JPH1120733A - Vehicle body structure - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To make it possible to effectively absorb a collision load even in a narrow crash space with good crush characteristics particularly in a vehicle body structure to which a crash box is attached. SOLUTION: Both front ends 16 of a pair of left and right front side frames 1 are connected by a cross member 3, and the front ends of the tie-down hooks 18 and the radiator bracket 1 are respectively connected to the front ends.
7 to form a highly rigid receiving portion 16a. By pressing the plate material, the crash box 2 combining the first and second crash boxes 20 and 30 each having a substantially bowl shape is fixed to the left and right receiving portions with bolts and nuts 35, and the left and right crash boxes are formed. To the bumper reinforcement member 13a. The distance between the distal end portions of the cylindrical wall portions and the collapse of the cylindrical wall portions are set such that the peak value of the load resistance of the second crush box is generated in the drop portion of the load resistance after the peak value of the load resistance of the first crush box occurs. Set the rigidity, etc.

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 provided with a crash box for initially absorbing impact energy to a vehicle at the time of a collision.

[0002]

2. Description of the Related Art Hitherto, as a body structure of a vehicle provided with a crash box of this type, a structure related to a collision detection function of an acceleration sensor for operating an airbag device has been proposed (for example, Japanese Patent Application Laid-Open No. H05-1993). 139242). In this vehicle, two different types of crash box portions having different total plastic load characteristics are connected in series to the front end of a front side frame of a vehicle body, and are projected forward of the vehicle. The front crash box portion is formed into a small rectangular cross section by using four thin plate members in a cylindrical shape, while the rear crash box portion is formed of a thick thick 4 plate member.
It is formed into a cylindrical shape with a large rectangular cross section by a single plate material, and the front and rear crash box portions are connected to each other via a step portion having increased rigidity. As a result, when receiving a collision load, only the front crash box portion collapses first with a lower load, and after the front crash box portion has been completely collapsed, the rear crash box portion has a higher load. The crushing is caused by a load of two levels, such as crushing, and the acceleration sensor is activated when the crushing of the rear crash box portion starts.

[0003]

In a conventional crash box having two front and rear crash box portions, the horizontal axis represents the amount of deformation, and the vertical axis represents the load for compressive deformation in the axial direction. As shown in FIG. 21, the load waveforms in the case where the front crash box portion is the peak value P1 of the load resistance as the deformation amount increases are shown in FIG.
After the front crash box portion is almost completely crushed, the rear crash box portion is more than the peak value P1 as the deformation amount increases. The high peak value P2 and the drop portion of the withstand load are alternately repeated in the same manner as described above. When the rear crash box portion is also completely crushed, a collision load acts directly on the front side frame (body frame).

However, in the above-mentioned conventional crash box, a peak portion where a peak value occurs in the load waveform,
A longitudinal displacement amount that alternates with a valley where the withstand load falls alternately is required in each of the front and rear crash boxes, and the front and rear crash boxes are moved in the longitudinal direction of the vehicle. Because of the necessity of serial connection, it is necessary to ensure a considerably long longitudinal dimension (crash space) between the front end of the vehicle body frame and the bumper. For this reason, while the total length of the vehicle body is increased, it is difficult or impossible to apply when a too long crash space cannot be secured on the front end side of the vehicle body frame due to restrictions on the vehicle body design with respect to the total length.

On the other hand, if the size of the above-mentioned conventional crash box is shortened in the front-rear direction, the load waveform of each of the front crash box and the rear crash box becomes one load-bearing peak and valley. As a result, the collision energy cannot be sufficiently absorbed at the time of the collision.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicle body structure for interrupting transmission of a collision load to a passenger compartment by absorbing a collision load. In particular, an object of the present invention is to provide a vehicle body structure to which a crash box is attached with better collapse characteristics, and more specifically, to provide a vehicle body structure capable of effectively absorbing a collision load even in a narrow crash space.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a collision force is applied to an end of a vehicle body frame by being crushed by receiving a load inward of the vehicle body during a collision. It is assumed that the vehicle has a vehicle body structure in which the absorbing crash box is provided. In this configuration, the crash box is provided with a load absorbing means for complementing a drop in the load-bearing value after the peak load-bearing value in the load waveform when the crash box is crushed and deformed.

In the case of the above configuration, the deformation-load characteristic (load waveform) when a collision load is applied to the crash box in FIG. 1 is illustrated by a solid line C1, and the load resistance with respect to the deformation amount reaches the peak value Pc1. When the crash box is reached and the crash box collapses, the load capacity value falls, but the drop in the load capacity value is complemented by the load absorbing means, that is, the peak of the load capacity in the deformation-load characteristic of the load absorbing means. The part (see the dashed line in the figure) is generated in the range of the deformation amount in which the above-mentioned depressed portion occurs.
As a result, the drop in the withstand load that occurs when only the crash box is used is reduced by the amount complemented by the load absorbing means, and therefore, the energy absorbed by the impact absorbing means is also reduced by the area (see FIG. ), And the initial absorption of the collision load can be effectively performed.

