JPH08268326A - Lower body structure for automobile - Google Patents

Abstract

PURPOSE: To provide the lower body structure for an automobile which can convert the load in the longitudinal direction of the body into load in the lateral direction of car body so as to absorb it, being equipped with a side frame in such form as is used usually. CONSTITUTION: Side frames 1 are equipped with width shrunk parts 1A which make the distance between the side frames 1 and 1 smaller as they go toward the front of the car body, front parallel parts 1B, front bends 1C, and rear bends 1D at the front of the car body, and extension frames 2 lower in rigidity than the side frames 2 are coupled to the front ends of the car body of the front parallel parts 1B. They are provided with the first cross member 3, both whose ends are coupled with the front bends (that is, the bends on the side where the distance between right and left side frames is small) 1C and 1C and which extend in the lateral direction of car body, and the second cross member 4 both whose ends are coupled with the rear bends (that is, the bends on the side where the distance between the right and left side frames is large) 1D and 1D and which extends in the lateral direction of car body, and shock absorbing parts are provided at three places of the first cross member 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lower body structure of an automobile for reducing the influence of a shock in the longitudinal direction of the vehicle body.

[0002]

2. Description of the Related Art Generally, in an automobile, a pair of side frames each having a closed cross section extending in the front-rear direction of the vehicle body are provided at the lower portions of both sides of the vehicle body. Is joined to the side frame, and an appropriate number of cross members having the same closed cross-sectional shape are provided. With such a structure, the side frame is deformed when it is subjected to an impact in the front-rear direction of the vehicle body and bends inwardly of the vehicle body, so the ability to absorb impact energy is small and the amount of inward deformation of the side frame is large. However, in order to solve this problem, a method of controlling the deformed state of the side frame to absorb impact energy has been proposed. For example,
In Japanese Utility Model Laid-Open No. 4-122281, vertical bending portions are provided on both side frames to avoid axles and the like, and the side frames are provided so as to be inclined inwardly of the vehicle body. When a shock is applied from the front of the vehicle body by connecting with a cross member that extends in the direction, the side frame in the front part moves downward from the bending portion in the vertical bending portion. Since it is inclined to the front, the front part from the bent part moves to the outside of the vehicle body, that is, it moves downward while increasing the distance between both side frames, and it is possible to absorb large impact energy. Has been described.

[0003]

However, in the above-mentioned conventional lower vehicle body structure, a special structure in which the side frame is inclined inwardly of the vehicle body is adopted.
Assembling work may be difficult, for example, it is difficult to set a reference plane during assembly because the corner of the closed cross section of the side frame is located at the lower end, and a special jig is required, or There was a problem that it was necessary to change the design of the joints at both ends of the cross member. Further, since the side frame is inclined inwardly of the vehicle body, there is a problem in that the rigidity may be lowered due to a twist caused by a normal vertical load and a horizontal load.

An object of the present invention is to provide a lower vehicle body structure for an automobile, which is provided with a side frame of a commonly used shape and is capable of converting a load in the vehicle longitudinal direction into a load in the vehicle width direction and absorbing the load. Is.

[0005]

