JP2003327156A - Vehicle body structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a sub-member deformed in prior to deformation of a main body member for forming a body skeleton, against an axis-directional input, even in low speed collision of relatively low damage, to say nothing of high speed collision. <P>SOLUTION: Plastic deformation reaction of the sub-member 11 is made high in a rear part 11B compared with a front part 11A, and the plastic deformation reaction of the rear part 11B in the sub-member 11 is made lower than yield point reaction of the main body member 10. A yield point lowering mechanism 20 is provided to bring the yield point reaction of the main body member 10 into a level substantially same to the plastic deformation reaction when the rear part 11B of the sub-member 11 is deformed. A relation of Fsd>(αs/αb)>Fbd is satisfied in the low speed collision, and the deformation is brought from the sub-member to the main body member 10 in order, even in the low speed collision, where αb is a braking ratio of the sub-member 11, Fbd is the plastic deformation reaction in the high speed collision in the rear part 11B of the sub-member 11, αs is a braking ratio of the main body 10, and Fsd is the yield point reaction in the high speed collision. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle body structure configured such that a collision load is axially input to a body member forming a vehicle body skeleton via a sub member.

[0002]

2. Description of the Related Art An example of a vehicle body structure of this type is disclosed in Japanese Patent Laid-Open No. 2000-53019.
When this is applied to the part where the bumper stay is connected to the front end of the front side member, the plastic deformation reaction force (F1) of the bumper stay, which is the auxiliary member, is greater than the yield point reaction force (F2) of the side member, which is the main member. It is low and higher than the plastic deformation reaction force (F3) of this side member.

[0003]

However, when the static-dynamic ratio of the bumper stay is lower than the static-dynamic ratio of the side member, the reaction force decrease rate of the side member becomes larger than the reaction force decrease rate of the bumper stay. In high-speed collision, F2> F1
Even if the relationship of> F3 is established and the deformation can be generated from the bumper stay side with respect to the axial input, the yield point reaction force F2 of the side member becomes lower than the plastic deformation reaction force F1 of the bumper stay at a low speed collision. , The bumper stay does not deform, but the side member deforms.

Therefore, even if the damage is relatively small during a low speed collision, the easily replaceable bumper stay is not deformed and the side members, which are the main body of the vehicle body frame, are damaged. Therefore, a lot of time and money will be spent on the repair.

Therefore, the present invention is not limited to the case of a high-speed collision,
Provided is a vehicle body structure capable of being deformed from a sub member prior to a main body member forming a vehicle body skeleton with respect to an axial input even in a low-speed collision with relatively little damage.

[0006]

In the vehicle body structure of the present invention, the collision load is axially input to the main body member constituting the vehicle body skeleton through the auxiliary member. In addition, the plastic deformation reaction force of the sub member is made higher in the load input direction rear part than in the load input direction front part, and the plastic deformation reaction force of this sub member rear part in the load input direction is made higher than the yield point reaction force of the main body member. A yield point reduction mechanism is provided that lowers the yield point reaction force of the main body member to approximately the same level as the plastic deformation reaction force when the rear portion of the auxiliary member in the load input direction is deformed. And
The static / dynamic ratio of the sub member is αb, the plastic deformation reaction force at the rear of the sub member in the load input direction at high speed collision is Fbd, the static / dynamic ratio of the main body member is αs, and the yield point reaction force of the main body member at high speed collision is Fs.
When d is set, Fsd> (αs / αb) at low speed collision
It is characterized by satisfying the relation of> Fbd.

[0007]

According to the vehicle body structure of the present invention, it is possible to sequentially deform the sub member from the sub member to the main body member irrespective of the high speed collision and the low speed collision and without reducing the plastic deformation reaction force of the sub member. Therefore, even when a relatively low-damage low-speed collision occurs, it is possible to limit the damage to the sub member as much as possible.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

1 to 7 show a first embodiment of a vehicle body structure according to the present invention, FIG. 1 is an exploded perspective view of a connecting portion between a sub member and a main body member, and FIG. 2 is an end perspective view of the main body member. FIG. 3 is a cross-sectional view of the connecting portion of the sub-member and the main body member when there is no collision, FIG. 4 is a cross-sectional view of the connecting portion of the sub-member and the main body member at the time of collision, and FIG. 6 is a schematic view showing force characteristics, FIG. 6 is a perspective view showing dimensions of the sub member, and FIG. 7 is an explanatory view showing reaction force characteristics of the sub member.