According to a second aspect of the present invention, there is provided a vehicle body structure in which a crash box is provided at an end of a vehicle body frame to absorb a collision energy by being crushed by receiving a load inward of the vehicle body during a collision. It is assumed. In this case, the crash box is provided with a load absorbing means configured to exert a load resistance separately from the crash box during the crushing process during the crush deformation of the crush box.

In the case of the above structure, during the crushing process during the crushing deformation of the crash box, for example, as shown by the solid line C1 in FIG. 1, the load with respect to the deformation reaches the peak value Pc1 due to the action of the collision load and the crash occurs. During the crushing process in which the withstand load value falls due to the collapse of the box, the withstand load by the load absorbing means is exerted separately from the crash box, so the withstand load exerted by the load absorbing means And the impact absorption energy increases by the amount, and the initial absorption of the collision load can be effectively performed.

According to a third aspect of the present invention, the load absorbing means according to the first or second aspect of the present invention is constituted by a second crush box provided inside or outside the first crush box. . And
The first and second crash boxes each have a cylindrical wall portion extending outwardly of the same vehicle body in the direction of load application, and the proximal ends of both cylindrical wall portions of the first and second crash boxes. The parts are attached to the same end of the body frame independently of each other, and the distal ends that receive the load in the event of a collision are arranged independently of each other and at positions offset from each other in and out of the body.

In the case of the above construction, the collision load is input to the distal end of the first crash box, and acts on the cylindrical wall between the distal end and the base attached to the end of the vehicle body frame. At this time, since the tip of the second crash box is independent of the end of the first crash box and is shifted inward of the vehicle body, the collision load does not act on the second crash box. Moreover, since the base end is also attached to the same end independently of the vehicle body frame, there is no influence from the first crash box side. When the first crash box reaches the peak value Pc1 (see FIG. 1) of the withstand load and collapses, the first crash box
Of the crash box itself starts to fall. On the other hand, when the progress of the deformation of the first crash box reaches the amount of displacement of the tip of the second crash box, the tip of the second crash box also receives a collision load, and the second crash box receives the collision load. Based on the load waveform of the crash box (see the curve indicated by C2 in FIG. 1), the load resistance is exerted toward the peak value Pc2 of the load resistance. Then, the peak value Pc2 of the load resistance of the second crash box is generated at the portion where the load value of the first crash box falls, whereby the first load is reduced.
The drop in the load bearing capacity of the crash box is complemented. For this reason, by combining the first and second crash boxes, the drop portion (the valley portion of the load waveform) of the load waveform in the load waveform of the first crash box is reduced to the load withstand load in the load waveform of the second crash box. (The peak portion of the load waveform), and the two load waveforms of the first and second crash boxes are added to make the overall load waveform characteristic flatter.

In addition, both the first and second crash boxes have a cylindrical wall extending in the same load acting direction, and the interior or exterior of the second crash box or the first crash box is provided. Therefore, for example, the length of the vehicle body in the front-rear direction is reduced as compared with the conventional case where the two parts are connected in series in the direction in which the load is applied. Therefore, even if the crash space becomes narrow as described above, the initial absorption of the collision energy can be performed sufficiently effectively by complementing the drop portion of the load resistance of the first crash box as described above.

According to a fourth aspect of the present invention, the second crush box according to the third aspect of the present invention is provided inside the first crush box, and both of the first and second crush boxes have cylindrical walls. The first crush boxes are arranged in a positional relationship where they interfere with each other due to the crushing deformation of the cylindrical wall portion.

In the case of the above configuration, the collision load acts on the tip of the first crash box to reach the peak value of the withstand load, and thereafter, the cylindrical wall of the first crash box starts to bend inward. When the crushing deformation rapidly advances and the load resistance falls, the crushing deformation causes the cylindrical wall portion to interfere with the cylindrical wall portion of the second crash box, and the interference causes the cylindrical wall portion of the second crash box to collapse. Will receive the load. Then, the second receiving the transmission of this load
The cylinder wall of the crush box exerts load resistance
This will complement the drop in the load capacity of the crash box. For this reason, the initial absorption of the collision energy can be performed sufficiently effectively by cooperation with the first and second crash boxes.

According to a fifth aspect of the present invention, in the third aspect of the present invention, the stiffness of the first crush box against collapse is relatively higher than that of the second crush box. Here, the level of rigidity against crushing is set by, for example, changing the plate thickness of the two cylindrical wall portions.

