JP4303659B2 - Shock absorption structure of automobile - Google Patents

Description

  The present invention is an automobile shock absorbing structure that absorbs the impact force at the time of a frontal collision of a vehicle body by buckling deformation of a side member in the axial direction. The present invention relates to a shock absorbing structure for an automobile, in which the buckling mode is obtained and the intrusion amount due to deformation of the side member is small.

  In an automobile, although depending on the vehicle type, as a body frame on the front side of the vehicle body, generally, as shown in a perspective view in FIG. 5, a radiator is provided between the front portions of the left and right side members 2a and 2b extending in the longitudinal direction of the vehicle body. Support 11 is installed. A bumper reinforcing member 10 is disposed on the vehicle body front side of the side members 2a and 2b, and is joined to front end portions of the left and right side members 2a and 2b with or without a stay (not shown).

  In this type of body frame on the front side of the vehicle body, if an excessive impact force acts from the front side of the vehicle body to the rear side during a vehicle body front collision, the impact force is applied to the left and right side members 2a, 2b. A structure that absorbs by buckling deformation in the axial direction (vehicle body longitudinal direction) is common. In the case of a relatively light collision that does not lead to buckling deformation of the side members 2a and 2b, the collision energy is absorbed by, for example, crushing in the cross-sectional direction of only the bumper reinforcing member 10 on the front side of the vehicle body.

  Conventionally, various structures have been proposed in which reinforcement is provided for the side members in order to increase the impact force absorbing ability of the left and right side members. For example, a structure has been proposed in which an inner pipe having a bellows tube portion is disposed in a side member, thereby enhancing the effect of absorbing impact force (Patent Document 1). In addition, in order to increase the strength of the side member against impact force, a reinforcing member is arranged in the side member in the shape of a partition wall, and a slit is formed on the reinforcing member as a buffering part against buckling deformation of the side member. (Patent Document 2).

  Furthermore, the rigidity against the bending force of the side member is increased, the bending of the side member at the time of the frontal collision is suppressed, and the axial buckling deformation of the side member at the time of the frontal collision is surely performed, thereby obtaining a stable buckling mode. There has also been proposed a shock absorbing structure for automobiles (Patent Document 3). This is because a lateral reinforcement having a substantially U-shaped cross section formed by bending the left and right side wall portions at both ends of the side wall portion in the side member is disposed with the horizontal wall portion facing horizontally and the left and right side walls. The portion is joined to the inner surfaces of the left and right side walls of the side member, and at least one convex wall portion protruding toward the upper wall or the lower wall of the side member is bent and formed on the lateral wall portion.

  In addition, a vehicle front body structure that can effectively absorb energy not only at the time of a frontal collision but also at the time of an offset collision without increasing the length of the front portion of the vehicle has been proposed (Patent Document 4). . This is because a connecting member that extends in the vehicle width direction and connects the pair of front side frames is provided at the front part of the pair of left and right front side frames, and the plate thickness of the plate member constituting the front side frame is set to The middle part is set thinner than the part and the rear part.

  In addition, the side frame has a cross-section that consists of a web panel (horizontal wall) and a flange panel (vertical wall), making the web panel easier to buckle than the flange panel, making the side frame an accordion (not Euler buckling) It has been proposed to buckle in a bellows shape and increase the impact force absorption capability (Patent Document 5).

In addition, when the buckling mode impact force is applied, the side frame is easily deformed to suppress the vehicle deceleration, and when the folding mode impact force is applied, the side frame is hardly deformed to suppress the vehicle deformation amount. This has also been proposed (Patent Document 6). In a vehicle having a pair of left and right side frames and a dash panel that is disposed at an upper portion of the vehicle and partitions a front end portion of the vehicle interior, the dash panel is disposed on a side frame portion that extends to the front and rear positions across the dash panel. An impact transmission mechanism for transmitting impact energy acting on the front portion of the dash panel to the rear portion of the dash panel is arranged.
Japanese Utility Model Publication No. 5-54160 (Claims, Fig. 1) Japanese Utility Model Publication No. 55-147970 (Claims, Fig. 1) Japanese Patent Laid-Open No. 11-310152 (Claims, FIG. 1, paragraph 0007) JP 2001-30949 A (Claims, FIG. 1) JP-A-6-247338 (Claims, FIG. 1) JP 2004-82859 A (Claims, FIG. 1)

  In recent years, due to stricter collision regulations, a front body structure capable of handling high-speed collisions such as 64 km / h has been required. That is, even in such a high-speed collision, a design capable of efficiently absorbing collision energy by the axial crushing deformation of the left and right side members is required.