In this embodiment, as shown in FIG. 1, the present invention is applied to a connecting portion of a front side member (hereinafter referred to as a side member) 10 as a main body member and a bumper stay 11 as a sub member.

The side members 10 are arranged on both sides in the vehicle width direction, and are formed as a rectangular closed cross-section structure by joining an inner panel 10a having a U-shaped cross section and an outer panel 10b having a flat plate shape. Numeral 10 is arranged so as to extend in the vehicle front-rear direction as a whole, and absorbs impact energy by axial crush deformation of the side member 10 against a collision load input in the axial direction of the side member 10 at the time of a frontal collision. It functions as the main energy absorbing member.

The bumper stay 11 is formed of an extruded material having a rectangular cross section or a panel material into a rectangular closed cross section structure, and its front end is joined to the rear surface 12a of both ends of the bumper armature 12 extending in the vehicle width direction. In addition, a first end plate 13 for attaching to the side member 10 is joined to the rear end.

On the other hand, a second end plate 14 is connected to the front end of the side member 10, and mounting holes 13a and 14a are formed at the four corners of the first and second end plates 13 and 14, respectively.
The side member 10 and the bumper stay 11 are coaxially joined by connecting with the bolt 15 and the nut 15a as fastening means through, and the collision load input to the bumper armature 12 at the time of frontal collision is passed through the bumper stay 11. Is input to the front end of the side member 10.

The first and second end plates 13 and 14
As shown in FIG. 3, openings 13b and 14b for inserting a projection 22b of a reinforcement 22, which will be described later, are formed in the respective central portions.

Here, in the present embodiment, the plastic deformation reaction force of the bumper stay 11 is in the load input direction rear portion (hereinafter, referred to as rear portion) rather than the load input direction front portion (hereinafter referred to as front portion) 11A. ) 11B is increased and the plastic deformation reaction force of the rear portion 11B of the bumper stay 11 is set lower than the yield point reaction force of the side member 10.

Further, when the rear portion 11B of the bumper stay 11 is deformed, the yield point reduction mechanism 20 is arranged to reduce the yield point reaction force of the side member 10 to substantially the same level as the plastic deformation reaction force.
Is provided.

The yield point reduction mechanism 20 includes the side member 10
A slit 21 as a yield point reduction portion formed at the front ends of the upper and lower walls 10c and 10d, and a reinforcing member attached to this slit 21 and removed when the deformation of the bumper stay 11 reaches the rear portion 11B. And a reinforcement 22 of

The reinforcement 22 has the slit 21.
Of the flat plate-like welded portion 22a welded (front spot welded spot Wf and rear spot welded spot Wr) across the front and rear in the load input direction and the bumper stay 11 is deformed in the rear portion 1.
When it reaches 1B, a convex portion 22b as a peeling force applying portion for deforming the welded portion 22a in the direction of peeling from the front spot welding spot Wf is provided.

A pair of upper and lower welding portions 22a are provided to cover the slit 21 from the inside of the upper and lower walls 10c and 10d, respectively, as shown in FIG.
On the other hand, the projecting portion 22b has a pair of upper and lower welded portions 2b.
The front end portion of these welded portions 22a and the rear end portion of the protruding portion 22b are located at the center between the two 2a and project forward from the vehicle.
The arms 22c are connected to each other via an arm portion 22c extending substantially at right angles to the load input direction (front-back direction).

When the reinforcement 22 is attached, as shown in FIG.
Of the opening 13 of the first and second end plates 13 and 14 as shown in FIG.
It is inserted into the inside of the bumper stay 11 from b and 14b.

At this time, when the total length of the bumper stay 11 is L as shown in FIG. 3, a gap is formed between the tip (front end) of the inserted protruding portion 22b and the rear surface 12a of the bumper armature 12. a is provided, and the portion corresponding to the gap a is the front portion 11A of the bumper stay 11 and the remaining portion (La) is the rear portion 11B.

Further, since the projecting portion 22b is located inside the bumper stay 11, it functions as a reinforcing member for the bumper stay 11, and the projecting portion 22b acts on the plastic deformation reaction force of the rear portion 11B of the bumper stay 11. It also has the function of increasing.

Here, by selecting a material for forming the side member 10 and the bumper stay 11, the static-dynamic ratio of the bumper stay 11 is set to αb, and the static-dynamic ratio of the side member 10 is set to αs.

When the plastic deformation reaction force at the time of high speed collision at the rear portion 11B of the bumper stay 11 is Fbd and the yield point reaction force at the time of high speed collision of the side member 10 is Fsd, Fsd> (αs / Αb)> Fbd.

