a predetermined interval P in the front-rear direction of the vehicle casing 1. The interval P is determined so as to obtain a desired amount of collision energy absorption in accordance with the cross-sectional shape, thickness, material, etc. of the vehicle casing 1.

  In the present embodiment, among the beads 13 provided in the front-rear direction of the vehicle casing 1, the depth D 1 of the concave stripe 14 a of the frontmost bead 13 and the height H 1 of the convex stripe 14 b are the same as those of other beads 13. It is larger than the depth D2 of the concave strip 14a and the height H2 of the convex strip 14b. In the present embodiment, the width W1 of the foremost bead 13 among the beads 13 provided in the front-rear direction of the vehicle casing 1 is larger than the width W2 of the other beads 13.

  In the present embodiment, each bead 13 includes a depth D1 (D2) of the groove 14a provided on one flat surface portion 12a of the two flat surface portions 12a and 12b adjacent to each other in the circumferential direction of the shock absorbing member 11, and the other. The height H1 (H2) of the ridges 14b provided on the flat surface portion 12b is substantially equal. Moreover, in this embodiment, each bead 13 has the width W1 (W2) of the groove 14a provided in one plane part 12a among the two plane parts 12a and 12b adjacent to the circumferential direction of the shock absorbing member 11, and the other. The width W1 (W2) of the ridge 14b provided on the flat surface portion 12b is substantially equal.

  In the present embodiment, the shock absorbing member 11 is formed by facing a pair of groove-shaped members 15 and 16 to each other and joining the flange portions of the groove-shaped members 15 and 16 by welding, rivets, bolts / nuts, or the like. .

  In the present embodiment, the web width on the inner side of one groove-shaped member 15 of the pair of groove-shaped members 15 and 16 is substantially equal to the web width on the outer side of the other groove-shaped member 16. One channel member 15 is superimposed on the outside of the other channel member 16.

  Next, a manufacturing method of the groove-shaped members 15 and 16 constituting the shock absorbing member 11 according to the present embodiment will be described with reference to FIG.

  As shown in FIG. 5, in this embodiment, the groove-shaped members 15 and 16 constituting the impact absorbing member 11 are formed by press-molding a metal plate 17, and the circumferential length of the cross-section of the bead 13 is a cross-section before press-molding. Is substantially equal to the circumferential length (the width of the metal plate 17). That is, the groove-shaped members 15 and 16 constituting the shock absorbing member 11 are not accompanied by local expansion / contraction deformation of the material when the beads 13 are formed by press molding.

  Specifically, as shown in FIG. 5 (a), the metal plate 17 is folded in a valley fold at a portion indicated by a broken line in the drawing, and is folded in a mountain fold at a portion indicated by a solid line as shown in FIG. 5 (b). In addition, a concave strip 14a is formed at a portion where the metal plate 17 (groove members 15, 16) is folded into a valley fold, and a convex strip 14b is formed at a portion where the metal plate 17 (groove members 15, 16) is folded into a mountain fold. An eggplant bead 13 is formed.

  Next, the operation of this embodiment will be described.

  When an impact load L (see FIG. 2) acts on the shock absorbing member 11 from the front to the rear in the front-rear direction of the vehicle frame 1 via a bumper (not shown) or the like, first, the shock absorbing member 11 The portion of the bead 13 on the front side is crushed toward the rear in the front-rear direction of the vehicle casing 1. Of the beads 13 provided in the front-rear direction of the vehicle casing 1, the depth D1 of the concave strip 14a of the frontmost bead 13 and the height H1 and the width W1 of the convex strip 14b are concave portions of the other beads 13, respectively. Since the depth D2 of the strip 14a and the height H2 and the width W2 of the convex strip 14b are larger, the foremost bead 13 portion of the shock absorbing member 11 is more easily crushed than other portions, and shock absorption. The location of the member 11 where the collapse starts can be controlled.

  The frontmost bead 13 portion of the shock absorbing member 11 is deformed so that the width W1 is reduced by crushing, and the depth H1 of the concave strip 14a and the height H1 of the convex strip 14b are larger.

