JP2009062034A - Energy absorbing member and vehicle bumper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently absorb collision energy. <P>SOLUTION: This energy absorbing member 4 is provided with a pair of arms 6, 6 extended to an impact pressure receiving direction and arranged vertically in parallel with each other and with a base 5 extended to the direction approximately orthogonal to the impact pressure receiving direction to connect root portions of the arms 6, 6 with each other, to have a vertical cross section of an approximately U-shape. Chamfered parts 7 as deformation promotion means to promote bend deformation of the root parts of the arms 6, 6 when receiving impact pressure are provided in the root portions of the upper and lower arms 6, 6. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an energy absorbing member and a vehicle bumper that can efficiently absorb energy when a vehicle collides with an obstacle.

  Conventional vehicle bumpers include a bumper reinforcement as a skeleton member disposed in the front part of the vehicle body along the vehicle width direction, a bumper fascia as an exterior member of a front bumper disposed in front of the bumper reinforcement, and these bumpers. And an energy absorbing member disposed between the reinforcement and the bumper fascia.

  When a vehicle collides with an obstacle, collision energy from the obstacle is applied to the energy absorbing member via the bumper fascia, and the energy absorbing member is crushed, so that the collision energy is absorbed.

For example, in Patent Document 1, the energy absorbing member of the front bumper is attached to the front surface of the bumper reinforcement in a state in which the vertical cross section has a U shape and the opening side of the U shape in the cross section faces rearward.
JP 2004-224106 A

  The inventor has a U-shaped energy absorbing member (that is, a pair of arms extending in the direction of shock receiving pressure and a base that connects the arms at the base of the arm). As a result of research on the energy absorbing member formed on the base, it was found that the base portion of the arm, that is, the connecting portion between the arm and the base is not easily deformed, and there is room for improvement.

  In the energy absorbing member or the vehicle front bumper of the present invention, the energy absorbing member includes a pair of arms extending in the shock receiving direction and provided in parallel with each other vertically, and a base portion of the arm. A base that extends in a direction substantially orthogonal to the shock pressure receiving direction to connect the arms to each other, so that the vertical cross section is formed in a U-shape, and the base of the upper arm and the lower arm at the base of the arm when receiving the shock pressure The gist is to include a deformation promoting means for promoting the curved deformation of the portion.

  Assuming a structure that does not include a chamfer, it is difficult for the base portion of the arm, that is, the connecting portion between the arm and the base, to be deformed. However, according to the present invention, since the root portion of the arm is provided with the deformation promoting means for accelerating the bending deformation of the root portion, the arm is bent and deformed as a whole including the root portion. Can absorb.

(First embodiment)
1 is an exploded perspective view of the front bumper of the first embodiment, FIG. 2 is a cross-sectional view of the front bumper, FIG. 3 is a cross-sectional view showing a state when an obstacle collides with the front bumper, and FIG. It is sectional drawing of the energy absorption member of a bumper.

  As shown in FIGS. 1 and 2, a bumper fascia 2 made of a soft resin is provided at the foremost part of the front bumper 1 of the automobile. A bumper reinforcement 3 having a rectangular closed cross-sectional structure is provided behind the bumper fascia 2. The bumper reinforcement 3 extends along the vehicle width direction, and when viewed in a plan view, the vehicle width direction central portion 3a is gently curved in a convex shape toward the front of the vehicle and both end portions 3c in the vehicle width direction. Is bent to the rear side via the bent portion 3b with respect to the central portion 3a in the vehicle width direction. The bumper reinforcement 3 is a metal strength member, and is fixed to the front portion of the vehicle body via a stay (not shown).

  On the front surface of the bumper reinforcement 3, an energy absorbing member 4 having a shape substantially similar to the bumper reinforcement 3 is attached in plan view. That is, the energy absorbing member 4 is attached to the front surface of the bumper reinforcement 3 so as to be interposed between the bumper fascia 2 and the bumper reinforcement 3.

  The energy absorbing member 4 is formed of a resin foam and is crushed between the bumper fascia 2 and the bumper reinforcement 3 at the time of a vehicle collision to absorb the collision energy.

  Next, the structure of the energy absorbing member 4 will be described in more detail with reference to FIGS.

  As for the shape of the energy absorbing member 4, the vertical cross section is formed in a U-shape that is open toward the front of the vehicle. That is, the energy absorbing member 4 extends in the vertical direction (that is, extends in a direction substantially orthogonal to the shock pressure receiving direction) and has a rectangular cross section, and extends substantially horizontally from the upper end of the base 5 toward the front of the vehicle (that is, An upper arm 6 having a rectangular cross section extending in the shock receiving direction and a lower arm 6 having a rectangular cross section extending substantially horizontally from the lower end of the base 5 toward the front of the vehicle (that is, extending in the shock receiving direction). Are formed in a U-shaped cross section. The upper arm 6 and the lower arm 6 basically have the same thickness (the same vertical dimension).

  Both arms 6 extend substantially parallel to each other, and both arms 6 and base 5 are substantially orthogonal. More specifically, the upper surface 6a and the lower surface 6b of the upper arm 6 and the upper surface 6d and the lower surface 6e of the lower arm 6 all extend substantially parallel to each other. The front surface 5b and the rear surface 5a of the base 5 are substantially orthogonal to the upper surfaces 6a and 6d and the lower surfaces 6b and 6e of the arms 6 and 6, respectively.