By the way, the static-dynamic ratio represents the ratio of the tensile strengths when the material is statically slowly deformed and when it is deformed at a high strain rate, and corresponds to, for example, a collision. High-speed deformation with a strain rate of 10 ³ / s or more (dynamic deformation)
It has been confirmed that the shape of the stress-strain curve of the steel sheet greatly differs between the time and the static deformation that slowly deforms at 10 ⁻³ to 10 ⁻¹ / s, and the strength increases significantly at high speed deformation.

Further, in the vehicle body structure of this embodiment, as shown in FIG. 6, the vertical and horizontal dimensions of the cross section of the bumper stay 11 are p and q, respectively, and the deformation of the bumper stay 11 is a plastic deformation reaction force from the initial stage of deformation. The stroke a (see FIG. 3) until reaching the rear portion 11B having a high height is a = (p + q) ×
It is set to satisfy the relationship of {(1/16) + (1/4 × n)} (n is an integer).

In the vehicle body structure of the first embodiment having the above structure, the collision load is axially input to the side member 10 via the bumper stay 11 while the bumper armature 12 is deformed by a frontal collision. Then, Fig. 4
When the gap a is crushed due to the deformation (axial crushing) of the bumper stay 11 as shown in FIG. 5, the rear surface 12a of the bumper armature 12 interferes with the tip of the protruding portion 22b of the reinforcement 22 and the protruding portion 22b is removed. Push backwards.

Then, the pressing force is transmitted to the front end portion of the welded portion 22a via the arm portion 22c, so that a moment M having the rear spot welded portion Wr as a fulcrum acts on the welded portion 22a, and the forward portion is moved forward. Since a peeling force is generated at the spot welded portion Wf and the spot welding is weak to the peeling force, the spot welded portion Wf is peeled off, the welded portion 22 a is removed from the slit 21, and the slit 21 is opened.

Since the slit 21 is opened in this way, the strength of the portion where the slit 21 is formed is reduced. Therefore, when the rear portion 11B of the bumper stay 11 is deformed, the yield point reaction force of the side member 10 is plastic. It will come down to almost the same level as the deformation reaction force.

From the relationship between the deformation amount (stroke) of the bumper stay 11 and the reaction force acting on the bumper stay 11 and the side member 10, the behavior during a high speed collision and a low speed collision will be described below with reference to the schematic diagram of FIG. It demonstrates using.

During a high-speed collision, when the front portion 11A of the bumper stay 11 having a low plastic deformation reaction force is deformed, the plastic deformation reaction force of the rear portion 11B of the bumper stay 11 is apparently Fbd. , Side member 10
The yield point reaction force of is in a state where the yield point reduction mechanism 20 does not operate,
That is, the slit 21 is the welded portion 2 of the reinforcement 22.
It is Fsd because it is covered by 2a.

When the deformation further progresses and reaches the rear portion 11B of the bumper stay 11, the reinforcement 2
Since the pressing force acts on the projecting portion 22b of the second welding portion 22a and the spot weld portion Wf in front of the welding portion 22a peels off, the slit 2
1 appears and the yield point reduction mechanism 20 is activated, and the yield point reaction force of the side member 10 decreases to the same level as the plastic deformation reaction force.

On the other hand, during a low speed collision, the bumper stay 11
Of the side member 10 is αb.
Therefore, the plastic deformation reaction force of the rear portion of the bumper stay 11 in the load input direction is Fbd / αb, and the yield point reaction force of the side member 10 is Fsd / αs.

At this time, Fsd> (αs / αb)> Fb
Since it is set to satisfy the relationship of d, the rear portion 11 of the bumper stay 11 before the side member 10 is deformed.
B is deformed, and due to this, a pressing force acts on the convex portion 22b of the reinforcement 20 and the yield point reduction mechanism 20 operates in the same manner, so that the yield point reaction force of the side member 10 is the same as during the high-speed collision. Decreases to the same level as the plastic deformation reaction force.

Therefore, the bumper stay 11 can be sequentially deformed into the side member 10 regardless of a high speed collision and a low speed collision, and without reducing the plastic deformation reaction force of the bumper stay 11.

Therefore, at the time of a low-speed collision with relatively little damage, the bumper stay 11 can be deformed prior to the side member 10, so that the damage can be stopped at the bumper stay 11 as much as possible.