In the case of the above configuration, when the load value of the first crash box falls when the peak value Pc1 of the load resistance of the first crash box is reached, a drop in the load value of the first crash box itself occurs. The peak value of the load capacity of the crash box 2 will be generated. Here, if the stiffness against crushing of the first and second crash boxes is set to be substantially the same, the peak value of the load bearing capacity of the second crash box is usually smaller than the residual load capacity of the first crash box. By adding, the peak load capacity of the first crash box becomes higher than the peak value Pc1. However, according to the fourth aspect of the present invention, the rigidity of the first crash box against crushing is relatively higher (stronger) than that of the second crash box, that is, the rigidity against crushing of the second crash box is increased. Since the box is set to be lower (weaker), the peak load-bearing value of the second crash box is represented by Pc2 in FIG.
Can be made almost the same as As a result, the change in the withstand load value is further reduced, and the initial absorption of the collision energy is more effectively achieved.

According to a sixth aspect of the present invention, in the invention of the third aspect, a receiving portion for receiving load transmission from both crash boxes to an end of the vehicle body frame to which the first and second crash boxes are attached. The rigidity of the receiving portion is set higher than that of the vehicle body frame on the inner side of the vehicle body.

In the case of the above construction, both the first and second crash boxes are attached to the receiving portion, and the receiving portions are formed so as to have higher rigidity than the body frame. As a result, each crash box can be crushed and deformed exactly as designed. In addition, if the two crash boxes are mounted on the front end of the vehicle body, for example, so that the load acting direction is in the front-rear direction of the vehicle body, the collision load is not exactly a frontal collision but in a direction slightly different from the front-rear direction. Even in the case of acting (for example, in the case of a so-called offset collision), both crash boxes can be reliably supported by the receiving portion against the collision load, so that the predetermined crash deformation characteristics of each crash box can be exhibited. Become. That is, it is possible to exhibit the collision energy absorbing function not only accurately from the inside and outside of the vehicle body but also from a collision load acting from a wider direction such as a direction slightly inclined to the inside and outside directions.

According to a seventh aspect of the present invention, in the third aspect of the invention, the first and second crush boxes are integrally formed by press drawing of a plate material.

In the case of the above configuration, each crush box is integrally formed by press drawing,
Since each of the cylindrical wall portions is surely formed uniformly, it is possible to make the crushing deformation when a collision load is received uniform. For example, when a cylindrical wall portion having a rectangular cross section is formed by welding four plate materials, uniform crushing deformation is hindered due to uneven welding quality and the presence of a weld bead. However, by forming a uniform cylindrical wall portion by press molding as described above, the above-described inconvenience is eliminated and uniform crushing deformation is caused, and as a result, accurate crushing deformation is generated as originally intended. It becomes possible to do.

According to an eighth aspect of the present invention, as the first and second crash boxes in the seventh aspect of the invention, a front wall portion and a cylinder extending inward from the periphery of the front wall portion to the vehicle body. It is configured to be formed in a substantially bowl shape composed of a wall portion.

In the case of the above configuration, the shape of each of the first and second crush boxes in the case of performing the press drawing in the invention according to claim 7 is specifically specified. In this case, a collision load is applied to the peripheral edge of the front wall portion, which is the distal end portion of the cylindrical wall portion, and the substantially bowl-shaped opening peripheral edge of the base end portion of the cylindrical wall portion is attached to the end of the vehicle body frame.

Further, the invention according to claim 9 is the same as the claim 1.
Alternatively, the load absorbing means in the invention according to claim 2 is constituted by an elastic body which is positioned on the inner side of the vehicle body with respect to the tip end of the crash box and exerts an elastic absorbing force when the crash box is deformed by a predetermined amount. It is.
Here, as the elastic body, polyurethane or rubber formed in a lump or the like may be used.

In the case of the above configuration, the crash box receives a collision load and a peak value of the load resistance in the load waveform is generated.
When the crash box receives a collision load and is deformed by a predetermined amount, the load absorbing means constituted by an elastic body exerts an elastic absorbing force. As a result, the amount of drop in the withstand load of the crash box is reduced, and even if the crash box is disposed in a narrow crash space, the initial absorption of the collision energy can be effectively performed.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a plan view of a vehicle body frame at a front portion of the vehicle to which the vehicle body structure according to the embodiment of the present invention is applied. In FIG. 1, reference numerals 1 and 1 denote front side frames as body frames which are disposed at both left and right (vehicle width direction) side positions of the vehicle so as to extend in the front-rear direction. The attached crash box, 3 is the front side frame 1
The front cross member 4 extends in the left-right direction so as to connect both front ends of the front cross member 4, and the shroud door 5 extends in the left-right direction substantially above the front cross member 3. It is a mounted dash panel.

The space in front of the dash panel 5 and between the front side frames 1 and 1 is an engine room 6 in which an engine and the like are disposed, and the space behind the dash panel 5 is a vehicle room 7. It is said. Also, 8,8
Is a tire house for the front wheels, and 9 and 9 are suspension towers for supporting the front wheels. Suspension brackets for supporting the suspension are supported by the front side frames 1. Further, a torque box 11 as a reinforcing member is bridged between the position of each of the front side frames 1 on the side of the cabin 7 and the side sill 10, and the torque box 11 allows the front side frames 1 and the side sill 10 to be connected to each other. Are connected to each other. Each of the torque boxes 11 is formed of a panel material into a cylindrical shape having a closed cross section, and the outer end thereof is fixed so as to cover the upper surface of the side sill 10.
Thereby, the resistance strength against the swing of each of the front side frames 1 around the vehicle width direction axis is enhanced. In FIG. 2, reference numeral 12 denotes a tunnel, and 13 denotes a bumper.

