JP5861288B2 - Front body structure of the vehicle - Google Patents

Description

  The present invention relates to a front body structure of a vehicle, and more particularly to a front body structure of a vehicle in which a crash can is provided between a front side frame and a bumper beam.

  Generally, in order to properly absorb the collision energy at the time of a vehicle collision, the rigidity between the front end of the front side frame extending in the vehicle front-rear direction and the side end of the bumper beam extending in the vehicle width direction is higher than that of the side frame. There has been known a technique of absorbing a collision energy at the initial stage of the collision with the crash can by providing a lowered cylindrical can that extends in the longitudinal direction of the vehicle and buckling and deforming the crash can at the initial stage of the collision. Various improvements have been proposed for the shape of the crash can.

  For example, in Patent Document 1, by making the cross-sectional shape of the crash can into a substantially cross-sectional shape, the cross-sectional coefficient of the crash can can be increased not only in the vertical direction but also in the vehicle width direction. There has been disclosed a technology that can increase the rigidity of the can in the vehicle width direction and prevent the crash can from falling down even when it receives an offset load in the vehicle width direction.

JP 2009-83686 A (paragraph 0012, FIG. 3)

  By the way, as described in paragraph 0003 of Patent Document 1, it is considered that by increasing the cross-sectional ridgeline of the crash can, the energy absorption amount of the crash can, in other words, the proof strength of the crash can is improved. In order to increase the cross-sectional ridgeline of the crash can, for example, when the cross-sectional shape of the crash can is a polygon, it is proposed to meander the sides in a zigzag manner or to form protrusions or depressions on the sides. . However, if it does so, the total extension of a cross-sectional ridgeline will become long, and more materials, such as a steel plate for manufacturing a crash can, will be needed, and the weight reduction of a vehicle will be prevented.

  Therefore, an object of the present invention is to maintain or improve the yield strength of the crash can by increasing the cross-sectional ridgeline of the crash can without hindering the weight reduction of the vehicle.

To achieve the above object, a vehicle front body structure according to the present invention includes a front side frame extending in the vehicle front-rear direction and a cylindrical crash can connected to the front end of the front side frame and extending in the vehicle front-rear direction. And a bumper beam having a side end connected to the front end of the crash can and extending in the vehicle width direction, the vehicle body structure of the front part of the vehicle, the crash in a plane perpendicular to the buckling axis of the crash can The cross-sectional shape of the can was a closed cross-sectional shape in which four convex portions having a top side and four concave portions having a bottom side were alternately arranged in the circumferential direction at equal intervals . Then, with this closed cross-sectional shape, every other side of the convex octagon is the apex side of the convex part, and the first wall surface part is extended from both ends of the apex side to the inner side of the polygon. The second wall surface portion connecting the first wall surface portions at a position on the outer side of the polygon from the intersection when the adjacent first wall surface portions extending from different top sides intersect with each other is formed as a recess. Set by forming as the base.

  According to such a configuration, the second wall surface portion that connects the first wall surface portions is formed as compared to the crush can having the shape when the first wall surface portions intersect at the intersection. The cross-sectional ridge line of the crash can increases, and the yield strength of the crash can is maintained or improved. In addition, since the second wall surface portion is connected so that the first wall surface portions are short-cut to each other at a position on the outer side of the polygon from the intersection point, the total extension of the cross-sectional ridge line is shortened, and a crash can is manufactured. Therefore, it is possible to reduce the material such as a steel plate to reduce the weight of the crash can. Therefore, the weight reduction of the vehicle is not hindered. On the contrary, weight reduction of the vehicle is promoted. That is, the front body structure of the vehicle according to the present invention can maintain or improve the energy absorption amount of the crash can while contributing to weight reduction of the vehicle.

