JP2013047046A - Vehicle front end structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle front end structure configured to reduce impact on a leg of a pedestrian when a front end part of a vehicle collides with the pedestrian.SOLUTION: A front bumper 12 includes an upper member U located at a height of a femur of a pedestrian and extended in a width direction of a vehicle V, and a lower member L located at a height of a leg region of the pedestrian and extended in the width direction of the vehicle V. The upper member U is arranged more rearward than the lower member L by a distance which is set on the basis of a maximum amount of deflection, in a rearward direction of the vehicle V, of a portion of the leg region below a contact position with the lower member L. The upper member U comes in contact with the femur until the deflection of the portion of the leg region below the contact position is eliminated, thereby applying a rotating force to the femur along a direction of eliminating the deflection of the leg region.

Description

  The present invention relates to a front end structure of a vehicle, and more particularly, to a front end structure of a vehicle that reduces an impact on a pedestrian when the front end of the vehicle collides with a pedestrian.

  As the vehicle front end structure as described above, for example, those described in Patent Documents 1 and 2 are known. The vehicle front end structure described in Patent Document 1 includes a vehicle width direction member at the front of the vehicle body, an energy absorber provided at the front of the vehicle width direction member, and a lower portion of the bumper. And a projecting member having a tip projecting forward from the member. Further, a bumper face is disposed at the front end portion of the vehicle width direction member and the protruding member, and the energy absorbing member is positioned ahead of a line connecting the tip of the bonnet and the tip of the protruding member.

  In Patent Document 1, by configuring the front end of the vehicle in this way, when the front end of the vehicle collides with a pedestrian, first, the projecting member contacts the pedestrian's knees downward, and the pedestrian's legs Pay. A pedestrian whose leg is removed tilts toward the vehicle. At that time, the energy absorber contacts the pedestrian's knee and absorbs the impact of the contact. As a result, pedestrians are placed on the hood, preventing secondary damage to pedestrians.

  Moreover, in patent document 2, the upper part (bumper reinforcement) of a front bumper is arrange | positioned in the height which substantially opposes the knee of a human body leg part, and the intermediate part and lower part (bumper lower panel) of a front bumper are from the knee of a leg part. It arrange | positions at the height corresponding to a lower part (henceforth a lower leg part).

  When the front end portion of the vehicle configured as described above collides with the leg portion, the upper portion of the front bumper contacts the knee. The impact at that time is transmitted to the bumper reinforcement while being absorbed by the foam material disposed behind the upper part of the front bumper. In addition, in the structure of patent document 2, before a foam material is crushed, it is comprised so that the intermediate part and lower part of a front bumper may contact | abut to a leg part. This restricts the crus from being displaced rearward while dispersing the collision load in the middle and lower parts of the front bumper.

Japanese Patent No. 3740901 JP 2007-055367 A (paragraph numbers 0059 to 0063, FIG. 2)

  Since the actual pedestrian's leg is an elastic body with a bend, when the front end of the vehicle collides with the actual pedestrian's leg, the leg bends around the collision site, and then Bends in the opposite direction due to the restoring force. At this time, a force in the bending direction acts on the knee, which may damage the knee.

  In other words, the front end structure of the vehicle that reduces the impact at the time of a collision with a pedestrian needs to consider the bending of the leg. However, the bends of the legs are not considered in the structures of Patent Documents 1 and 2 described above.

  In view of the above problems, an object of the present invention is to provide a vehicle front end structure that reduces an impact on a pedestrian's leg when the vehicle front end collides with a pedestrian.

  In order to solve the above problems, the front end structure of the vehicle according to the present invention is located at the height of the thigh of the pedestrian, and is an upper member that extends in the width direction of the vehicle inside the front bumper of the vehicle. And a lower member positioned at the height of the lower leg of the pedestrian and extending in the width direction inside the front bumper, and the upper member is lower than the lower member. The member is disposed rearward by a distance set based on the maximum amount of bending in the rearward direction of the vehicle at a position below the contact position of the lower leg when the member comes into contact with the lower leg. When the bend of the lower part of the lower leg part is eliminated, the thigh is brought into contact with the thigh so that a rotational force in a direction along the direction in which the flexion is eliminated is applied to the thigh. Make it work.

