JP2000016327A - Front structure of car body - Google Patents

Abstract

(57) [Problem] To provide a front structure of a vehicle body of an automobile which enables effective energy absorption and two-stage energy absorption. SOLUTION: This is a front structure of a vehicle body including a subframe (10) and a front side member (12) connected to the subframe via a mount bracket (14). The front side member includes a front portion (16) located in front of the mounting bracket and a rear portion (17) located behind. The front portion (16) of the front side member is formed so as to be compressed and deformed when a predetermined first axial load is applied from the front, and the rear portion (17) of the front side member is configured to receive the first axial load from the front. It is formed so as not to be deformed when applied and to bend and deform when a predetermined second axial load larger than the first axial load is applied from the front.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front structure of an automobile body, and more particularly, to an automobile body having a sub-frame and a front side member connected to the sub-frame and arranged on a side of an engine room. The front structure of

[0002]

2. Description of the Related Art A front structure of a vehicle body is provided in which a crash box is provided in front of a front side member, and the crash box is divided into a front portion and a rear portion. It has been proposed (JP-A-5-139242).

In this front structure, when a predetermined impact load is applied from the front, the front portion is compressed and deformed, and when an impact load larger than the impact load is applied, the front portion and the rear portion are compressed and deformed. As a result, a two-stage deformation load having a large difference is obtained, so that the acceleration sensor does not work when a small deformation load is generated, but the acceleration sensor is set so that the acceleration sensor works when a large deformation load is generated. Can be. With this configuration, the acceleration sensor can be reliably operated at the set acceleration or an acceleration close to the set acceleration, and the airbag device installed in the automobile can be operated.

[0004]

In the front structure according to the above proposal, the front and rear portions of the crash box are intended to be compressed and deformed, but the amount of deformation required in various types of collision is stabilized. In some cases, it is difficult to perform compression deformation in two stages.

By the way, depending on the type of vehicle, the right and left front side members are connected to the subframe, and a so-called cross-girder structure is sometimes employed at the front of the vehicle body. There is a request to generate.

SUMMARY OF THE INVENTION The present invention provides a front structure of an automobile body capable of generating a two-stage deformation load in a body having a cross-girder structure.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a sub-frame and a front side member connected to a front end and a rear end of the sub-frame, the front end of the sub-frame. A front structure of an automobile body including a front side member including a front portion located in front of a connection portion with a portion and a rear portion located behind the connection portion. The front portion of the front side member is formed to be compressed and deformed when a predetermined first axial load is applied from the front, and the rear portion of the front side member is applied with the first axial load from the front. At the time of deformation, and bends and deforms when a predetermined second shaft load larger than the first shaft load is applied from the front.

When a predetermined first axial load is applied from the front,
The front portion of the front side member is compressed and deformed, but the rear portion is not compressed and deformed. When a predetermined second shaft load larger than the first shaft load is applied from the front, the front portion is compressed and deformed, and the rear portion is bent and deformed.

The front portion of the front side member is compressed and deformed by the first shaft load, the front portion is compressed and deformed by the second shaft load, and the rear portion is bent and deformed. As a result, two-stage deformation loads having large and small differences due to the first shaft load and the second shaft load are generated. Therefore, in an automobile that activates the airbag when the acceleration sensor operates, the acceleration sensor does not operate when the first axial load is applied, and the acceleration sensor operates so that the acceleration sensor operates when the second axial load is applied. If set, energy is absorbed by compressive deformation of the front part of the front side member without actuating the airbag at a low axial load, the airbag is actuated at a high axial load, and the airbag is activated at a high axial load. Energy can be absorbed by the compression deformation and the bending deformation of the rear part.

[0010] Since the front portion of the front side member is compressed and deformed, and the rear portion is bent and deformed, a two-stage deformation load can be stably generated as compared with the case where the front and rear portions are compressed and deformed.

It is preferable that the front portion of the front side member has a fragile portion which is deformed by the first axial load.

By providing the fragile portion, the front portion of the front side member can be reliably compressed and deformed.

