JP5092680B2 - Body front structure - Google Patents

Description

  The present invention relates to a vehicle body front structure for fixing left and right end portions of a front bumper reinforcement to front end portions of left and right front side members of a vehicle body.

  In order to absorb and mitigate the impact of a frontal collision of an automobile body, the left and right end portions of the front bumper reinforcement of the vehicle body are generally fixed to the front end portions of the left and right front side members via impact absorbers. .

  As this type of vehicle body front structure, for example, in Patent Document 1, the rear end of the tubular body (impact absorber) 16 of the bumper stay 12 is connected to the front end of the side member (front side member) 10 via the rear side mounting plate 18. A structure is disclosed in which the left and right ends of the bumper reinforcement front bumper reinforcement) 14 are fixed to the front end portion of the cylindrical main body (impact absorber) 16 via the front side mounting plate 20. .

Here, the front-side mounting plate 20 includes a strut 28 extending obliquely rearward inward in the vehicle width direction from an extended portion of the bumper reinforcement (front bumper reinforcement) 14 extending toward the bent end portion 14-2. The rear end portion of the strut 28 is welded to the rear end portion of the cylindrical main body (impact absorber) 16.
Japanese Patent Laying-Open No. 2003-48498 (paragraph 0021, paragraph 0023, FIG. 1)

  By the way, in the vehicle body front part structure described in Patent Document 1, when a frontal collision load of the vehicle body is input to the bent end portion 14-2 side of the bumper reinforcement 14, the collision load is applied to the bumper stay 12 via the strut 28. Since this is transmitted to the rear end portion of the cylindrical main body 16, the cylindrical main body 16 that is an impact absorber is not sufficiently crushed and the impact of the frontal collision may not be sufficiently absorbed.

  On the other hand, when the longitudinal length of the cylindrical main body 16 is longer than the cross-sectional width, when the frontal collision load of the vehicle body is transmitted from the bumper reinforcement 14 to the front end portion of the cylindrical main body 16, Lateral bending may occur, and there is a risk that the impact of the frontal collision will not be sufficiently absorbed due to the occurrence of crushing residue in the cylindrical body 16 that is an impact absorber.

  Therefore, an object of the present invention is to provide a vehicle body front structure that can sufficiently and reliably absorb an impact at the time of a frontal collision of a vehicle body.

A vehicle body front structure according to the present invention is a vehicle body front structure for fixing left and right ends of a front bumper reinforcement to front ends of left and right front side members of a vehicle body. Left and right square cylindrical shock absorbers with a front end fixed to the end and a rear end fixed to the front ends of the left and right front side members, and a rear end on the outer periphery of the middle portion in the front-rear direction of the shock absorber There is fixed, the front end portion is provided with a left and right of the square hollow horn-shaped front bumper support that is fixed to the left and right ends of the front bumper reinforcement, front bumper support, the front end from the rear end It is set to the shape which a width | variety spreads at least in the vehicle width direction toward it.

  Here, at the left and right ends of the front bumper reinforcement, at least the front end of the front bumper support that is widened inward in the vehicle width direction is fixed, and the support points of the front bumper reinforcement by the left and right front bumper supports The distance is short. As a result, the bending moment acting on the front bumper reinforcement due to the frontal collision load of the vehicle body decreases, and the bending strength in the front-rear direction of the front bumper reinforcement increases accordingly.

  On the other hand, since the rear end of the front bumper support is fixed to the middle part of the shock absorber in the front-rear direction, the buckling strength of the shock absorber is compared with that of the front half stiffened by the front bumper support. The strength of the latter half is low. The front and rear length of the shock absorber is substantially halved to the front and rear length of the latter portion having low strength.

  Therefore, in the vehicle body front structure according to the present invention, when a collision load is input to the front bumper reinforcement in the case of a frontal collision of the vehicle body, the shock absorption from the front bumper reinforcement whose bending strength in the front-rear direction is increased. The collision load is sufficiently and reliably transmitted to the front end portion of the body, and the collision load is sufficiently and reliably transmitted from the front bumper reinforcement through the front bumper support to the middle portion in the front-rear direction of the shock absorber. As a result, the shock absorber starts crushing sufficiently and reliably in the axial direction in a stable state from the low-strength second half whose longitudinal length is halved, and then the front half is also crushing in the axial direction sufficiently and reliably. To do. Thus, the impact at the time of the frontal collision of the vehicle body is sufficiently and reliably absorbed by the impact absorber.

  According to the vehicle body front structure according to the present invention, in the event of a frontal collision of the vehicle body, the collision load is sufficiently and reliably transmitted from the front bumper reinforcement to the front end of the shock absorber, and from the front bumper reinforcement to the front. It is sufficiently and reliably transmitted to the middle part in the front-rear direction of the shock absorber via the bumper support. Then, crushing in the axial direction is sufficiently and surely started in a stable state in the second half of the shock absorber, and then the front half of the shock absorber is also crushed in the axial direction sufficiently and reliably. The impact at that time can be sufficiently and reliably absorbed by the sufficient and reliable crushing of the impact absorber, and the impact can be sufficiently and reliably mitigated.