  Chamfered portions 7 and 7 are formed at corners on the fixed end side (rear end side) of the upper and lower outer surfaces of the upper and lower arms 6 and 6. In other words, chamfered portions 7 that are inclined with respect to the upper surface 6a of the upper arm 6 and the rear surface 5a of the base 5 are provided, and the lower surface 6e of the lower arm 6 and the base 5 are A chamfered portion 7 is provided at a corner with respect to the rear surface 5a.

  As a result, in a structure without a chamfered portion, a surplus portion cannot be formed at a corner portion (see reference symbol K in FIG. 5) that becomes a surplus portion. In this embodiment, any chamfered portion 7 is formed in a straight line.

  Further, the corners on the fixed end side (rear end side) on the upper and lower inner surfaces of the upper and lower arms 6 and 6 are formed in an arc shape. In other words, the corners of the upper arm lower surface 6b and the base front surface 5b are formed in an arc shape so as to be smoothly continuous with each other, and the corners of the lower arm upper surface 6d and the base front surface 5b are also mutually connected. It is formed in an arc shape so as to continue smoothly.

  Further, a chamfered portion 8 smaller than the chamfered portion 7 is formed at a corner portion on the free end side (front end side) of the upper and lower outer surfaces of the upper and lower arms 6, 6. In other words, a chamfered portion 8 that is inclined with respect to the upper surface 6a and the front surface 6c of the upper arm 6 is provided, and a corner portion between the lower surface 6e of the lower arm 6 and the front surface 6f. Is provided with a chamfered portion 8 which is inclined with respect to these. The chamfered portion 8 on the free end side of these arms 6 is formed in a smaller size than the chamfered portion 7 on the fixed end side described above, and the angle thereof is an angle of approximately 45 ° with respect to the front surfaces 6c and 6f. Is set to

Operation Next, the operation of the present embodiment will be described with reference to FIG.

  When the front bumper 1 having such a structure hits the obstacle G, energy Z as an impact by the obstacle G is applied to the energy absorbing member 4 via the bumper fascia 2 as shown in FIG. The energy absorbing member 4 absorbs the collision energy Z between the bumper fascia 2 and the bumper reinforcement 3.

  At this time, in the structure without the chamfered portion 7 as in the comparative example of FIG. 5, the corner portion K exists as a pre-curved portion, so that the corner portion K becomes a hindrance and the root portion of the arm 6 (that is, the arm 6). And the base 5 are not easily deformed, and the entire arm 6 is not bent.

  However, as shown in FIG. 2, the energy absorbing member 4 of the present embodiment includes the chamfered portion 7 at the base portion of the arm 6, so that the arm 6 is not simply crushed in the front-rear direction, but as shown in FIG. 3. It is bent and deformed so as to swell up and down while being crushed in the front-rear direction, and absorbs energy. That is, in this embodiment, the chamfered portion 7 facilitates the deformation of the root portion of the arm 6, whereby the energy absorption of the energy absorbing member 4 is caused by the compression deformation and bending deformation of the upper and lower arms 6, 6. It becomes the absorption structure using and. Therefore, the energy absorption efficiency is improved and the compression reaction force is reduced. Thereby, the reaction force to the obstacle which collided becomes small, and the damage to the said obstacle can be reduced.

  The chamfered portion 8 on the free end side of the upper and lower arms 6 and 6 is curved so that the arms 6 and 6 bulge outward in the vertical direction when the free end of the arms 6 and 6 collides with the obstacle G. It fulfills the function of promoting deformation.

Deformation Mode Next, the deformation mode of the energy absorbing member will be described with reference to FIGS.

  FIG. 5 shows the inversion phenomenon of the energy absorbing member 4. As shown in FIG. 5, in the structure without the chamfered portion 7, the corner portion K exists as a pre-walled portion so that the corner portion K becomes an obstacle and the upper and lower arms 6, 6 are tilted to the inside. It will cause the internal falling phenomenon to deform. Such inversion phenomenon is inferior in energy absorption efficiency.

  Further, even if the chamfered portion 7 is present, the corner portion K still exists as a pre-walled portion in the structure in which the chamfered portion 7 is small (in the structure in which the vertical dimension C and the longitudinal dimension D of the chamfered portion 7 are small). Thus, although the compression reaction force is reduced and the energy absorption efficiency is improved as compared with the structure without the chamfered portion 7, the inversion phenomenon still occurs.

  FIG. 6 shows the outward opening phenomenon of the energy absorbing member 4. As shown in FIG. 6, in the structure in which the dimensions C and D of the chamfered portion 7 are large, the upper and lower arms 6 and 6 cause an outward opening phenomenon that is a deformation spreading from the root to the outside. In the outward opening phenomenon, the roots of the upper and lower arms 6 and 6 are bent, so that the compression reaction force is lower and the energy absorption efficiency is improved than the inversion phenomenon (see FIG. 5) in which the roots of the upper and lower arms 6 and 6 are not bent. Only the base portions of the upper and lower arms 6 and 6 are bent and most of the arms 6 and 6 are not bent, and the energy absorption is inferior compared to the case where the entire arms 6 and 6 are bent.

  FIG. 7 shows the optimum deformation mode of the energy absorbing member 4. When the size of the chamfered portion 7 is within the optimum range as shown in FIG. 7, the point P at the front end of the upper and lower arms 6, 6 moves backward on the line L that matches the inner edge of the arms 6, 6, This is an optimal deformation mode in which the upper and lower arms 6 are bent outward in the vertical direction. In such an optimal deformation mode, neither the inversion phenomenon nor the outward opening phenomenon occurs, and the energy absorption efficiency is most excellent.

