JP2653248B2 - Vehicle frame members and side members - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a skeletal member for a vehicle and a side member capable of increasing the amount of energy absorption at the time of a vehicle collision or the like.

[0002]

2. Description of the Related Art As a conventional frame member for a vehicle, for example, there is a side member 101 shown in FIG.

The side member 101 is of a general shape having a closed sectional structure as shown in FIG. Further, a bellows-shaped side member 102 as shown in FIG.
There is also a similar structure (Japanese Utility Model Application No. 60-66745).
Reference). For example, when a collision load is input from the bumper 103 side to the side member 101 during a frontal collision of the vehicle, the collision energy is absorbed by deformation of the side member 101 or the like. However, FIG.
Since it is not possible to predict how the side member 101 having a general shape such as 8 deforms at the time of a collision, there is a possibility that the side member 101 itself becomes large in order to sufficiently absorb energy.

Further, since the side member 102 shown in FIG. 19 has a bellows shape, crush deformation at the time of collision can be predicted.
Although the collision energy that can be absorbed can be predicted, the entire energy absorption amount is small for the size because the deformation is easy, and the size may be increased in order to sufficiently absorb the energy.

Accordingly, an object of the present invention is to provide a vehicle skeletal member and a side member which can specify a collapsed deformation state, can easily set an absorbed energy, and can be reduced in size.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a vehicle frame member having a closed cross-sectional structure having upper, lower, left and right wall portions and having corner portions, wherein the upper, lower, left and right wall portions face each other. A concave streak is provided on one of the two wall portions and at least one wall portion sandwiched between the two wall portions, and a convex streak is provided on the other, and the concave streak is continuous with the convex streak through the corner portion. It is characterized by.

Further, the side member has a closed cross-sectional structure composed of upper, lower, left and right wall portions and having a corner portion. At least one of the walls sandwiched by the walls is provided with a concave groove having a closed cross-section in the circumferential direction, and the other is provided with a convex ridge having a closed cross-section in the circumferential direction. It is characterized by being continuous.

[0008]

First, in a vehicle frame member, when an input load in the compression direction is applied, stress concentration occurs in the concave and convex ridges provided on the wall, and the convex ridge is deformed so as to protrude outward and passes through the corner. Pull in the ridge. Therefore, the crushing deformation at the corners is promoted, and the wall portion of the vehicle skeletal member is crushed and deformed centering on the concave and convex ridges.

Further, when a collision load is input from the bumper to the side member at the time of a vehicle collision, the side member can be crushed and deformed mainly on the concave and convex ridges provided on the front end side.

[0010]

Embodiments of the present invention will be described below.

FIG. 1 is a perspective view showing a distal end side of a side member 1 as a vehicle frame member according to an embodiment of the present invention. As shown in FIG.
5, 7, and has a closed cross-sectional structure having a corner portion 9. The upper and lower wall portions 3 and the right wall portion 7 are integrally formed in the shape of a channel material, and a coupling flange 11 is provided at an end of the upper and lower wall portions 3. Are connected by

As the upper and lower left and right wall portions of the side member 1 facing each other, for example, the upper and lower wall portions 3 are provided with concave grooves 13 having a closed cross-section circumferential direction. Also, at least one of the walls sandwiched between the two walls, for example, the right wall 7, is provided with a ridge 15 having a closed cross-sectional circumferential direction. Dent 13
Is continuous with the ridge 15 through the corner 9 and the ridge 13
The ridge 15 has a configuration in which the upper and lower walls 3 and the right wall 7 are continuous in the closed section circumferential direction of the side member 1.
Therefore, the concave stripe 13 has a shape such that the corner 9 is cut off obliquely. The distance between the concave ridge 13 and the convex ridge 15 from the tip of the side member 1 is within the position indicated by the dotted line where the height of the right wall portion 7 is taken from the tip. The basis will be described later.

