JPH1081257A - Front frame structure body of car body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a front frame structure body of a car body, not to be affected by softening caused by a weld heat affected part, having excellent energy absorbing performance in collision, and to be easily replaced. SOLUTION: A front frame structure body of a vehicle is provided with a first front cross member 1 extending in the car body width direction in the front part of the car body, a second front cross member 4 arranged in parallel with and ahead of the first cross member 1, and a bracket 20 for connecting the first and second front cross members 1, 4 to each other. This bracket 20 is provided with a first fitting part 10 for fitting the first front cross member 1 and having the U-shaped section, a second fitting part 11 for fitting the second front cross member 4 and having the U-shaped section, and a beam 12 for connecting the first and second fitting parts 10, 11 to each other. The first and second fitting part 10, 11 are mechanically joined to the first and second front cross members 1, 4 by rivets. A softening part is formed on the beam 12 by spot welding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle body frame for an automobile such as a truck manufactured by welding a rectangular tubular member made of aluminum or an aluminum alloy (hereinafter, collectively referred to as an aluminum material). The present invention relates to a frame structure, and more particularly, to a front frame structure of a vehicle body in which energy absorption at the time of a collision is enhanced and repairability is improved.

[0002]

2. Description of the Related Art Conventionally, an automobile body such as a truck and a vehicle body such as a transportation machine are reinforced by folding an end portion of a formed steel plate and joining the portion by resistance spot welding. The monocoque structure assembled in this manner is a general vehicle body structure such as a truck.

[0003] However, this method has the advantage of being easy to assemble easily, but has many overlapping parts, has a lot of useless parts in structure formation, is not slim, and has a complicated shape of a molded member. However, there is a disadvantage that the weight increases.

[0004] On the other hand, if butt welding is performed by arc welding and beam welding, the structure becomes slim, but the welding quality is greatly affected by the butt accuracy of the members before welding. For example, when a gap is formed between members, welding quality is significantly reduced. Therefore, a jig for holding the member in an assembled state by pressing the member is required, and the member itself requires high-precision machining. Therefore,
It is difficult to automate assembly.

Recently, attempts have been made to manufacture a vehicle body from an aluminum alloy material in order to reduce the weight of the vehicle body. In this case, the aluminum material has low spot weldability, and in a monocoque structure, it is necessary to perform welding at thousands of points, but in that case, there is a disadvantage that the electrode is greatly consumed. Further, there is a disadvantage that the formability of the plate material is worse than that of the aluminum material.

Therefore, a space frame structure has been proposed in which a vehicle such as a truck and a vehicle such as a transport machine is supported by a hollow pipe-shaped frame. In this space frame structure, the contour of the vehicle body is assembled by cross members extending in the vehicle body width direction and side members extending in the front-rear direction, and the members are joined by welding. Then, a structural plate is attached so as to cover the space frame, and an automobile body is completed.

As shown in FIG. 9, a conventional front frame structure of a vehicle body is provided at the front ends of two front side members 51 and 52 at the front end of the vehicle body in the vehicle width direction. A front cross member 53 arranged to extend is fixed. These side members 51, 5
2 and the front cross member 53 are joined by welding, and the side members 51 and 52 are made to have energy absorbing properties at the time of collision.

[0008] However, if a rectangular cylindrical member made of aluminum or an aluminum alloy is used for the side member and the front cross member to reduce the weight of the vehicle body, when the front cross member and the side member are joined by welding. In addition, a heat affected zone is generated on both of the members by welding, and the strength characteristics are deteriorated. For this reason, the energy absorption at the time of collision is adversely affected.

In order to avoid the influence of such a heat affected zone, there has been proposed a structure using a JIS7000-based aluminum alloy as a front cross member and a side member (Japanese Patent Laid-Open No. Hei 7-31015).
6). This 7000 series alloy has the property of being age-hardened by being left at room temperature after welding, and restoring the softening of the weld heat affected zone.

[0010]

However, a load is continuously applied to the front cross member and the side members of the vehicle body, and the vehicle body is easily exposed to a high temperature due to heat generation of the engine. Therefore, since the 7000 series alloy is an alloy in which stress corrosion cracking is liable to occur, it is problematic to use it in such a site.

Also, when a slight frontal collision occurs,
When attempting to replace and repair a damaged front cross member, since the front cross member is fixed by welding, removing the front cross member requires a complicated operation and cannot be easily replaced.

The present invention has been made in view of the above-mentioned problems, and is not affected by softening caused by a heat affected zone by welding, has excellent energy absorption at the time of collision, and is easy to replace. It is an object to provide a frame structure.