  In addition, when the deformation | transformation shape at the time of a collision is substantially the same, the thing with low stress which generate | occur | produces in the arm 6 is preferable. When the stress generated in the arm 6 is high, that is, when the unevenness of the stress distribution is large, the reaction force to the collision object is large, and conversely, the stress generated in the arm 6 is low, that is, the unevenness of the stress distribution is small. This is because the reaction force to the collision object becomes small.

  Therefore, the vertical dimension of the upper and lower arms is A, the longitudinal dimension of the energy absorbing member is B, the vertical dimension of the chamfered part is C, the longitudinal dimension of the chamfered part is D, the vertical dimension of the energy absorbing member is E, and the longitudinal dimension of the base When the dimension is F, the dimensions C and D of the chamfered portion are preferably in the range of C ≧ 0.75A> 0 and D ≧ 0.22B> 0. This is because the inversion phenomenon can be avoided by setting C ≧ 0.75A and D ≧ 0.22B as a result of the experiment.

  More preferably, the dimensions C and D of the chamfered portion are C = 0.5A and D = 0.22B. This is because when the dimensions C and D of the chamfered portion 7 are set to C = 0.5A and D = 0.22B, an optimum deformation mode having excellent energy absorption efficiency as shown in FIG. 7 is obtained.

  In addition, when C> 0.5A and D> 0.22B, the dimensions C and D of the chamfered portion 7 are large, so that the upper and lower arms 6 and 6 cause an outward opening phenomenon in which the deformation spreads outward from the root. However, the energy absorption efficiency is superior to the inversion phenomenon.

Experiment 1
The inventor measured the difference in energy absorption efficiency depending on the presence or absence of the chamfered portion 7 (see FIGS. 8 and 9).

  Sample: As a sample, an energy absorbing member having no chamfered portion (comparative example) and an energy absorbing member having a chamfered portion (this example) were used. The energy absorbing member having no chamfered portion (comparative example) is a polypropylene 12-fold foamed resin foam, the arm 6 has a thickness A of 20 mm, the energy absorbing member has a front-rear dimension B of 90 mm, and upper and lower of the energy absorbing member. The dimension E was 100 mm, and the base 5 had a thickness dimension F of 30 mm. On the other hand, the energy absorbing member (this example) having a chamfered portion was formed in the same manner as the comparative example except that C = 5 mm and D = 5 mm.

  Evaluation: When the load vs. stroke and the moment vs. stroke were measured for these samples, the results of FIGS. 8 and 9 were obtained. 8 and 9, the solid line indicates the measurement result of the present example having the chamfered portion, and the broken line indicates the measurement result of the comparative example without the chamfered portion.

  As shown in FIGS. 8 and 9, the present embodiment having the chamfered portion has an effect of about −10 mm in the stroke, about −700 N in the maximum load, and about −30 Nm in the maximum moment as compared with the comparative example having no chamfered portion. It can be seen that the energy absorption efficiency has been expanded. As a result, the energy absorption efficiency is improved by about 10%. Thus, it turns out that energy absorption efficiency improves by forming a chamfer.

Experiment 2
In addition, the present inventor conducted the following experiment to specify the optimum value of the chamfered portion size (see FIGS. 10 to 12).

  Samples: Samples A, B, C, D, E, C1, C2, C3, C4, D1, and D2 were prepared as shown in FIGS. These samples are polypropylene foam 12 times foamed resin, the arm 6 has a thickness dimension A of 20 mm, the energy absorbing member has a longitudinal dimension B of 115 mm, and the chamfered section 7 has a vertical dimension C of 0 to 20 mm. 7 with a front-to-back dimension D of 0 to 40 mm, an energy absorption member with a vertical dimension E of 90 mm, and a base 5 with a thickness dimension F of 15 mm. Changed in units.

  Evaluation: Assuming that the initial deformation mode of the energy absorbing member 4 at the time of collision is similar to the deformation mode of the static analysis, the deformation mode of the energy absorbing member 4 was examined using static analysis. Assuming that the mass of the obstacle G is 9.5 kg and the collision speed is 11.1 m / s, the optimum value of the chamfered portion is specified from the deformation mode (deformed shape) of the sample. In addition, in FIGS. 10-12, the isobar of the compressive stress which arose in each sample is shown as the continuous line.

  Discussion: As shown in FIGS. 10 to 12, it was found that the inversion phenomenon was avoided in samples D, E, C3, C4 and D1, D2. That is, in the range where the vertical dimension C of the chamfered portion 7 is 15 mm or more and the front-rear dimension D is 25 mm or more, there is an effect in avoiding the inversion phenomenon. When the dimensions C and D of the chamfered portion 7 are expressed as a ratio with respect to the entire size of the energy absorbing member 4, the inversion phenomenon is avoided in the range of C ≧ 0.75A> 0 and D ≧ 0.22B> 0. It turns out that there is an effect.

  Moreover, the optimal deformation mode (refer FIG. 7) of the upper and lower arms 6 and 6 was obtained by the sample C3. In other words, the vertical dimension C of the chamfered portion 7 was 10 mm, the front-rear dimension D was 25 mm, and the optimum deformation mode was obtained. When the dimensions C and D of the chamfered portion 7 are expressed as a ratio with respect to the overall size of the energy absorbing member 4, it can be seen that the optimum deformation mode is obtained in the relationship of C = 0.5A and D = 0.22B.

  The above experiment was performed in the same manner even when the B dimension was 100 mm. As a result, the inversion phenomenon could be avoided when C ≧ 0.75A> 0 and D ≧ 0.22B> 0, and C = 0.5A and D = 0.22B. It was found that the optimal deformation mode can be obtained.