  In this configuration, when the front end of the vehicle collides with the pedestrian, the lower member first comes into contact with the lower leg of the pedestrian. At this time, the lower end of the crus is displaced toward the rear of the vehicle with the contact position as a base point. At the same time, the thigh tilts toward the vehicle rear side. Thereafter, the lower end of the displaced crus starts to move in the vehicle forward direction by reaction. On the other hand, the thigh is in contact with the upper member while the lower end of the lower leg is displaced forward of the vehicle, that is, the lower end of the lower leg is resolved. By this contact, a rotational force is applied to the thigh along the direction in which the bending of the lower leg is eliminated with the contact position as the center. Therefore, forces in substantially the same direction act on both the lower leg and the thigh. As a result, the lower leg and the knee move in substantially the same direction, and the bending of the lower leg is reduced. Therefore, the bending force to the knee is reduced and the knee damage can be efficiently suppressed.

It is a figure showing the behavior of the leg when the vehicle which has the front-end part structure of the vehicle which concerns on this invention, and the leg of a pedestrian collide. It is a figure showing the behavior of the leg when the vehicle which has the front end part structure of the conventional vehicle, and the pedestrian's leg collide. It is side sectional drawing of the front-end part of a vehicle. It is a perspective view inside the front end part of a vehicle. It is a graph showing the time passage of the injury value when a leg collides with the front-end part of a vehicle. It is a graph showing the time passage of the injury value when a leg collides with the front end part of the vehicle in the present invention.

  First, the concept of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating the behavior of a leg 1 when a front end portion of a vehicle V to which a vehicle front end structure according to the present invention is applied collides with a pedestrian leg 1. In addition, this figure is the figure seen from the left side of the vehicle V, and the left in the drawing is the front of the vehicle V.

  As shown in the figure, the leg 1 of the pedestrian has a thigh 1U and a crus 1L connected by a knee 1N. The leg 1 is not a rigid body but an elastic body having a flexure.

  On the other hand, an upper member U and a lower member L are provided at the front end of the vehicle V. As is apparent from the figure, the upper member U is located near the thigh 1U, that is, above the knee 1N, and the lower member L is located near the crus 1L, ie, below the knee 1N. Further, the upper member U is located on the rear side of the vehicle V compared to the lower member L. In the following description, the amount of rearward displacement of the vehicle V relative to the lower member L of the upper member U is referred to as a retraction amount D.

  When the front end portion of the vehicle V collides with the pedestrian's leg 1, as shown in FIG. 1B, the lower member L first comes into contact with the crus 1L. As described above, since the leg 1 has a bend, the lower end side portion (hereinafter referred to as the lower end portion) of the lower leg portion 1L is in contact with the lower member L. Is displaced to the rear of the vehicle V from the base point. In the following description, the displacement amount (bending amount) at the time of the collision is referred to as a maximum amount x.

This maximum bending amount x can be obtained statistically through an experiment using a dummy. However, according to the study of the inventors of the present invention,
x = qh ⁴ / 8EI
It can be approximated by Here, q is a value determined by the mass of the lower leg 1L, the hardness of the lower member L, etc., h is the height of the lower member, E is the elastic modulus of the lower leg 1L, and I is the cross section 2 of the lower leg 1L. Next moment. Note that these feature values of the lower leg 1L can be obtained by statistically processing feature values of a large number of adults.

  In the vehicle front end structure according to the present invention, the retraction amount D of the upper member U with respect to the lower member L is set to x to 3x based on the maximum bending amount x. When the retraction amount D is set in this way, it is clear from experiments by the inventors of the present invention that the leg 1 behaves as shown in FIGS. In the experiment, the height (h) of the lower member L is 230 mm, the height of the upper member U is 730 mm, the height of the knee 1N is 600 mm, and the retraction amount D is 2.5x.

  As shown in FIG. 1 (c), the crus 1L, which is in contact with the lower member L and whose lower end is displaced rearward of the vehicle V, is flipped up in front of the vehicle V by the reaction, and the crus 1L The bending of the lower end of the will be eliminated. During this time, the thigh 1U tilts toward the vehicle V side. The lower end of the lower leg 1L is eliminated, and particularly preferably, when the lower end of the lower leg 1L is eliminated, the thigh 1U contacts the upper member U. Touch. With this contact, a force in the front upper direction of the vehicle V and the rear lower direction of the vehicle V is applied to the end on the knee 1N side of the thigh 1U and the end on the upper body with the contact position P2 as the center. To do. That is, a rotational force in a direction (clockwise in the figure) along the direction in which the bending of the crus 1L is eliminated acts on the thigh 1U. As a result, as shown in FIG. 1 (d), when the leg 1 is flipped up, the lower leg 1L and the knee 1N move in the same direction, thereby reducing the bending of the lower leg 1L. Damage to the knee 1N can be reduced. Further, since the rotational force acts on the thigh 1U before the lower end of the crus 1L is displaced to the front side of the vehicle V, after the bending of the crus 1L is resolved, the front side of the vehicle V is further increased. Can be suppressed, and damage to the knee 1N can be reduced.

