JP2009126411A - Bumper structure for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bumper structure for a vehicle reducing a forward and backward length of a bumper while improving energy absorbing efficiency, and further reducing a knee bending angle of a pedestrian. <P>SOLUTION: In this bumper structure for a vehicle, side members 28 are arranged on right and left sides of a vehicle body front, and a bumper beam 12 is mounted to ends of the side members 28 via an extension member 27. An energy absorbing member 13 is mounted to a front face of the bumper beam 12. A pair of right and left brackets 16 extend downward from the bumper beam 12, and a lower beam 17 is mounted to ends of the brackets 16 and below the energy absorbing member 13, and the lower beam 17 side is elastically deformed by collision of the lower beam 17 and legs of a pedestrian so as to move the lower beam 17 backward. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an improvement in a vehicle bumper structure.

As a conventional vehicle bumper structure, a bumper system provided with a push bar that presses a leg is known (see, for example, Patent Document 1).
US Pat. No. 6,460,909

FIG. 10 will be described with reference to FIG. In addition, the code was reassigned.
FIG. 6 is a cross-sectional view showing a conventional vehicle bumper structure. The bumper system 100 includes a bumper beam 101, a spring device 103 attached to the lower portion of the bumper beam 101 with a bolt 102, and a lower leg push bar 104.
The lower leg push bar 104 is disposed on the front side of the spring device 103 and presses the lower leg forward when the lower leg hits the pedestrian from the front of the vehicle.

  Generally, an energy absorbing member constituting a vehicle bumper structure can absorb a large impact energy with a small displacement by increasing energy absorption efficiency (that is, making it hard), but the bumper collides with a pedestrian's leg, When a high load is input to the knee, for example, a large bending moment acts on the tibia of the lower leg, or the bending angle of the knee joint (that is, the angle between the thigh and the lower leg. Simply written as “knee bend angle”).

  Therefore, in order to suppress the input load, it is necessary to lower the energy absorption efficiency (soften the energy absorption member). Therefore, if the displacement of the vehicle bumper structure is increased in order to obtain a sufficient amount of energy absorption, the bumper becomes longer in the vehicle front-rear direction.

  In Patent Document 1, the lower leg push bar 104 can reduce the impact load on the lower leg of the pedestrian. However, in the spring device 103, the lower leg push bar 104 bends when pressing the lower leg of the pedestrian. It is easy to generate a reaction force that reduces the knee bending angle of a pedestrian.

  An object of the present invention is to provide a vehicle bumper structure that can improve energy absorption efficiency, shorten the length of the bumper, and reduce the knee bending angle of a pedestrian.

  The invention according to claim 1 is a vehicle in which side members are arranged on the left and right of the front part of the vehicle body, a bumper beam is attached to the front ends of these side members via extension members, and an energy absorbing member is attached to the front surface of the bumper beam. In the bumper structure, the bracket is extended downward from the bumper beam, and the lower beam is attached to the end of the bracket so as to be positioned below the energy absorbing member, and the lower beam side is elastically deformed by the collision between the lower beam and the leg of the pedestrian. The lower beam is caused to recede by being deformed.

  As an action, when the bumper collides with the leg part of the pedestrian, both the energy absorbing member and the lower beam hit the leg part of the pedestrian. Specifically, the energy absorbing member hits the knee part and the lower beam hits the lower knee part. And it becomes possible to absorb a large energy at the time of collision by sharing with the lower beam.

  In addition, for example, in a bumper structure that does not include a lower beam, the knee part where the energy absorbing member collides is decelerated, and the lower part of the knee and the upper part of the knee are not decelerated, so the knee bending angle is increased. Since it is received by the lower beam, the lower knee is also decelerated and the knee bending angle is reduced.

  According to a second aspect of the present invention, the energy absorbing member includes a soft first energy absorbing member disposed on the front side and a rear side of the first energy absorbing member, and is harder than the first energy absorbing member. Two energy absorbing members, and the first energy absorbing member and the second energy absorbing member perform shock absorption on the pedestrian leg in two stages. In the first stage of the shock absorption, the first energy absorbing member And the lower beam absorbs the impact by the deformation of the second energy absorbing member, and the lower beam absorbs the impact by the deformation of the second energy absorbing member. It is characterized in that the elastic deformation of the side is restored.