Effects Next, main effects of the first embodiment will be described.

  (1) In the present embodiment, the energy absorbing member 4 is provided with the deformation promoting means 7 for accelerating the bending deformation of the root portion of the arm 6 at the time of impact pressure reception at the root portion of the upper and lower arms 6. Therefore, when the upper and lower arms 6 are curved including the root portion, the compressive stress of the energy absorbing member 4 is reduced, the reaction force to the collision object can be reduced, and the energy absorption efficiency can be increased. Damage can be reduced.

  Further, as an accompanying effect, there is an effect that the front-rear dimension B of the energy absorbing member 4 can be shortened and the restrictions on the vehicle design can be reduced.

  (2) According to this embodiment, the deformation promoting means 7 is the chamfered portion 7 formed at the upper and lower corners of the energy absorbing member 4 on the bumper reinforcement 3 side. Therefore, the deformation promoting means 7 can be configured with an extremely simple structure, leading to cost reduction.

  (3) According to the present embodiment, the energy absorbing member 4 is a synthetic resin foam. Therefore, it is easy to set the optimal strength for the energy absorbing member 4 depending on the degree of foaming. In addition, the synthetic resin foam is lightweight and excellent in moldability. By forming the chamfered portion 7, it is possible to reduce the cost and mass due to the reduction of the input material at the time of molding.

  (4) Further, in this embodiment, when the thickness dimension of the arm 6 is A, the longitudinal dimension of the energy absorbing member is B, the vertical dimension of the chamfered part is C, and the longitudinal dimension of the chamfered part is D, C ≧ 0.75A> 0 (optimum is C = 0.5A) and D ≧ 0.22B> 0 (optimum is D = 0.22B). Therefore, the extreme outward opening phenomenon of the upper and lower arms 6 and 6 can be prevented, and efficient energy absorption can be performed.

  (5) In particular, when the conditions of C = 0.5A and D = 0.22B are satisfied, the front ends of the upper and lower arms 6 move rearward along a straight line while maintaining the vertical height, and the upper side An optimum bending mode is obtained in which the central portions of the arm 6 and the lower arm 6 are each curved outward.

  (6) Further, according to the present embodiment, the chamfered portion 8 is provided at the corners of the tips of the upper arm 6 and the lower arm 6. Therefore, when the front end of the arm 6 or 6 collides with the obstacle G, it is promoted that the arm 6 or 6 is curved and deformed so as to bulge outward in the vertical direction, thereby (1) to (5). The effect of can be further promoted.

(Second Embodiment)
FIG. 13 is a cross-sectional view showing the energy absorbing member of the second embodiment, FIG. 14 is a cross-sectional view showing a deformation mode of the energy absorbing member of the second embodiment, and FIG. 15 is a view for explaining the arrangement positions of the grooves. FIG. 6 is a cross-sectional view showing a maximum stress site and a maximum displacement site in an energy absorbing member without a groove. In addition, about the component similar to 1st Embodiment, a common code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  In the second embodiment, grooves 13 and 14 are formed in the chamfered portions 7 of the energy absorbing member 9 and the substantially center positions in the front-rear direction on the upper and lower outer surfaces of the upper and lower arms 6 and 6, respectively. This is different from the first embodiment. The grooves 13 and 14 are both formed along the longitudinal direction of the energy absorbing member 4, that is, along the vehicle width direction.

  The grooves 13 and 14 are formed at positions where the maximum stress generation site X (the chamfered portion 7) of the arm 6 and the maximum displacement site of the upper and lower arms 6 in the structure without the grooves 13 and 14 as shown in FIG. Y (substantially central portion in the longitudinal direction on the upper and lower outer surfaces of the upper and lower arms 6).

  As described above, in the second embodiment, since the groove portion 13 is formed in the portion corresponding to the maximum stress portion X of the chamfered portion 7, in addition to the effect of the first embodiment, the stress is further dispersed (equalized) and vertically The curved shape of the arms 6 and 6 can be enlarged.

  In the second embodiment, since the groove portion 14 is formed in the portion corresponding to the maximum displacement portion Y of the upper and lower arms 6, 6, the groove portion 14 becomes a base point for deformation, and the curved shape of the upper and lower arms 6, 6 can be enlarged.

Thus, by forming the groove parts 13 and 14, the curved bending deformation of the upper and lower arms 6 and 6 is further expanded, and the energy absorption efficiency can be further increased. Further, the formation of the grooves 13 and 14 can also reduce the cost and mass due to the reduction of the input material at the time of molding.

  In the second embodiment, the groove portion 13 is formed in the chamfered portion 7 and the groove portion 14 is formed in a substantially central portion in the longitudinal direction of the arm 6. However, if either the groove portion 13 or the groove portion 14 is present, , Energy absorption efficiency can be improved.

  The following other embodiments will be described. Hereinafter, in the third and subsequent embodiments, the chamfered portion 7 as the above-described deformation promoting means is omitted and illustrated.

(Third embodiment)
16 to 23 show a third embodiment of the present invention. FIG. 16 is a front perspective view showing a predetermined length portion of the center portion in the vehicle width direction of the energy absorbing member of the third embodiment provided with reaction force difference generating means, and FIG. FIG. 18 is an explanatory diagram showing the deformation state of the upper arm and the lower arm when the obstacle collides with the energy absorbing member, together with the reaction force characteristics, and FIG. It is explanatory drawing which shows the deformation | transformation state of the upper arm and lower arm of an energy absorption means with reaction force characteristic.