  However, each of the prior arts described above cannot sufficiently cope with such a problem. In this regard, Fig. 8 shows the general load-displacement characteristics (relationship) in the case of impact energy absorption by axial crushing deformation of the left and right side members. In the high-speed collision, the drop amount of the load drop B immediately after the initial peak load (maximum load) A becomes larger. As a result, there is a problem that the average load is reduced and the vehicle body intrusion amount (displacement amount) is increased. In addition, simply increasing the thickness and material properties of the left and right side members improves the average load, but the initial peak load A, the subsequent secondary peak load C, the tertiary peak load D, etc. There is also a problem that the peak load following A becomes too high, and the obstacle value to the human body deteriorates.

  In order to reduce the drop amount of the load drop B immediately after the initial peak load A, the reinforcement is applied to the left and right side member spaces along the axial direction of each side member, as in each of the prior arts described above. It is effective to extend and increase the crushing strength of the side member. However, on the other hand, when such a reinforcement is provided, the initial peak load A (maximum load), the subsequent buckling loads C 1 and D 2 and the like are greatly increased. If the initial peak load A and the subsequent buckling loads C 1, D 2, etc. increase too much, the impact force on the occupant increases at the time of a vehicle collision, and the rear side of the side member is ahead of the front end of the side member. As a result, the energy absorption efficiency is lowered. The same applies to the case where the YP and thickness of the steel plate constituting the side member are increased.

  Therefore, it can cope with the high-speed collision, reduces the drop amount of the load drop B immediately after the initial peak load A without increasing the initial peak load A, and improves the average load without increasing the subsequent peak load. There is a need for a vehicle front structure or shock absorbing structure that can be used. However, the conventional shock absorption structure of a vehicle that extends the reinforcement along the axial direction of the side member and increases the crushing strength of the side member has not been able to perform such a function sufficiently. Is the actual situation.

  Therefore, the object of the present invention is to cope with the high-speed collision, can reduce the drop amount of the load drop B immediately after the initial peak load A without increasing the initial peak load A, and can reduce the subsequent peak load. An object of the present invention is to provide a shock absorbing structure for an automobile that can increase the average load and reduce the amount of intrusion into the vehicle body without increasing it.

To achieve this object, the gist of the shock absorbing structure of the present invention is a pair of left and right side members having a substantially rectangular cross-sectional shape arranged so as to extend along the vehicle body longitudinal direction on both sides in the vehicle body width direction. And a reinforcement extending in the axial direction of the side member in the side member space, and both the side member and the reinforcement are buckled and deformed in the axial direction due to an impact force at the time of a frontal collision of the vehicle body. In the automobile impact absorbing structure, the reinforcement is disposed substantially horizontally over the width direction in the side member space, and has a plate thickness of 1.0 to 2.0 mm and a tensile strength of 340 MPa or more. These reinforcements are bent at both ends in the width direction and integrally joined to the side walls constituting the side members. The end position of the reinforcement on the front side of the vehicle body is [(W + H) / 4] × 1.2>L> [(W + H) from the end position of the side member on the front side of the vehicle body. /4]×0.8 is shifted to the rear side of the vehicle body by a length L defined by × 0.8, and the hole for promoting buckling deformation is formed along the longitudinal direction of this reinforcement [[W + H ) / 2] × 1.2>P> [(W + H) / 2] × 0.8.
In the above formula, W is the width of the side member, and H is the height of the side member.

  The present invention is the same as the conventional one in that the impact force at the time of a frontal collision of the vehicle body is collided and deformed in the axial direction together with the side member and the reinforcement to absorb the collision energy.

  However, in the present invention, as a precondition, the reinforcement is constituted by a steel plate having a specific plate thickness and a specific strength, which is disposed substantially horizontally over the width direction in the side member space. And the both ends of the width direction of this reinforcement (steel plate) shall be integrally joined to the side wall which comprises the said side member, respectively.

  The reinforcement preconditions make it easy to collapse the reinforcement integrally with the side members and in a bellows shape in the front-rear direction of the vehicle body. As a result, even if the axial crushing strength of the side member is increased by installing the reinforcement in response to the high-speed collision, the initial peak load A in the load-displacement characteristic is not increased.

  However, if the strength, thickness, and arrangement direction are specified in this way, the load level is significantly improved as a whole compared to the case of only the side member, but the effect of reducing the initial peak load A, The effect of reducing the peak loads C and D, the effect of suppressing the drop amount of the load drop B immediately after the initial peak load A, etc. are not sufficient for the target load-displacement characteristics shown in FIG.