[0013]

According to the present invention, a front frame structure for a vehicle body includes a first front cross member extending in a vehicle width direction at a front portion of the vehicle body, and a first front cross member provided in front of the first front cross member. A second front cross member arranged in parallel with the cross member; and a bracket for connecting the first front cross member and the second front cross member. The bracket engages the first front cross member. A first fitting portion having a U-shaped cross section, a second fitting portion having a U-shaped cross section for fitting the second front cross member, and a beam connecting the first and second fitting portions. The first and second fitting portions are mechanically joined to the first and second front cross members by rivets, respectively. In this case, the beam may be formed with a softened portion by spot welding.

In the present invention, two front cross members are provided, and a second front cross member in front of the vehicle body and a first front cross member constituting the vehicle body are provided by:
They are connected by brackets. The bracket and the first and second front cross members are mechanically joined by rivets after each front cross member is fitted to each fitting portion. Therefore, no heat affected zone is generated by welding, and the strength characteristics are not degraded. Further, when a softened portion is formed on the beam of the bracket by spot welding, the softened portion of the beam is preferentially damaged at the time of a collision, and the transmission of collision energy to the vehicle body can be further reduced. it can. Further, since the bracket can be easily removed from the first front cross member, repair in the event of a collision is easy.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing a first embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing the same bracket, and FIG. 3 is a plan view of the same bracket. At the front ends of a pair of side members 2, 3 arranged at the front of the vehicle body so as to extend in the front-rear direction of the vehicle body,
A first front cross member 1 extending in the width direction of the vehicle body is fixed by welding.

The first front cross member 1
A second front cross member 4 is arranged in parallel with the first and second front cross members 1, 4.
They are connected by a pair of brackets 5,6.

As shown in FIG. 2, the bracket 5 has first and second fitting portions 10 and 11 having a U-shaped cross section, and a beam 12 between the fitting portions 10 and 11. In addition,
Since the bracket 6 has the same shape as the bracket 5, its description is omitted. Fitting portion 10 of bracket 5,
Numeral 11 has a bottom plate and side plates erected at both ends of the bottom plate, and a U-shaped cross section is constituted by the bottom plate and the side plates.
The beam 12 has a plate shape so as to connect both end portions of the bottom plates of the fitting portions 10 and 11 to each other. In addition, the fitting portion 10,
The bent lines of the side plate and the bottom plate are parallel to each other, and the cross-sectional shape of the bracket is uniform in the longitudinal direction of the bent line.

As shown in FIG. 3, a point softened portion 13 is formed at the center of the beam 12 by spot welding.

In the vehicle body front frame structure thus configured, the first fitting portions 10 of the brackets 5 and 6 are fitted to the conventionally existing first front cross member 1 from the side. , 6 of the second fitting portion 11
Next, the second front cross member 4 first employed in the present invention is fitted to the side. Then, as shown in FIG. 3, the side plates of the fitting portions 10, 11 of the brackets 5, 6,
The upper and lower surfaces of the front cross members 1 and 4 are fixed to each other by a blind rivet 14. The blind rivet is a rivet that can be installed on one side. As a result, a structure in which the second front cross member 4 is connected to the front cross member 1 via the brackets 5 and 6 in front of the first front cross member 1 is obtained.

As described above, in this embodiment, the front cross members are mechanically joined using the blind rivets 14 instead of welding. Therefore, it is possible to prevent the strength characteristics of the front cross member from deteriorating due to the influence of welding heat and adversely affecting the energy absorption at the time of collision. The front cross members 1, 4 and the bracket 12 are not made of JIS 7000 alloy,
Since an aluminum alloy having no risk of stress corrosion cracking can be used, stress corrosion cracking does not occur even when the alloy is exposed to a high temperature due to engine heat or the like.

When an automobile collides, since the point softening portion 13 is formed, as shown in FIG. 4, the beam 12 is preferentially deformed to absorb the impact. Therefore, transmission of the impact force to the vehicle body can be reduced.

Further, when the second front cross member 4 is damaged due to an accident or the like, the bracket 12 is mechanically joined by the blind rivet 14, so that the bracket 12 is easily removed and repaired. . Further, since the bending lines of the bracket are all parallel, the bracket can be easily manufactured by an extrusion molding and cutting process, and the manufacturing cost is low.