  Here, in this embodiment, the foremost bead 13 that triggers the start of crushing is provided over the entire circumference of the shock absorbing member 11, and two planes adjacent to the circumferential direction of the shock absorbing member 11. Of the portions 12a and 12b, one flat surface portion 12a has a concave strip 14a, and the other flat surface portion 12b has a convex strip 14b. Therefore, the impact absorbing member 11 can be easily crushed by the bead 13, and the initial impact The load can be effectively reduced.

  Further, when forming the beads 13 by press molding, the impact members 11 and 16 constituting the impact absorbing member 11 can be molded without causing local expansion / contraction deformation of the material. Since the absorbing member 11 (the groove-shaped members 15 and 16) can be easily deformed, the impact absorbing member 11 can be easily crushed by the bead 13, and the initial impact load can be effectively reduced.

  If the frontmost bead 13 portion in the shock absorbing member 11 is crushed in this way, then the flat portions 12a and 12b behind the frontmost bead 13 in the shock absorbing member 11 and other parts The portion of the bead 13 is crushed sequentially. The shock absorbing member 11 as a whole is crushed in a bellows shape starting from the foremost bead 13 toward the rear.

  The other bead 13 has a depth D2 of the concave stripe 14a, a height H2 of the convex stripe 14b, and a width W2 of the depth D1 of the concave stripe 14a and the height H1 of the convex stripe 14b, respectively. Since the width of the bead 13 is smaller than the width W1, the other bead 13 portion of the shock absorbing member 11 is less likely to be crushed than the frontmost bead 13 portion. The bead 13 is easily crushed due to the crushed effect.

  That is, the portion of the other bead 13 that is crushed after the second is formed by appropriately reducing the depth H2 of the concave stripe 14a and the height H2 and width W2 of the convex stripe 14b, so that Since the influence of the deformation of the bead 13 can be minimized and an excessive decrease in deformation resistance can be suppressed, it is possible to effectively absorb the impact energy.

  The other bead 13 is formed on the side of the vehicle frame 1 by providing the bead 13 by appropriately reducing the depth D2 of the recess 14a and the height H2 and width W2 of the protrusion 14b. The increase in the length of the member 2 and the interference with the cross member 3 and brackets (not shown) attached to the side member 2 can be minimized.

  The result of having performed the simulation about the impact absorption structure 10 which concerns on this embodiment is shown in FIG. In the load-stroke diagram shown in FIG. 6, the vertical axis is the load (impact load), the horizontal axis is the stroke (crush amount), and the area enclosed by the curve and the horizontal axis is the amount of shock energy absorbed. It corresponds to. As a result of the simulation, it was found that the initial impact load is reduced to about one-third as compared with an impact absorbing member not provided with a bead.

  By the way, in this embodiment, each groove-shaped member 15 and 16 which comprises the impact-absorbing member 11 press-molds the metal plate 17, and the circumference of the cross section in the bead 13 is the circumference of the cross section before press molding. It is almost equal. Therefore, when the groove-shaped members 15 and 16 constituting the impact absorbing member 11 are press-molded, there is no local expansion and contraction of the material.

  Therefore, according to the present embodiment, it is not necessary to use a high-grade material having a low yield point (easily stretched) because it is difficult to reduce thickness and crack such as necking during press molding, and it is possible to reduce material costs. It becomes. 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 can be improved without increasing the weight. Is 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.

  Further, if there is a local expansion / contraction deformation of the material at the time of press molding, the end portions of the channel members 15 and 16 are uneven, and the trim cut that trims the end portions of the channel members 15 and 16 after press molding is performed. Where it is necessary to add a stroke, in this embodiment, since it is difficult for variations to occur at the ends of the groove-shaped members 15 and 16 during press molding, there is no need to add a trim stroke after press molding. The yield can be improved and the material cost can be reduced.

  Further, since there is no local material expansion / contraction deformation during the press molding of the respective groove-shaped members 15 and 16 constituting the shock absorbing member 11, no stress remains in the bead 13 or its peripheral portion. Suppression of crushing due to stress is avoided.

