JP2015172402A - Energy absorbing member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress obliquely-eccentric crush progress while using a composite-material made cylindrical member whose cross section vertical to an axial direction is formed in an equal wall thickness.SOLUTION: A crush box 1 comprises: a cylindrical member 11 which is mounted to each of both left and right sides of a vehicle front, absorbs impact energy while being crushed to a fore-and-aft direction of a vehicle, is constituted of a composite material, formed cylindrical along the fore-and-aft direction, and has a cross section vertical to the fore-and-aft direction having a substantially-equal wall thickness; and a reinforcing member 12 which is constituted of the composite material, and integrally formed at the inside of the vehicle of the cylindrical member 11. The crush box 1 is constituted so that a product of a vertical elastic modulus and a cross section area at a portion at the inside of the vehicle rather than a center axis of the cylindrical member 11 becomes larger than that at the other portion at the outside of the vehicle.

Description

  The present invention relates to an energy absorbing member that is mounted on an automobile and absorbs impact energy during a collision or the like.

  2. Description of the Related Art Conventionally, an energy absorbing member that is mounted on a front portion of an automobile and mainly absorbs impact energy from the front is known. This energy absorbing member is generally formed in a cylindrical shape along the longitudinal direction of the automobile, and absorbs the impact load (impact energy) by receiving the impact load and crushing in the axial direction. As the energy absorbing member, a member made of a metal (for example, an aluminum alloy) has been used, but in recent years, it is made of a composite material (for example, fiber reinforced plastic) that has a more excellent energy absorbing performance and is lightweight. Things have been developed and put into practical use (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-235763

  By the way, such an energy absorbing member is generally provided on each of the left and right sides between the bumper beam and the front frame of the automobile. Therefore, in each energy absorbing member, as shown in FIG. 4 (a), the load acting on the vehicle inner side during the frontal collision is caused by the influence that the left and right sides of the bumper beam are inclined obliquely. It is larger than the one that acts on the portion of FIG.

  At this time, if the energy absorbing member is a simple cylindrical tube having a uniform thickness, the load distribution in the cross section perpendicular to the front-rear direction becomes uniform, and as shown in FIG. The crushing of the energy absorbing member proceeds in a state of being obliquely biased toward the vehicle inner side. Then, if the energy absorbing member is obliquely biased and crushed, there arise problems that the load that can be absorbed is not stable and the crushing residual amount (residual crushing) becomes large.

  It seems that this problem can be solved by using a cylindrical energy absorbing member formed thicker on the inner side of the vehicle. However, since the energy absorbing member is made of a composite material such as fiber reinforced plastic, it is difficult to form it in the above-described uneven cylindrical shape by a manufacturing method such as pultrusion which is preferable in terms of productivity. That is, it is not preferable in terms of productivity to form the energy absorbing member in an unevenly cylindrical shape.

  The present invention has been made in view of the above problems, and suppresses the development of crushing that is obliquely biased while using a cylindrical member made of a composite material in which a cross section perpendicular to the axial direction is formed with a uniform thickness. An object of the present invention is to provide an energy absorbing member that can be used.

In order to achieve the above object, the invention described in claim 1
An energy absorbing member that is mounted on each of the left and right sides of the front part of the vehicle and absorbs impact energy by crushing in the longitudinal direction of the vehicle,
A first member that is made of a composite material reinforced with resin and is formed in a cylindrical shape along the front-rear direction and a cross-section perpendicular to the front-rear direction is formed with a substantially uniform thickness;
A second member formed of a composite material in which resin is reinforced with fibers, and integrally provided on the vehicle inner side of the first member;
With
In each cross section perpendicular to the front-rear direction, the product of the longitudinal elastic modulus and the cross-sectional area in the portion inside the vehicle relative to the central axis of the first member is configured to be larger than that in the portion outside the vehicle. It is characterized by that.
Here, the “longitudinal elastic modulus” is an elastic modulus with respect to a load (compressive load) along the front-rear direction.

The invention according to claim 2 is the energy absorbing member according to claim 1,
The second member has a higher longitudinal elastic modulus than the first member.

The invention according to claim 3 is the energy absorbing member according to claim 1 or 2,
Said 2nd member is affixed on the outer peripheral surface inside the vehicle of said 1st member, It is characterized by the above-mentioned.