  As an action, in the first stage of impact absorption at the time of collision, the soft first energy absorbing member of the energy absorbing members hits the knee of the pedestrian, and the first energy absorbing member is crushed and deformed to absorb the impact. The lower beam hits the lower part of the pedestrian's knee and rotates backward about the bumper beam side, so that the lower beam itself, the bracket, the bumper beam, and the extension member are deformed to have elastic deformation and absorb the energy at the time of collision.

  If the lower beam is made harder than the first energy absorbing member, the energy absorption amount of the first energy absorbing member is reduced, the input load to the pedestrian's knee is suppressed, and the energy absorption amount of the lower beam is increased. Is possible.

  In the second stage of shock absorption, the second energy absorbing member that is harder than the first energy absorbing member is crushed and deformed to absorb a large energy at the time of collision, and the lower beam itself, bracket, bumper beam, and extension member are elastically deformed. By returning to the original position, the knee bending angle can be reduced by rebounding the lower knee of the pedestrian to the side away from the bumper with the bumper beam.

  In the invention according to claim 1, the bracket is extended downward from the bumper beam, and the lower beam is attached to the end of the bracket so as to be positioned below the energy absorbing member, and the lower beam side is caused by the collision between the lower beam and the leg of the pedestrian. Since the lower beam is retracted by deforming it with elastic deformation, the energy absorbing member and the lower beam can share the large energy at the time of collision with a smaller displacement, improving the energy absorption efficiency and the bumper's The front and rear length can be shortened.

  Further, for example, in the bumper structure that does not include the lower beam, the lower knee can also be decelerated by the lower beam in the present invention, compared with the case where only the knee portion where the energy absorbing member collides is decelerated. can do.

  In the invention which concerns on Claim 2, an energy absorption member is arrange | positioned on the back side of the soft 1st energy absorption member arrange | positioned at the front side, and this 1st energy absorption member, and is harder than a 1st energy absorption member. Two energy absorbing members, and the first energy absorbing member and the second energy absorbing member perform shock absorption on the pedestrian leg in two stages. In the first stage of the shock absorption, the first energy absorbing member And the lower beam absorbs the impact by the deformation of the second energy absorbing member, and the lower beam absorbs the impact by the deformation of the second energy absorbing member. So that the elastic deformation of the side is restored, it absorbs a large amount of energy, mainly in the lower beam in the first stage of the collision, In the latter half of the crash, the energy absorption efficiency is improved mainly by the second energy absorbing member, while the pedestrian's leg deceleration and knee bending angle injury values can be satisfied, and pedestrian leg protection A corresponding vehicular bumper structure can be provided.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
FIG. 1 is a perspective view showing an essential part of a vehicle bumper structure according to the present invention (an arrow (FRONT in the figure represents the front of the vehicle; the same applies hereinafter)), and a bumper body 11 is arranged in the vehicle width direction. A bumper beam 12 made of a steel plate extending in a curved manner, an energy absorbing member 13 made of foamed resin attached to the front surface of the bumper beam 12, and a vehicle attached to the lower part of the bumper beam 12 via a pair of left and right brackets 14 and 16. The lower beam 17 extends so as to bend in the width direction.

FIG. 2 is a cross-sectional view of the vehicle bumper structure according to the present invention. The bumper 10 includes a bumper body 11 and a resin bumper face 21 that covers the front side of the bumper body 11.
The bumper beam 12 includes an upper beam 22 and a lower beam 23 having a rectangular cross section sharing the front wall 12A, and a front connection portion 24 for connecting the upper beam 22 and the lower beam 23. In the member in which the recess 26 is formed, the rear walls 22d and 23d of the upper beam 22 and the lower beam 23 are extended members at the distal ends of a pair of left and right side members 28 and 28 (only one reference numeral 28 is shown). 27 is attached.

  The upper beam 22 includes a front wall 12A, an upper wall 22b and a lower wall 22c extending rearward from the upper edge of the front wall 12A and the upper edge of the front connection portion 24, and the upper wall 22b and the lower wall 22c. And a rear wall 22d connecting the respective rear edges.