FIG. 5 is a front view showing a bracket 20 used for a front frame structure of a vehicle body according to a second embodiment of the present invention, FIG. 6 is a plan view thereof, and FIG. 7 is a left side view thereof. FIG. 8 is a perspective view showing a space frame 50 of a truck. As shown in FIG. 8, in the space frame 50, a rectangular cylindrical aluminum material 51 is formed.
Into the shape of the front of the truck,
1 are joined by welding, and the profiles 51 are fixed to each other. As a result, a so-called space frame structure is formed, and a structural plate is attached so as to cover the space frame 50, thereby completing the automobile body.

The bracket 20 of this embodiment has a first front cross member 1 at the front end of the structure of the space frame 50 shown in FIG. 8, and a second front cross member 1 disposed in front of and parallel to the first front cross member 1. Front cross member 4
And a front member 7 extending obliquely downward from the second front cross member 4. First
The front cross member 1 is fixed to the side member 8 by welding.

The bracket 20 has the same structure as the first embodiment.
Fitting portion 10, second fitting portion 11, beam 12 between them
And these structures have the same structure as the first embodiment. This embodiment differs from the first embodiment shown in FIG. 2 in that a third fitting portion 15 is provided below the second fitting portion 11. The depth direction of the third fitting portion 15 is inclined downward and forward of the vehicle body. In addition,
Also in this bracket 20, the fitting portions 10, 11, 1
The bending lines of the side plate and the bottom plate of No. 5 are all parallel to each other. In the center of the beam 12, a point softening portion 13 spot-welded by TIG is provided.

Using the bracket 20 configured as described above, the members 1, 4, and 5 are assembled as shown in FIG. That is, as shown in FIGS. 5, 6, and 7, the first fitting portion 10 is fitted to the horizontally extending first front cross member 1 from the side thereof, and similarly extends horizontally to the second fitting portion 11. The second front cross member 4 is fitted to the side. The upper end of the front member 7 extending downward and forward is fitted into the third fitting portion 15 from below.

Then, the side plates of the fitting portion having a U-shaped cross section and the side plates of the members 1, 4, and 7 are joined by a blind rivet 14. Thus, the front frame structure shown in FIG. 8 is assembled. Also in this embodiment, it is possible to obtain a front frame structure of a vehicle body which has a high absorption of impact energy, is easy to replace, and is free from deterioration of characteristics due to thermal influence and stress corrosion cracking.

As shown in FIGS. 2 and 5, the joining member of each of the above embodiments has a uniform cross-sectional shape and can be manufactured by extrusion and cutting. Therefore, this bracket is used. Therefore, the increase in the manufacturing cost of the welded structure is extremely small.

The vehicle body front frame structure of each of the above embodiments functions as a bumper, which is provided on a space frame of the vehicle body and is different from a bumper mounted outside the vehicle body. .

[0030]

As described above, according to the present invention,
A second front cross member in front of the vehicle body and a first front cross member constituting the vehicle body are connected by a bracket, and the bracket is mechanically joined to the first and second front cross members by rivets. Therefore, no heat affected zone is generated by welding, and the strength characteristics of the front cross member are not degraded. Further, since the softened portion of the beam of the bracket is formed by spot welding, the softened portion of the beam is preferentially damaged at the time of a collision, so that transmission of collision energy to the vehicle body can be reduced. it can. Furthermore, since the bracket is mechanically joined, it can be easily removed from the first front cross member, so that repair in the event of a collision is easy.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing the bracket similarly.

FIG. 3 is a plan view of the bracket.

FIG. 4 is a diagram illustrating the absorption of collision energy by a bracket.

FIG. 5 is a front view showing a second embodiment of the present invention.

FIG. 6 is a plan view of the same.

FIG. 7 is a left side view of the same.

FIG. 8 is a perspective view showing a space frame structure.

FIG. 9 is a perspective view showing a conventional vehicle body front frame structure.

[Explanation of symbols]

 1: First front cross member 2, 3: Side member 4: Second front cross member 5, 6, 20: Bracket 7, 8: Member 10, 11, 15: Fitting portion 12: Beam 13: Point softening portion 14: Rivet

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tohru Hashimura 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel, Ltd. Kobe Research Institute

Claims (2)

[Claims] A first portion extending in a vehicle width direction at a front portion of the vehicle body;
A front cross member, a second front cross member disposed in front of the first front cross member in parallel with the first cross member, and a bracket connecting the first front cross member and the second front cross member. The bracket includes a first fitting portion having a U-shaped cross section for fitting the first front cross member, a second fitting portion having a U-shaped cross section for fitting the second front cross member, A beam connecting the first and second fitting portions, wherein the first and second fitting portions are mechanically joined to the first and second front cross members by rivets, respectively. The front frame structure of the vehicle body. 2. The front frame structure according to claim 1, wherein a softened portion is formed in the beam by spot welding.