Therefore, when only the bumper stay 11 is damaged, it is sufficient to remove the first end plate 13 from the second end plate 14 and replace the bumper stay 11 and the bumper armature 12 with each other. By omitting the work of repairing the member 10, it is possible to shorten the time required to repair the damaged portion and reduce the repair cost.

In this embodiment, the vertical and horizontal dimensions of the cross section of the bumper stay 11 are p and p, respectively, as shown in FIG.
7 and the stroke a shown in FIG. 3 is a = (p + q) × {(1/16) + (1/4 × n)} (n is an integer) ... (1) The reaction force characteristic of the bumper stay 11 shown can be obtained, and the reaction force of the bumper stay 11 approaches a flat with respect to the stroke, which is a desirable result in terms of stabilizing the vehicle body deformation characteristic and the occupant obstacle value.

That is, it is known that the relationship between the bumper stay 1 and the reaction force characteristic has the relationship shown in FIGS. 6 and 7 (Proceedings of the Automotive Engineering Society, No. 7, 197).
4, "Energy absorption characteristics of vehicle body (first report)", etc.).

Therefore, in terms of reaction force characteristics, the size of the gap a is determined by sequentially collecting n {(p + q) / 4} in the initial {(p + q) / 16} as shown in FIG. The result is as follows: a = {(p + q) / 16}, {(p + q) / 16} + (p + q) / 4, ..., (p + q) × {(1/16) + (1 / 4 × n)} (n is an integer) (2) From the formula (2), the general formula (1) is derived.

By the way, in the vehicle body structure of the first embodiment, the yield point reduction mechanism 20 is provided with a slit 21 as a yield point reduction portion formed on the side member 10, and a bumper stay attached to the slit 21. Since it is configured with the reinforcement 22 as a reinforcing member that is removed when the deformation of 11 reaches the rear portion 11B, the yield point reduction mechanism 20 can be operated with a simple configuration.

Further, the reinforcement 22 as the reinforcing member is provided with a welded portion 22a and a protruding portion 22b as a peeling force applying portion, and the welded portion 22a is provided across the slit 21 in the front and rear direction of the load input. While welding, when the deformation of the bumper stay 11 reaches the rear portion 11B, the protruding portion 22b deforms the welding portion 22a in a direction in which the welding portion 22a is separated from the front welding portion in the load input direction (front spot welding portion Wf). Therefore, the slit 21 can be revealed by applying the deforming force of the rear portion 11B to the convex portion 22b, so that the yield point reduction mechanism 20 has a simple structure.
Can be operated reliably.

Further, the protruding portion 22b serving as the peeling force applying portion is located at the rear portion 11B of the bumper stay 11 and is used as a reinforcing member, whereby the protruding portion 22b is formed.
Has a function of increasing the plastic deformation reaction force of the rear portion 11B of the bumper stay 11, so it is not necessary to change the structure of the bumper stay 11 itself between the front portion 11A and the rear portion 11B. Can be easy.

Furthermore, an arm portion 22c extending substantially at right angles to the load input direction is provided between the protruding portion 22b serving as a peeling force applying portion and the welding portion 22a.
Since the load (pressing force) input to the protruding portion 22b via c is transmitted as the peeling force of the welded portion 22a, a large peeling moment M (see FIG. 4) is applied to the welded portion 22a via the arm 22c. ) Can be generated, the welded portion 22a can be reliably separated with a simple structure.

Further, the peeling force applying portion is provided with a convex portion 22b.
As the protruding portion 22b is protruded forward from the arm portion 22c and inserted into the rear portion 11B of the bumper stay 11 and arranged in parallel, the bumper armature 12 interferes with the protruding portion 22b when the rear portion 11B is deformed. Since the pressing force is input to, the operation timing of the yield point reduction mechanism 20 can be accurately set with a simple structure.

Further, since the yield point reduced portion is the slit 21 formed on the upper and lower walls 10c and 10d of the side member 10, it is easy to process, and the opening area of the slit 21 reduces the yield point. It can be adjusted easily and accurately.

Further, since the bumper stay 11 and the side member 10 are coupled to each other, the first and second end plates 13 and 14 respectively provided on the bumper stay 11 and the side member 10 can be freely attached and detached by the bolts 15 and the nuts 15a, so that the bumper damaged by a collision is damaged. The stay 11 can be easily replaced.

FIGS. 8 and 9 show a second embodiment of the present invention, in which the same components as those in the first embodiment are designated by the same reference numerals, and a duplicate description will be omitted.