  As shown in FIG. 16, the energy absorbing member 100 of the present embodiment has basically the same configuration as the energy absorbing member 4 of the first embodiment, and includes a base 101 extending in the vertical direction and an upper end portion of the base 101. An upper arm 102 that extends substantially horizontally toward the front of the vehicle and a lower arm 103 that extends substantially horizontally from the lower end of the base 101 toward the front of the vehicle are formed in a U-shaped cross section that opens to the front of the vehicle. Yes.

  Here, this embodiment is mainly different from the first embodiment in that the reaction force difference generating means for making the reaction force of the upper arm 102 smaller than the reaction force of the lower arm 103 with respect to the impact pressure at the time of frontal collision. 110 is provided.

  As shown in FIG. 16, the reaction force generation means 110 forms the upper arm 102 and the lower arm 103 in a wave shape, and makes the waveform of the upper arm 102 and the waveform of the lower arm 103 different. The reaction force of the upper arm 102 is smaller than the reaction force of the lower arm 103. In this embodiment, the waveforms of the upper arm 102 and the lower arm 103 alternate between the inner tiers 102a and 103a approaching the counterpart arm and the outer tiers 102b and 103b separated from the counterpart arm in the longitudinal direction of the energy absorbing member 100. The corrugated portions 111 and 112 are formed by connecting the adjacent inner steps 102a and 103a and the outer steps 102b and 103b with connecting portions 102c and 103c.

  That is, when the reaction force adjustment by the corrugated portions 111 and 112 is illustrated by taking the upper arm 102 as an example, as shown in FIG. 17, the longitudinal length a of the energy absorbing member 100 of the outer step 102b and the inner step 102a. The longitudinal length b of the energy absorbing member 100, the height difference c between the inner step 102a and the outer step 102b, the inclination angle d of the connecting portion 102c connecting the inner step 102a and the outer step 102b, and the arm thickness e. The reaction force difference between the upper arm 102 and the lower arm 103 can be obtained by adjusting at least one element.

  In the present embodiment, the reaction force generation means 110 shown in FIG. 16 has a rough interval between the inner step 102 a and the outer step 102 b of the corrugated portion 111 of the upper arm 102, and the inner step 103 a of the corrugated portion 112 of the lower arm 103. The distance from the outer stage 103b is close. Accordingly, the upper arm 102 having the rough corrugated portion 111 has a low rigidity and the reaction force is set to be small, and the lower arm 103 having the corrugated portion 112 densely formed has a high rigidity and has a large reaction force. Thus, a reaction force difference can be obtained between the upper arm 102 and the lower arm 103.

  Accordingly, when the obstacle G collides with the energy absorbing member 100 as shown in FIG. 18, the reaction force characteristic α1 of the upper arm 102 is small and the lower arm is shown in FIG. The reaction force characteristic α2 103 is set large. Therefore, as shown in FIG. 5B, when the load F when the obstacle G collides is equally input to the upper arm 102 and the lower arm 103 by 0.5 F, the deformation amount of the upper arm 102 (Stroke) is large, and the deformation amount (stroke) of the lower arm 103 is small. As a result, the obstacle G is greatly inclined (inclination angle θ) in the upper part rather than the lower part toward the rear of the vehicle (rightward in the figure).

  Incidentally, as shown in FIG. 19, in the energy absorbing member EA not provided with the reaction force difference generating means 110, the reaction force characteristics α of the upper arm A1 and the lower arm A2 are equally deformed by equal amounts. The obstacle G maintains a substantially vertical state with respect to the road surface.

  FIG. 20 is a schematic diagram of a dummy doll as an obstacle used in the frontal collision test. FIG. 21 shows the behavior of the energy absorbing member when the upper leg of the dummy doll collides with a vehicle bumper provided with a reaction force difference generating means ( FIG. 22 is a diagram illustrating the behavior of the energy absorbing member when the lower leg portion of the dummy doll collides with the vehicle bumper. FIG. 22 is a diagram illustrating the behavior of the energy absorbing member in sequence. FIG. 23 is an explanatory view showing a comparative example corresponding to FIG. 21 when no reaction force difference generating means is provided.

  Here, as shown in FIG. 20, the dummy doll G is composed of a lower leg part G1, an upper leg part G2, and a body part G3, which are connected in order from the bottom with bendable nodes, and each mass is G1. > G2> G3. As shown in FIG. 21, when the upper leg G2 of the dummy doll G collides with the front bumper 1 provided with the reaction force difference generating means 110, it is shown in order in FIGS. 21 (a) to 21 (d). In addition, both the lower leg part G1 and the upper leg part G2 can be flipped obliquely upward. In FIGS. 21 (b) to 21 (d) and FIGS. 22 (b), 23 (b) to (d), FIGS. 26 (b) and 26 (c) which will be described later, for convenience, the dummy dolls G1 and G2 are front. Although shown in a state in which the bumper 1 has entered the inside, the bumper fascia 2 and the energy absorbing member 100 (100A, EA) are actually crushed between the dummy dolls G1, G2 and the bumper reinforcement 3 It becomes.

  In addition, as shown in FIG. 22, even when the lower leg G1 of the dummy doll G collides with the front bumper 1, the lower leg G1 can be flipped upward.

  Incidentally, as shown in FIG. 23, when the above-described upper leg portion G2 collides with the front bumper 1 not provided with the reaction force difference generating means 110, the lower leg portion G1 is moved as shown in (a) to (d). There is a possibility that it cannot be flipped up.