In addition, according to such a configuration, in the case where the cross-sectional shape of the crush can is a substantially cross-shaped closed cross-sectional shape, the cross-sectional ridge line of the crush can is compared to the case where the first wall portions intersect at the intersection. The number increases from 12 to 16, and the strength of the crash can is maintained or improved while reducing the weight of the crash can.
Further, a vehicle front body structure according to the present invention includes a front side frame extending in the vehicle front-rear direction, a cylindrical crash can connected to the front end of the front side frame and extending in the vehicle front-rear direction, and the crash can A front body structure of a vehicle including a bumper beam connected to a front end portion of the front end portion and extending in a vehicle width direction, wherein a cross-sectional shape of the crash can in a plane orthogonal to the buckling axis of the crash can is , A closed cross-sectional shape in which convex portions having a top side and concave portions having a base side are alternately arranged in the circumferential direction, and this closed cross-sectional shape is formed by projecting every other side of an even convex polygon that is a hexagon or more. As the top side of the part, the first wall surface part was extended from the both ends of the top side to the inner side of the polygon, and the adjacent first wall surface parts extended from different top sides crossed each other. Outside the polygon from the intersection of cases It is set by forming a second wall surface portion connecting the first wall surface portions at the side position as the bottom of the recess, and the front end portion of the front side frame is a cross section corresponding to a crash can It has a shape, and the front end portion of the front side frame and the crash can overlap in a front view.
According to such a configuration, when receiving a collision load, the crash can is firmly supported in the buckling axial direction by the front end portion of the front side frame, so the crash can is against the compressive load in the buckling axial direction. The buckling deformation of the crash can is promoted in the most balanced manner, and the buckling deformation of the crash can is promoted, and the energy absorption at the initial stage of the collision by the crash can is surely performed.

  As a more specific configuration of the present invention, in the cross-sectional shape of the crush can having a substantially cross-sectional shape, the first wall surface portion extends perpendicularly to the top side, and the second wall surface portion includes two There may be mentioned those having an angle of 135 ° with the first wall portion.

  According to such a configuration, the cross-sectional shape of the entire crash can becomes highly symmetric, and even when subjected to offset loads in various directions, the crash can is prevented from falling.

  As a more specific configuration of the present invention, when the cross-sectional shape of the crush can is a substantially cross-shaped closed cross-sectional shape, the second wall surface portion is the first wall surface when the first wall surface portions intersect each other. Assuming that the total length of the portions is L, the first wall surface portions may be connected to each other at a position on the outer side of the polygon by a length of 0.25L to 0.5L from the intersection. .

  According to such a configuration, as demonstrated in the embodiment, the crash can is reduced in weight as compared with the crash can having a shape when the first wall portions intersect with each other at the intersection. The strength of the can is clearly maintained at a comparable level or better.

Further, a vehicle front body structure according to the present invention includes a front side frame extending in the vehicle front-rear direction, a cylindrical crash can connected to the front end of the front side frame and extending in the vehicle front-rear direction, and the crash can A front body structure of a vehicle including a bumper beam connected to a front end portion of the front end portion and extending in a vehicle width direction, wherein a cross-sectional shape of the crash can in a plane orthogonal to the buckling axis of the crash can is , A closed cross-sectional shape in which three convex portions having a top side and three concave portions having a base side are alternately arranged at equal intervals in the circumferential direction, and this closed cross-sectional shape is obtained by arranging every other side of the convex hexagon. As the top side of the convex part, a first wall surface part is extended from both ends of the top side to the inner side of the polygon, and adjacent first wall surface parts extended from different top sides intersect. Polygon from the intersection By forming the second wall portion at a position of the outer side connecting said first wall portions as the bottom of the recess, characterized in that the one set.