Each of the front side frames 1 is formed in a so-called double hat shape, and a pair of panels having a hat-shaped cross section are opposed to each other and welded at both upper and lower flange portions to form a rectangular closed cross section. It was done. Each of the front side frames 1 has a vertically long rectangle extending vertically from the dash panel 5 side to the portion that supports the suspension bracket, and the aspect ratio is closer to 1 toward the front end of the vehicle, that is, a square. Is formed so that the aspect ratio of the rectangular cross section changes in the front-rear direction so as to have a rectangular shape close to. in addition,
Each front side frame 1 is formed so as to bulge outward in the vehicle width direction and increase in lateral width as it advances forward from the portion supporting the suspension bracket.
In this manner, in the vicinity of the portion supporting the suspension bracket on the rear side, the resistance to the swing around the vehicle width direction axis is increased against the input load from the suspension, etc. Alternatively, even if a collision load is input diagonally from the front, bending in the vehicle width direction is unlikely to occur, and the collision load is easily absorbed by crush deformation in the front-rear direction.

As shown in FIGS. 3 to 5, first and second side walls of the front side frame 1 are bent so as to repeat irregularities in the vehicle width direction, as shown in FIGS. The beads 14 are formed. When a heavy collision load is applied by the first beads 14 such that the collision load due to a frontal collision reaches each front side frame 1, each of the front side frames 1 is reliably formed. The heavy collision load is absorbed by crushing deformation in the front-rear direction. The first bead 1
4 and 14 are bent at both side walls so as to have the same uneven shape in the vehicle width direction, so that when the accordion type is bent at opposite side walls at opposite directions, the upper and lower flange portions are formed. In order to avoid the possibility of being opened, uniform crushing deformation is ensured in the front-rear direction. .. In FIG. 3 are V-shaped bent portions formed on the lower flange portion corresponding to the irregularities of the first bead 14.

Further, a second bead 15 is formed at the front end position of each of the first beads 14, 14, and is continuous with the entire periphery of the rectangular cross section of each front side frame 1.
When a collision load acts on the bead 15 from the front,
First, when the second bead 15 is compressed and crushed, a trigger is provided so that each front side frame 1 is reliably crushed in the front-rear direction.

Each of the front side frames 1 which is a part in front of the part where the second bead 15 is formed is provided.
The left and right ends of the front cross member 3 are attached to the lower surface of the front end 16 of the front cross member 3. The front cross members 3 connect the left and right front side frames 1, 1 at the front ends 16, 16. In addition, a radiator bracket 17 (not shown) for mounting a radiator is mounted on the inner surface in the vehicle width direction of the front end portion 16 of each of the front side frames 1, and the upper end of a tie-down hook 18 is mounted on the outer surface in the vehicle width direction. Part is attached. The upper ends of the radiator bracket 17 and the tie-down hook 18 are both bent into an L-shape, and are projected to the left and right sides in a state flush with the front surface of the front end 16 of each of the front side frames 1. The radiator bracket 17, the tie-down hook 18, and the front edge of the front end 16 constitute a receiving portion 16 a to which the crash box 2 is attached (see FIG. 5). The receiving portion 16a is provided with the radiator bracket 1
By attaching the tie-down hooks 7 and the tie-down hooks 18, the rigidity is increased as compared with the case where the receiving portion is constituted only by the front end portion 16 of the front side frame 1. Here, the radiator bracket 17 and the tie-down hook 18 are used to reinforce the receiving portion 16a to increase rigidity and to form a fixing portion of the crash box 2 described later. The number of components can be reduced and the weight can be reduced as compared with the case where a dedicated reinforcing member or a mounting member dedicated only for the purpose is provided.

The crash box 2 is constructed by combining a first crash box 20 and a second crash box 30 as load absorbing means. As shown in FIG. 6, the first crash box 20 has a rectangular front wall 21 and a cylindrical wall portion having a rectangular cross section extending from the peripheral edge of the front wall 21 so as to slightly widen toward the rear of the vehicle body. 22 and a flange wall portion 23 extending outward from the rear end opening edge of the cylindrical wall portion 22 to form a substantially bowl shape. The second crash box 30 is formed so as to be housed in the cylindrical wall portion 22 of the first crash box 20, and has a rectangular front wall 31 and a A cylindrical wall portion 32 having a rectangular section extending continuously from the periphery of the front wall 31 so as to slightly widen toward the rear of the vehicle body, and a flange wall portion 33 extending outward from the rear end opening edge of the cylindrical wall portion 32. It is formed in a substantially bowl shape. In this case, the front end of each of the cylindrical wall portions 22 and 32 is
By the peripheral edges of the cylindrical walls 1, 31, the base ends are respectively constituted by the rear opening edges of the respective cylindrical wall portions 22, 32. These first and second crash boxes 20, 30,
What is necessary is just to form integrally the said predetermined shape using one sheet | seat material of a predetermined size, for example by press drawing, especially when forming the said cylindrical wall parts 22 and 32 uniformly, by said press drawing. Is preferred.

