JPH11348812A - Subframe structure for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a subframe which can ensure a high strength but which is lightweight and inexpensive. SOLUTION: A subframe is composed of a front member and side members 2 which are formed from pipes, and a extrusion-molded block-like bracket 4 which is formed therein with a plurality of through-holes extending in the extruding direction thereof, and with pipe insertion holes 7a, 7b communicated with those 6a, 6b of the through-holes, orthogonal thereto, and inserted therein with the members which are then welded to the bracket 4 at parts thereof confronting the through-holes. Accordingly, aluminum alloy materials can be used for the components constituting the subframe, instead of steel material, and accordingly, the subframe may be lightweight. Further, bending of the pipes and extrusion molding of the bracket can reduce the costs since the necessity of investment for dies and the costs of pressing and forging can be eliminated, and the pipes can be axiallywelded so that the structure thereof can resist against its bending.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sub-frame structure of an automobile mounted on a vehicle body to support components mounted on the vehicle body such as a suspension and a steering device.

[0002]

2. Description of the Related Art Conventionally, there has been a vehicle in which an engine, a suspension, a steering device and the like of an automobile are mounted on a vehicle body via a subframe.
No. 283577.

According to the above-described structure, the ends of the side member formed by casting or forging an aluminum alloy and the cross member made of a steel pipe are connected to each other by press-fitting. In this way, by partially aluminum alloying the subframe, the weight of the subframe can be reduced with respect to the subframe structure formed by pressing a steel plate.

[0004]

With the above structure,
Since a steel pipe material is used in part, the weight reduction effect is small, and it is desired to further reduce the weight. Therefore, it is preferable to form each member constituting the sub-frame from an aluminum alloy material as much as possible. In that case, by forming each member by press molding or casting, the shape of the joint between the members can be relatively freely adjusted. In such a structure, each member may be bolted to each other.

[0005] However, in the above-mentioned structure, there is a problem that the cost of the die is high when each member is formed by press molding. In the structure in which a press-formed product or a cast product is bolt-connected, the connection is difficult. When the thickness is increased in order to increase the strength of the portion, the weight increases, so that it is difficult to reduce the weight.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and to realize a reduction in weight and cost while securing sufficient strength, the present invention relates to a method for mounting on a vehicle body. A sub-frame attached to the vehicle body to support the attachment component has a structure in which a pipe is connected to a block-shaped member, and the block-shaped member is formed at the same time as being formed by extrusion molding; A pipe insertion hole formed in a direction crossing the through-hole, wherein the pipe is welded in the through-hole at a portion facing the through-hole by being inserted into the pipe insertion hole, thereby forming the block-shaped portion. It was assumed to be connected to the member. Further, it is preferable that a suspension mounting portion is formed in the block-shaped member in the vicinity of a joint portion with the pipe by the extrusion molding.

With this configuration, when a block-shaped member is used at the corner when the sub-frame is formed in a rectangular shape, even if a bending stress is applied to the joint between the block-shaped member and the pipe, Since the connection between the block-shaped member and the pipe is performed by welding at a portion facing the through hole corresponding to the deep portion of the pipe insertion hole, it is possible to prevent a load concentration point from being generated at the insertion port of the pipe insertion hole. The load at the time of bending input can be dispersed. Further, by providing the suspension mounting portion near the joint between the block-shaped member and the pipe, the input (lateral force) from the suspension can be efficiently distributed to the pipe.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to specific examples shown in the accompanying drawings.

FIG. 1 is a perspective view showing an entire front subframe of an automobile to which the present invention is applied. This subframe is formed by combining a front member 1, a side member 2, and a rear member 3 each formed of an aluminum alloy pipe in a cross-girder shape, and attached to a vehicle body (not shown). The front member 1 and the side member 2 are connected to each other via a bracket 4 as a block-shaped member, and the side member 2 and the rear member 3 are welded at a portion where they cross each other at the top and bottom.

The bracket 4 is formed by extruding an aluminum alloy material. As shown in the figure, a pair of parallel projections are used to connect the front pivot 5a of the suspension arm 5 during the extrusion. A suspension mounting portion 4a made of one piece is formed, and a plurality of through holes 6 are simultaneously formed.