  Therefore, in the present invention, a plurality of holes (through holes) for promoting buckling deformation are connected in the longitudinal direction of the reinforcement. Further, in the present invention, the distance (pitch) P between the holes is determined by the relationship between the width W of the side member and the height H of the side member [(W + H) / 2] × 1.2> P> [ (W + H) / 2] × 0.8.

  As a result, the secondary peak load C and the tertiary peak load D after the initial peak load A in FIG. 6 can be reliably reduced in response to the high-speed collision, and the average load can be increased efficiently. it can.

  Further, in the present invention, the end position of the flat plate reinforcement on the vehicle body front side is shifted from the end position of the side member on the vehicle body front side toward the vehicle rear surface side. As a result, when a collision load is applied from the front side of the vehicle body, first, the side member starts to collapse in the axial direction, and then, with a certain time delay, the flat reinforcement is then moved in the axial direction. Start crushing. After that, they both buckle and deform in the front-rear direction of the vehicle body (crush in a bellows shape).

  In the present invention, the initial peak load A in the above-described load-displacement characteristics is reduced and the amount of drop in the load drop B immediately after the initial peak load A is reduced by the time delay of the flattening start of the flat reinforcement. can do. If the amount of drop in load drop B immediately after the initial peak load A can be reduced, the average load will be increased to significantly increase the amount of collision energy absorption, and the amount of side member displacement, that is, the amount of penetration into the vehicle body, will be reliably reduced. it can.

  In the present invention, further, in order to ensure the reduction in the amount of load drop B immediately after the initial peak load A corresponding to the high-speed collision, in the present invention, the end of the flat reinforcement on the front side of the vehicle body is further provided. A length L for shifting the position of the side member to the rear surface side of the vehicle body from the end position of the side member on the front surface side of the vehicle body is defined. That is, this length L is determined by the relationship between the width W of the side member and the height H of the side member [[W + H) / 4] × 1.2> L> [(W + H) / 4] × It is specified as 0.8.

Embodiments of the present invention will be described below with reference to the drawings.
(Body frame structure on the front side of the car body)
First, one embodiment of the vehicle body frame on the front side of the vehicle body, which is a premise of the shock absorbing structure for automobiles of the present invention, will be described in more detail with reference to FIG. FIG. 5 is a perspective view of the vehicle body frame on the front side of the vehicle body.

  As shown in FIG. 5, a radiator support 11 is installed between the front portions of the left and right side members 2a, 2b extending in the longitudinal direction of the vehicle body. A bumper reinforcing member 10 is disposed on the vehicle body front side of the side members 2a and 2b, and is joined to front end portions of the left and right side members 2a and 2b with or without a stay (not shown).

  The pair of left and right side members 2a, 2b are arranged on both sides in the vehicle body width direction so as to extend along the vehicle body longitudinal direction. Each side member 2a, 2b is composed of a steel plate shaped member 3a, 3b that constitutes the main body portion of the side member, and a flat plate-shaped lid member 5a, 5b joined from the top of the shaped member 3a, 3b. Each having a substantially rectangular cross-sectional shape.

  The shape members 3a and 3b, which will be described in detail in FIG. 1 to be described later, have a substantially HAT (hat) type cross section, and have flanges 4a and 4b that respectively extend on both sides and extend in the longitudinal direction of the side member. is doing. The flanges 4a and 4b are respectively joined to the flange portions 6a and 6b at both end portions of the lid members 5a and 5b.

  In the vehicle body frame on the front side of the vehicle body having the above configuration, when an excessive impact force is applied from the front side to the rear side of the vehicle body at the time of a vehicle body front collision, the impact force is applied to the pair of left and right side members 2a. , 2b is absorbed by buckling deformation in the axial direction (vehicle body longitudinal direction).

(Automobile shock absorbing structure)
Based on the above-mentioned body frame on the front side of the vehicle body, the impact force at the time of vehicle body frontal collision is absorbed by the buckling deformation in the axial direction between the pair of left and right side members 2a, 2b and the reinforcement provided on the side members 2a, 2b. The automobile impact absorbing structure of the present invention will be described below with reference to FIGS. 1, 2, 3, and 4. FIG. FIG. 1 is a perspective view (part) of a side member according to the automobile impact absorbing structure of the present invention. 2 is a front view of FIG. 1, FIG. 3 is a side view of FIGS. 1 and 2, and FIG. 4 is a plan view of FIGS.

  1 to 4 show only the side member 2a side of FIG. 5 and omit the illustration of the side member 2b side. However, the side member 2b side is also symmetrical with the side member 2a in the same configuration. It is.