  Hereinafter, the best embodiment of a vehicle body front structure according to the present invention will be described with reference to the drawings. In the drawings to be referred to, FIG. 1 is a plan view schematically showing a vehicle body front part structure according to one embodiment, and FIG. 2 is a partially enlarged perspective view of the right vehicle body front part structure shown in FIG.

  The vehicle body front structure according to the embodiment is a structure for fixing the left and right end portions of the front bumper reinforcement 2 to the front end portions of a pair of left and right front side members 1 and 1 as shown in FIG. A pair of left and right crash boxes 3 and 3 and a pair of left and right front bumper supports 4 and 4 are provided.

  The front side members 1 and 1 are extended along the front-rear direction of the vehicle body, and connecting flanges 1A and 1A are fixed to the front end portions thereof. On the other hand, the front bumper reinforcement 2 has round corners 2A and 2A whose left and right end portions are slightly curved toward the rear side of the vehicle body, and connection base portions 2B and 2B are provided on the rear side of the round corners 2A and 2A. Is formed.

  The crash boxes 3 and 3 constitute a shock absorber that absorbs the collision energy at the time of a frontal collision of the vehicle body and relaxes the shock, and is formed in, for example, a rectangular tube shape that can buckle and deform in the axial direction. . In the crash boxes 3 and 3, the connecting flanges 3A and 3A formed at the front end are connected to the rear side of the round corners 2A and 2A of the front bumper reinforcement 2 in a state where the axial direction is along the longitudinal direction of the vehicle body. The connection flanges 3B and 3B formed at the rear end portion are fixed to the base portions 2B and 2B, and are fixed to the connection flanges 1A and 1A at the front end portions of the front side members 3 and 3, respectively.

  Notches 3C and recesses 3D that induce buckling deformation are formed on the peripheral surface of the crash box 3 so that the crash box 3 can be reliably buckled and crushed by the input of a frontal collision load (FIG. 2). reference).

  Here, since the front bumper supports 4 and 4 shown in FIG. 1 are configured symmetrically, the right front bumper support 4 will be described as a representative of both. As shown in an enlarged view in FIG. 2, the front bumper support 4 is formed into a square hollow trumpet shape by bending a steel plate.

  In other words, the front bumper support 4 is a rectangular hollow whose front end on the front bumper reinforcement 2 side has a left-right width wider than a rear end left-right width, and an intermediate left-right width increases from the rear end toward the front end. The front end portion of the trumpet is larger than the outer side in the vehicle width direction. A pair of upper and lower joining pieces 4 </ b> A and 4 </ b> A are bent at the front end portion of the front bumper support 4.

  Such a front bumper support 4 is spot-welded to the upper and lower surfaces of the round corner 2A of the front bumper reinforcement 2 with the pair of upper and lower joining pieces 4A and 4A at the front end thereof being mounted on the crash box 3. It is fixed. And the rear-end part of the front bumper support 4 fits to the outer periphery of the center part in the front-rear direction of the crash box 3 and is fixed by spot welding.

  In the vehicle body front structure of one embodiment configured as described above, when a collision load as shown by a white arrow in FIG. 1 is input to the front bumper reinforcement 2 at the time of a frontal collision of the vehicle body, A collision load is transmitted from the hosement 2 to the front ends of the crash boxes 3 and 3 as shock absorbers, and the front and rear center of the crash boxes 3 and 3 through the front bumper supports 4 and 4 from the front bumper reinforcement 2. The collision load is transmitted to the part.

  Here, since the front end portions of the front bumper supports 4 and 4 protrude greatly inward in the vehicle width direction, the distance between the support points of the front bumper reinforcement 2 by the front bumper supports 4 and 4 is shortened. For this reason, the bending moment acting on the front bumper reinforcement 2 with the front bumper supports 4 and 4 as supporting points when the frontal collision load of the vehicle body is input decreases, and accordingly, the front and rear of the front bumper reinforcement 2 are reduced accordingly. The bending strength in the direction will increase.

  On the other hand, the rear end portion of the front bumper supports 4 and 4 is fixed at the center in the front-rear direction of the crash boxes 3 and 3, so that the buckling strength of the crash boxes 3 and 3 is compensated by the front bumper supports 4 and 4. The second half is lower than the first half, which is stiff. The front and rear lengths of the crash boxes 3 and 3 are substantially halved to the front and rear lengths of the latter half portion having low strength.

  Therefore, in the vehicle body front structure according to the embodiment, when the collision load is input to the front bumper reinforcement 2 at the time of a frontal collision of the vehicle body, the front bumper reinforcement 2 whose bending strength in the front-rear direction is increased. The collision load is sufficiently and reliably transmitted to the front ends of the crash boxes 3 and 3, and the collision load is transmitted from the front bumper reinforcement 2 to the front and rear center portions of the crash boxes 3 and 3 via the front bumper supports 4 and 4. It is communicated sufficiently and reliably.