The first and second crush boxes 20 and 30 are welded and combined by the two flange walls 23 and 33 in a state where the two flange walls 23 and 33 are overlapped with each other. . The above welding may be performed, for example, by spot welding at predetermined intervals over the entire circumferential direction.
It is preferable to interpose a flat plate 34 large enough to cover the flange wall portion 33 when attaching the “0” to the receiving portion 16a.

The specifications of the first and second crash boxes 20 and 30 will be described.
The crash box 20 is formed so that the rigidity of the cylindrical wall portion 22 against collapse in the front-rear direction (the direction indicated by the arrow in FIG. 6) is relatively higher than that of the second crash box 30. Specifically, the cross-sectional area expanding in the direction perpendicular to the front-rear direction is set to the cylindrical wall portion 32 by the cylindrical wall portion 32.
As a means for this, the rectangular cross-sectional shape of the cylindrical wall portion 22 is made larger than that of the cylindrical wall portion 32, or in addition, the plate thickness of the cylindrical wall portion 22 is larger than that of the cylindrical wall portion 32. What is necessary is just to set thicker than the wall part 32.

The crash box 2 in a state where the first and second crash boxes 20 and 30 are connected by the respective flange walls 23 and 33, as shown in FIGS. 4, 5 and 7. Are fixed to the receiving portion 16a, specifically, the radiator bracket 17 and the upper end of the tie-down hook 18 by bolts and nuts 35, 35,. At this time, as shown in FIG. 8, the rear end opening edge which is the base end of the cylindrical wall portion 22 of the first crash box 20 and the second
A rear end opening edge which is a base end of the cylindrical wall portion 32 of the crash box 30 is connected to the front end 16 of the front side frame 1.
4 shown by a, b, c and d in FIG.
They are arranged so as to intersect at each point. Thereby, the respective base ends of the two cylindrical wall portions 22 and 32 are independently contacted with the same portion of the front end portion 16 of the front side frame 1, and the front end portion formed in a rectangular closed cross section The respective cylindrical wall portions 22 and 32 are securely brought into contact with and supported by the distal end edges of the 16.

On the other hand, as shown in FIGS. 9 and 5, the first crash boxes 20, 20 of the two crash boxes 2, 2 fixed to the front ends of the front side frames 1, 1 are provided with bumper reinforcements 13a. Each end is covered so as to cover, and is fixed to each front wall 21 by bolts and nuts 131, 131. The bumper 13 is attached to the bumper reinforcement 13a. Thereby, the collision load input to the bumper 13 at the time of a head-on collision or an offset collision is input to each crash box 2 via the bumper reinforcement 13a.

In the embodiment having the above-described structure, when a collision load from the front is input to each of the crash boxes 2, FIG.
As shown in FIG. 0, the collision load first acts on the entire front wall 21 of the first crash box 20, and the collision load is transmitted from the periphery of the front wall 21 to the cylindrical wall 22.
Then, the load resistance against the collapsing deformation of the cylindrical wall portion 22 increases steeply (see the load waveform C1 in FIG. 1), and the deformation of the cylindrical wall portion 22 at that time, that is, the cylindrical wall portion 22
The portion on the side of the front wall portion 21 bulges outward, and the intermediate portion bends inward to come into contact with the cylindrical wall portion 32 of the second crash box 30. Next, the cylinder wall 22
When the load bearing capacity of the cylinder wall reaches the peak value Pc1, the cylindrical wall 2
2 abuts against the cylinder wall 32 of the second crash box 30 to transmit a collision load to the cylinder wall 32 and
Is bent inward (see FIG. 11). After passing the peak value Pc1 of the load resistance on the first crash box 20 side, the load resistance of the cylindrical wall portion 32 of the second crash box 30 then has a peak value Pc2 (see FIG. 1). After the peak value Pc2, both crash boxes 20, 30 are completely crushed, and the collision load is directly transmitted to the receiving portion 16a. Absorption of collision energy is performed in the process of the crush deformation of each of the crash boxes 20 and 30 described above.

Here, even in the case of an offset collision in which the collision load is input not diagonally but from the front, for example, the crash boxes 20 and 30 are securely supported by the radiator bracket 17 and the tie-down hook 18. As a result, the crushing characteristics of the crash boxes 20, 30 can be effectively exhibited even for the above-mentioned collision load input from the oblique front, so that the collision energy can be absorbed.