FIG. 8 is an exploded perspective view of the connecting portion of the main body member,
FIG. 9 is a sectional view of a connecting portion of the main body member.

In the vehicle body structure of the second embodiment, as shown in FIGS. 8 and 9, the bead 30 is used as the yield point reducing portion,
The beads 30 are attached to the upper and lower walls 10c of the side member 10.
10d, that is, a position corresponding to the slit 21 of the first embodiment.

Of course, also in the second embodiment, the welded portion 22a of the reinforcement 22 is welded across the front and rear of the bead 30 in the load input direction (the front spot welded portion Wf and the rear spot welded portion Wr). The other configurations are the same as those in the first embodiment.

Therefore, in the vehicle body structure of the second embodiment, the bead 30 serving as the yield point reducing portion can, of course, have the same operation and effect as the first embodiment. This bead 3 is formed by peeling off the spot welded portion Wf in front of the welded portion 22a of the reinforcement 22.
0 becomes a stress concentration portion, and the yield point can be reduced.

Further, since the bead 30 is used as the yield point reducing portion, it is only necessary to make a recess by pressing, so that the processing becomes easy.

10 and 11 show a third embodiment of the present invention, in which the same components as those of the first embodiment are designated by the same reference numerals, and a duplicate description will be omitted.

FIG. 10 is an exploded perspective view of the connecting portion of the main body member, and FIG. 11 is a sectional view of the connecting portion of the main body member.

In the vehicle body structure of the third embodiment, as shown in FIG. 10, the yield point reducing portion is formed of a thin plate 31 having a smaller wall thickness than the wall surface of the general portion of the side member 10.

The thin plate 31 is formed to have a U-shaped cross section which is the same as the cross sectional shape of the inner panel 10a of the side member 10, and the thin plate 31 is integrated with the front end portion of the inner panel 10a by laser welding.

Then, as shown in FIG. 11, the welding portion 22a of the reinforcement 22 is connected to the thin plate 31 and the side member 10.
Are welded (front spot-welded portion Wf and rear spot-welded portion Wr), and other configurations are the same as those in the first embodiment.

Therefore, in the vehicle body structure according to the third embodiment, it goes without saying that the same actions and effects as those of the first embodiment are exhibited, and the welded portion 22a of the reinforcement 22 is obtained.
By peeling off the spot welded portion Wf in front of, the load is input to the thin plate 31 having a small thickness and reduced strength, so that the yield point can be reduced.

Further, since the thin plate 31 is formed in a U-shaped cross section which is the same shape as the inner panel 10a of the side member 10, the upper and lower walls 10c, 10 of the side member 10 are formed.
The yield point can be controlled not only by d but also by the portion corresponding to the inner wall 10e.

12 and 13 show a fourth embodiment of the present invention, and the same components as those of the first embodiment will be designated by the same reference numerals and the duplicate description will be omitted.

FIG. 12 is an exploded perspective view of the connecting portion of the main body member, and FIG. 13 is a sectional view of the connecting portion of the main body member.

In the vehicle body structure of the fourth embodiment, as shown in FIG. 12, as the yield point reducing portion, a low strength member 32 lower than the material strength of the general portion of the side member 10 is used.

The low-strength member 32 is the inner panel 1 of the side member 10 as in the thin plate 31 of the third embodiment.
The low-strength member 32 is integrated with the front end portion of the inner panel 10a by laser welding.

Then, as shown in FIG. 13, the welded portion 22a of the reinforcement 22 is welded across the low-strength member 32 and the side member 10 (the front spot-welded portion Wf and the rear spot-welded portion Wr). The other configurations are the same as those in the first embodiment.

Therefore, in the vehicle body structure according to the fourth embodiment, it goes without saying that the same action and effect as those of the first embodiment can be obtained, and the spot welded portion at the front is the same as that of the third embodiment. By removing Wf, the low-strength member 32
A load can be input to reduce the yield point.

Also in the fourth embodiment, the low-strength member 32 is the inner panel 10a of the side member 10.
Since it is formed in a U-shaped cross section having the same shape as the above, the yield point can be controlled not only by the upper and lower walls 10c and 10d of the side member 10 but also by the portion corresponding to the inner wall 10e.

14 to 16 show a fifth embodiment of the present invention, and the same components as those of the first embodiment will be designated by the same reference numerals and overlapping description will be omitted.

FIG. 14 is an exploded perspective view of the connecting portion of the main body member, FIG. 15 is a sectional view of the connecting portion of the sub member and the main body member when there is no collision, and FIG. FIG.