  In FIG. 2, the shape member 3a constituting the side member 2a has a substantially HAT (hat) cross section composed of a pair of side walls (vertical walls) 7a, 7b and a bottom plate 8 connecting the side walls 7a, 7b at the bottom. In addition, flanges 4a and 4b are provided on both sides and extending in the longitudinal direction of the side member. The flanges 4a and 4b are respectively joined to the flange portions 6a and 6b at both end portions of the lid member 5a to constitute side members having a substantially rectangular cross section.

(Reinforcement)
9 is a reinforcement installed in the hollow (space) of the side member 2a. The reinforcement 9 is composed of steel plates arranged substantially horizontally over the width direction in the space of the side member 2a. Then, both side end portions 9a and 9b in the width direction of the steel plate are bent upward to have a substantially U-shaped cross-sectional shape. The side end portions 9a and 9b are integrally joined to the side walls 7a and 7b constituting the side member 2a by welding or mechanical joining means. It should be noted that, within a range where the initial peak load A is not increased, changes such as appropriate unevenness and other members are allowed.

  FIG. 6 shows the ideal load-displacement characteristics of the side member aimed at by the present invention. The linear load-displacement characteristic indicated by the thin line in FIG. 6 shows the ideal load-displacement characteristic of the side member. That is, in response to the high-speed collision, without increasing the initial peak load A, there is no drop in the load drop B immediately after the initial peak load A, and the average load is increased constantly without increasing the subsequent peak load. It is a thing.

  In this respect, the reinforcement 9 that satisfies the requirements of the present invention, such as the plate thickness and strength described later, the hole, and the position to be provided, approaches the ideal load-displacement characteristic indicated by the thin line in FIG. The load-displacement characteristics of the side member shown can be achieved, and the amount of penetration into the vehicle body can be reduced. That is, in response to the high-speed collision, the amount of drop in the load drop B immediately after the initial peak load A can be reduced without increasing the initial peak load A, and the subsequent peak loads C and D can be increased. Without increasing the average load.

(Reinforcement tensile strength, thickness)
In order not to increase the initial peak load A (maximum load) in response to the high-speed collision, it is premised on the design conditions of normal automobile side members, particularly side members made of high-tensile steel plates with a tensile strength of 340 MPa or more. The thickness of the steel plate constituting the reinforcement is selected from a range of 1.0 to 2.0 mm, and a high strength steel plate having a tensile strength of 340 MPa or more.

  In order not to increase the weight as a part to be newly added to the side member, the reinforcement 9 is preferably composed of a thin steel plate having a thickness of 2.0 mm or less. When the thickness of the steel sheet exceeds 2.0 mm, the crushing strength of the reinforcement 9 becomes too high and the initial peak load A (maximum load) becomes high. Moreover, the weight increase of the vehicle body is also large. On the other hand, if the plate thickness of the steel plate is less than 1.0 mm, the crushing strength becomes too low, and the impact energy absorption effect depending on the plate thickness is significantly reduced.

  Furthermore, if the tensile strength of the steel sheet is less than 340 MPa, it is necessary to increase the thickness to meet the required crushing strength of Reinforcement 9, resulting in an increase in the initial peak load A (maximum load) and an increase in the weight of the vehicle body. .

(Reinforcement placement direction)
The reason why the reinforcement 9 (steel plate) is arranged substantially horizontally over the width direction in the space of the side member 2a is to obtain the reinforcement effect by the reinforcement 9 most efficiently. However, even if the reinforcement 9 is arranged at an angle of ± 10 degrees from the horizontal direction other than substantially horizontal, the effect can be obtained.

  When the reinforcement 9 is placed in a position other than approximately horizontal, depending on the state of the reinforcement 9 joining and the degree of impact at the time of the vehicle collision, a vertical folding mode may occur during crushing, or buckling may occur. There is a possibility that the pitch becomes unstable and energy is not absorbed efficiently. Further, it has an adverse effect on the time and cost of joining the reinforcement 9 integrally with the side member 2a and the cost.

  In relation to this, both end portions 9a and 9b in the width direction of the flat plate need not be bent upward as long as the above-described joining strength can be ensured. Reinforcement 9 is basically the side member 2a. What is necessary is just to make it the cross-sectional shape which is easy to join integrally to the side wall 7a, 7b to comprise.

  FIG. 7 shows the load-displacement characteristics of the side member 2a assuming the high-speed collision when the reinforcement 9 is provided in the range (preconditions) described above. This is the case where the lower load-displacement curve is only the side member 2a without the reinforcement 9 and the upper load-displacement curve is the side member 2a with the reinforcement 9.