  Similarly, the lower beam 23 includes a front wall 12A, an upper wall 23b and a lower wall 23c extending rearward from each of the lower edge of the front connection portion 24 and the lower edge of the front wall 12A, and the upper wall 23b and the lower wall. The rear wall 23d connects the rear edges of the walls 23c.

  The energy absorbing member 13 is made harder than the first energy absorbing member 31 while being disposed on the rear side of the first energy absorbing member 31 and the soft first energy absorbing member 31 disposed on the front side. The second energy absorbing member 32 is included.

  The first energy absorbing member 31 has a U-shaped cross section including a front wall 31a, an upper wall 31b extending rearward from the upper edge of the front wall 31a, and a lower wall 31c extending rearward from the lower edge of the front wall 31a. It is a member, and is formed softer than the second energy absorbing member 32 by making the cross-sectional area smaller or making a cut.

  The second energy absorbing member 32 includes a front wall 32a to which the rear edges of the upper wall 31b and the lower wall 31c of the first energy absorbing member 31 are attached, and a first wall extending obliquely upward and rearward from the upper edge of the front wall 32a. An inclined wall 32b, a second inclined wall 32c extending diagonally upward and rearward from the upper edge of the first inclined wall 32b, an upper wall 32d extending rearward from the upper edge of the second inclined wall 32c, and a lower part of the front wall 32a The lower wall 32e extending rearward from the edge and the rear wall 32f connecting the rear edges of the upper wall 32d and the lower wall 32e, and the boss shape formed on the rear wall 32f is the front wall 12A of the bumper beam 12. The rear wall 32 f is attached to the front wall 12 </ b> A of the bumper beam 12 by being inserted into a hole formed in the hole or by bonding.

The brackets 14 and 16 (only one reference numeral 16 is shown. Reference numeral 14 refers to FIG. 1) are attached to the lower wall 23c of the lower beam 23 by welding at the upper ends.
The lower beam 17 is a member attached to the lower front portion of the brackets 14 and 16 by welding. The lower beam body 17a has a U-shaped cross section, and is formed by bending upward and downward from the rear end of the lower beam body 17a. It consists of a flange 17b and a lower flange 17c.

  The bumper face 21 includes a grill lower portion 21 a that covers the lower portion of the front grill of the vehicle, an upper face 21 b that covers the front and upper sides of the energy absorbing member 13 and the bumper beam 12, and a plurality of lateral portions located in front of the upper portions of the brackets 14 and 16. It is a resin-made integral molded body comprising a lower grille 21c formed of a crosspiece and a lower face 21d that covers the lower portions of the brackets 14 and 16 and the front and lower portions of the lower beam 17.

Next, the operation of the bumper 10 (see FIG. 2) described above will be described.
3A to 3C are operation diagrams showing the operation of the vehicle bumper structure according to the present invention. In the drawing, the bumper face 21 (see FIG. 2) of the bumper 10 (see FIG. 2) is omitted for convenience of explanation.
(A) has shown the state immediately before the bumper main body 11 collides with the leg part impactor 40 which simulated the leg part of the pedestrian.
The first energy absorbing member 31 and the lower beam 17 of the energy absorbing member 13 protrude to substantially the same position in the longitudinal direction of the vehicle.

  The leg impactor 40 includes a crus 40A, a thigh 40B disposed above the crus 40A, and joints that swingably connect the crus 40A and the thigh 40B. Knee part 41 is set on the upper part of the lower leg part 40A close to the joint part 40C, the lower knee part 42 is set on the lower leg part 40A below the knee part 41, and the middle part of the thigh part 40B. An upper knee 43 is set in the part.

Sensors for detecting displacement and acceleration are embedded in the knee 41, the lower knee 42, and the upper knee 43. The knee part 41, the lower knee part 42, and the upper knee part 43 are provided inside, but in the following description, the knee part 41, the lower knee part 42, and the upper knee part 43 including the periphery and the surface close thereto are used.
Further, an angle meter for detecting a bending angle (knee bending angle) between the crus 40A and the thigh 40B is provided in the crus 40A or the thigh 40B.