<Other Embodiments> It should be noted that the present invention is not limited to the above-described embodiments, but includes various other embodiments. That is, in the above embodiment,
As a crushing characteristic, the load waveform of the first crash box 20 falls after generating one load-bearing peak value Pc1 as shown in FIG. Although the peak value Pc2 of the withstand load in the waveform is generated,
For example, as shown in FIG. 12, both load waveforms C of the first crash box and the second crash box
Both C1 and C2 are designed so that the load bearing capacity alternates between peaks (peaks) and valleys (falls) against an increase in the amount of deformation, and the phase of the deformation waveform of the second crash box is shifted. The crush characteristic may be such that the peaks of the load resistance in the deformation waveform of the second crash box are located at the respective valleys of the load resistance of the first crash box.

As a structure for realizing the above-mentioned crushing characteristics, for example, a first crash box 40 and a second crash box 50 as shown in FIG. The first crash box 40 has a cylindrical wall portion 41 having a rectangular cross section and extending in the axial direction X, for example, and a flange wall portion 42 protruding outward from the base opening edge of the cylindrical wall portion 41 at both ends. It is formed in an open cylindrical shape. Further, the second crash box 50 has a rectangular cross-sectional shape, for example, a rectangular cross-sectional shape such that the second crash box 50 is housed at a predetermined gap from the inner peripheral surface of the cylindrical wall portion 41 of the first crash box 40; The flange wall portion 42 and the overlapped flange wall portion 52 are formed in a cylindrical shape with both ends opened. Then, the second crush box 50 is mounted on the first crush box 40 on the same axis X and the flange walls 42 and 52 are joined by welding or the like, or the bolts and nuts 35 and It is fixed by 35 and integrated. Here, the thickness t1 of the first crash box 40 is set to be thicker than the thickness t2 of the second crash box (t1> t2), and the first crash box 40
The length L1 of the cylindrical wall portion 41 in the axis X direction is set to be longer than the length L2 of the cylindrical wall portion 51 of the second crash box 51 in the axial X direction (L1> L2).
The length (L1-L2) from the front end opening 41a to the front end opening 51a of the cylindrical wall portion 51 is relatively short compared to L2 so that the length (L1-L2) is relatively short corresponding to the phase shift of the load waveform. It is set to be shorter (L1-L2
>> L2). With the above-described structure, as described above, the load waveforms in which the peaks and the valleys are alternately repeated in each of the two crash boxes 40 and 50, and the peaks of the load waveform in the second crash box 50 are the first. The phase is shifted so as to be located at the valley of the crash box 40.

In the above-described embodiment, the first crash box 20 is formed as an independent and integral part. However, the present invention is not limited to this.
As shown in FIG. 5, an end of the bumper reinforcement 13b is extended, and a split piece 132 having a shape corresponding to one of the left and right sides of the first crash box 20a is formed at this end.
The first crush box 20a is fixed to the upper end of the tie-down hook 18 by a bolt / nut 35.
The split piece 25 having a shape corresponding to the left and right other side portions is bolted to the split piece portion 132 by bolts and nuts 131a, and the radiator bracket 17 is bolted to nuts 3
The second crash box 20a may be formed by fixing each of the second crash boxes 20a.

In the above embodiment, both the first and second crush boxes 20 and 30 are connected to the front wall portions 21 and 3.
1, a cylindrical wall portion 22, 32 and a mounting flange wall portion 23,
33, but is not limited to this, and is not limited thereto, and at least the cylindrical wall portions 22 and 32 that cause crush deformation.
Therefore, each of the crush boxes may be formed in a cylindrical shape with both ends opened.

Further, in the above embodiment, the second crush box 30 as the load absorbing means is formed in a substantially bowl shape using a plate material similarly to the first crush box 20, but is not limited thereto. For example, as shown in FIG. 15, an elastic body 30a formed of polyurethane or rubber or the like into a predetermined shape (for example, the same outer shape as the second crash box 30) and having an elastic coefficient set to a predetermined value is used as the load absorbing means. You may.

[0045]

The thickness of the first crush box 20 shown in FIG. 6 is set to 1.4 mm, the thickness of the second crush box 30 is set to 1.2 mm, and the flange wall of the second crush box 30 is set. The height L2 from 33 to the front wall 31 is 25 mm, and the first crash box 20
The height L1 from the flange wall portion 23 to the front wall portion 21 is set to 50 mm as an example.
The crash characteristics of the crash box 2 were confirmed by E (Computer Aided Engineering) analysis.

The relationship between the elapsed time and the deformation property with respect to the elapsed time when an impact load in a flat plate state is loaded rightward in the drawing from the no-load state shown in FIG. Figure 1 shows that after 1 msec
As shown in FIG. 7, the cylindrical wall portion 2 of the first crash box 20
2 crushes and interferes with the cylinder wall portion 32 of the second crash box 30, and after 2 msec, the cylinder wall portion 32 also crushes and deforms together with the cylinder wall portion 22 as shown in FIG.
After sec, as shown in FIG. 19, both of the crash boxes 20 and 30 were almost completely crushed and in a state of shuffling. Then, the transmission of the impact load to the front side frame 1 caused the front side frame 1 to start crushing and deforming.