  However, in the case of the side member indicated by b provided with the reinforcement 9 within the range in which the tensile strength, the plate thickness, and the arrangement direction are specified, the load level as a whole is higher than that of the side member indicated by a. Significantly improved. However, the initial peak load A becomes high, the drop amount of the load drop B immediately after the initial peak load A is large, and the subsequent peak loads C 1 and D etc. become high, so that the average load cannot be increased efficiently and sufficiently. That is, although the initial peak load A is reduced as compared with the prior art in which the reinforcement is extended along the axial direction of the side member to increase the crushing strength of the side member, Will be the same.

(Reinforcement connection holes)
For this reason, in the present invention, first, a connection hole shown in the form of c in FIG. 7 is provided in the reinforcement. Then, as shown in FIG. 7, the peak loads C, D, etc. after the initial peak load A are lowered to each peak indicated by the dotted line as shown by the arrows for reducing each peak corresponding to the high-speed collision. And increase the average load efficiently.

  Such connecting holes include holes (through holes) 8a, 8b, 8c for promoting buckling deformation in the longitudinal direction of the reinforcement 9 as shown in FIGS. A plurality of are connected. In the present embodiment, holes 8a, 8b, 8c are provided in two rows in the width direction of the flat reinforcement 9 (two in the width direction).

  These holes 8a, 8b, and 8c are positions (peaks) that are the starting points of buckling deformation in the longitudinal direction (front-rear direction of the vehicle body) of the flat reinforcement 9 or the side member 2a when an impact force due to a vehicle body collision is applied. Corresponding to the position where the load C, D, etc. stands. For this reason, it becomes possible to reduce the peak of loads such as peak loads C and D after the initial peak load A. After that, when buckling deformation progresses and the area between the holes 8a, 8b, 8c of the reinforcement 9 in the side member 2a collapses in a bellows shape, the load is reduced due to the reinforcement effect of the reinforcement 9 itself. It is suppressed and the average load is improved. This phenomenon is repeated in buckling after the peak loads C 1 and D 2.

(Connection hole interval P)
Furthermore, in the present invention, the distance (pitch) P between the holes 8a, 8b, 8c is determined by the relationship between the width W of the side member 2a and the height H of the side member [(W + H) / 2] × 1.2. >P> [(W + H) / 2] x 0.8. The above-mentioned buckling pitch in the longitudinal direction of the reinforcement 9 to the side member 2a is determined by the interval (pitch) P between the holes 8a, 8b, 8c. Accordingly, the peak loads C 1 and D 2 following the initial peak load A such as the secondary peak load C and the tertiary peak load D can be reduced in response to the high-speed collision as shown in FIG.

  The reason for determining the pitch P of the holes 8a, 8b, and 8c in relation to the above (W + H) / 2 is that the buckling pitch at the time of axial collapse of the member is usually determined by the width W of the member and the H of the member. This is because it is almost (W + H) / 2. In the present invention, in accordance with the buckling pitch at the time of the axial collapse of the member, at the position where the buckling at the axial collapse of the side member 2a occurs (the position at which the buckling deformation starts in the longitudinal direction of the side member 2a). Corresponding 9 positions of reinforcements are provided with holes 8a, 8b, 8c, making it possible to reduce only the peak load. Therefore, in order to reduce the peak load when the impact force due to the high-speed collision is applied to the side member 2a, it is connected over the longitudinal direction of the reinforcement 9 rather than the common sense size of the holes 8a, 8b, 8c. The distance (pitch) P between the formed holes 8a, 8b, 8c contributes more greatly.

  When the interval P between the holes 8a, 8b, 8c is larger than [(W + H) / 2] x 1.2 ([(W + H) / 2] x 1.2 ≤ P), it means that the holes 8a, 8b, 8c are provided. Disappears. That is, the above-mentioned buckling pitch in the longitudinal direction of the reinforcement 9 or the side member 2a and the pitch of the holes 8a, 8b, 8c are not matched, and the initial peak load such as the secondary peak load C and the tertiary peak load D The peak load reduction effect following A is lost.

  On the other hand, when the interval P between the holes 8a, 8b, and 8c is smaller than [(W + H) / 2] × 0.8 ([(W + H) / 2] × 0.8 ≧ P), the plate-shaped reinforcement 9 is longitudinal. The crushing strength of the reinforcement 9 itself is no longer meaningful.

  The size (diameter) and the number of holes 8a, 8b, 8c provided in the longitudinal direction of the reinforcement 9 are determined after determining the connecting hole interval P for inducing the buckling deformation as described later. Depending on the design strength, thickness, and width of the steel plate constituting the reinforcement 9, it is selected as appropriate according to the assumed impact force of the high-speed collision.