The sub-frame is formed so that when the second axial load is applied from the front, the sub-frame is deformed so as to forcibly bend and deform the rear portion of the front side member.

When the second axial load is applied, the sub-frame deforms so as to forcibly bend and deform the rear portion of the front side member.
Since the rear portion of the front side member is deformed so as not to hinder the bending deformation, the rear portion of the front side member can be reliably bent and deformed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 showing a side view and FIG. 2 showing a plane view, a front structure of a vehicle body 8 of a vehicle comprises a sub-frame 10 and a front side member 12 of the vehicle body 8. The front part 9 is provided. Front side member 12
Has a mounting bracket 14 and is connected to the sub-frame 10 via the mounting bracket 14. A front portion 16 located in front of the mounting bracket 14, a rear portion 17 located behind the mounting bracket 14, Consists of A pair of front side members 12
However, they are arranged on both sides of a virtual vertical plane including a center line extending in the front-rear direction of the vehicle body. The front side member 12 is formed such that a cross section cut along a virtual vertical plane perpendicular to the virtual vertical plane exhibits a closed structure.

The sub-frame 10 is, in the illustrated embodiment,
Cross members 20 and 22 arranged in the width direction of the vehicle body at an interval in the front-rear direction, and side rails 24 connected to these cross members 20 and 22 at intervals in the width direction and arranged in the front-rear direction of the vehicle body , 26. The subframe 10 and the front side member 12 are connected by bolts 30 with a mount cushion 28 interposed between the cross member 20 and the mount bracket 14 on each side of the cross member 20. The mounting brackets 3 provided on the cross member 22 and the front side member 12 on each side of the cross member 22 are provided.
2 and a mount cushion 34 interposed therebetween, and are connected by bolts 36.

The front portion 16 of the front side member 12
Is formed so as to be compressed and deformed when a predetermined first axial load is applied from the front, and the rear portion 17 of the front side member 12 is not deformed when the first axial load is applied from the front, and It is formed to bend and deform when a predetermined second axial load larger than the first axial load is applied from the front. That is, the front portion 16 that is compressed and deformed by the first axial load further absorbs the kinetic energy of the vehicle traveling at a certain speed within a range where the front portion 16 is compressed and deformed. The rear portion 17 that bends and deforms due to the axial load of the vehicle, the kinetic energy of the vehicle traveling at a speed higher than the above speed,
In order that the front portion 16 is compressed and deformed in the above range and the rear portion 17 completes the absorption in the range where it is bent and deformed,
Determine dimensions and length.

In the illustrated embodiment, the front portion 16 of the front side member 12 has a fragile portion 40 that is deformed by the first axial load. The fragile portion 40 is a plurality of beads in the form of a dent extending vertically. The plurality of beads are dimensioned such that the front one is longer than the rear one, provided on each of the two side walls of the front side member 12, and the beads of the two side walls in a plan view are staggered. It is arranged so that it becomes. On the other hand, the rear portion 17 of the front side member 12 is formed such that the centroid of the bent portion 42 is higher than the centroid of the load input portion 44 by a distance H. Thus, the fragile portion 4 of the front portion 16
0 and the centroid height of the bent portion 42 of the rear portion 17, the front portion 16 is easily compressed and deformed by the first axial load, and the rear portion 17 is not deformed by the first axial load.
It is easy to bend and deform with a second shaft load larger than the first shaft load.

In the illustrated embodiment, the sub-frame 10 is located below the front side member 12 and has a bent portion 46 that induces the sub-frame 10 to bend upward and deform. The bent portion 46 is located behind the connecting portion between the subframe 10 and the mounting bracket 14,
And is located below the front side member 12.
Is forcibly bent and deformed.

When a running vehicle collides and a predetermined first axial load is applied from the front through the bumper reinforcement 48, the front portion 16 of the front side member 12 is compressed and deformed. Front part 1 as in the embodiment shown
6 has a fragile portion 40, and when the fragile portions 40 are a plurality of beads and are arranged in a staggered manner, the front portion 16 is compressed and deformed in a bellows-like manner.