According to such a configuration, the second wall surface portion that connects the first wall surface portions is formed as compared to the crush can having the shape when the first wall surface portions intersect at the intersection. The cross-sectional ridge line of the crash can increases, and the yield strength of the crash can is maintained or improved. In addition, since the second wall surface portion is connected so that the first wall surface portions are short-cut to each other at a position on the outer side of the polygon from the intersection point, the total extension of the cross-sectional ridge line is shortened, and a crash can is manufactured. Therefore, it is possible to reduce the material such as a steel plate to reduce the weight of the crash can. Therefore, the weight reduction of the vehicle is not hindered. On the contrary, weight reduction of the vehicle is promoted. That is, the front body structure of the vehicle according to the present invention can maintain or improve the energy absorption amount of the crash can while contributing to weight reduction of the vehicle.
In addition, according to such a configuration, the cross-section ridgelines of the crash can increase from 9 to 12 compared with the case where the first wall surfaces intersect at the intersection, and the crash can is reduced in weight while the crash can is reduced in weight. The proof stress is maintained or improved.

  ADVANTAGE OF THE INVENTION According to this invention, the yield strength of a crash can can be maintained or improved, achieving weight reduction of a crash can. Therefore, the collision energy at the initial stage of the collision can be absorbed well while promoting the weight reduction of the vehicle.

1 is a perspective view of a front body structure of a vehicle according to an embodiment of the present invention. It is an enlarged front view which shows the positional relationship of the crash can and the front side frame of the vehicle body right side in the said vehicle. It is an enlarged front view of a crash can according to another embodiment of the present invention. It is a front view for demonstrating the shape of the crush can produced in the Example of this invention, (a) shows the comparative example 1, (b) shows Example 4, (c) shows the reference example 1. is there. It is a perspective view for demonstrating the execution conditions of the Example of this invention. It is a characteristic view of the deformation amount (crash stroke) and load of the crash can for each shape of the crash can, showing the result of the embodiment of the present invention. It is a correlation diagram of the shape of a crash can and the amount of energy absorption which shows the result of the Example of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this embodiment is only an illustration and this invention is not limited to this embodiment at all. Further, in the following description, the terms indicating directions such as front and rear, left and right, and up and down are based on a vehicle or a vehicle body unless otherwise specified.

  In the present embodiment, the present invention is applied to the vehicle front body structure shown in FIG. As shown in FIG. 1, this vehicle has a front body structure, first, a dash panel 3 that forms a partition wall between a vehicle compartment 1 and an engine room 2, a dash cross member 4 below the dash panel 3, and a dash cross. A pair of left and right front side frames 10 and 10 extending in the vehicle longitudinal direction from below the member 4 via the kick-up portion 5 is included.

  The front side frame 10 is formed by pressing a relatively thick steel plate, and has an inner member 11 with a hat-shaped cross section positioned on the inner side in the vehicle width direction and a plate-shaped outer member positioned on the outer side in the vehicle width direction. 12 are joined by spot welding with the upper and lower flange portions 13 and 13 so as to form a vertically long rectangular closed cross section.

  A fixing plate 20 having bolt holes 21... 21 (see FIG. 2) formed at the four corners is joined to the front end portion of the front side frame 10. A mounting plate 30 having bolt holes 31... 31 (see FIG. 2) formed at the four corners is overlapped with the front surface of the fixed plate 20. And the attachment plate 30 is couple | bonded with the fixed plate 20 by the fastening of the volt | bolt 41 and the nut 42 which were penetrated to the corresponding bolt holes 21 and 31 (refer FIG. 2).

  A crash can 50 is joined to the front surface of the mounting plate 30 for absorbing and mitigating an initial impact at the time of a vehicle collision. The crush can 50 is formed by pressing a relatively thin steel plate into substantially the same shape and dimensions, and an inner member 51 positioned on the inner side in the vehicle width direction and an outer member 52 positioned on the outer side in the vehicle width direction. However, it is the structure by which upper surfaces and lower surfaces were faced | matched and joined (refer FIG. 2). The crash can 50 has a cylindrical shape extending in the vehicle front-rear direction, and as will be described later, the cross-sectional shape of the crash can 50 on the surface orthogonal to the buckling axis P1 (see FIG. 2) is a polygonal closed cross-sectional shape. .

  Here, the buckling axis P <b> 1 of the crash can 50 refers to an axis that passes through the longitudinal center of the crash can 50 and is orthogonal to the flat front surface of the mounting plate 30.