  According to the first aspect of the present invention, a composite material is also formed on the vehicle inner side of the first member made of a composite material having a cylindrical shape along the front-rear direction and a cross section perpendicular to the front-rear direction formed to have a substantially uniform thickness. A second member made of a material is integrally provided, and in each cross section perpendicular to the front-rear direction, the product of the longitudinal elastic modulus and the cross-sectional area at the portion inside the vehicle with respect to the central axis of the first member is the vehicle outer side. It is comprised so that it may become larger than the thing in this part. As a result, unlike the conventional case where the cylinder is formed with a simple uniform wall thickness, even when the impact load is biased toward the inside of the vehicle, the crushing of the energy absorbing member proceeds in a state of being obliquely biased. Can be suppressed. Therefore, it is possible to suppress the crushing development that is obliquely biased while using the cylindrical member (first member) made of the composite material in which the cross section perpendicular to the axial direction is formed with a uniform thickness.

  According to the invention described in claim 2, since the second member has a higher longitudinal elastic modulus than the first member, the weight can be reduced as compared with the conventional case in which the second member is formed in a single cylindrical shape with uniform thickness. be able to.

It is a top view which shows typically the principal part of the vehicle by which the crash box in embodiment is mounted. It is sectional drawing in the II-II line of FIG. It is sectional drawing which shows the modification of the crush box in embodiment. It is a figure for demonstrating the crushing progress in the conventional crash box.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view schematically showing a main part of a vehicle 100 on which a crash box 1 according to this embodiment is mounted, and FIG. 2 is a cross-sectional view taken along line II-II in FIG.
In the following description, “front”, “rear”, “left”, and “right” refer to directions viewed from the vehicle 100 on which the crash box 1 is mounted, unless otherwise specified.

  As shown in FIG. 1, a crash box 1 is an energy absorbing member according to the present invention, and is mounted on both left and right sides between a bumper beam 101 and a front frame 102 of a vehicle (automobile) 100, mainly for a vehicle. Absorbs impact from the front. Specifically, as shown in FIGS. 1 and 2, the crash box 1 includes a cylindrical member 11 that is a main part thereof, and a reinforcing member 12 that reinforces the cylindrical member 11.

  Among these, the cylindrical member 11 has a cylindrical shape having a central axis Ax along the front-rear direction and a cross section perpendicular to the front-rear direction formed to have a substantially uniform thickness. The cylindrical member 11 is made of fiber reinforced plastics (FRP), which is a composite material in which resin is reinforced with fibers. Examples of the fiber include carbon fiber, glass fiber, basalt fiber, and aramid fiber, and it is preferable to use a carbon fiber excellent in energy absorption and strength. The cylindrical member 11 has a front end surface attached to the bumper beam 101 and a rear end surface attached to the front frame 102.

  On the other hand, the reinforcing member 12 is formed in a semi-cylindrical shape and is integrally provided on the vehicle inner side over the entire length of the cylindrical member 11. In this embodiment, the outer periphery of the cylindrical member 11 on the vehicle inner side is provided. Affixed to the surface. Similar to the cylindrical member 11, the reinforcing member 12 is made of FRP, which is a composite material in which resin is reinforced with fibers, and is preferably made of FRP using carbon fibers. However, the reinforcing member 12 has a higher elastic modulus (hereinafter referred to as “longitudinal elastic modulus”) with respect to a load (compressive load) along the front-rear direction than the cylindrical member 11.

  By providing such a reinforcing member 12, the crash box 1 has a cross section perpendicular to the front-rear direction so that the product of the longitudinal elastic modulus and the cross-sectional area in the portion inside the vehicle with respect to the center axis Ax is the portion outside the vehicle. It is comprised so that it may become larger than the thing in. In particular, in the present embodiment, the above-described product in the inner portion of the vehicle is about 1.4 times that in the outer portion of the vehicle.

  In the crash box 1 having the above configuration, for example, when the vehicle 100 collides with an object in front, an impact load from the front is applied to the crash box 1 via the bumper beam 101. And the crash box 1 absorbs the said impact load (impact energy) by receiving this impact load and crushing to an axial direction (front-back direction).

At this time, a load that is larger and obliquely outward than the portion on the vehicle outer side acts on the inner portion of the crash box 1 (see FIG. 4A). Therefore, if the crash box 1 has a simple uniform wall thickness, the crushing of the crash box 1 proceeds in a state of being inclined obliquely toward the inner side of the vehicle (FIG. 4B). reference).
However, in each of the cross sections perpendicular to the front-rear direction, the crash box 1 of the present embodiment has a product of a longitudinal elastic modulus and a cross-sectional area in the vehicle inner portion, that is, a load that deforms the vehicle inner portion in the front-rear direction. It is comprised so that it may become larger than the thing in the part outside a vehicle. Therefore, it is possible to suppress the crushing of the crush box 1 from proceeding in an obliquely biased state, and the crush box 1 can be crushed while maintaining a crushing surface substantially perpendicular to the front-rear direction.

