JPH082441A - Vehicle body front part structure for automobile - Google Patents

Abstract

PURPOSE:To eliminate a disconnection point in a connection part between a front member and a rear member in a front side member so as to improve strength. CONSTITUTION:A front side member extending in the vehicle longitudinal direction consists of a front member 10 having a U-shaped cross section and a rear member 11 having a U-shaped cross section, and a fender apron 2 is connected to the outside face of the front member 10, so that a closed cross sectional structure is provided. The rear end part of the front member 10 and the rear end part of the fender apron 2 are connected to the front end part of the rear member 11. In the inside of the front member 10, a reinforcement 12 having a U-shaped cross section is connected, and in the rear part of the reinforcement 12, a gradually variable part, 12a whose cross section is gradually flattened toward the fender apron 2 side from the front member 10 side is formed. The rear end of the gradually variable part 12a is connected to the front end part of the rear member 11 with the fender apron 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a vehicle body front structure,
In particular, the present invention relates to a reinforcing structure for a front side member that extends in the front-rear direction at the front of the vehicle body.

[0002]

2. Description of the Related Art Conventionally, a front side member extending in the front-rear direction of a vehicle body is composed of a front member having a U-shaped cross section and a rear member having a U-shaped cross section which are joined to each other, and a fender apron is joined to an outer surface of the front member. There is known a vehicle body front structure in which the rear end portion of the front member and the rear end portion of the fender apron are joined to the front end portion of the rear member while having a closed cross-section structure. A dash panel is joined to the upper surface of the rear member to form a closed cross-section structure, and the rear end of the front member is also joined to the dash panel.

In the above structure, since the rear member has an extremely small cross-sectional shape with respect to the front member, most of the load is concentrated on the dash panel when an external force is applied to the front side member from the front, such as during a collision. To prevent this, the front member is bent so as to incline toward the fender apron, the rear end is joined to the fender apron, and the gusset is joined to the front member and the dash panel so as to cover the bent portion. , JP-A-62-1
It is disclosed in Japanese Patent No. 105780.

However, while the front and rear members, gussets and the like which form the front side member are formed of relatively thick steel plates, the fender apron and dash panel are usually formed of thinner steel plates. Is. Therefore, even if the front member is bent to increase the rigidity as described above, the load from the front is likely to concentrate on the fender apron portion having low strength, and it is not possible to eliminate the drawback of breaking strength.

[0005]

On the other hand, there is one in which the cross-sectional shape of the rear member is enlarged so that the front member and the rear member are joined substantially continuously. In this case,
Most of the load applied to the front member from the front can be received by the rear member, and the load on the dash panel can be reduced. In this case, in order to improve the strength of the joint between the front member and the rear member, a reinforcement is arranged inside the front member, and the rear end of the reinforcement is joined to the rear member together with the front member. Are being reinforced. However, even in this case, the strength of the front side member in the vehicle width direction is improved, but the strength of the joint portion between the fender apron and the rear member outside the vehicle body is not sufficient, and the joint portion is resistant to the load from the front. The cross-section collapses easily and it becomes a break point in strength.
Therefore, an object of the present invention is to eliminate a break point in a connecting portion between a front member and a rear member of a front side member,
An object of the present invention is to provide a vehicle body front structure capable of improving strength.

[0006]

To achieve the above object, according to the present invention, a front side member extending in the longitudinal direction of a vehicle body is composed of a front member having a U-shaped cross section and a rear member having a U-shaped cross section. In the vehicle body front structure in which a fender apron is joined to the outer surface of the vehicle to form a closed cross-section structure, and the rear end of the front member and the rear end of the fender apron are joined to the front end of the rear member. , A reinforcement having a U-shaped cross section for reinforcing the front member is joined to the inside of the front member, and the rear portion of this reinforcement has a gradually flat cross section from the front member side toward the fender apron side. A gradual change part is formed and the rear end of this gradual change part of the reinforcement is joined to the front end part of the rear member together with the fender apron. It is characterized in that is.

[0007]

When a load is applied to the front side member from the front as in the case of a collision, the load is concentrated on the joint between the front member and the rear member. Due to this load, the front side member is likely to bend at the joint between the fender apron having low strength and the rear member as a break point. However, since the rear end of the gradual change portion of the reinforcement is joined to the rear member together with the fender apron, the gradual change portion, the front member and the rear member form a substantially triangular structure similar to the truss structure. Is responsible for the bending stress. As a result, it is possible to prevent the joint portion between the fender apron and the rear member from becoming a break point and bending, and it is also possible to prevent the cross-sectional collapse of the front side member due to this.

[0008]

1 to 5 show an example of a vehicle body front structure according to the present invention. In FIG. 1, a fender apron 2 that constitutes a wheel house is provided on both sides of a front portion of a vehicle body 1, and a radiator support 3 is fixed to a front end portion of the fender apron 2. Left and right radiator support 3
A cross member 4 and an upper support 5 are provided between the cross member 4 and the upper support 5, and a hood lock support 6 is provided between the cross member 4 and the upper support 5 in the vertical direction.

A front side member 7 extending in the front-rear direction of the vehicle body is provided below the inner side surface (engine room side) of the fender apron 2.
The front end portion of is extended forward of the radiator support 3, and an extension member 8 is joined so as to cover the outer surface and the front surface of the extension portion 7a. Extension 7 above
A has a closed cross-section structure, and a crushable zone is formed by the extension portion 7a and the extension member 8 and absorbs impact energy at the time of collision. Both ends of the cross member 4 are fixed to the extension member 8 by bolts or the like.