The vehicle body structure of the fifth embodiment is shown in FIG.
As shown in FIG. 15, while forming a recessed portion 33 to be inserted from the arm portion 22c of the reinforcement 22 to the inside of the side member 10, the push rod 34 is integrally extended from the front portion 11A of the bumper stay 11. The recessed portion 33 and the push rod 34 constitute a peeling force applying portion.

The push rod 34 penetrates through the openings 13b and 14b of the first and second end plates 13 and 14 and has a predetermined space (stroke a) between it and the bottom 33a of the recess 33. It is provided and inserted.

Therefore, in this embodiment, when the front portion 11A of the bumper stay 11 is deformed and the deformation reaches the rear portion 11B, the tip of the push rod 34 interferes with the bottom portion 33a of the recessed portion 33 and further. By inputting the load, a moment M in the peeling direction is generated in the welding portion 22a via the arm portion 22c as shown in FIG. 16, and the front spot welding portion Wf is generated.
Can be peeled off.

Further, in the fifth embodiment, the stroke a
Can be determined by the length of the push rod 34. Therefore, the same yield point reduction mechanism 20 can be shared by a plurality of vehicle models having different vehicle body weights only by changing the length of the push rod 34. it can.

17 and 18 show a sixth embodiment of the present invention, in which the same components as those in the first embodiment are designated by the same reference numerals, and a duplicate description will be omitted.

FIG. 17 is an exploded perspective view of the connecting portion of the sub member and the main body member, and FIG. 18 is a sectional view of the connecting portion of the sub member and the main body member.

The vehicle body structure of the sixth embodiment is shown in FIG.
As shown in FIG. 18, at the front end portion of the side member 10, both upper and lower portions 10b1 and 10b2 of the outer panel 10b are provided.
The inner panel 10a by bending the upper and lower walls 10c, 1
The side member 10 is overlapped with the outer surface of 0d and spot-welded.
The outer side of the front end portion is formed into a rectangular cross section without a substantially protruding portion, and the front end portion is fitted inside the bumper stay 11.

Then, the side members 10 and the bumper stay 11 are detachably coupled with bolts and nuts (not shown) as fastening members through mounting holes 35 formed in the fitting portions.

Therefore, even in the vehicle body structure of the sixth embodiment, since the side member 10 and the bumper stay 11 are detachably coupled with the bolts and nuts, the replacement work of the bumper stay 11 is simplified. , The time and cost required for repair can be reduced.

19 and 20 show a seventh embodiment of the present invention, and the same components as those of the first embodiment will be designated by the same reference numerals and overlapping description will be omitted.

FIG. 19 is an exploded perspective view of the connecting portion of the sub member and the main body member, and FIG. 20 is a perspective view of the connecting state of the sub member and the main body member.

In the vehicle body structure according to the seventh embodiment, the reinforcing member is composed of the plate-like reinforcement 36, and the plate-like reinforcement 36 is used as the upper and lower walls 10c and 10d of the side member 10 having the slit 21. Bumper stay 11
And the side member 10 side is a welding portion and is welded across the front and rear of the slit 12 (the front spot weld portion Wf and the rear spot weld portion Wr), and on the bumper stay 11 side. It is joined by arc welding Wa.

At this time, the front end of the flat plate-like force 36 is joined to the bumper stay 11 at the bumper stay 1.
It is located at the rear portion 11B of the first bumper stay 11 and also has a function of increasing the plastic deformation reaction force of the bumper stay 11.

Further, in this embodiment, the bumper stay 1
1 and the side member 10 have flange portions 11c and 10f formed by bending the connection side end portions outward, and these flange portions 11c and 10f are butted against each other so that bolts and nuts not shown in the drawing can be formed without an end plate. I am trying to combine with.

Therefore, in the vehicle body structure of the seventh embodiment, when the deformation of the bumper stay 11 reaches from the front portion 11A to the rear portion 11B, the flat plate-like force 36 moves rearward as a whole. Spot weld part W
A shearing force acts on f and Wr to separate them.

Further, in this embodiment, since the reinforcing member is the plate-shaped reinforcement 36, the structure can be simplified.

FIG. 21 shows an eighth embodiment of the present invention, and the same components as those of the first embodiment will be designated by the same reference numerals and the description thereof will be omitted.

FIG. 21 is a cross-sectional view of the connecting portion between the sub member and the main body member. In the vehicle body structure of the eighth embodiment, the corrugated portion 37 is formed on the arm portion 22c of the reinforcement 22.