In the above state, the bumper body 11 is moved forward to collide with the leg impactor 40 as indicated by the white arrow. The collision speed at which the vehicle including the bumper body 11 collides with the leg impactor 40 at this time is, for example, 40 km / h .

FIG. 5B shows a first stage of the collision in which the energy absorbing member 13 collides with the knee 41 of the leg impactor 40 and the lower beam 17 collides with the lower knee portion 42 of the leg 41.
When the energy absorbing member 13 collides with the knee portion 41, the soft first energy absorbing member 31 of the energy absorbing member 13 is crushed and absorbs energy at the time of collision, so that the input load to the knee portion 41 is suppressed.

  Further, when the lower beam 17 collides with the lower knee portion 42, the lower beam 17 itself, the brackets 14 and 16, the bumper beam 12, and the extension member 27 are elastically deformed, and the lower beam 17 is centered on the bumper beam 12 or a portion close to the bumper beam 12 by an arrow. As shown, it rotates backwards and absorbs energy at the time of collision.

  At this time, the lower beam 17 side is retracted while being elastically deformed, so that the foot portion of the knee lower portion 42 is avoided. Further, since the first energy absorbing member 31 and the lower beam 17 absorb the energy by controlling the respective generated loads, the knee portion 41, the lower knee portion 42, and the upper knee portion 43 are synchronously relative to the bumper body 11. Displace. Therefore, no knee bending angle occurs.

(C) has shown the 2nd step of the collision which the vehicle further advanced from the state of (b).
The harder second energy absorbing member 32 is further crushed from the state in which the first energy absorbing member 31 is crushed, and a larger energy is absorbed than in the case of the first energy absorbing member 31.

  Further, when the deflection of the lower beam 17 toward the rear of the vehicle increases, the reaction force also gradually increases, and after the absorption of energy by the second energy absorbing member 32 is completed, the load generated on the lower beam 17 decreases, and each part on the lower beam 17 side Thus, the lower beam 17 rotates forward as indicated by the arrow. Along with this, the lower knee portion 42 rotates in the clockwise direction in the figure as with the lower beam 17.

At this time, the knee upper part 43 also rotates clockwise, but the knee bending angle β between the crus 40A and the thigh 40B can be reduced by rotating the knee lower part 42 clockwise.
When the lower beam 17 is not provided, clockwise rotation of the lower knee part 42 (that is, the lower leg part 40A) does not occur, so the lower leg part 112 and the thigh part 40B indicated by a two-dot chain line in the figure The knee bending angle, which is the angle formed, becomes large.

FIG. 4 is a first graph showing the evaluation results of the vehicle bumper structure according to the present invention, and shows the time course of the relative displacement amount of each part of the leg impactor when the bumper collides with the leg impactor.
The vertical axis represents the relative displacement of each part of the leg impactor (the knee 41, the lower knee 42 and the upper knee 43 shown in FIGS. 3A to 3C) with respect to the bumper, and the horizontal axis represents the elapsed time from the collision. ing.
The solid line in the graph indicates the relative displacement of the knee, the broken line indicates the lower knee, and the alternate long and short dash line indicates the upper knee.

  In the range from time zero to time t1 in the figure, that is, the A range (that is, the first stage of the collision shown in FIG. 3B), the knee, lower knee, and upper knee lines overlap, This shows that the lower knee and the upper knee are relatively displaced relative to the bumper body.

  That is, as shown in FIG. 3B, the first energy absorbing member 31 and the lower beam 17 are set with loads generated by the collapse of the first energy absorbing member 31 and the displacement of the lower beam 17, respectively. Since the load is controlled and energy is absorbed, the knee portion 41, the lower knee portion 42, and the upper knee portion 43 are relatively displaced relative to the bumper body 11 in synchronization. Therefore, the knee bending angle of the leg impactor 40 can be suppressed.

  For example, in a conventional bumper that does not include the lower beam 17, only the knee 41 is decelerated with respect to the lower knee 42 and the upper knee 43, so that the knee bending angle of the leg impactor 40 is generated from the initial stage of the collision.