  With the above configuration, the energy absorbing member 100 of the third embodiment has the following effects.

  The energy absorbing member 100 of the third embodiment is provided with a reaction force difference generating means 110 so that the reaction force of the upper arm 102 is smaller than the reaction force of the lower arm 103 with respect to the impact pressure at the time of frontal collision. . As a result, when the dummy doll G collides with the front bumper 1, the center of gravity located on the body G3 of the dummy doll G moves obliquely downward on the vehicle side, so that the dummy doll G can be flipped upward. it can.

  Further, according to the third embodiment, the upper arm 102 and the lower arm 103 are provided with the corrugated portions 111 and 112, respectively, and the shape of the upper and lower corrugated portions 111 and 112 is adjusted, so that the reaction force of the upper arm 102 is increased. Is formed smaller than the reaction force of the lower arm 103. Thus, in this embodiment, since the upper and lower arms 102 and 103 are formed in a corrugated shape, the reaction force of the energy absorbing member 100 is increased compared to a structure in which the upper and lower arms 102 and 103 are flat, and the energy absorbing member 100 In addition, the desired reaction force can be obtained even when a high-magnification low-reaction material (for example, a resin foam having a foaming ratio of 20 to 45 times) is used. Therefore, mass reduction (for example, 50% reduction) and cost reduction (for example, 30% reduction) of the energy absorbing member 100 can be achieved.

  Further, in the third embodiment, as shown in FIG. 24, the reaction force difference generation shown in FIG. 12B is performed on the energy absorbing member EA not provided with the reaction force difference generation means 110 shown in FIG. In the energy absorbing member 100 provided with the means 110, the rigidity of the upper arm 102 and the lower arm 103 is increased by corrugation, and a larger collision energy can be absorbed with a small stroke, so that the width of the energy absorbing member 100 can be shortened.

(Fourth embodiment)
25 and 26 show a fourth embodiment of the present invention, in which the same components as in the third embodiment are denoted by the same reference numerals and redundant description is omitted. FIG. 25 is a cross-sectional view of the energy absorbing member, and FIG. 26 is an explanatory view showing the behavior of the energy absorbing member in order from (a) to (c) when the upper leg of the dummy doll collides with the vehicle bumper.

  As shown in FIG. 25, the energy absorbing member 100A of the present embodiment basically includes a base 101, an upper arm 102, and a lower arm 103, similarly to the energy absorbing member 100 of the third embodiment. It is formed in a U-shaped cross section that opens to the front of the vehicle.

  Here, this embodiment is mainly different from the third embodiment in that the reaction force difference generating means 110 of the third embodiment is not provided, that is, the upper arm 102 and the lower arm 103 are wave-shaped. The protrusion length L1 of the upper arm 102 from the base 101 is shorter than the protrusion length L2 of the lower arm 103 from the base 101 (L1 <L2).

  With the above configuration, in the energy absorbing member 100A of the fourth embodiment, the upper arm 102 is made shorter than the lower arm 103, so that the center of gravity position of the dummy doll G is as shown in FIGS. Can be moved obliquely downward on the vehicle side at an early stage of deformation of the energy absorbing member 100A. Thereby, like the third embodiment, both the lower leg portion G1 and the upper leg portion G2 can be flipped up obliquely upward.

(Modification of the fourth embodiment)
As a modification, the third embodiment and the fourth embodiment may be combined. That is, although not shown, the reaction force difference generating means formed by making the upper arm 102 and the lower arm 103 into a wave shape and making the waveform density of the upper arm 102 larger than the waveform density of the lower arm 103. 110 and the protruding length L1 of the upper arm 102 from the base 101 may be shorter than the protruding length L2 of the lower arm 103 from the base 101 (L1 <L2).

  Thus, according to the modification which combined 3rd Embodiment and 4th Embodiment, the obstruction G can be flipped up more reliably by the time of front collision.

(Fifth embodiment)
27 to 28 show a fifth embodiment of the present invention, in which the same components as those in the third embodiment are denoted by the same reference numerals and redundant description is omitted. FIG. 27 is a schematic view of the automobile as viewed from the front, and FIG. 28 is a front view showing a portion of the energy absorbing member extending from the vehicle center to one end in the vehicle width direction.

  As shown in the first embodiment, the front bumper 1 of the present embodiment includes a bumper fascia 2 that covers the bumper reinforcement 3 and the energy absorbing member 100B and is attached to the vehicle body, and forms the outer shape of the front bumper 1. The reaction force of the energy absorbing member 100B is adjusted in consideration of the reaction force of the bumper fascia 2.

  That is, in the bumper fascia 2, the reaction force (hereinafter referred to as fascia reaction force) at the time of a frontal collision changes in the vehicle width direction due to the design shape, the mounting structure of the bumper fascia 2, and the like.

  For example, when the bumper fascia 2 has a design shape that gradually inclines rearward from the vehicle width direction center toward the vehicle width direction outer side, the fascia reaction force at the time of a vehicle front collision is from the vehicle width direction center. It gradually increases toward the outside in the vehicle width direction.

  Further, as shown in FIG. 27, the fascia reaction force of the bumper fascia 2 changes in the vehicle width direction without being constant due to the mounting structure of the bumper fascia (BMPR) 2. In the structure of the bumper fascia 2 shown in FIG. 27, depending on the positional relationship between the left and right headlamps (LAMP), the grille (GRILLLE), and the vehicle body fixing part (M), as indicated by numerals (1 to 4) in FIG. The fascia reaction force gradually increases from the center of the vehicle toward the outside in the vehicle width direction. The numbers in FIG. 27 indicate the magnitude of the fascia reaction force. In FIG. 27, LAMP is the left and right headlamps, GRILLLE is the grille, FDR is the left and right fenders, HOOD is the engine hood, and M is This is the body fixing part.