The through holes 6 are formed by extruding in the thickness direction of the bracket 4. As shown in FIGS. 2 and 3, the bracket 4 has a plurality of through holes 6. Each pipe insertion hole 7a, 7b drilled from the side surface of the bracket 4 is formed so as to communicate with a part 6a, 6b of the bracket 4 in a direction orthogonal thereto. The pipe insertion holes 7a and 7b are formed by, for example, cutting after extruding the bracket 4.

One through hole 6a corresponds to the pipe insertion hole 7a for the front member 1, and the other through hole 6b corresponds to the pipe insertion hole 7b for the soot side member 2. Therefore, the front member 1 and the side members 2
Part of each of the insertion ends of the front member 1 and the side member 2 inserted into each of the pipe insertion holes 7a and 7b
a.6b.

The insertion ends of the front member 1 and the side members 2 are welded (indicated by W in FIG. 2) to the inner peripheral edges of the through holes 6a and 6b.
Is fixed to the bracket 4 by fitting into the pipe insertion holes 7a and 7b and welding W at the above-mentioned locations.
Thereby, the bracket 4 of the pipe (each member 1 and 2)
Will extend in the axial direction of the pipe, allowing for high rigidity of the pipe against bending.

Further, since welding is performed at the openings formed by the through holes 6a and 6b, the occurrence of distortion due to welding can be suppressed. Further, the shape of the inner peripheral edge of the through hole 6b, which is the target of the welding W on the bracket 4 side, is stepped as shown in FIG. The pipe thickness is about the same. As a result, the heat capacities of the welded portions can be matched with each other, and the reliability of welding can be improved. However, since the bracket 4 is extruded, the stepping can be easily performed. .

Also, a pipe insertion hole 7b for the side member 2
Is formed adjacent to the suspension mounting portion 4a, external inputs to the suspension mounting portion 4a can be distributed to the bracket 4 and the side members 2, respectively, so that the external input (lateral force) from the suspension can be reduced. Again, a strong structure can be achieved. Such a structure can be easily achieved by the extrusion processing of the bracket 4.

Note that the bracket 4 according to the present embodiment is
Are attached to the vehicle body (in the figure, mounting bolt insertion holes 4
Although b) is provided, a stabilizer support portion (not shown) may be further provided, or a gear box mounting bracket (not shown) of the steering device may be welded.

The pipe according to the present invention (each member 1.
By bending process 2) and 3), it is possible to eliminate the joining portion by joining the press-formed products in order to obtain a closed cross-sectional structure in the structure using the conventional press-formed product, so that the weight and cost are reduced. Can be improved.

[0018]

As described above, according to the present invention, each component constituting the sub-frame can be replaced from a steel material to an aluminum alloy material, and the weight can be reduced. Further, by bending the pipe, it is not necessary to use a press-processed product, and the production cost can be significantly reduced by reducing the investment in the mold and the processing cost. In addition, by using an extruded product, it is not necessary to use a cast product, and the manufacturing cost can be further reduced and the weight can be improved by reducing the die investment and processing cost. In addition, a welding structure that is strong against bending can be obtained by a simple shape, bolt connection can be eliminated, the number of parts can be reduced, the hole processing of the fastening portion can be reduced, and the weight and cost can be reduced. further,
By providing the suspension mounting portion near the joint between the block-shaped member and the pipe, the input (lateral force) from the suspension can be efficiently distributed to the pipe.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an entire front subframe of an automobile to which the present invention is applied.

FIG. 2 is a plan view of an essential part of a front subframe of an automobile to which the present invention is applied.

FIG. 3 is a side view as viewed from the arrow III line in FIG. 2;

FIG. 4 is an enlarged sectional view of an essential part taken along line IV-IV in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Front member 2 Side member 3 Rear member 4 Bracket, 4a Suspension mounting part 5 Suspension arm, 5a Front side pivotal support part 6 Through hole, 6a, 6b Through hole 7a, 7b Pipe insertion hole

Claims (2)

[Claims] 1. A subframe attached to a vehicle body to support a component attached to the vehicle body, the subframe has a structure in which a pipe is connected to a block-shaped member, and when the block-shaped member is formed by extrusion molding, It has a formed through-hole and a pipe insertion hole formed in a direction crossing the through-hole, and the pipe faces a portion facing the through-hole by being inserted into the pipe insertion hole inside the through-hole. A sub-frame structure for an automobile, wherein the sub-frame structure is welded to the block-shaped member. 2. The sub-frame structure of an automobile according to claim 1, wherein a suspension mounting portion is formed in the block-shaped member near the connecting portion with the pipe by the extrusion molding.