JPS6235643Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a lower body structure of an automobile, and more particularly to a lower body structure around a differential support portion.

In conventional automobiles, differentials, which are subject to large vertical loads, are mounted on a pair of sturdy side frames (for example, the rear side frames for rear-wheel drive vehicles) via differential mount members. It was often supported. However, due to the layout of other devices such as the suspension, there are cases where it is necessary to support the differential on the vehicle body inwardly from the side frames. A differential may be supported by a cross member (an example of which is shown in Japanese Utility Model Application Laid-open No. 57-98975).

However, since the above-mentioned cross member is generally only connected to the side frame at both ends, it is not possible to sufficiently increase the joint strength with the side frame. A vehicle body structure designed to support the differential is disadvantageous in receiving vertical loads acting on the differential.

The present invention was developed in view of the above circumstances, and its purpose is to provide an automobile lower body structure in which the strength of the joint between the cross member and the side frame, on which the differential is supported, is sufficiently increased. It is something to do.

The lower body structure of an automobile according to the present invention uses a cross member having a hat-like cross-sectional shape with an open upper part as the cross member connected to the side frame as described above, and at least one outer end of the side wall of the cross member is connected to the side frame. These side walls are expanded and joined to the vertical walls of the side frame, and a differential mount bracket that supports the differential is placed within the end of the cross member and joined to the cross member, and the outside of the bracket is The end portion is joined to the side wall of the side frame.

In the above structure, the side frame and the cross member are directly joined, and further, these two members are indirectly joined via the differential mount bracket, so that the strength of the joint between these two members is increased.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an automobile underbody structure according to one embodiment of the present invention as viewed from the inside of the vehicle body.
The rear side frame 1, which is paired with another rear side frame (not shown) and extends in the fore-aft direction of the vehicle body, has a so-called hat-shaped cross section with flanges 1a, 1b formed at its upper part, as shown in cross section by the thick line in the drawing. A cross member 2 extending in the left-right direction of the vehicle body is disposed inside the rear side frame 1, and one end of the cross member 2 is joined to the rear side frame 1 and the other end is joined to the other rear side frame to strengthen the frame structure.

This cross member 2 has a cross-sectional shape of a hat with an open upper part, as shown by the thick line in the figure, and the outer ends of the side walls 2a and 2b are widened. A differential mount bracket 3 is fixed within this outer end. As shown in detail in FIG. 2, in this differential mount bracket 3, a pipe 3b is arranged upright within a frame 3a having a substantially U-shaped cross-sectional shape narrowed at the center, and the bottom and side surfaces of the pipe 3b are They are each welded to the center of the bottom wall 3c of the frame 3a, and side walls 3d and 3e with narrower spacing between them, and the bottom wall 3c has a bolt passage hole that aligns with the through hole inside the pipe 3b. 3f
is provided. Further, a mount bolt 3g is fixed to the upper part of the pipe 3b by welding.
And the outer ends of the side walls 3d and 3e (the ends located on the outer side of the vehicle body when fixed to the cross member 2)
Flanges 3h and 3k are formed at the bottom wall 3c, and a flange 3l is formed at the outer end of the bottom wall 3c.

The outer surfaces of the flanges 3h, 3k, and 3l of the differential mount bracket 3 are the flanges 2c, 2d.
The inner end of the side walls 3d and 3e are joined to the side walls 2a and 2b, and the inner end of the bottom wall 3c is joined to the bottom wall 2g. It is fixed to the cross member 2. Note that the above-mentioned parts are usually joined by spot welding, and the other members described below are joined in the same manner.