FIG. 20 shows the above-mentioned crushing characteristics in terms of the relationship between the amount of deformation and the load. In FIG. 18, the first crash box 20 without the second crash box 30 is shown.
The case where the crash box is composed of only the first and second crash boxes 20 and 20 is shown by a solid line.
The case of the crash box 2 in which 30 are combined is indicated by a dashed line. In view of this, in the case where only the first crash box 20 is used, the load capacity rapidly drops after the peak value Pc1 of the load capacity of the first crash box 20 occurs, and the first crash box 20 is almost completely collapsed. After that, the peak value Pf1 of the load resistance by the front side frame 1 occurs at the deformation amount δ1, and thereafter, the drop of the load resistance and the peak value Pc2 alternately occur based on the crush deformation characteristic of the front side frame 1. On the other hand, in the case of the present embodiment in which the first and second crash boxes 20 and 30 are combined, the drop amount of the load resistance after the peak value Pc1 occurs is reduced, and the load resistance of the load resistance is reduced. The peak value Pc2 of the withstand load due to the second crash box 30 is generated in the fall portion.

From the above analysis results, to make the value of the peak value Pc2 by the second crush box 30 approximately equal to the value of the peak value Pc1 by the first crush box 20,
The stiffness (for example, plate thickness) against crushing deformation is relatively weak in the second crush box 30 with respect to the first crush box 20 or in the second crush box 30.
In contrast, it is considered that the first crash box 20 should be made relatively strong. In this case, the rigidity against the crushing deformation is set to the second crash box
By making the crash box 30 relatively weak, the position of the deformation amount at which the peak value Pc2 is generated by the second crash box 30 is shifted to a smaller value side than in the case of FIG. It is conceivable that it is possible to shift to the position of the amount of deformation at which the lowest withstand load occurs in the drop portion of the first crash box 20, thereby reliably complementing the drop portion of the first crash box 20 with the load resistance.

[0049]

As described above, according to the vehicle body structure of the first aspect of the present invention, the drop in the withstand load that occurs when only the crash box is used can be reduced by the amount complemented by the load absorbing means. Also, the impact absorption energy can be increased by the amount complemented by the load absorbing means. As a result, the initial absorption of the collision load can be effectively performed.

According to the second aspect of the present invention, it is possible to reduce the drop in the withstand load caused only by the crash box by the amount of the withstand load by the load absorbing means.
The shock absorption energy can also be increased by the amount of the load resistance exerted by the load absorbing means. As a result, the initial absorption of the collision load can be effectively performed.

According to the third aspect of the present invention, the effects of the first or second aspect of the present invention can be concretely realized, and even if the crash space becomes narrow, the first aspect can be realized. By complementing the drop portion of the load resistance of the crash box with the second crash box, the initial absorption of the collision energy can be performed sufficiently effectively, and the entire load waveform characteristic is made flatter. can do.

According to the fourth aspect of the present invention, in addition to the effect of the third aspect of the present invention, the first crash due to the cooperation between the first and second crash boxes due to the interference of the two cylinder wall portions. The initial absorption of the collision energy can be performed sufficiently effectively by compensating for the drop in the withstand load value of the box.

According to the fifth aspect of the present invention, in addition to the effect of the third aspect of the invention, the peak value of the load resistance of the second crash box is substantially the same as the peak value of the load resistance of the first crash box. , The change in the load-bearing value is further reduced, and the initial absorption of collision energy can be more effectively achieved.

According to the invention of claim 6, in addition to the effect of the invention of claim 3, both the first and second crush boxes can be reliably supported by the receiving portions, and each crush box can be It can be crushed and deformed exactly as designed. In addition, it is possible to exhibit the collision energy absorption function not only accurately from the inside and outside of the vehicle body, but also against a collision load acting from a wider direction such as a direction slightly inclined to the inside and outside directions. Become.

According to the seventh aspect of the present invention, in addition to the effect of the third aspect of the present invention, each cylinder wall of each crush box can be reliably and uniformly formed, and when a collision load is received. The crushing deformation can be surely made uniform, and as a result, the crushing deformation can be generated accurately as originally intended.

According to the eighth aspect of the present invention, the shapes of the first and second crush boxes when the press drawing in the seventh aspect of the present invention is performed can be specifically specified.

Further, according to the ninth aspect of the present invention, in addition to the effects of the first or second aspect of the present invention, a drop in the withstand load of the crash box is complemented by a configuration different from that of the third aspect of the present invention. As a result, the fall amount can be reduced, and even if the crash box is disposed in a narrow crash space, the initial absorption of the collision energy can be effectively performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a crushing characteristic for explaining a gantry of the present invention and a load bearing characteristic with respect to a deformation amount showing the crushing characteristic according to the present invention.

FIG. 2 is an explanatory plan view of a vehicle body structure at a front portion of the vehicle according to the embodiment;

FIG. 3 is an enlarged view as viewed in the direction of arrows AA in FIG. 2;

FIG. 4 is a partial perspective view of a left crash box portion facing forward.