  A side end portion of the bumper beam 70 extending in the vehicle width direction is joined to the front end portion of the crash can 50. The bumper beam 70 includes a beam member 71 having a hat-like cross section located on the rear side in the vehicle longitudinal direction and a plate-like beam plate 72 located on the front side in the vehicle longitudinal direction, each formed by pressing a steel plate. It is the structure joined by the upper and lower flange parts 73 and 73 so that a rectangular closed cross section may be formed. Although not shown, the upper and lower surfaces of the crash can 50 are extended forward from the front end portion of the crash can 50, and the extended portion sandwiches the hat-shaped protrusion of the beam member 71 from above and below, and extends in this state. When the portion is fillet welded to the beam member 71, the crash can 50 and the bumper beam 70 are firmly joined.

  As shown in FIG. 2, the crash can 50 has a hexagonal closed cross-sectional shape on a surface perpendicular to the buckling axis P <b> 1. Although FIG. 2 shows the crash can 50 and the front side frame 10 on the right side of the vehicle body, the crash can 50 and the front side frame 10 on the left side of the vehicle body have the same configuration. Therefore, in this embodiment, the configuration on the right side of the vehicle body in FIG. 2 will be described as a representative, and the description on the configuration on the left side of the vehicle body will be omitted.

  Here, FIG. 2 also shows the central axis P2 of the front end portion of the front side frame 10 that overlaps with the buckling axis P1 in front view, along with the buckling axis P1 of the crash can 50. The central axis P2 of the front end portion of the front side frame 10 refers to an axis that passes through the center in the longitudinal direction of the front end portion of the front side frame 10 and is orthogonal to the flat rear surface of the fixed plate 20.

  In FIG. 2, the crush can 50 has four protrusions, an upper protrusion 53 protruding upward, a right protrusion 54 and a left protrusion 55 protruding in the vehicle width direction, and a lower protrusion 56 protruding downward. Each part has an allocation angle interval of 90 °. And between these convex parts 53-56, it has the 1st-4th four recessed parts 57-60 at the allocation angle space | interval of 90 degrees, respectively. As a result, the crash can 50 as a whole has a substantially cross-shaped closed cross-sectional shape in which the four convex portions 53 to 56 and the four concave portions 57 to 60 are alternately arranged at equal intervals of 45 ° in the circumferential direction. Presents.

  Each of the convex portions 53 to 56 includes a top side 53a to 56a that constitutes the outermost side of the crash can 50, and a first side that extends from the both ends of the top side 53a to 56a at a substantially right angle to the top side 53a to 56a. Wall surface portions 53b to 56b. The first wall surface portions 53b to 56b are downward if the upper convex portion 53, leftward if the right convex portion 54, rightward if the left convex portion 55, and if the lower convex portion 56. It extends upward.

  Each recessed part 57-60 has the 2nd wall surface part 57a-60a which connects the 1st wall surface parts of an adjacent convex part as a base. The second wall surface portions 57a to 60a form an angle of approximately 135 ° with the two first wall surface portions in each of the recesses 57 to 60.

  The closed cross-sectional shape of the crash can 50 is generally set as follows. First, a convex octagon having apexes at both ends of the apex sides 53a to 56a of the four convex portions 53 to 56 is assumed, and every other side of the convex octagon is set to the apex side 53a of the convex portions 53 to 56. First wall surface portions 53b to 56b are extended from both ends of the top sides 53a to 56a to the inner sides of the convex octagons at substantially right angles to the top sides 53a to 56a. Next, assuming an adjacent point O when adjacent first wall surfaces extending from different top sides 53a to 56a cross each other, the first point at a position on the outer side of the polygon from the intersection point O is assumed. The second wall surface portions 57a to 60a that connect the wall surface portions to each other are formed as the bottom sides of the recess portions 57 to 60.