FIG. 2 shows the crush deformation when the side member 1 is subjected to a compressive load from the tip thereof with time.
The upper part of FIG. 2 is a perspective view of the same state as FIG.
(C) shows a state in which it is crushed and deformed with time.
The one in the middle of the figure schematically shows a state seen from a plane, and the one in the bottom is an R surrounded by a dotted-line square in the middle.
Area is shown in an enlarged manner.

FIG. 3 is a schematic diagram of the upper part of FIG. Therefore, as shown in the upper part of FIG. 2 and FIG. 3, when a collision load is applied to the tip in the state before the deformation of (a), the load concentrates on the concave ridge 13 and the convex ridge 15 (b).
Thus, the ridge 15 is deformed so as to protrude outward. Due to this deformation, the concave stripe 13 is pulled in the corner 9 in the direction in which the convex stripe 15 is deformed, and the corner 9 is crushed and deformed.
In the case of a minor collision, the concave streak 1 as shown in FIGS.
Sufficient energy absorption is performed by the deformation of the ridges 3 and the ridges 15. When an even greater collision load is applied, the deformation of the side member 1 reaches up to (c) in FIGS. 2 and 3, and the side member 1 is crushed and deformed on the tip side around the concave ridge 13 and the convex ridge 15. Therefore, the crush deformation portion can be specified, and the side member 1
Can be predicted, and the setting of the absorbed energy becomes easy.
Also, the ridge 15 protrudes outward, and the ridge 1 is formed at the corner 9.
3 is deformed such that it pulls in, so that sufficient energy absorption can be performed as compared with the bellows, and the side member 1 can be downsized as a whole.

Next, the theoretical basis of the above embodiment will be described.

(1) Comparison of Maximum Generated Load Here, the side member 1 of the present invention will be described in comparison with the side member 101 of FIG.

(1,1) Maximum generated load of the basic side member (FIG. 4) where a, b, c: sectional dimensions of the member (b> a) t: plate thickness, λ: buckling pitch E: young Rate ν: Poisson's ratio σ _y : yield stress, _Et : slope of stress-strain curve after yield

[0018]

(Equation 1)

The maximum generated stress σ _max = σ _cr ^0.43 · σ _y ^0.57 (when σ _cr <σ _y ) (when the corner is bent) σ _max = σ _cr (when σ _cr > σ _y ).

(1.2) Maximum generated load of the side member (FIG. 1) of this embodiment (1.21) Wall buckling Here, the sectional dimensions of the members are the same as those in FIG. Also, e: height of the ridge P: compression load δ: deflection of the wall surface caused by P

When a compressive load is applied to the side member 1 in the axial direction, the right wall 7 has the ridges 15 so that it buckles more easily than other portions of the wall 7. The load reducing effect of the ridge 15 can be obtained by solving the differential equation of the deflection δ generated in the right wall 7 having the height e of the ridge 15.

[0022]

(Equation 2)

The right side of the above equation represents the bending moment acting on the right wall 7, and D represents the bending rigidity. Here, x is the axial direction and y is the thickness direction.

[0024]

(Equation 3)

Y = C ₁ sin kx + C ₂ cos kx + e + δ

[0026]

(Equation 4)

Is obtained. If e = φ and the buckling load without protrusion is P _cr (= P _max ),

[0028]

(Equation 5)

When e> φ, δ increases as the load approaches P _cr . Assuming that δ> e as a criterion for buckling, the buckling load P ′ _cr of the present embodiment is

[0030]

(Equation 6)

That is, the wall 7 is formed by the ridge 15
It buckles with a load of at most about 4/9 compared to other parts that do not have. The same applies to the upper and lower wall portions 3 having the concave stripes 13.

(1.22) Corner Depression In a member having only a wall surface projection, corner deflection occurs after wall buckling.

[0033]

(Equation 7)

In a member having a sharpened corner, the corner is deformed simultaneously with buckling of the wall surface.