  In the range from the time t1 to the time t2 in the drawing, that is, the B range (that is, the second stage of the collision shown in FIG. 3C), the relative displacement amount of the upper knee is almost the same as the A range. However, the relative displacement amount of the knee gradually decreases with time, and the relative displacement amount of the lower knee increases further with time than the knee. After the latter period, the increased relative displacement has decreased.

This means that the lower part of the knee that has moved to the bumper body side in the range B is separated from the bumper body side (the lower part of the knee rebounds). That is, the knee bending angle of the leg impactor is reduced.
From this, the knee bending angle of the leg impactor can be further reduced by performing the rebound of the lower part of the knee with the lower beam as early as possible in the B range.

FIG. 5 is a second graph showing the evaluation result of the vehicle bumper structure according to the present invention, and shows the relationship between the deceleration of each part of the leg impactor and the relative displacement when the bumper collides with the leg impactor. . The vertical axis represents the deceleration of each part of the leg impactor, and the horizontal axis represents the relative displacement of each part of the leg impactor with respect to the bumper. In the figure, the alternate long and short dash line indicates the knee, the broken line indicates the lower knee, and the solid line indicates the sum of the deceleration of the knee and the deceleration of the lower knee.
In the first stage (A range) in which the bumper collides with the leg impactor, the knee deceleration peak is g1. This occurs when the energy absorbing member 13 shown in FIG. 3 (b), particularly the soft first energy absorbing member 31 disposed on the front side, is crushed.
In the first stage, the deceleration of the lower knee is larger than the deceleration of the knee, and the peak is g2. The deceleration g2 is larger than the deceleration g1.

In the second stage (B range) in which the bumper collides with the leg impactor, the knee deceleration increases from the first stage and increases to g3. This is generated by the second energy absorbing member 32 of the energy absorbing member 13 as shown in FIG.
Further, the deceleration of the lower knee greatly decreases after the peak g2 in the first stage and approaches zero as the relative displacement amount increases. This is due to the rebound of the lower knee.

  As described above, in the first stage of the collision, the first energy absorbing member and the lower beam share and absorb energy. Specifically, when the energy absorption amount by the first energy absorbing member is E1, and the energy absorption amount by the lower beam is E2, the energy absorption amount E2 is larger than twice the energy absorption amount E1 (E1x2 <E2).

  That is, the first energy absorbing member is crushed and absorbs a small amount of energy to reduce the knee deceleration, and the lower beam side (the lower beam itself, the bracket, the bumper beam, and the extension member) is elastically deformed and rotated backward to produce a large amount. The lower knee deceleration is reduced by absorbing energy.

  In the second stage, of the second energy absorbing member and the lower beam, the second energy absorbing member bears most of the energy absorption, and the lower beam 17 rebounds the lower part of the knee by the return of elastic deformation, and the leg impactor It works to reduce the knee bending angle.

  The total deceleration of the knee and lower knee decelerations is peak g4 in the first stage and increases to deceleration g5 in the second stage, but the maximum allowable deceleration (injury standard) (Injury value) of GP) These decelerations g4 and g5 are less than that, and the determination is OK. Further, the knee bending angle of the leg impactor is also below the injury value, and the determination is OK.

  Thus, d2 which is the total relative displacement amount of the first stage and the second stage is obtained by making the total sum of the deceleration below the injury value and as large as possible in the first stage and the second stage of the collision, respectively. Can be made smaller, whereby the front-rear length of the bumper 101 (see FIG. 2) can be made shorter.

  As shown in FIGS. 2 and 3 (a) to 3 (c), in the present invention, the side members 28, 28 are arranged on the left and right of the front portion of the vehicle body, and extend to the tips of these side members 28, 28. In the vehicle bumper structure in which the bumper beam 12 is attached via the member 27 and the energy absorbing member 13 is attached to the front surface of the bumper beam 12, the brackets 14, 16 are extended downward from the bumper beam 12. A lower beam 17 is attached at the tip and below the energy absorbing member 13, and the lower beam 17 is deformed to have elastic deformation by a collision between the lower beam 17 and a leg impactor 40 as a pedestrian leg. Since the lower beam 17 is moved backward by this, the energy absorbing member 13 and the lower beam 17 share the size at the time of collision. Energy can be absorbed by a smaller displacement and it is possible to shorten the longitudinal length of the bumper 10 improves the energy absorption efficiency.