(Reinforcement installation position)
Further, in the present invention, in order to reduce the initial peak load A and to reduce (suppress) the amount of load drop B immediately after the initial peak load A, the tip position of the reinforcement 9 is changed to the tip position of the side member 2a. Rather than the rear side of the vehicle. That is, as shown in FIGS. 1, 3, and 4, the end position 9 c of the flat plate reinforcement 9 on the front side of the vehicle body is set to be more rear than the end position 2 c of the side member 2 a on the front side of the vehicle body. Shift to the side (retract) and place.

  As a result, when a collision load F is applied from the front side of the vehicle body, first, the side member 2a starts crushing in the front-rear direction (axial direction) of the vehicle body, and then with a certain time delay, The flat reinforcement 9 starts crushing in the longitudinal direction (axial direction) of the vehicle body. After that, both of them collapse in a bellows shape in the longitudinal direction of the vehicle body.

  Figure 7 also shows the effect of the delay in the start of collapse of this reinforcement 9. In FIG. 7, after satisfying the requirements of the invention including the above-mentioned connecting holes, the mode in which the tip position 9c of the reinforcement 9 is shifted from the tip position 2c of the side member 2a toward the rear side of the vehicle body is d. By this mode d, in the upper load-displacement curve (when reinforcement 9 is provided), the initial peak load A is reduced, and the amount of drop in the load drop B immediately after the initial peak load A is reduced (suppressed). It can be a load-displacement curve indicated by a dotted line. If the amount of drop in load drop B immediately after the initial peak load A can be reduced, the average load will be increased to significantly increase the amount of collision energy absorption, and the amount of side member displacement, that is, the amount of penetration into the vehicle body, will be reliably reduced. it can.

(Reinforcement shift length L)
Further, in the present invention, the shift length L of the tip position 9c of the reinforcement 9 is defined in order to exert these effects with certainty. That is, the length L of the reinforcement end position 9c that is shifted from the end position 2c of the side member 2a toward the rear side of the vehicle body (the amount of retraction of the front end) is defined by the width W of the side member and the height H of the side member. In relation, [(W + H) / 4] × 1.2>L> [(W + H) / 4] × 0.8 is specified.

  The reason why the displacement length L of the tip position 9c of the reinforcement 9 is determined in relation to the (W + H) / 4 is that the pitch (W + H) at which the side member 2a is buckled when the shaft is crushed. This is because it is determined in relation to) / 2. That is, if the buckling of the reinforcement 9 can be started at 1/2 of the pitch (W + H) / 2 at which the buckling of the side member 2a occurs, the load drop due to the buckling of the end of the side member 2a This is because it has been found that this can be minimized. Therefore, by setting L to the range of the above-mentioned formula defined in relation to (W + H) / 4, it is possible to reduce the drop amount of the load drop B immediately after the initial peak load A in response to the high-speed collision. You can be sure.

When L is larger than [(W + H) / 4] × 1.2 ([(W + H) / 4] × 1.2 ≦ L), the time delay of the above-described collapse start of the reinforcement 9 is too large, The side member 2a alone bears most of the collision load, and the installation of the reinforcement 9 itself disappears.
When L is smaller than [(W + H) / 4] × 0.8 ([(W + H) / 4] × 0.8 ≧ L), the time delay of the above-mentioned crushing start of reinforcement 9 is too small. At the same time as the side member 2a, the reinforcement 9 collapses. For this reason, the initial peak load A cannot be reduced, and the drop amount of the load drop B immediately after the initial peak load A cannot be reduced (suppressed).

  The side member 2a provided with the reinforcement 9 having the U-shaped cross section shown in FIGS. 1 to 4 is assumed to have a 100 kg weight at 64 km / h, assuming a barrier collision at the front of the vehicle body at a high speed of 64 km / h. An experiment was performed in which the collision with the tip of the side member 2a was performed at h. The experiment was performed by changing conditions such as the shift length L and the connecting hole interval P together with the thickness and tensile strength of the reinforcement 9. The measurement results such as maximum load (kN), load drop after initial peak (kN), and maximum penetration (maximum displacement: mm) are shown for each plate thickness and tensile strength of Reinforcement 9. Tables 1 to 4 show the results.

  Table 1 shows the reinforcement 9 thickness 1.2mm and tensile strength 590MPa. Table 2 shows the reinforcement 9 thickness 1.2mm and tensile strength 340MPa. Table 3 shows the reinforcement 9 thickness 1.6mm and tensile strength 590MPa. Table 4 shows the reinforcement 9 thickness 1.4mm and tensile strength 590MPa. In Tables 1 to 4, the case where the shift length L of the reinforcement 9 and the connecting hole interval P meet each specified inequality sign is indicated as ◯, and the case where it is not satisfied is indicated as ×.

