JP3191455B2 - Rear underbody structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear underbody structure for an automobile body.

[0002]

2. Description of the Related Art Generally, an input to a tire from a road surface is transmitted to a body via a suspension. In particular, when the vehicle is traveling on a rough road, the input to the tires becomes large, which increases the vibration of the body and generates road noise.

On the other hand, road noise can be reduced by cutting off the input from the road surface, but in this case, the steering stability is deteriorated. It is also conceivable to set a sound-insulating material at a portion where the body sounds, or to increase the rigidity of the body input portion of the suspension. However, in these cases, there are problems such as an increase in body weight and cost. .

A rear underbody structure which solves these problems is disclosed in Japanese Utility Model Laid-Open No. 2-108672.

[0005] As shown in FIG. 4, in the rear underbody structure 70, the cross member 7 of the rear floor pan 72 is provided.
A portion near the connecting portion between the lower arm 4 and the lower arm 76 is bulged upward to form a buffer space 78 between the rear floor pan 72 and the cross member 74, and input from the rear wheel 80 via the lower arm 76. This shock load is absorbed by the buffer space 78, and the vibration of the rear floor pan 72 is suppressed to reduce road noise.

[0006]

However, in the rear underbody structure 70, the vicinity 74A of both ends of the cross member 74 in the vehicle width direction is bent upward, and the tip is connected to the rear floor side member 82. . Accordingly, the cross-sectional deformation of both end portions 74B in the vehicle width direction of the cross member 74 due to the input load becomes large, and the vibration of the rear side member 80 to which the both end portions 74B in the vehicle width direction of the cross member 74 are joined is increased. Become. For this reason, there was a problem that the vibration of the rear floor pan 72 could not be sufficiently suppressed, and the road noise could not be sufficiently reduced.

In view of the above, it is an object of the present invention to provide a rear underbody structure capable of sufficiently suppressing vibration of a rear floor pan and sufficiently reducing road noise.

[0008]

According to a first aspect of the present invention, there is provided a rear underbody structure, comprising: a pair of rear floor side members disposed along the vehicle front-rear direction near both ends in the vehicle width direction at the rear lower part of the vehicle; with the vehicle width direction both end portions on opposite sides of the pair of the rear floor side member is coupled respectively spaced apart from the rear floor pan extending to the vehicle width direction in a substantially linear shape, and the cross-sectional shape as viewed from the vehicle width direction , Body
A cross member having an aspect ratio that is long in the front-rear direction and short in the up-down direction of the vehicle body, and a lower arm bracket that is coupled to the cross member and supports a rear lower arm.

[0009]

In the rear underbody structure according to the first aspect of the present invention, since the cross member is formed to extend substantially linearly, when a load is input to the cross member from the rear lower arm via the lower arm bracket. The cross-sectional deformation at both ends in the vehicle width direction of the cross member is smaller than in the conventional structure in which the vicinity of both ends in the vehicle width direction of the cross member is curved. For this reason, the vibration of the rear floor side member to which both ends of the cross member in the vehicle width direction are coupled can be sufficiently suppressed,
Road noise can be sufficiently reduced.

Further, in the case of vibrating in the direction in which the pair of the rear floor side member are close to each other, a cross member extending substantially linearly with the role of the beam sufficiently suppress vibration of the pair of the rear floor side member.

[0011] In addition, since the rear floor pan is separated from the cross member, without being transmitted to the vibration directly to the rear floor pan of the cross member, it is possible to sufficiently suppress the vibration of the rear floor pan, it is possible to sufficiently reduce the road noise . Also, input from tires vibrated by rough road running
Via the rear lower arm and lower arm bracket
Input to the cross member, but the cross member
As the aspect ratio is large, the cross member body
Although vertical vibration of the
The longitudinal vibration of the floor side member is reduced. this
Therefore, when vibration of the rear floor pan can be suppressed
In both cases, the in-phase and out-of-phase
The position is also very small, resulting in very good maneuverability
Bring.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a rear underbody structure according to the present invention will be described with reference to FIGS.

In the drawings, an arrow FR indicates a forward direction of the vehicle body, an arrow IN indicates an inward direction of the vehicle width, and an arrow UP indicates an upward direction of the vehicle body.

As shown in FIG. 3, a pair of rear floor side members 12 are arranged in the rear underbody 10A constituting the rear lower portion of the vehicle body 10 near both ends in the vehicle width direction along the vehicle longitudinal direction. . The front ends of these rear floor side members 12 are joined to the floor side inner members 13, and the rear ends of the rear floor side members 12 are connected to the lower back panel 1.
7.

As shown in FIG. 1, the cross-sectional shape of the rear floor side member 12 as viewed from the vehicle front-rear direction is a U-shaped cross-section with the opening directed upward, and the upper end of the inner wall portion 12A in the vehicle width direction. Is bent inward in the vehicle width direction to form a flange 12B. The flange 12B is welded to the lower surface 14A of the rear floor pan 14. On the other hand, the end of the rear floor pan 14 in the vehicle width direction is bent upward to form a flange 14B.
Is the outer side wall 1 of the rear floor side member 12 in the vehicle width direction.
The upper end of the 2C is welded to the inner surface in the vehicle width direction.

Accordingly, the rear floor side member 12 and the rear floor pan 14 form a closed cross-sectional structure 16 extending in the vehicle longitudinal direction.