  Further, for example, in the bumper structure that does not include the lower beam 17, compared to the case where only the knee portion 41 with which the energy absorbing member 13 collides is decelerated, in the present invention, in addition to the knee portion 41, the lower knee portion 42 is also the lower beam 17. The speed can be reduced, and the knee bending angle of the leg can be reduced.

  In the present invention, the energy absorbing member 13 includes a soft first energy absorbing member 31 disposed on the front side, and a rear side of the first energy absorbing member 31. The first energy absorbing member 31 is harder than the first energy absorbing member 31. The first energy absorbing member 31 and the second energy absorbing member 32 absorb the impact on the pedestrian leg in two stages. In the first stage of the impact absorption, The shock is absorbed by the crushing deformation of the energy absorbing member 31 and the deformation having the elastic deformation in which the lower beam 17 rotates rearward around the bumper beam 12 side. In the second stage of shock absorption, the second energy absorbing member 32 is crushed and deformed. Absorbs the impact and restores the elastic deformation on the lower beam 17 side to the original state. In the first stage, the lower beam 17 is mainly used, and the second energy absorbing member 32 is mainly used in the second half of the collision, thereby improving the energy absorption efficiency, and the pedestrian's leg deceleration and knee bending angle injury values. It is possible to provide a vehicle bumper structure that can satisfy the requirements and protect the pedestrian legs.

  In the present invention, the lower beam undergoes plastic deformation in addition to elastic deformation. In addition, the bumper beam has a B-shaped cross section to facilitate elastic deformation. In addition, the bumper beam can be cut out to facilitate the elastic deformation.

  In the present embodiment, as shown in FIG. 2, the first energy absorbing member 31 and the second energy absorbing member 32 are separated from each other. However, the first energy absorbing member 31 and the second energy absorbing member are not limited to this. The member 32 may be integrally formed.

  The bumper structure of the present invention is suitable for a four-wheeled vehicle.

It is a perspective view which shows the principal part of the bumper structure for vehicles which concerns on this invention. It is sectional drawing of the bumper structure for vehicles which concerns on this invention. It is an operation view showing an operation of the vehicle bumper structure according to the present invention. It is a 1st graph which shows the evaluation result of the bumper structure for vehicles which concerns on this invention. It is a 2nd graph which shows the evaluation result of the bumper structure for vehicles which concerns on this invention. It is sectional drawing which shows the conventional bumper structure for vehicles.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Bumper, 12 ... Bumper beam, 13 ... Energy absorption member, 14, 16 ... Bracket, 17 ... Lower beam, 27 ... Extension member, 28 ... Side member, 31 ... First energy absorption member, 32 ... Second energy absorption member, 40. Leg (leg impactor).

Claims (2)

In the vehicle bumper structure in which side members are arranged on the left and right of the front part of the vehicle body, a bumper beam is attached to the front ends of these side members via extension members, and an energy absorbing member is attached to the front surface of the bumper beam.
A bracket extends downward from the bumper beam, and a lower beam is attached to the tip of the bracket and below the energy absorbing member, and the lower beam side is elastically deformed by a collision between the lower beam and a pedestrian leg. A bumper structure for a vehicle, wherein the lower beam moves backward by being deformed.   The energy absorbing member includes a soft first energy absorbing member arranged on the front side and a second energy absorbing member arranged on the rear side of the first energy absorbing member and harder than the first energy absorbing member. The first energy absorbing member and the second energy absorbing member absorb shocks to the pedestrian leg in two stages. In the first stage of shock absorption, the first energy absorbing member is deformed and the lower beam is absorbed. Is absorbed by the deformation having elastic deformation that rotates backward about the bumper beam side, and in the second stage of the shock absorption, the impact is absorbed by the crushing deformation of the second energy absorbing member and the lower beam side The vehicular bumper structure according to claim 1, wherein the elastic deformation of the vehicle returns to its original state.

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