  The experimental conditions for the side member 2a are the same, made of steel plate with a thickness of 1.6mm and tensile strength of 590MPa, welding assembly, side member width W is 70mm, side member height H is 100mm, length (vehicle body longitudinal direction) ) Was 400mm.

  The experimental conditions for reinforcement 9 are made of steel plate with a thickness of 1.5mm and a tensile strength of 590MPa.The total width of the flat plate part is 63.8mm, the width of the side edges 9a and 9b bent upwards is 20mm each, and the length ) Depending on the length of the side member 2a, the displacement length L was changed. Further, both side end portions 9a and 9b are integrally joined to the side walls 7a and 7b constituting the side member 2a by spot welding with a pitch of 40 mm over the entire length. In addition, as shown in FIGS. 1, 3, and 4, two holes to be connected are arranged in parallel in the width direction, and a total of six holes (2 pieces / row) are connected.

  In the case where the thickness of the reinforcement 9 in Table 1 is 1.2 mm and the tensile strength is 590 MPa, Invention Example 8 satisfies the requirements of the tip retraction amount L and the interval P of the connecting holes together with the tensile strength and thickness of the reinforcement 9. As a result, as compared with Comparative Examples 1 to 7, the maximum load is not increased, and the amount of load decrease after the initial peak is suppressed.

  In contrast, in Comparative Example 1, the end position of the reinforcement 9 on the front side of the vehicle body is the same as the end position of the side member on the front side of the vehicle body, and is not shifted to the rear side of the vehicle body (the tip retraction amount L is provided). Not: L = 0). Also, no connecting hole is provided. As a result, the maximum load and the amount of load decrease after the initial peak are large as compared with Invention Example 8 in which the other conditions are the same.

  In Comparative Example 2, the tip retraction amount L satisfies the specification, but no connection hole is provided. As a result, the maximum load and the amount of load decrease after the initial peak are large as compared with Invention Example 8 in which the other conditions are the same.

  In Comparative Example 3, although the connecting hole satisfies the regulation of the interval P, the tip retraction amount L is not provided. As a result, the maximum load and the amount of load decrease after the initial peak are large as compared with Invention Example 8 in which the other conditions are the same.

  In Comparative Example 4, the tip retraction amount L is far from higher. As a result, the time delay of the above-described crushing start of the reinforcement 9 is too large, and the maximum load and the load decrease amount after the initial peak are large as compared with the invention example 8 in which the other conditions are the same.

  In Comparative Example 5, the tip retraction amount L is slightly lower. As a result, the time delay of the start of the collapse of the reinforcement 9 is too small, and the reinforcement 9 collapses at the same time as the side member 2a. Is equally small, but the load drop after the initial peak is large and the maximum penetration is large.

  In the comparative example 6, the interval P between the connecting holes is high. As a result, the effect of inducing buckling deformation over the longitudinal direction of the reinforcement 9 is lost. Therefore, although the maximum load is equally small compared with Invention Example 8 in which the other conditions are the same, the amount of load decrease after the initial peak is large and the maximum penetration amount is also large.

In Comparative Example 7, the interval P between the connecting holes is slightly lower. As a result, the crushing strength in the longitudinal direction of the reinforcement 9 is remarkably reduced, and the maximum load and the amount of load decrease after the initial peak are large as compared with the invention example 8 in which the other conditions are the same.

  In the case where the thickness of the reinforcement 9 of Table 2 is 1.2 mm and the tensile strength is 340 MPa, Invention Example 11 satisfies the requirements of the tip retraction amount L and the interval P of the connecting holes together with the tensile strength and thickness of the reinforcement 9. As a result, compared to Comparative Examples 9 and 10, the maximum load is not increased, and the amount of load decrease after the initial peak is suppressed.

  In contrast, in Comparative Example 9, the end position of the reinforcement 9 on the front side of the vehicle body is the same as the end position of the side member on the front side of the vehicle body, and is not shifted to the rear side of the vehicle body (the tip retraction amount L is provided). Not: L = 0). Also, no connecting hole is provided. As a result, the maximum load and the amount of load decrease after the initial peak are larger than those of Invention Example 11 in which the other conditions are the same.

  In Comparative Example 10, the tip retraction amount L satisfies the regulation, but the interval P between the connecting holes is slightly lower. As a result, the crushing strength in the longitudinal direction of the reinforcement 9 is remarkably reduced, and the maximum load and the amount of load decrease after the initial peak are large as compared with the invention example 11 in which the other conditions are the same.

  In the case where the thickness of the reinforcement 9 in Table 3 is 1.6 mm and the tensile strength is 590 MPa, Invention Example 14 satisfies the requirements of the tip retraction amount L and the interval P of the connecting holes together with the tensile strength and thickness of the reinforcement 9. As a result, compared with Comparative Examples 12 and 13, the maximum load is not increased, and the load decrease after the initial peak is suppressed.