In order to achieve the above object, a lower body structure for an automobile according to the present invention is provided with side frames extending in the vehicle front-rear direction on both sides of the vehicle body, and at the same position of the left and right side frames, the front half of the vehicle body is provided. The distance between the left and right side frames decreases toward the front end in the front half of the vehicle body, and the distance between the left and right side frames decreases toward the rear end in the rear half. A width portion, a bent portion provided on each of the front and rear end portions of the reduced width portion, and a first cross extending in the vehicle width direction and connecting the bent portions on the side where the distance between the left and right side frames is small. A member, a second cross member extending in the width direction of the vehicle body, connecting the bent portions on the side where the distance between the left and right side frames is large, and a shock absorbing portion provided on the first cross member. By was example, when receiving an impact load in the longitudinal direction of the vehicle body, when absorbed in place of the lateral loads bending the side frame inwardly in the vicinity of the reduced width portion, the first
The cross member and the second cross member, particularly the first cross member, prevent a large inward fall of the side frame, while the shock absorbing portion of the first cross member can provide a sufficient shock absorbing ability. By providing the extension frame on the side frame closer to the end portion in the vehicle front-rear direction than the width-reduced portion, the side frame is deformed after the extension frame is deformed first, so that the shock absorbing ability can be further increased. By joining both ends of the first cross member to the side frame at the bent portion or at the vehicle body front-rear end side of the bent portion, bending at the bent portion of the side frame when an impact load in the vehicle body front-rear direction is received. Since it is suppressed by the first cross member, it is possible to improve the ability to prevent a large inward fall of the side frame. First
By joining both ends of the cross member to the side frame on the side where the distance between the left and right side frames is large with respect to the bent portion, when the impact load in the vehicle front-rear direction is applied, the bent portion and the first cross member joint After that, the side frame is deformed inward to absorb the impact, and then the impact absorbing portion of the first cross member absorbs the impact, so that the impact absorbing ability can be increased. By providing the reinforcement on the side frame between the joint portions of the first cross member and the second cross member to the side frame, deformation of the reduced width portion of the side frame is suppressed, and the vehicle interior due to the deformation of the side frame. Control the effect on.

[0006]

Embodiments of the present invention will be described with reference to the drawings. In FIG. 1, a pair of parallel side frames 1 and 1 each having a substantially rectangular cross section and extending in a vehicle front-rear direction are provided on both sides of a lower portion of a vehicle body. Each side frame 1 is a vehicle body. At the front part, a reduced width portion 1A is formed in which the distance between the side frames 1, 1 decreases toward the front of the vehicle body, and a front parallel portion 1B extending from the front end of the reduced width portion 1A toward the vehicle body is formed. , Reduced width section 1A
And the front parallel portion 1B, that is, the front bent portion 1C on the side where the distance between the left and right side frames of the reduced width portion 1A is small, and the vehicle body rear end of the reduced width portion 1A, that is, the left and right side frames of the reduced width portion 1A. And a rear bent portion 1D having a large distance therebetween.

An extension frame 2 which is formed separately from the side frame 1 and has a rigidity lower than that of the side frame 1 is connected to the front end of the front parallel portion 1B and extends in the vehicle front-rear direction. A cross member that extends in the vehicle width direction and has both ends joined to the front ends of the extension frames 2 and 2 on both sides.
Ten are provided. In addition, a hollow first hollow cross having a rectangular cross-section extending in the vehicle width direction and having both ends connected to the front bent portions (that is, the bent portions on the side where the distance between the left and right side frames is small) 1C and 1C of both side frames 1 and 1. A member 3 is provided, and a second cross member 4 that extends in the vehicle width direction and has both ends connected to a rear bent portion (that is, a bent portion on the side where the distance between the left and right side frames is large) 1D, 1D is provided. At the rear of the vehicle body of the second cross member 4, there are provided cross members 5, 6, 7, 8, 9 which are joined at their both ends to the side frames 1, 1 and extend in the vehicle width direction. The second cross member 4 may also serve as a suspension cross member.

With the above structure, both side frames 1, 1
Since both ends of the first cross member 3 are joined to the front bent portions 1C, 1C, both front bent portions 1C, 1C by the first cross member 3 when an impact load is applied from the front of the vehicle body.
1C is supported to suppress the deformation of both front bent portions 1C, 1C from falling toward the inside of the vehicle body, and the front parallel portion 1B and the extension frame 2 ahead of the front bent portion 1C are deformed first. Since the impact is absorbed, the influence of the impact on the rear side of the vehicle body with respect to the first cross member 3 can be suppressed.