Σ ′ _max = σ ′ _cr Therefore, the maximum generated load of the present invention is:

[0036]

(Equation 8)

It is considered that:

(1.3) Comparison between the maximum generated load reduction effect by calculation and the analysis result of the finite element method (1.31) Calculation result: A = 50 mm b = 70 mm c = 20 mm t = 1.6 mm E = 21000 kgf / mm ² Et = 250 kgf / mm ² ν = 0.30 σ _y = 22.0 kgf / mm ² σ _max = 32.3 kgf / mm ² σ ′ _max = 14.4 kgf / mm ² P _max = 14.47 ton (static ) P ′ _max = 6.45ton (static) ∴P ′ _max = 0.45P _max The maximum load P _'max of the present application as because it has a low value of about 45% compared with the conventional member, very easily crushed, without generating a peak, it is possible to reliably collapse.

(1.32) Analysis Result of Finite Element Method FIG. 5 is a perspective view schematically showing the side member 1 before deformation, and FIG. 6 shows that the side member 1 divided into finite elements is deformed by receiving a collision load. It is a perspective view of the state after performing. FIG.
FIG. 7A is a side view showing a crushed deformation state of the side member 1 divided into finite elements, and FIG. 7B is a side view of the side member 1 after the crush deformation. FIG. 8 is a side view corresponding to FIG. 7 showing a deformed state of the side member 101 having another structure having no concave and convex stripes.

The ridges 13 and the ridges 15 provided on the walls 3 and 7 at the end of the side member 1 reliably start crushing from this portion. Side member 10 without this structure
In No. 1, since the crushing starts near the center, a large bending moment acts to cause bending.

[0041] Here, in conditions view of the analysis, the average cross-sectional dimension 70 × 50 mm thickness 1.2mm collision speed 35mph side member 1,101 (56km / h) Material: iron ^{E = 21000kgf / mm 2, ν} = 0.3, when ^{_{σ y = 22kgf / mm 2 Et}} = 250kgf / mm 2, P max = 23.3ton as shown in Figure _{9, P 'max = 10.0ton ∴P'max} = 0.43P max Therefore It can be seen that the result substantially matches the above calculation result.

Further, since the corner 9 of the side member 1 according to the embodiment of the present invention is linear except at the tip, the average crushing load during crushing also keeps a high value stably.

(2) Positions at Which Concave and Protrusions Should be Installed FIG. 10 shows a simplified bending moment acting on the side member 1 during crushing. The bending moment around the tip when the side member 1 is bent with a certain point as a joint is as follows.

M = PHsin θ where P is the load, H is the distance from the tip of the side member position to the joint, and θ is the inclination angle of the joint in the load direction. During a collision, the side member 1 receives load inputs from various directions,
Since θ changes, it is desirable to reduce P and H in order to prevent bending. That is, the maximum generated load Pm
It is desirable that ax be set to a value as low as possible, and that the position of the joint (the first crushed wall surface) be the most distal wall surface of the side member 1.

More specifically, FIG. 11 shows the position of the wall surface to be crushed first, that is, the position where the concave ridge 13 and the convex ridge 15 are to be set. The buckling wavelength λ of the wall surface of the thin structure is represented by a diagram.

[0046]

(Equation 9)

Here, _Et is the slope of the stress-strain curve after yielding.

From the above formula, the length of the wall to be folded is in the range of 0.7b <λ <b for a normal steel plate. Since the concave ridges 13 and the convex ridges 15 are provided in the range of the long side b from the tip, the wall surface that is crushed by the embodiment of the present invention is always the wall surface of the concave ridges 13 and the convex ridges 15. Concave ridge 13 and convex ridge 15
In order to make the effect of reducing the maximum generated load _Pmax by the most effective, the position of 0.5λ from the tip is good in the range of b.

FIG. 12 shows another embodiment. In this embodiment, the ridges 15 are provided on the upper and lower walls 3 and the ridges 1 are provided on the right wall 7.
3 are provided. When a collision load is applied, the ridge 15
Project outward, and a deformation substantially similar to the above can be performed.