As described above, according to the crash box 1 of the present embodiment, the cylindrical member 11 made of a composite material that has a cylindrical shape along the front-rear direction and a cross-section perpendicular to the front-rear direction has a substantially uniform thickness. Similarly, a reinforcing member 12 made of a composite material is integrally provided on the inner side of the vehicle, and in each cross section perpendicular to the front-rear direction, the product of the longitudinal elastic modulus and the cross-sectional area in the portion inside the vehicle with respect to the central axis Ax is It is configured to be larger than that in the portion outside the vehicle. Thus, unlike the conventional case where the cylinder is formed with a simple uniform wall thickness, even when the impact load is biased toward the inside of the vehicle, the crushing of the crash box 1 proceeds obliquely. Can be suppressed.
Accordingly, it is possible to suppress the crushing development that is obliquely biased while using the cylindrical member 11 made of a composite material in which a cross section perpendicular to the axial direction is formed with an equal thickness. As a result, the use of the cylindrical member 11 that is similarly formed with a uniform thickness as compared with the conventional case that is formed into a single cylindrical shape with a uniform thickness, while maintaining good productivity and stable energy absorption performance. And reduction of the remaining crushing amount (remaining crushing).

Further, since the reinforcing member 12 has a higher longitudinal elastic modulus than that of the cylindrical member 11, the weight can be reduced as compared with the conventional case where the reinforcing member 12 is formed in a single cylindrical shape having a uniform thickness.
Hereinafter, the lightening effect will be specifically described.
The crush box 1 of the present embodiment is provided with the reinforcing member 12 having a high elastic modulus, so that the load at the time of crushing is increased as compared with the conventional one formed in a single cylindrical shape having a uniform thickness. On the other hand, it is necessary to reduce the thickness of the cylindrical member 11 because of the necessity of maintaining the overall load-displacement characteristics with respect to this conventional one.
Here, since there is a correlation between the product of the longitudinal elastic modulus, the cross-sectional area, and the crushing load, “the weight increase due to the provision (addition) of the reinforcing member 12” <“the thickness of the cylindrical member 11 “Weight reduction due to reduced thickness” is established.
Therefore, the crush box 1 of the present embodiment has a cross-sectional area perpendicular to the front-rear direction smaller than that of a conventional one formed in a uniform cylindrical shape, and these are made of the same composite material and have a density. Since it is almost the same, it is lighter than the conventional one. However, it is a premise that the crash box 1 and the conventional one have the same overall length, or that all of them are formed in a uniform shape along the front-rear direction.

  The embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention.

For example, in the above embodiment, the cylindrical member 11 is cylindrical, but the cylindrical member 11 may not be cylindrical as long as the cylindrical member 11 is cylindrical, as shown in FIG. There may be.
Moreover, the cylindrical member 11 should just be formed in the cross-section perpendicular | vertical to the front-back direction in substantially uniform thickness, and is formed in the shape from which thickness changes along the front-back direction, or it is formed in the shape of a hollow truncated cone. It may be done.

  Further, if the reinforcing member 12 is integrally provided inside the vehicle of the cylindrical member 11, the reinforcing member 12 does not have to be semi-cylindrical so as to cover the outer peripheral half of the cylindrical member 11, and is provided more locally. May be.

1 Crash box (energy absorbing member)
11 Cylindrical member (first member)
Ax Center shaft 12 Reinforcement member (second member)
100 Vehicle 101 Bumper beam 102 Front frame

Claims (3)

An energy absorbing member that is mounted on each of the left and right sides of the front part of the vehicle and absorbs impact energy by crushing in the longitudinal direction of the vehicle,
A first member that is made of a composite material reinforced with resin and is formed in a cylindrical shape along the front-rear direction and a cross-section perpendicular to the front-rear direction is formed with a substantially uniform thickness;
A second member formed of a composite material in which resin is reinforced with fibers, and integrally provided on the vehicle inner side of the first member;
With
In each cross section perpendicular to the front-rear direction, the product of the longitudinal elastic modulus and the cross-sectional area in the portion inside the vehicle relative to the central axis of the first member is configured to be larger than that in the portion outside the vehicle. An energy absorbing member characterized by that.   The energy absorbing member according to claim 1, wherein the second member has a higher longitudinal elastic modulus than the first member.   The energy absorbing member according to claim 1 or 2, wherein the second member is affixed to an outer peripheral surface of the first member inside the vehicle.

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