  On the other hand, FIG. 2 is a diagram illustrating the behavior of the leg 1 when the front end of the vehicle V and the leg 1 collide with the retraction amount D set to 3x or more. When the front end of the vehicle V collides with the pedestrian's leg 1, as shown in FIG. 2 (b), the lower member L first comes into contact with the lower leg 1L, and the lower end of the lower leg 1L is It is displaced (becomes) rearward of the vehicle V with the contact position P1 with the lower member L as a base point.

  As shown in FIG. 2 (c), the crus 1L, which is in contact with the lower member L and whose lower end is displaced rearward of the vehicle V, is flipped up in front of the vehicle V by the reaction, and the crus 1L The bending of the lower end of the will be eliminated. During this time, the thigh 1U tilts toward the vehicle V side. However, since the retraction amount D of the upper member U is set to be larger than 3x, the thigh 1U is not in contact with the upper member U when the bending of the lower end of the crus 1L is resolved. . Therefore, the lower end portion of the crus 1L is displaced to the front side of the vehicle V due to the action of the upward force of the vehicle V. Thereafter, the thigh 1U comes into contact with the upper member U.

  Then, as shown in FIG. 2D, a clockwise rotational force in the drawing acts on the thigh 1U that is in contact with the upper member U with the contact position P2 as the center. This rotational force acts on the end of the lower leg 1L on the knee 1N side via the knee 1N. On the other hand, a force toward the rear side of the vehicle V acts again on the lower end of the lower leg 1L due to a flexible restoring force, and a force in the flip-up direction acts on the end of the lower leg 1L on the knee 1N side. To do. That is, a clockwise force in the figure acts on the thigh 1U, and a counterclockwise force in the figure acts on the crus 1L. Thereby, the bending force with respect to the knee 1N increases, and the damage to the knee 1N increases.

  FIG. 5 is a graph showing the change over time of the injury value (impact magnitude) when the leg collides with the front end of the vehicle. When the leg is a rigid body, the injury value is almost a parabolic curve, as indicated by the solid line in the figure. Therefore, when the conventional rigid body dummy is used, the front end of the vehicle is designed so that the vertex of the curve (maximum value of injury value) is smaller than a predetermined threshold value. However, since the actual leg has a bend, as shown by the alternate long and short dash line in the figure, it has a shape that vibrates along the curve of the solid line. That is, the maximum actual injury value is larger than the maximum injury value at the time of design. Therefore, when the actual leg collides with the front end of a vehicle designed so that the vertex of the curve is slightly smaller than a predetermined threshold using a rigid dummy, the maximum injury value is predetermined as shown in the figure. There is a risk of exceeding the threshold.

  On the other hand, according to the structure of the front end portion of the vehicle of the present invention, the leg 1 collides with the front end portion of the vehicle, the lower leg 1L is paid off by the lower member L, When the crus 1L is flipped up, the upper member U gives the thigh 1U a rotational force in a direction along the direction in which the bending of the crus 1L is eliminated, whereby the knee 1N of the crus 1L. A force in substantially the same direction can be applied to the end on the side and the end on the knee 1N side of the thigh 1U to reduce the bending force to the knee 1N. That is, according to the present invention, since the bending of the crus 1L is reduced, as shown in FIG. 6, the vibration of the injury value is suppressed, and the injury value curve of the leg having the bending (the dashed line in the figure). ) Approximates the shape of the injury value curve (solid line in the figure) of the rigid dummy. Therefore, the maximum value of the injury value for the bent leg can be reduced.

  The vehicle front end structure according to the present invention will be described below with reference to the drawings. FIG. 3 is a side sectional view of the front end portion of the vehicle V to which the present invention is applied, and FIG. 4 is a perspective view of the internal structure of the front end portion of the vehicle V.

  As shown in FIG. 3, the vehicle V includes a hood hood 11 that covers an engine room in which an engine or the like is disposed, and a front bumper 12 that is disposed below the front end of the hood hood 11. The front bumper 12 of the present embodiment includes an upper bumper member 12a, a middle bumper member 12b, and a lower bumper member 12c.