Further, by connecting the extension frame 2 having a rigidity lower than that of the side frame 1, when an impact load is applied from the front of the vehicle body, the extension frame 2 is fixed before the front parallel portion 1B of the side frame 1 is deformed. Since it is deformed and absorbs the shock, the shock is absorbed by the two-stage stance, so that the shock absorbing capacity is increased.

The end portion of the first cross member 3 is separated from the front bent portion 1C by a preset distance L (for example, 120 m).
It is joined to the reduced width portion 1A which is displaced by m) toward the rear of the vehicle body (Fig.
As a result, since the reduced width portion 1A (side frame 1) between the front bent portion 1C and the joint portion of the first cross member 3 can be deformed, the shock absorbing capacity is further increased.

Further, although the first cross member 3 in the above-mentioned embodiment is formed so as to maintain the same rigidity over the entire length, as shown in FIGS. 3 and 4, the first cross member 3 has rigidity at appropriate places. By providing the lowered impact absorbing portion, the first cross member 3 is bent at the impact absorbing portion when the side frame falls down inside the vehicle body, and the impact absorbing ability is improved. More specifically, in the structure shown in FIG. 3, a shock absorbing portion 3A having the smallest cross-sectional area is formed in the central portion of the first cross member 3, and a shock is applied from both ends 3B of the first cross member 3 having the largest cross-sectional area. Absorption part 3A
The cross-sectional area gradually decreases toward
In the structure shown in FIG. 4, a bead portion 3C having a plurality of beads extending in the up-down direction on the front and rear side surfaces thereof is formed at the central portion of the first cross member 3 having the same cross-sectional area over the entire length. When the side frame falls inward of the vehicle body, the load resistance does not sharply decrease, and the first cross member 3 is deformed after the extension frame or the like is deformed. The influence of the load on the rear of the vehicle body can be suppressed.

A different embodiment will be described with reference to FIGS. 5 and 6. The side frame 11 is an outer frame 111 which is formed in a substantially lateral concave section and which is open to the inside of the vehicle body.
Similarly, an inner frame 112 that is also open on the outer side of the vehicle body is combined with the open sides facing each other to form a rectangular closed cross section, and the tip opening is closed by a plate 113. Front bent portion 11C and rear bent portion 11D formed before and after the reduced width portion 11A, and front bent portion
The front parallel part 11 which meets 11C and continues in front of the reduced width part 11A
B and an extension frame 12 at the front end of the front parallel portion 11B.
Are joined.

Front bent portions 11 of the left and right side frames 11, 11.
A first cross member 13 having both ends joined to C and 11C and extending in the vehicle width direction, front suspension cross member brackets 14A and 14A fixed to the rear bent portions 11D and 11D, and front suspension cross member bracket 14A and A front suspension cross member 14 that is a second cross member that extends in the vehicle width direction and has both ends joined to 14A, and a rear suspension cross member bracket that is installed on the left and right side frames 11, 11 behind the front suspension cross member 14 in the vehicle body. 15A, 15A,
Rear suspension cross member bracket 15A, 15A
A rear suspension cross member 15 extending in the vehicle width direction is joined to both ends of the rear suspension cross member 15, and the joining position of the first cross member 13 and the front suspension cross member bracket 14A (that is, the joining position of the second cross member). A reinforcement 16 having a substantially concave cross section with an open lower surface is fitted and fixed on the upper side between and.

According to this structure, since the reinforcement is provided on the side frame between the joints of the first cross member and the second cross member to the side frame, the reduced width portion of the side frame, that is, the front bent portion. The deformation of the portion between 11C and the rear bent portion 11D is suppressed, and the influence of the deformation of the side frame on the passenger compartment is suppressed. The first
The joining position of the cross member 13 may be lowered rearward of the vehicle body with respect to the front bent portion 11C.