  In short, according to the present embodiment, it is possible to provide the shock absorbing structure 10 for the vehicle casing 1 that has excellent press formability and a small initial impact load.

  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, in the above-described embodiment, the bead 13 is formed in a substantially triangular cross section. However, the present invention is not limited to this, and the bead 13 has a substantially trapezoidal cross section as shown in FIG. As shown in FIG. 7B, the bead 13 may be formed in a substantially semicircular cross section.

  Further, in the above-described embodiment, the bead 13 has the concave strip 14a on the side surface of the shock absorbing member 11 and the convex strip 14b on the top and bottom surfaces. Contrary to the above-described embodiment, all or part of the beads 13 provided in the front-rear direction of 1 have concave ridges 14a on the upper and lower surfaces of the shock absorbing member 11, and convex ridges 14b on the side surfaces. May be.

  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 15 and 16 having different web widths. However, the present invention is not limited to this, and as shown in FIG. In addition, the shock absorbing member 11 may be formed by overlapping a pair of groove-shaped members 15 and 16 having the same web width. As shown in FIG. 8B, the shock absorbing member 11 has a pair of web widths equal to each other. The groove-shaped members 15 and 16 may be abutted against each other, and the shock absorbing member 11 may be composed of one cylindrical member 18 as shown in FIG.

  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 embodiment of FIG. The impact-absorbing member which concerns on embodiment of FIG. 1 is shown, (a) is a top view, (b) is a front view, (c) is a side view. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. It is the schematic which shows an example of the procedure of press molding, (a) shows the expansion | deployment shape of a metal plate, (b) shows the shaping | molding shape of a metal plate. It is a load-stroke diagram. (A) And (b) is a fragmentary sectional view of the impact-absorbing member which concerns on a modification. (A) to (c) is a front view of an impact absorbing member according to a modification. It is a perspective view of the conventional vehicle frame. It is a perspective view of the conventional impact-absorbing member. It is a perspective view of the conventional impact-absorbing member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle frame 10 Shock absorption structure 11 Shock absorption member 12a, 12b Planar part 13 Bead 14a Concave strip 14b Convex strip 15 Groove member 16 Groove member

Claims (6)

  A shock absorbing structure for a vehicle frame including a square tube-shaped shock absorbing member having a plurality of flat portions extending in the front-rear direction of the vehicle frame, and formed over the entire circumference of the shock absorbing member, In addition, one of the two planar portions adjacent to the circumferential direction of the shock absorbing member is provided with an annular bead that forms a ridge on the one hand and a ridge on the other, and the shock absorbing member has a circumferential length of a cross section of the bead. Is substantially equal to the circumferential length of the cross section of the portion where the bead is not provided.   The shock absorbing structure for a vehicle frame according to claim 1, wherein the shock absorbing member is formed by joining a pair of groove-shaped members facing each other.   3. The vehicle frame according to claim 1, wherein the bead has a depth of one of the two planar portions adjacent to each other in a circumferential direction of the shock absorbing member and a height of the other convex is substantially equal. Shock absorbing structure.   4. The vehicle according to claim 1, wherein, in the bead, the width of one concave stripe and the width of the other convex stripe are approximately equal to each other among two plane portions adjacent to each other in the circumferential direction of the shock absorbing member. Shock absorption structure of the car frame.   A plurality of the beads are provided on the shock absorbing member at a predetermined interval in the front-rear direction of the vehicle frame, and the depth of the concave stripe and the height of the convex stripe of at least one of the plurality of beads are provided. The shock absorbing structure for a vehicle vehicle frame according to any one of claims 1 to 4, wherein the shock absorbing structure is larger than the depth of the ridges and the height of the ridges of the other beads.   A plurality of the beads are provided on the shock absorbing member at a predetermined interval in the front-rear direction of the vehicle frame, and at least one of the plurality of beads is wider than the width of the other beads. Item 6. The vehicle body frame shock absorbing structure according to any one of Items 1 to 5.

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