  As shown in FIG. 4, a side member 13 that supports an engine, a suspension, a suspension member, and the like, and a radiator support 20 that supports the radiator and the like are provided inside the front end of the vehicle V. The radiator support 20 is disposed such that the front end face of the vehicle V faces the inside of the front bumper 12.

  The radiator support 20 includes an upper support member 21 and a lower support member 22 that extend in the width direction of the vehicle V, a right support member 23 that extends in the height direction of the vehicle V, and a left support member 24. Configured. In the present embodiment, the radiator support 20 is integrally formed of resin, but may be formed of other materials.

  A protrusion 22 a that protrudes forward of the vehicle V is integrally formed in front of the vehicle V of the lower support member 22. The protruding portion 22a is formed in a substantially flat plate shape over the entire width of the lower support member 22, and the strength is increased by appropriately providing a rib or the like.

  Further, the front end portion of the side member 13 is connected to an intermediate portion in the height direction of the rear end face of the vehicle V of the right support member 23 and the left support member 24. On the other hand, a metal bumper reinforcement 14 is provided in the width direction of the vehicle V over the intermediate portion in the height direction of the front end surface of the right support member 23 and the left support member 24 with respect to the vehicle V. The bumper reinforcement 14 is bolted to the side member 13 via a right support member 23 and a left support member 24 at the right end portion and the left end portion, respectively.

  In the present embodiment, the upper support member 21 and the protruding portion 22a of the lower support member 22 are used as the upper member U and the lower member L of the present invention, respectively. Therefore, as shown in FIG. 3, the upper member U is displaced further to the rear side of the vehicle V than the lower member L. As described above, if the members constituting the radiator support 20 are used as the upper member U and the lower member L, it is not necessary to separately provide an EA material, which is advantageous in terms of cost, weight, and productivity.

  By configuring the front end portion of the vehicle V in this way, when the vehicle V collides with a pedestrian, the projecting portion 22a first comes into contact with the lower leg portion of the pedestrian to pay the pedestrian's leg. At this time, the lower end of the lower leg is displaced to the rear side of the vehicle V. Thereafter, the lower end of the lower leg starts to move forward of the vehicle V due to the reaction. At this time, the thigh of the pedestrian tilts toward the rear of the vehicle V and comes into contact with the front bumper member 12a and the front end of the hood hood 11. Since the strength of the upper bumper member 12a and the hood hood 11 is not so high, the upper bumper member 12a and the hood hood 11 are crushed to the rear side of the vehicle V by contact with the thigh. The thigh is in contact with the upper support member 21. As a result, a rotational force in a direction along the direction to eliminate the bending of the lower leg acts on the thigh, and the bending force to the pedestrian's knee is reduced as described above.

  In this embodiment, the bumper reinforcement 14 is set to a height that makes contact with the pedestrian's knee. Therefore, when the front end portion of the vehicle V collides with a pedestrian's leg, the bumper reinforcement 14 does not hinder the rotation of the thigh.

  In addition, the pedestrian in this invention is an adult who has the average body shape obtained statistically.

[Another embodiment]
(1) In the above-described embodiment, the members constituting the radiator support 20 are used as the upper member U and the lower member L. However, one or both of the upper member U and the lower member L may be composed of other members. Absent.

(2) In the above embodiment, the upper member U and the lower member L are made of resin, but may be formed of a rigid body such as metal.

  INDUSTRIAL APPLICABILITY The present invention can be used for a vehicle, in particular, a low floor design vehicle in which the lower end portion of the bumper is located on the lower leg portion of a pedestrian.

D: Retraction amount L: Lower member U: Upper member V: Vehicle 12: Front bumper 12a: Upper bumper member 12b: Middle bumper member 12c: Lower bumper member 21: Upper support member 22: Lower support member 22a: Projection

Claims (1)

An upper member located at the height of the thigh of the pedestrian and extending in the width direction of the vehicle inside the front bumper of the vehicle;
A lower member located at the height of the lower leg of the pedestrian and extending in the width direction inside the front bumper,
The upper member is larger than the lower member in the rearward direction of the vehicle at a position below the contact position of the lower leg when the lower member comes into contact with the lower leg. Is arranged rearward by a distance set on the basis of the thigh, and the thigh is brought into contact with the thigh while the bending of the portion below the abutment position of the lower thigh is eliminated. A front end structure of a vehicle, wherein a rotational force in a direction along a direction in which bending is eliminated is applied.

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