FIG. 5 is a partially omitted sectional view taken along line BB of FIG. 3;

FIG. 6 is an explanatory cross-sectional view of the crash box in a plane direction.

7 is a partially omitted enlarged view taken along the line CC of FIG. 2;

FIG. 8 is an enlarged cross-sectional explanatory view of the crash box of FIG. 7 cut at a base end side position.

FIG. 9 is a partial perspective view of a front end of FIG. 2;

FIG. 10 is an explanatory sectional view conceptually illustrating a process of crush deformation of the crash box.

FIG. 11 is an explanatory sectional view conceptually showing a crush deformation in the next process of FIG. 10;

FIG. 12 is an explanatory diagram of load-bearing characteristics with respect to a deformation amount, which is a crushing characteristic different from the above embodiment.

FIG. 13 is an explanatory sectional view of an embodiment different from the above-described embodiment for realizing the crushing characteristic of FIG. 12;

FIG. 14 is a diagram corresponding to FIG. 5, showing an embodiment different from the embodiment shown in FIG. 5 and the like.

FIG. 15 is a diagram corresponding to FIG. 6, showing still another embodiment.

FIG. 16 is a skeleton diagram in a CAE analysis of a crash box and a front side frame portion.

FIG. 17 is a diagram corresponding to FIG. 16 after 1 msec when an impact load is applied to the structure of FIG. 16;

FIG. 18 is a diagram corresponding to FIG. 16 after 2 msec.

FIG. 19 is a diagram corresponding to FIG. 16 after 3 msec.

FIG. 20 is a crushing characteristic diagram showing a result of CAE analysis in a relationship between a deformation amount and a load resistance.

FIG. 21 is a relationship diagram showing a deformation waveform of a conventional crash box crushing characteristic.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Front side frame (body frame) 2, 2 'Crash box 16 Front end of front side frame (front end of body frame) 16a Receiving part 20, 20a, 40 First crush box 21, 31, Front wall part 22, 32 , 41, 51 Cylinder wall part 30, 50 Second crash box (load absorbing means) 30a Elastic body (load absorbing means) Pc1 Peak value of load bearing capacity of first crash box Pc2 Peak value of load bearing capacity of second crash box Peak value

Continued on the front page (72) Inventor Yasutoshi Kobayashi 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (72) Inventor Sakae 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd.

Claims (9)

[Claims] 1. A vehicle body structure in which a crash box is provided at an end of a vehicle body frame to absorb a collision energy by being crushed by receiving a load inward of the vehicle body during a collision. And a load absorbing means for compensating for a drop in the load resistance value after the peak value of the load resistance in the load waveform characteristic at the time of the crush deformation of the crash box. 2. A vehicle body structure in which a crash box is provided at an end portion of a vehicle body frame to absorb a collision energy by being crushed by receiving a load inward of the vehicle body during a collision, And a load absorbing means configured to exert a load resistance separately from the crash box during the crushing process when the crush box is crushed and deformed. 3. The first and second crash boxes according to claim 1, wherein the load absorbing means is constituted by a second crash box provided inside or outside the first crash box. Each have a cylindrical wall portion extending outwardly of the same vehicle body in the direction of load application, and both cylindrical wall portions of the first and second crash boxes have base ends independent of each other and have the same shape as the body frame. A vehicle body structure for a vehicle, wherein tip portions attached to an end portion and receiving a load at the time of a collision are arranged independently of each other and shifted from each other in and out of the vehicle body. 4. The crush box according to claim 3, wherein the second crush box is provided inside the first crush box, and both of the first and second crush boxes have cylindrical walls. A vehicle body structure for a vehicle, wherein the vehicle body structure is arranged in a positional relationship that causes mutual interference with a crushing deformation of a wall portion. 5. The crush box according to claim 3, wherein the first crush box has a second rigidity against collapse.
A vehicle body structure which is configured to be relatively higher than the crash box of the vehicle. 6. The receiving part according to claim 3, wherein a receiving part for receiving load transmission from both of the crash boxes is disposed at an end of the vehicle body frame to which the first and second crash boxes are attached. A vehicle body structure in which rigidity is set higher than that of a vehicle body frame on the inner side of the vehicle body. 7. The vehicle body structure according to claim 3, wherein the first and second crash boxes are formed integrally by press drawing of a plate material. 8. The crush box according to claim 7, wherein each of the first and second crush boxes includes a front wall portion,
A vehicle body structure for a vehicle, wherein the vehicle body structure is formed in a substantially bowl shape including a cylindrical wall portion extending inward from the periphery of the front wall portion. 9. The load absorbing means according to claim 1, wherein the load absorbing means is positioned closer to the vehicle body than the tip end of the crash box and exerts an elastic absorbing force when the crash box is deformed by a predetermined amount. A vehicle body structure for a vehicle, comprising: an elastic body.