  In this way, when the fascia reaction force increases from the vehicle width direction center portion toward the vehicle width direction outer side due to the vehicle design, the mounting structure, or the like, the upper and lower arms 102, 103 of the energy absorbing member 100 as shown in FIG. Is reduced from the vehicle center toward the vehicle outer side, the reaction force of the upper and lower arms 102 and 103 is decreased from the vehicle center toward the vehicle outer side, and the fascia reaction force and the reaction force of the energy absorbing member 100 are reduced. The sum can be made substantially uniform at any part in the vehicle width direction.

  In the fifth embodiment as well, as shown in FIG. 28, the lower arm 103 is formed by making the waveform density of the lower arm 103 larger than the waveform density of the upper arm 102 at any part in the vehicle width direction. Is larger than the reaction force of the upper arm 102, thereby improving the effect of jumping up the collision object G.

(Modification of the fifth embodiment)
For example, the bumper fascia mounting structure shown in FIG. 29 is different from the bumper fascia mounting structure shown in FIG. 27, but the fascia reaction force is similar to that shown in FIG. Since it gradually changes toward the outside, the same effect as that of the fifth embodiment can be obtained by using the same energy absorbing member 100 as that of the fifth embodiment shown in FIG.

  Further, for example, the modified example of FIG. 30A and the modified example of FIG. 30B are different from FIG. 27 in the mounting structure and fascia reaction force of the bumper fascia. In consideration, the same effect as that of the fifth embodiment can be obtained by changing the reaction force of the upper arms 102 and 103 of the energy absorbing member 100 in the vehicle width direction.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and various modifications can be made.

  For example, in the above embodiment, the planar chamfered portion 7 is taken as an example, but it may be slightly convex or concavely curved.

  In the third and fifth embodiments, the corrugated portions provided on the upper and lower arms 102 and 103 are configured by alternately combining the inner steps 102a and 103a and the outer steps 102b and 103b, but the shape is not limited thereto. For example, the outer steps 102b and 103b may be bulged as shown in FIG. 31 (a), and the outer steps 102b and 103b are projected in a mountain shape as shown in FIG. 31 (b). Alternatively, other shapes can be employed.

It is a disassembled perspective view of the front bumper concerning a 1st embodiment of the present invention. It is sectional drawing of the front bumper. It is sectional drawing which shows the state at the time of the front bumper colliding with an obstacle. It is sectional drawing of the energy absorption member of the front bumper. It is a figure for demonstrating the inversion phenomenon of an energy absorption member. It is a figure for demonstrating the outward opening phenomenon of an energy absorption member. It is a figure for demonstrating the optimal deformation | transformation mode of an energy absorption member. The graph which compared with the present Example and comparative example which show the relationship of load vs. stroke. The graph which compared the relationship of a moment versus a stroke with a present Example and a comparative example. It is a figure which shows the deformation | transformation mode of the samples A, B, C, D, and E used for the experiment for specifying the optimal value of a chamfer part. It is a figure which shows the deformation | transformation mode of the samples C, C1, C2, C3, and C4 used for the experiment for specifying the optimal value of a chamfering part. It is a figure which shows the deformation | transformation mode of the samples D, D1, and D2 used for the experiment for pinpointing the optimal value of a chamfer part. It is sectional drawing which shows the energy absorption member which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the deformation | transformation mode of the energy absorption member of 2nd Embodiment. It is a figure for demonstrating the arrangement | positioning location of the groove part formed in an energy absorption member, Comprising: It is sectional drawing which shows the largest stress generation | occurrence | production site | part X and the maximum displacement site | part Y in the energy absorption member without a groove part. It is a front perspective view which shows the predetermined length part of the vehicle width direction center part of the energy absorption member which provided the reaction force difference generation means concerning 3rd Embodiment of this invention. It is a principal part enlarged front view of the waveform part concerning 3rd Embodiment of this invention. It is explanatory drawing which shows the deformation | transformation state of the upper arm and lower arm of an energy absorption member when the obstacle concerning 3rd Embodiment of this invention collides with each reaction force characteristic. It is explanatory drawing which shows the comparative example corresponding to FIG. 18 when the reaction force difference generation means is not provided. It is a schematic diagram of the dummy doll as an obstacle used for the frontal collision test concerning 3rd Embodiment of this invention. The description which shows the behavior of the energy absorbing member in order from (a) to (d) when the upper leg of the dummy doll collides with the vehicle bumper provided with the reaction force difference generating means according to the third embodiment of the present invention. FIG. It is explanatory drawing which shows a behavior of the energy absorption member at the time of the lower leg part of a dummy doll colliding with the vehicle bumper concerning 3rd Embodiment of this invention later on to (a), (b). It is explanatory drawing which shows the comparative example corresponding to FIG. 21 when the reaction force difference generation means is not provided. It is explanatory drawing which shows the load balance at the time of the curvature of the energy absorption member by the presence or absence of a reaction force difference generation means. It is sectional drawing of the energy absorption member concerning 4th Embodiment of this invention. It is explanatory drawing which shows the behavior of an energy absorption member at the time of the upper leg part of a dummy doll colliding with the vehicle bumper concerning 4th Embodiment of this invention later on to (a)-(c). It is the schematic diagram which looked at the motor vehicle concerning 5th Embodiment of this invention from the front, respectively. It is a front view which shows the part from the vehicle center of the energy absorption member concerning 5th Embodiment of this invention to the edge part of the vehicle width direction one side. It is a mimetic diagram concerning the 1st modification of a 5th embodiment of the present invention, and saw bumper fascia from the front of the car. It is the mimetic diagram concerning the other modification of a 5th embodiment of the present invention, and has looked at bumper fascia from the front of the car, respectively. It is a cross-sectional front view which shows the outer stage concerning other embodiment of this invention to (a) and (b), respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Front bumper 2 Bumper facia 3 Bumper reinforcement 4 Energy absorption member 5 Base 6 Arm 7 Chamfering part 13, 14 Groove part 100, 100A, 100B Energy absorption member 102 Upper arm 102a Inner stage 102b Outer stage 103 Lower arm 103a Inner stage 103b Outer stage 110, 110A Reaction force difference generating means 111, 112 Waveform part G Obstacle K Corner part L Line P Point X Maximum stress part Y Maximum displacement part Z Energy a Longitudinal length of outer stage b Longitudinal direction of inner stage Length c Height difference between inner step and outer step d Inclination angle of connecting part connecting inner step and outer step e Arm thickness L1 Projection length of upper arm L2 Projection length of lower arm