A lower edge 15A of the rear wheel house inner 15 is welded to the outer side in the vehicle width direction at the upper end of the outer wall portion 12C of the rear floor side member 12 in the vehicle width direction.

[0018] As shown in FIG. 2, between the site where a substantially central portion of the rear wheel house inner 15 of the pair of rear floor side member 12, cross member 18 is a rear floor pan 14 extending in the vehicle width direction in a substantially linear shape It is arranged at a distance from the lower side. The cross-sectional shape of the cross member 18 as viewed from the vehicle width direction is a rectangular shape having an aspect ratio that is sufficiently long in the vehicle front-rear direction and short in the vehicle vertical direction, and both end portions 18A of the cross member 18 in the vehicle width direction are: The rear floor side member 12 is welded to the vehicle width direction inner side surface of the vehicle width direction inner side wall portion 12A.

As shown in FIG. 1, a lower arm bracket 22 for supporting a rear lower arm 20 is provided at the center of the lower surface of the cross member 18 in the vehicle width direction. This lower arm bracket 22 has sufficient rigidity,
It is connected to the cross member 18 by welding or a bolt and nut. There are a total of four rear lower arms 20 pivotally supported on the front and rear surfaces of a lower arm bracket 22. These rear lower arms 20 support tires via wheel carriers (not shown), and constitute a so-called double link suspension. ing.

Next, the operation of this embodiment will be described.
In the rear underbody structure of this embodiment, the cross member 1
8 is formed to extend substantially linearly, so that when a load is applied to the cross member 18 from the rear lower arm 20 via the lower arm bracket 22, the cross-sectional deformation of both end portions 18A in the vehicle width direction of the cross member 18 is prevented. Therefore, the cross member is smaller than the conventional structure in which the vicinity of both ends in the vehicle width direction is curved.

Therefore, both end portions 18A of the cross member 18 in the vehicle width direction are connected to the rear floor side member 12
Can be sufficiently suppressed, and road noise can be sufficiently reduced.

The pair of rear floor side members 12
There is the case for vibration in the direction approaching each other, cross member 18 extending substantially linearly in the role of the beam sufficiently suppress vibration of the pair of rear floor side member 12.

Further, since the rear floor pan 14 is separated from the cross member 18, the vibration of the cross member 18 is not directly transmitted to the rear floor pan 14, so that the vibration of the rear floor pan 14 can be sufficiently suppressed, and the road noise can be sufficiently reduced. Can be reduced.

In this embodiment, the input from the tire vibrated by the rough road is input to the cross member 18 via the rear lower arm 20 and the lower arm bracket 22, but the cross member 18 is sufficiently moved forward and backward. Because of the large aspect ratio, the vertical vibration of the main body of the cross member 18 occurs, but the longitudinal vibration is small, and the longitudinal vibration of the rear floor side member 12 is small. Therefore, the vibration of the rear floor pan 14 can be suppressed, and the in-phase and out-of-phase displacements during traveling of the lower arm 20 before and after forming the double link suspension are extremely small, and as a result, the stability is also very good. Bring results.

[0025]

According to the present invention, a pair of rear floor side members arranged along the vehicle front-rear direction near both ends in the vehicle width direction at the lower rear portion of the vehicle body, and a vehicle is mounted on opposite side surfaces of the pair of rear floor side members. extending the vehicle width direction substantially linearly widthwise ends are spaced apart from the rear floor pan together are coupled, and the cross-sectional shape as viewed from the vehicle width direction, the vehicle body
The structure includes a cross member that is long in the front-rear direction and short in the vertical direction of the vehicle body and a lower arm bracket that is connected to the cross member and supports the rear lower arm, so that the vibration of the rear floor pan is sufficient. , Road noise can be sufficiently reduced, and operation is also possible.
It has an excellent effect of giving very good results also to the properties.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rear underbody structure according to an embodiment of the present invention, as viewed from the front of a vehicle body.

FIG. 2 is a perspective view showing a part of the rear underbody structure according to the embodiment of the present invention, as viewed obliquely from the front inside the vehicle body.

FIG. 3 is a perspective view showing a lower portion of the vehicle body to which the rear underbody structure according to the embodiment of the present invention is applied, as viewed obliquely from the front of the vehicle body.

FIG. 4 is a cross-sectional view of a conventional rear underbody structure viewed from the front of a vehicle body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Auto body 10A Rear underbody 12 Rear floor side member 12A Inner side wall part in vehicle width direction 14 Rear floor pan 18 Cross member 18A Both ends in vehicle width direction 20 Rear lower arm 22 Lower arm bracket

──────────────────────────────────────────────────続 き Continued on the front page (56) References JP-A 2-108672 (JP, U) JP-A 60-170207 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B62D 25/20

Claims (1)

(57) [Claims] 1. A pair of rear floor side members arranged along the vehicle front-rear direction near both ends in the vehicle width direction of a lower rear portion of a vehicle body, and both end portions in the vehicle width direction opposed to both sides of the pair of rear floor side members. There extends the vehicle width direction substantially linearly spaced apart from the rear floor pan together are coupled, and the cross-sectional shape as viewed from the vehicle width direction, in the longitudinal direction of the vehicle body
A rear underbody structure, comprising: a cross member having a long aspect ratio that is short in the vertical direction of the vehicle body; and a lower arm bracket connected to the cross member to support a rear lower arm.