Similarly, the left wall 5 can be provided with a concave or a convex stripe.

FIGS. 13 and 14 show the side member 1 in relation to the bumper 17. That is, the tip of the side member 1 is connected to the first cross member 19, and the concave ridge 13 and the convex ridge 15 are provided at a position approximately 0.5b behind the rear end A of the mounting portion of the side member 1. . The stay 17a of the bumper 17 is fixed to the tip of the side member 1. Arrow F in FIG. 15 at the time of collision
When the load is applied as described above, the side member 1 is deformed as described above. However, since the tip portion of the side member 1 is restrained by the first cross member 19 and the like, the purely bellows-shaped portion is attached to the mounting portion. After the rear end A. In this embodiment, the first cross member 19
Since the concave ridge 13 and the convex ridge 15 are provided at a position approximately 0.5b behind the rear end A, the side member 1 always starts crushing from this portion. Since the crushing start position is near the tip of the side member 1 as described above, the bending moment is small. Therefore, as in the above embodiment, crushing deformation occurs at a certain position, and sufficient energy absorption can be performed.

The present invention is not limited to the above embodiment. For example, the invention can be applied to a rear side member or the like as a vehicle body frame member. Further, in the above-described embodiment, three surfaces are provided with irregularities, but four surfaces may be provided with irregularities.

[0053]

As is clear from the above, according to the structure of the present invention, the crushing deformation position can be specified and the absorption energy can be easily set by the simple structure in which the concave and convex ridges are provided. Further, downsizing can be achieved by sufficient energy absorption.

[Brief description of the drawings]

FIG. 1 is a perspective view according to an embodiment of the present invention.

FIG. 2 is an operation explanatory view.

FIG. 3 is an operation explanatory view.

FIG. 4 is a perspective view illustrating a maximum generated load of a basic side member without concave and convex stripes.

FIG. 5 is an explanatory view schematically illustrating a side member according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram in which a finite element method is applied to the embodiment of the present invention.

FIG. 7 is an explanatory diagram in which the finite element method is applied to the embodiment of the present invention.

FIG. 8 is an explanatory diagram in a case where the finite element method is applied to a side member having no concave and convex stripes.

FIG. 9 is a graph of an analysis result.

FIG. 10 is a diagram illustrating generation of a bending moment.

FIG. 11 is an explanatory diagram of positions where concave and convex stripes are provided.

FIG. 12 is a perspective view according to another embodiment.

FIG. 13 is a perspective view of a side member shown in relation to a first cross member.

FIG. 14 is a plan view of a side member shown in relation to a first cross member and a bumper.

FIG. 15 is an operation explanatory view.

FIG. 16 is an operation explanatory view.

FIG. 17 is a perspective view of the entire vehicle.

FIG. 18 is a perspective view of a conventional side member.

FIG. 19 is a perspective view of a conventional side member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Side member (frame member for vehicles) 3 Upper and lower wall parts 5 Left wall part 7 Right wall part 9 Corner part 13 Concave strip 15 Convex strip 17 Bumper

Claims (2)

(57) [Claims] 1. A vehicle skeletal member having a closed cross-sectional structure having upper, lower, left and right wall portions and having corners, wherein at least one of the upper, lower, left and right wall portions facing each other and at least one of the two wall portions sandwiched therebetween. Provide a concave in the circumferential direction of the closed cross section on one side with the wall,
A skeletal member for a vehicle, wherein a ridge having a closed section circumferential direction is provided on the other side, and the ridge is continuous with the ridge through the corner. 2. A side member having a closed cross-sectional structure having upper, lower, left and right wall portions and having a corner portion. In a side member having a bumper attached to a front end thereof, both side walls facing each other on the front end side of the upper, lower, left and right wall portions, and both sides thereof. At least one of the walls sandwiched by the walls is provided with a concave groove having a closed cross-section in the circumferential direction, and the other is provided with a convex ridge having a closed cross-section in the circumferential direction. Side members that are continuous with