  As a result, the crash boxes 3 and 3 start crushing sufficiently and reliably in the axial direction in a stable state from the low-strength second half whose longitudinal length is halved, and then the first half is also fully and reliably axially Crush to. At that time, the crush boxes 3 and 3 are crushed starting from the notches 3C and the recesses 3D that induce buckling deformation. Thus, the impact at the frontal collision of the vehicle body is sufficiently and reliably absorbed by the crash boxes 3 and 3.

  Here, the simulation results assuming the frontal collision in the vehicle body front structure shown in FIG. 1 are shown in the graphs of FIGS. The graph of FIG. 3 shows the temporal change of the reaction force (bending strength) of the front bumper reinforcement 2 in comparison with the conventional example. As shown by the solid line graph, 30 ms elapses from the time of occurrence of the frontal collision. Until then, the reaction force (bending strength) of the front bumper reinforcement 2 is increased as compared with the conventional example shown by the dotted line graph.

  Further, the graph of FIG. 4 shows a temporal change in the load input to the crash boxes 3 and 3 in comparison with the conventional example. As shown by the solid line graph, 30 ms elapses from the time of occurrence of the frontal collision. Until then, the load input to the crash boxes 3 and 3 is increased as compared with the conventional example shown by the dotted line graph.

  Further, the graph of FIG. 5 shows a temporal change in the amount of energy absorbed by the crash boxes 3 and 3 in comparison with the conventional example. As shown by the solid line graph, until 50 ms elapses from the time of occurrence of the frontal collision. In the meantime, the amount of energy absorbed by the crash boxes 3 and 3 is doubled compared to the conventional example shown by the dotted line graph.

  Therefore, according to the vehicle body front structure of one embodiment, the collision load at the time of a frontal collision of the vehicle body is sufficiently and reliably transmitted from the front bumper reinforcement 2 to the front bumper supports 4 and 4 and the crash boxes 3 and 3. Can do. And by the sufficient and reliable crushing of the crash boxes 3 and 3, it is possible to sufficiently and reliably absorb the impact at the time of the frontal collision of the vehicle body, and it is possible to sufficiently and reliably mitigate the impact.

  The vehicle body front structure according to the present invention is not limited to the above-described embodiment. For example, the connection bases 2B and 2B on the rear surface side of the front bumper reinforcement 2 shown in FIG. 1 are omitted, and the connection flanges 3A and 3A at the front ends of the crash boxes 3 and 3 are directly connected to the rear surface of the front bumper reinforcement 2. It may be fixed.

  Moreover, as long as the rear-end part of the front bumper support 4 and 4 is fixed to the outer periphery of the front-back direction intermediate part, the shape and structure of the crash boxes 3 and 3 can be changed suitably.

  Furthermore, the shape of the front bumper supports 4 and 4 can be changed as appropriate, such as a trumpet shape with an elliptical cross section, as long as the shape widens at least inward in the vehicle width direction from the rear end portion toward the front end portion.

It is a top view showing typically the body front part structure concerning one embodiment of the present invention. FIG. 2 is a partially enlarged perspective view of the right vehicle body front structure shown in FIG. 1. It is a graph which shows the result of the simulation which assumed the time of the frontal collision in the vehicle body front part structure shown in Drawing 1, and is a graph which shows the temporal change of the reaction force (bending strength) of a front bumper reinforcement compared with the conventional example. is there. It is a graph which shows the result of the simulation, and is a graph which shows the time change of the load inputted into a crash box compared with a conventional example. It is a graph which shows the result of the simulation, and is a graph which shows the time change of the amount of energy absorption by a crush box compared with a conventional example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Front side member, 1A ... Connection flange, 2 ... Front bumper reinforcement, 2A ... Round corner, 2B ... Connection stand part, 3 ... Crash box, 3A ... Connection flange, 3B ... Connection flange, 3C ... Notch, 3D ... Indentation, 4 ... Front bumper support, 4A ... Joint piece.

Claims (2)

A vehicle body front structure for fixing the left and right ends of the front bumper reinforcement to the front ends of the left and right front side members of the vehicle body,
Front and rear bumper reinforcements have left and right end portions fixed to the front end portions, and rear end portions fixed to the front end portions of the left and right front side members.
A left and right square hollow trumpet-shaped front bumper support having a rear end fixed to the outer periphery of the front and rear intermediate portion of the shock absorber and a front end fixed to the left and right ends of the front bumper reinforcement. With
The front bumper support is configured to have a shape that widens at least inward in the vehicle width direction from the rear end portion toward the front end portion. The front bumper support is fitted and fixed to the outer periphery of the middle portion in the front-rear direction of the shock absorber in a state where the front bumper support is mounted on the shock absorber. Vehicle body front structure as described.

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