Claims (13)

A pair of arms extending in the shock pressure receiving direction and provided vertically in parallel with each other; and a base extending in a direction substantially orthogonal to the shock pressure receiving direction so as to connect the arms at the base portion of the arm. An energy absorbing member having a vertical cross section formed into a U shape by comprising,
An energy absorbing member, comprising: a base portion of each of the upper arm and the lower arm provided with a deformation promoting unit that promotes bending deformation of the base portion of the arm when receiving an impact pressure. The energy absorbing member according to claim 1,
The deformation promoting means includes a chamfered portion that is formed at a corner portion between the upper surface of the upper arm and the rear surface of the base that are substantially orthogonal to each other, and a lower surface of the lower arm that is substantially orthogonal to the base and the base. An energy absorbing member comprising: a chamfered portion formed at a corner portion with respect to the rear surface and inclined with respect to these. The energy absorbing member according to claim 2,
When the vertical dimension of the upper arm and the lower arm is A, the longitudinal dimension of the energy absorbing member is B, the vertical dimension of the chamfered part is C, and the longitudinal dimension of the chamfered part is D, C and D Is set to be larger as A and B are larger, respectively. The energy absorbing member according to claim 3,
An energy absorbing member satisfying the conditions of C ≧ 0.75A and D ≧ 0.22B. The energy absorbing member according to any one of claims 1 to 4,
An energy absorbing member, wherein each chamfered portion is formed with a groove. The energy absorbing member according to any one of claims 1 to 5,
An energy absorbing member, wherein a groove is provided in a substantially central portion in the longitudinal direction of the upper arm and a lower surface of the lower arm. The energy absorbing member according to any one of claims 1 to 6,
The energy absorbing member is a synthetic resin foam. It is an energy absorption member of any one of Claims 1-7,
An energy absorbing member provided with a reaction force difference generating means for making a reaction force of an upper arm smaller than a reaction force of a lower arm with respect to impact pressure. The energy absorbing member according to claim 8,
The upper arm and the lower arm are formed in a waveform in the longitudinal direction of the energy absorbing member, and the waveform of the upper arm and the waveform of the lower arm are made different so that the reaction force of the upper arm can be lowered. An energy absorbing member, characterized in that a reaction force difference generating means for making the reaction force smaller than an arm reaction force is formed. The energy absorbing member according to claim 9,
The wave shape of the upper arm and the lower arm is such that an inner step close to the counterpart arm and an outer step separated from the counterpart arm are alternately provided in the longitudinal direction of the energy absorbing member, and the outer step and the inner step are provided. It is formed into a wave shape by providing a connecting part to connect,
The longitudinal length of the energy absorbing member of the outer stage, the longitudinal length of the energy absorbing member of the inner stage, the height difference between the inner stage and the outer stage, and the inclination angle of the inclined portion connecting the inner stage and the outer stage; An energy absorbing member characterized by obtaining a reaction force difference between an upper arm and a lower arm by making at least one element of the arm thickness different between the upper arm and the lower arm. It is an energy absorption member given in any 1 paragraph of Claims 1-10,
An energy absorbing member, wherein a protruding length of the upper arm from the base is shorter than a protruding length of the lower arm from the base. The energy absorbing member according to any one of claims 1 to 11,
The energy absorbing member is disposed between the bumper fascia that forms the contour of the front bumper and the bumper reinforcement disposed at the rear of the bumper fascia, and along the vehicle width direction on the front surface of the bumper reinforcement. It can be attached
In the energy absorbing member, the upper arm and / or the lower arm has a reaction force against an impact pressure changing in a vehicle width direction. A vehicle bumper comprising a bumper reinforcement and an energy absorbing member attached to a surface of the bumper reinforcement on the impact pressure side,
The energy absorbing member extends in an impact pressure receiving direction and is provided in a vertical direction substantially perpendicular to the shock pressure receiving direction so as to connect the arms to each other at a base portion of the arm and a pair of arms provided in parallel vertically. And a base that extends to the base, the vertical cross section is formed in a U-shape, and the base portion of the upper arm and the lower arm is provided with a deformation promoting means for accelerating the bending deformation of the base portion of the arm when receiving an impact. A bumper for a vehicle.

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