2 and 3 show the front structure on the right side of the vehicle body as seen from the engine room side. The front side member 7 includes a front member 10 having a U-shaped cross section located on the front side of the vehicle body and a rear member 11 having a U-shaped cross section located on the rear side of the vehicle body. Inside the front member 10, a reinforcement 12 whose cross section changes from the front to the rear as shown in FIG. 4 is arranged, and is joined by spot welding at a position indicated by a cross mark. That is, reinforcement 1
The front end of 2 reinforces only the lower part of the front member 10 as shown in FIG. 4 (a), and the middle part has a U-shape along the inner surface of the front member 10 as shown in FIG. 4 (b). As shown in FIG. 4 (c), the rear end portion is formed with a gradually changing portion 12a that changes so as to have a gradually flat cross section from the front member 10 side toward the fender apron 2 side. As shown in FIG. 5, the gradual change portion 12a is gradually inclined from the front member 10 side to the fender apron 2 side in a plan view, and the rear end of the gradual change portion 12a is outside the rear member 11 together with the fender apron 2. Is joined to the vertical wall portion 11a by spot welding. Further, the rear end portion of the front member 10 is joined to the vertical wall portion 11b inside the rear member 11 by spot welding.

The rear member 11 is bent downward in accordance with the shape of the wheel house, and the floor member 1 is provided at the rear end thereof.
3 (see FIG. 3) are joined. A dash panel 14 is joined to the upper surface of the rear member 11 to form a closed cross section structure. A part of the rear end of the front member 10 is also joined to the dash panel 14. The floor member 13 has a U-shaped cross section similar to the rear member 11, and a floor panel 15 is joined to the upper surface thereof to form a closed cross section structure. An extension 10a is formed on the inner surface of the vehicle body at the rear end of the front member 10, and the extension 10a is joined to the rear member 11 by spot welding. The extension 10a reinforces the joint between the front member 10 and the rear member 11 from the inside of the vehicle body.

The plate thickness of each member constituting the vehicle body front structure is as follows in this embodiment. Fender apron: 0.7mm Front member: 1.0mm Rear member: 1.2mm Reinforcement: 1.4mm Dash panel: 0.8mm For the same material, bending strength is almost proportional to the cube of the thickness, so fender The strength of the front member 10 is about 3 times, that of the rear member 11 is about 5 times, and that of the reinforcement 12 is about 8 times that of the apron 2.

The operation of the vehicle body front structure having the above structure will now be described. The impact force from the front applied to the front side member 7 at the time of a vehicle collision is due to the closed cross-sectional structure composed of the front member 10 and the fender apron 2 and the rear portion via the connecting portion of the front member 10 and the rear member 11. Transmitted to. In particular, the fender apron 2 has a front member 10
Since the strength is about ⅓ as compared with, the joint portion between the fender apron 2 and the rear member 11 becomes a break point and tends to bend as shown by the chain double-dashed line in FIG. However, since the gradually changing portion 12a of the reinforcement 12 and the front member 10 and the rear member 11 have a substantially triangular structure similar to a truss structure, the rigidity against a load from the front is increased and the above bending is prevented. it can. As a result, it is possible to eliminate a break point at the joint between the fender apron 2 and the rear member 11 and prevent the cross-section of the front side member 7 from collapsing. By joining the reinforcement 12 to the fender apron 2 side, the front member 10
Although the strength of the joint between the rear member 11 and the rear member 11 is reduced, since both members 10 and 11 are both made of members having a large plate thickness, there is no risk of this joint becoming a breaking point in strength. Moreover, since the extension portion 10a is reinforced as in the embodiment, the strength of the joint portion is further improved.

In the above embodiment, the extension 10a is provided integrally with the front member 10 inside the vehicle body at the joint between the front member 10 and the rear member 11. However, the extension 10a may be omitted.

[0015]

As is apparent from the above description, according to the present invention, the reinforcement is joined to the inside of the front member, and the rear portion of the reinforcement is sectioned from the front member side toward the fender apron side. Forms a gradually changing flat portion, and the rear end of this gradually changing portion is joined to the front end of the rear member together with the fender apron, so that the truss structure is formed by the gradually changing portion, the front member, and the rear member. By forming a substantially triangular structure similar to, it is possible to reduce the load on the joint between the fender apron and the rear member. As a result, it is possible to prevent the joint portion between the fender apron and the rear member from becoming a break point and bending, and it is also possible to prevent the cross-sectional collapse of the front side member due to this.

[Brief description of drawings]

FIG. 1 is an overall perspective view of a vehicle body front structure according to the present invention.

FIG. 2 is a perspective view of the vehicle body front structure of the present invention viewed from the engine room side.

FIG. 3 is a side view of the vehicle body front structure of the present invention viewed from the engine room side.

4 (a) to (d) are lines AA and BB in FIG. 3, respectively.
It is a line, CC line, and DD sectional view.

5 is a sectional view taken along line VV of FIG.

[Explanation of symbols]

 2 Fender apron 7 Front side member 10 Front member 11 Rear member 12 Reinforcement 12a Gradual change part

Claims (1)

[Claims] 1. A front side member extending in the vehicle front-rear direction is composed of a front member having a U-shaped cross section and a rear member having a U-shaped cross section, and a fender apron is joined to an outer surface of the front member to form a closed cross-section structure. In the vehicle body front structure in which the rear end of the front member and the rear end of the fender apron are joined to the front end of the rear member, a cross section for reinforcing the front member is provided inside the front member. A U-shaped reinforcement is joined, and at the rear of this reinforcement is formed a gradually changing portion whose cross-section gradually becomes flat from the front member side toward the fender apron side. A vehicle body front structure, wherein a rear end of the gradually changing portion is joined to a front end of a rear member together with a fender apron.