Therefore, in the vehicle body structure of the eighth embodiment, the corrugated portion 37 is extended when the pressing force input to the protruding portion 22b is transmitted as the peeling force of the welded portion 22a via the arm portion 22c. Since the peeling moment M (see FIG. 4) can be generated later, this corrugated portion 37
The shock absorbing function can smooth the change in the yield point reaction force of the side member 10 and soften the shock.

FIG. 22 shows a ninth embodiment of the present invention, and the same components as those of the first embodiment will be designated by the same reference numerals and the duplicate description will be omitted.

FIG. 22 is a cross-sectional view of the connecting portion of the sub member and the main body member. The vehicle body structure of this ninth embodiment has a welding portion 22.
The spot welds Wf in front of a are provided at a plurality of locations (two locations in this embodiment) at a predetermined distance in the load input direction.

Therefore, in the vehicle body structure of the ninth embodiment, when the peeling moment M acts on the welded portion 22a, the plurality of spot welded portions Wf provided in the front-rear direction are peeled off in order from the front side. The change in the yield point reaction force of the member 10 can be smoothly changed to reduce the shock.

The vehicle body structure of the present invention has been described above with reference to the first to ninth embodiments. However, in the fifth to eighth embodiments, when the slit 21 is formed as the yield point reducing portion as in the first embodiment. , But of course not limited to this, the second
Bead 30 of the embodiment, thin plate 31 of the third embodiment, fourth
It goes without saying that the low-strength member 32 of the embodiment may be used as the yield point reducing portion.

Further, in the sixth, eighth, and ninth embodiments, the protruding portion 22b is used as the peeling force applying portion of the reinforcement 22.
However, the invention is not limited to this, and the peeling force applying portion can be configured by the recessed portion 33 and the push rod 34 shown in the fifth embodiment.

By the way, the vehicle body structure of the present invention has the above
Not limited to the ninth embodiment, various other embodiments can be adopted without departing from the scope of the present invention.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a connecting portion between a sub member and a main body member according to a first embodiment of the present invention.

FIG. 2 is an end perspective view of the main body member according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of the coupling portion between the sub member and the main body member when there is no collision in the first embodiment of the present invention.

FIG. 4 is a cross-sectional view of the first embodiment of the present invention at the time of collision of the connecting portion between the sub member and the main body member.

FIG. 5 is a schematic diagram showing reaction force characteristics of a sub member and a main body member at the time of a collision in the first embodiment of the present invention.

FIG. 6 is a perspective view showing dimensions of a sub member according to the first embodiment of the present invention.

FIG. 7 is an explanatory diagram showing reaction force characteristics of a sub member according to the first embodiment of the present invention.

FIG. 8 is an exploded perspective view of a connecting portion of a main body member according to the second embodiment of the present invention.

FIG. 9 is a sectional view of a connecting portion of a main body member according to the second embodiment of the present invention.

FIG. 10 is an exploded perspective view of a connecting portion of a main body member according to the third embodiment of the present invention.

FIG. 11 is a sectional view of a connecting portion of a main body member according to the third embodiment of the present invention.

FIG. 12 is an exploded perspective view of a connecting portion of a main body member according to the fourth embodiment of the present invention.

FIG. 13 is a cross-sectional view of a connecting portion of a main body member according to the fourth embodiment of the present invention.

FIG. 14 is an exploded perspective view of a connecting portion of a main body member according to the fifth embodiment of the present invention.

FIG. 15 is a cross-sectional view of a connecting portion between a sub member and a main body member in a non-collision state according to the fifth embodiment of the present invention.

FIG. 16 is a cross-sectional view of the sub-member and the main body member at the joint portion according to the fifth embodiment of the present invention at the time of collision.

FIG. 17 is an exploded perspective view of a connecting portion between a sub member and a main body member according to the sixth embodiment of the present invention.

FIG. 18 is a sectional view of a connecting portion between a sub member and a main body member according to the sixth embodiment of the present invention.

FIG. 19 is an exploded perspective view of a connecting portion between a sub member and a main body member according to the seventh embodiment of the present invention.

FIG. 20 is a perspective view of a sub member and a main body member in a coupled state according to a seventh embodiment of the present invention.

FIG. 21 is a cross-sectional view of a joint portion between a sub member and a main body member according to the eighth embodiment of the present invention.

FIG. 22 is a sectional view of a connecting portion between a sub member and a main body member according to a ninth embodiment of the present invention.