When a predetermined second axial load is applied from the front,
As shown schematically in FIG. 3, the front side member 1
The front part 16 of 2 is compressed and deformed. Further, the sub-frame 10 is bent at the bent portion 46, and an angle change α occurs on the mounting surface 11 of the sub-frame 10. Since the sub-frame 10 and the front side member 12 are connected by the bolt 30, a change in the angle of the mounting surface 11 of the sub-frame 10 is transmitted to the mount bracket 14, and acts to push the front side member 12 downward. As a result, a bent portion 42 is formed in the rear portion 17 of the front side member 12 and a bent portion 50 is formed in front of the bent portion 42 and near the mount bracket 14, so that a so-called two-node break occurs. Thereby, forcible bending deformation of the front side member 12 occurs.

As shown in FIG. 4, deformation load F ₁ when the front portion 16 of the front side member 12 is compressed and deformed is generated. Further, after completing the compressive deformation of the front portion 16, deformation load F ₂ when the rear part 17 to the bending deformation occurs. In this way, a two-stage load characteristic having a difference in magnitude is obtained.

In the above embodiment, the front side member 1
The front portion 16 of the second is provided with a weakened portion 40 in the form of a concave bead. Alternatively, the fragile portion 40 can be a convex bead. In addition, a weak portion is provided in the front portion 16 by making the thickness of the front portion 16 smaller than the thickness of the rear portion 17 or making the cross-sectional area of the front portion 16 smaller than the cross-sectional area of the rear portion 17. It is also possible to form the portion 16 to be compressed and deformed by a first axial load and the rear portion 17 to bend and deform by a second axial load.

The sub-frame 10 and the front side member 12 are connected to each other with a mounting bracket 14 provided on the front side member 12 and the mounting bracket 14 as a connecting portion.
The sub-frame 10 can be directly connected to the front side member 12 without providing the mount bracket 14, and the front portion of the connection portion and the rear portion of the connection portion can be formed as described above.

Further, it is preferable that the sub-frame 10 is deformed so as to forcibly bend the front side member 12. In this case, as schematically shown in FIG. 5, the sub-frame 10 is deformed so as not to hinder the bending deformation of the rear portion 17 of the front side member 12, whereby the front end 52 of the sub-frame 10 and The front side member 1 behind each of the rear ends 53
Bending deformation can be induced in the subframe 12 at the second portions 54 and 55.

[Brief description of the drawings]

FIG. 1 is a side view showing a front structure of a vehicle body of an automobile according to the present invention.

FIG. 2 is a plan view of the front structure shown in FIG. 1;

FIG. 3 is a schematic view showing the operation of the front structure shown in FIG. 1;
It is seen from the side.

FIG. 4 is a graph showing an effect obtained by the front structure shown in FIG. 1;

FIG. 5 is a schematic view showing an action that can occur in the front structure of the vehicle body according to the present invention, as viewed from the side.

[Explanation of symbols]

 Reference Signs List 8 car body 9 front part 10 subframe 12 front side member 14 mount bracket 16 front part 17 rear part 40 fragile part 42, 46 bent part

Claims (3)

[Claims] 1. A front side member connected to a subframe and a front end and a rear end of the subframe, the front side member being located in front of a connection portion with the front end of the subframe. And a front side member comprising a front side member including a rear portion positioned behind the connection portion, wherein the front portion of the front side member has a predetermined first axial load. Is formed to compressively deform when applied from the front, and the rear portion of the front side member is
An automobile body formed so as not to deform when the first axial load is applied from the front and to bend and deform when a predetermined second axial load larger than the first axial load is applied from the front. Front structure. 2. The front structure of a vehicle body according to claim 1, wherein the front portion of the front side member has a fragile portion deformed by the first axial load. 3. The sub-frame is formed to deform so as to forcibly bend and deform the rear portion of the front side member when the second axial load is applied from the front. 3. The front structure of the vehicle body of the vehicle according to 2.