  On the other hand, in Comparative Example 12, the end position of the reinforcement 9 on the front side of the vehicle body is the same as the end position of the side member on the front side of the vehicle body, and is not shifted to the rear side of the vehicle body (the tip retraction amount L is provided). Not: L = 0). Also, no connecting hole is provided. As a result, the maximum load and the amount of load decrease after the initial peak are larger than those of Invention Example 14 in which the other conditions are the same.

  In Comparative Example 13, although the tip retraction amount L satisfies the regulation, the interval P between the connecting holes is slightly lower. As a result, the crushing strength in the longitudinal direction of the reinforcement 9 is remarkably reduced, and the maximum load and the load decrease amount after the initial peak are large as compared with the invention example 14 in which the other conditions are the same.

  In the case where the thickness of the reinforcement 9 in Table 4 is 1.4 mm and the tensile strength is 590 MPa, Invention Example 17 satisfies the requirements of the tip retraction amount L and the distance P between the connecting holes together with the tensile strength and thickness of the reinforcement 9. As a result, compared with Comparative Examples 15 and 16, the maximum load is not increased, and the load decrease after the initial peak is suppressed.

  In contrast, in Comparative Example 15, the end position of the reinforcement 9 on the front side of the vehicle body is the same as the end position of the side member on the front side of the vehicle body, and is not shifted to the rear side of the vehicle body (the tip retraction amount L is provided). Not: L = 0). Also, no connecting hole is provided. As a result, the maximum load and the amount of decrease in load after the initial peak are larger than those of Invention Example 17 in which the other conditions are the same.

  In Comparative Example 16, the tip retraction amount L satisfies the regulation, but the interval P between the connecting holes is slightly lower. As a result, the crushing strength in the longitudinal direction of the reinforcement 9 is remarkably reduced, and the maximum load and the load decrease amount after the initial peak are larger than those of the invention example 17 in which the other conditions are the same.

  According to the present invention, it is possible to cope with a high-speed collision, and without reducing the initial peak load A, it is possible to reduce the amount of drop in the load drop B immediately after the initial peak load A, to increase the average load and to enter the vehicle body. It is possible to provide a shock absorbing structure for an automobile capable of reducing the amount. For this reason, even in a high-speed collision, the safety of the automobile can be ensured without increasing the weight of the side member or the like or complicating the structure.

It is a perspective view (part) of the side member concerning the automobile shock absorption structure of the present invention. FIG. 2 is a front view of FIG. FIG. 3 is a side view of FIGS. FIG. 3 is a plan view of FIGS. It is a perspective view which shows the aspect of the vehicle body frame of the vehicle body front side. It is explanatory drawing which shows the load-displacement characteristic of the axial direction crushing deformation | transformation of the side member which concerns on this invention. It is explanatory drawing which shows the load-displacement characteristic of axial direction crushing deformation | transformation of each requirement for the side member which concerns on this invention. It is explanatory drawing which shows the load-displacement characteristic of an axial crushing deformation | transformation of a general side member.

Explanation of symbols

1: body frame, 2: side member, 3a: profile, 4: flange, 5: lid,
6: Flange, 7: Side wall, 8: Hole, 9: Reinforcement, 10: Bumper reinforcement,
11: Radiator support,

Claims (1)

A pair of left and right side members having a substantially rectangular cross-sectional shape arranged so as to extend along the vehicle body longitudinal direction on both sides in the vehicle body width direction, and extending in the side member space along the axial direction of the side members In a shock absorbing structure for a vehicle, wherein the reinforcement is configured to absorb the impact force at the time of a vehicle body front collision by buckling and deforming the side member and the reinforcement together in the axial direction. The high-strength steel plate having a thickness of 1.0 to 2.0 mm and a tensile strength of 340 MPa or more, which is disposed substantially horizontally over the width direction in the side member space, is bent at both ends in the width direction of this reinforcement. Each of the side members constituting the side member is integrally joined, and the end position of the reinforcement on the front side of the vehicle body is From the end position of the side member on the front side of the vehicle body, the length L defined by [(W + H) / 4] × 1.2>L> [(W + H) / 4] × 0.8 Further, the hole for promoting the buckling deformation is formed along the longitudinal direction of the reinforcement [[W + H) / 2] × 1.2>P> [(W + H) / 2 ] A shock-absorbing structure for an automobile characterized in that a plurality of pieces are connected at intervals P defined by × 0.8.
In the above formula, W is the width of the side member, and H is the height of the side member.

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