[Explanation of symbols]

10 Front side member (main body member) 11 Bumper stay (auxiliary member) 11A load input direction front 11B Load input direction rear 15 bolts (fastening members) 15a Nut (fastening member) 20 Yield point reduction mechanism 21 slits (yield point reduction part) 22 Reinforce (reinforcing member) 22a welded part 22b Convex portion (peeling force applied portion) 22c arm 30 beads (yield point reduction section) 31 Thin plate (yield point reduction part) 32 Low strength member (yield point reduction part) 33 Recessed part (part to which peeling force is applied) 34 Push Rod (Peeling force added part) 36 Flat Reinforcement (Reinforcement member) 37 Waveform part Wf Front spot weld Wr Rear spot weld

Claims (15)

[Claims] 1. In a vehicle body structure in which a collision load is axially input to a main body member forming a vehicle body skeleton through a sub member, a plastic deformation reaction force of the sub member is applied to a rear portion in the load input direction rather than a front portion in the load input direction. At the same time as making it higher, the plastic deformation reaction force of the rear part of the sub member in the load input direction is made lower than the yield point reaction force of the main body member, and the yield point reaction force of the main body member at the time of deformation of the rear part of the sub member in the load input direction is A yield point reduction mechanism that reduces the plastic deformation reaction force to approximately the same level is provided. The static-dynamic ratio of the sub-member is αb, the plastic deformation reaction force at the rear of the sub-member in the load input direction during high-speed collision is Fbd, and the static force of the main body member is The dynamic ratio is αs, and the yield point reaction force during high-speed collision of the main body member is Fs
When d is set, Fsd> (αs / αb) at low speed collision
A vehicle body structure characterized by satisfying a relation of> Fbd. 2. Letting the vertical and horizontal dimensions of the cross section of the sub member be p and q, respectively, and letting the stroke from the initial stage of deformation of the sub member to the rear of the load input direction where the plastic deformation reaction force is high, a. , A = (p + q) × {(1/16) + (1 /
4. The vehicle body structure according to claim 1, wherein the relationship of 4 × n)} (n is an integer) is satisfied. 3. The yield point reduction mechanism includes a yield point reduction portion formed on a main body member and a reinforcement member attached to the yield point reduction portion and removed when the deformation of the sub member reaches the rear portion in the load input direction. The vehicle body structure according to claim 1 or 2, comprising: 4. The reinforcing member comprises a welded portion welded across the front and rear of the yield point reducing portion in the load input direction, and when the deformation of the sub member reaches the rear portion in the load input direction, the welded portion is welded forward in the load input direction. The vehicle body structure according to claim 3, further comprising: a peeling force applying portion that is deformed in a direction of peeling from a location. 5. The vehicle body structure according to claim 4, wherein the peeling force applying portion also has a function of increasing a plastic deformation reaction force of a rear portion of the sub member in the load input direction. 6. An arm portion extending substantially at right angles to the load input direction is provided between the peeling force applying portion and the welding portion, and a load input to the peeling force applying portion is welded through the arm portion. 5. It transmits as a peeling force of a part.
Or the vehicle body structure described in 5. 7. The vehicle body according to claim 6, wherein the peeling force applying portion is a protruding portion protruding from the arm portion in the load input direction and arranged in parallel at a rear portion of the auxiliary member in the load input direction. Construction. 8. The peeling force applying portion includes a recessed portion inserted from the arm portion inward of the main body member, and a bottom portion of the recessed portion which extends integrally from the front portion of the auxiliary member in the load input direction. 7. The vehicle body structure according to claim 6, wherein the push rod is inserted between the push rods at a predetermined interval. 9. The vehicle body structure according to claim 6, wherein a corrugated portion is formed on the arm portion. 10. The vehicle body structure according to claim 4, wherein a plurality of welding points are provided in front of the load input direction at a predetermined distance in the load input direction. 11. The yield point reduction portion is a slit formed on the wall surface of the main body member.
The vehicle body structure according to any one of 1. 12. The vehicle body structure according to claim 3, wherein the yield point reducing portion is a bead formed on a wall surface of the main body member. 13. The vehicle body structure according to claim 3, wherein the yield point reducing portion is formed of a thin plate having a wall thickness smaller than a wall surface of a general portion of the main body member. 14. The vehicle body structure according to claim 3, wherein the yield point reduction portion is a low-strength member having a material strength lower than the material strength of the general portion of the main body member. 15. The sub-member and the main body member are coupled via a detachable fastening member.
The vehicle body structure according to any one of 1.