Next, the connection between the cross member 2 and the rear side frame 1 formed as described above will be explained. Flanges 2c and 2d formed at the outer ends of the side walls 2a and 2b of the cross member 2 are joined to the inner wall 1c of the rear side frame 1, and
The upper flanges 2e and 2f of the rear side frames 1 and 2b are joined to the lower surface of the upper flange 1a of the rear side frame 1 and to the lower surface of a rear floor (not shown). Furthermore, the bottom wall 2g of the cross member 2 extends below the rear side frame 1 and is joined to the lower surface of the bottom wall 1d of the rear side frame 1 (the joint between these bottom walls 1d and 2g is shown in FIG. is not shown, but is shown in FIG. 3, which will be described later).

and the flange 3h of the differential mount bracket 3 that is in contact with the inner wall 1c of the rear side frame 1,
3k is joined to the side wall 1c. Also, flange 3
is joined to the inner wall 1c of the rear side frame 1 together with the vertical wall portion of the bottom wall 2g of the cross member 2. That is, the rear side frame 1 and the cross member 2 are not only directly joined to each other, but also connected via the differential mount bracket 3, and therefore the joint strength between the rear side frame 1 and the cross member 2 is equal to that of each other. This is almost double compared to the case where only direct bonding is performed. Although not shown, the opposite end of the cross member 2 is similarly connected to the other rear side member.

On the frame structure formed as described above, the rear floor 4 is joined as shown in FIG. 3 (in FIG. 3, a partially broken surface is shown by a bold line). That is, upper flanges 1a, 1b of rear side frame 1 and upper flanges 2e, 2f of cross member 2 are joined to the lower surface of rear floor 4. If you want to join the cross member 2 to the rear side frame 1 and the rear floor 4 after joining the rear side frame 1 to the lower surface of this rear floor 4, make a small working hole in the upper part of the differential mount bracket 3 of the rear floor 4. If you do, use this work hole to attach flanges 3h and 3k of differential mount bracket 3.
and the inner wall 1c of the rear side frame 1 can be welded together. Also, if such a work hole is provided, even if the pipe 3b or mount bolt 3g is damaged during differential mounting work, you can remove them from the work hole and replace them with new ones, or repair them. can do.

As shown in FIG. 3, a differential mount member 6 for fixing a differential differential 5 is disposed below the lower structure in which the rear side frame 1, cross member 2, and rear floor 4 are integrated. The differential mount member 6 is supported by the cross member 2 via the spacer 8 by fastening the mount nut 7 to the mount bolt 3g.

A large vertical load is now applied to the differential mount member 6 from the differential differential 5.
Therefore, a large load acts on the joint between the cross member 2 that supports the differential mount member 6 and the rear side frame 1;
As described above, since the joint strength between the cross member 2 and the rear side frame 1 is increased, these joints are strong against the above-mentioned vertical loads. Further, since a substantially triangular closed cross section is formed by the expanded outer end of the cross member 2, the side wall 1c of the frame 1, and the side wall of the differential mount bracket 3, the cross member 2 can be prevented from falling.

In the embodiment described above, both outer ends of the two side walls 2a and 2b of the cross member 2 are expanded, but one side wall of the cross member is not expanded, and that portion is attached to the differential mount bracket. Even if the outer end of the differential mount bracket is joined to the side frame together with the outer end of the cross member, if the outer end of the differential mount bracket is joined to the side frame separately from that side wall on the other side wall (the expanded side) of the cross member, it will work as described above. The bond strength is increased.

As explained in detail above, the lower body structure of the present invention effectively increases the joint strength between the side frame and the cross member through a simple reinforcement structure using a differential mount bracket. It is the best choice for supporting the traditional.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the present invention;
The figure is an exploded perspective view showing a part of the above-described embodiment, and FIG. 3 is a partially cutaway elevational view showing a state in which a differential is attached to the lower vehicle body structure of the above-described embodiment. 1...Rear side frame, 1c...Inner wall of rear side frame, 2...Cross member, 2
a, 2b... side wall of cross member, 2c, 2d
...Cross member flange, 3...Differential mount bracket, 3h, 3k, 3l...Differential mount bracket flange.

Claims (1)

[Scope of utility model registration request] a pair of side frames extending in the front-rear direction of the vehicle body, each having a cross-sectional shape of a hat with an open upper part;
a cross member in which at least one outer end of the side walls is widened and these side walls are joined to the vertical wall of the side frame; and a cross member having a substantially U-shaped cross-sectional shape;
It consists of a differential mount bracket disposed within the end of the cross member, the inner end of the side wall being joined to the side wall of the cross member, and the outer end of the side wall being joined to the side wall of the side frame. An automobile lower body structure in which a closed section is formed by the side wall of the side frame and the side wall of the differential mount bracket.