[0015]

Since the present invention is configured as described above, it has the following effects. At the same position on the left and right side frames, it is provided on at least one of the front half or the rear half of the car body.In the front half of the car body, the distance between the left and right side frames decreases, and in the rear half, it moves toward the rear end. The reduced width portion that reduces the distance between the left and right side frames, the bent portion that is provided on the vehicle front and rear end side of the reduced width portion, and the side that extends in the vehicle width direction and that has the small distance between the left and right side frames First to connect between bent parts of
A cross member, a second cross member extending in the width direction of the vehicle body and connecting between bent portions on the side where the distance between the left and right side frames is large, and a shock absorbing portion provided on the first cross member are provided. As a result, when an impact load in the front-rear direction of the vehicle body is received and the side frame is changed to a lateral load that bends inward in the vicinity of the reduced width portion and is absorbed, the first cross member and the second cross member, especially the second cross member, are absorbed. The one cross member can prevent a large inward fall of the side frame, while the shock absorbing portion of the first cross member can provide a sufficient shock absorbing ability. By providing the extension frame on the side frame closer to the end portion in the vehicle front-rear direction than the width-reduced portion, the side frame is deformed after the extension frame is deformed first, so that the shock absorbing ability can be further increased. By joining both ends of the first cross member to the side frame at the bent portion or at the vehicle body front-rear end side of the bent portion, bending at the bent portion of the side frame when an impact load in the vehicle body front-rear direction is received. Since it is suppressed by the first cross member, it is possible to improve the ability to prevent a large inward fall of the side frame. By joining both ends of the first cross member to the side frame on the side where the distance between the left and right side frames is large with respect to the bent portion, the bent portion and the first cross member are subjected to an impact load in the vehicle body front-rear direction. After the side frame is deformed inward with the joint portion to absorb the impact, the impact absorbing portion of the first cross member absorbs the impact, and the impact absorbing ability can be increased. First cross member and second
By providing the reinforcement on the side frame between the joints of the cross member to the side frame,
The deformation of the reduced width portion of the side frame is suppressed, and the influence of the deformation of the side frame on the passenger compartment is suppressed.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a plan view showing a modified example of the present invention.

FIG. 3 is a perspective view of a first cross member according to the present invention.

FIG. 4 is a perspective view of another example of the first cross member of the present invention.

FIG. 5 is a perspective view showing another embodiment of the present invention.

FIG. 6 is an exploded view of the embodiment shown in FIG.

[Explanation of symbols]

1 side frame, 1A reduced width part, 1B front parallel part, 1C front bent part 1D rear bent part, 2 extension frame, 3 first cross member 4 2nd cross member

Claims (5)

[Claims] 1. A side frame extending in the front-rear direction of the vehicle body is provided on both sides of the vehicle body, the side frame being provided at the same position on at least one of a front half portion or a rear half portion of the vehicle body,
In the front half of the vehicle body, the distance between the left and right side frames decreases toward the front end, and in the rear half, the distance between the left and right side frames decreases toward the rear end.
A bent portion that is provided on each of the front and rear end portions of the reduced width portion, and a first cross member that extends in the vehicle width direction and that connects the bent portions on the side where the distance between the left and right side frames is small, A second cross member extending in the width direction and connecting bent portions on the side where the distance between the left and right side frames is large, and a shock absorbing portion provided on the first cross member. The lower body structure of an automobile. 2. The lower vehicle body structure for an automobile according to claim 1, wherein an extension frame is provided on a side frame on the vehicle front-rear direction end side with respect to the reduced width portion. 3. The lower vehicle body structure for an automobile according to claim 1, wherein both ends of the first cross member are joined to the side frame at a bent portion or at a front and rear end side of the vehicle with respect to the bent portion. 4. The first cross member according to claim 1, wherein both ends of the first cross member are joined to the side frame on the side where the distance between the left and right side frames is large with respect to the bent portion. The lower body structure of an automobile. 5. The reinforcement is provided on the side frame between the joints of the first cross member and the second cross member to the side frame.
The lower vehicle body structure of the vehicle according to any one of claims 1 to 4.