  Here, the shape of the crash can when the first wall surface portions intersect at the intersection point O is a dodecagon having 12 vertices and 12 cross-sectional ridge lines. On the other hand, the crash can 50 according to the present embodiment is formed of the second wall surface portions 57a to 60a that connect the first wall surface portions to each other, so that the vertex is 16 hexagons, and the cross-sectional ridge line is It has increased to 16. Therefore, in the crash can 50 according to the present embodiment, the proof stress of the crash can 50 is maintained or improved as compared with the case where the second wall surface portions 57a to 60a are not formed.

  And the 2nd wall surface parts 57a-60a are connected so that the 1st wall surface parts may shortcut each other in the position of the polygon outer side from the said intersection O. Therefore, in the crash can 50 according to the present embodiment, the cross-sectional ridge line is increased, but the total extension of the cross-sectional ridge line is short as compared with the case where the second wall surface portions 57a to 60a are not formed. As a result, a material such as a steel plate for manufacturing the crash can 50 can be reduced, and the crash can 50 is reduced in weight and does not hinder the weight reduction of the vehicle. On the contrary, lighter vehicles are being promoted.

  Therefore, the front body structure of the vehicle according to the present embodiment can maintain or improve the energy absorption amount of the crash can 50 while contributing to the weight reduction of the vehicle.

  Moreover, in this embodiment, the 1st wall surface parts 53b-56b are extended substantially perpendicularly to the top sides 53a-56a, or the 2nd wall surface parts 57a-60a are respectively substantially the two 1st wall surface parts. The cross-sectional shape of the entire crash can 50 is highly symmetric, such as forming an angle of 135 °. Therefore, even when the crash can 50 receives offset loads in various directions, the crash can 50 is prevented from falling.

  In this embodiment, the dimension of each part of the crash can 50 is not particularly limited, and can be variously changed according to the situation. For example, when the length of the first wall surface when the first wall surfaces intersect each other, that is, the length from one end of the top sides 53a to 56a to the intersection O is L, L is about 40 mm. It can be. At this time, the length of the top sides 53a to 56a is preferably about 40 mm. That is, the total length L of the first wall surface and the lengths of the top sides 53a to 56a when the first wall surfaces intersect each other are made substantially the same. Thereby, even when an offset load in the vehicle width direction is received, an advantageous result can be obtained from the viewpoint of preventing the crash can 50 from falling down.

  In addition, it is preferable that the second wall surface portions 57a to 60a connect the first wall surface portions to each other at a position on the outer side of the polygon by a length of 0.25L to 0.5L from the intersection point O. More preferably, it is a position on the outer side of the polygon by a length of 0.25L to 0.38L from the intersection point O. Thereby, while the weight of the crash can 50 is reduced, the proof strength of the crash can 50 is maintained at the same level or higher than that in which the second wall surface portions 57a to 60a are not formed. From which advantageous results are obtained.

  Further, the length of the crash can 50 in the buckling axis P1 direction is a viewpoint of how much energy is absorbed by the crash can 50 and a viewpoint of how easy the buckle deformation of the crash can 50 is made. For example, it is preferably about 80 mm.

  In the present embodiment, the front end portion of the front side frame 10 to which the crash can 50 is connected has four convex portions having a top side and four concave portions having a bottom side corresponding to the crash can 50 in the circumferential direction. It exhibits a substantially cross-shaped closed cross-sectional shape alternately arranged at equal intervals of 45 °. As shown in FIG. 2, the front end portion of the front side frame 10 and the crash can 50 overlap each other in front view. Further, the buckling axis P1 of the crash can 50 and the center axis P2 of the front end portion of the front side frame 10 coincide with each other.

  That is, in FIG. 2, the inner member 11 of the front side frame 10 corresponds to the upper convex portion 53 of the crash can 50 at the front end portion thereof, and the position and length of the upper surface portion 10 a of the hat-shaped ridge portion are the same. The position and length of the lower surface portion 10b of the hat-shaped protrusion are set in correspondence with the lower convex portion 56 of the crash can 50, and the upper convex portion 53 and the lower convex portion 56 of the crash can 50 are set. The position of the left surface portion 10c of the hat-shaped ridge portion is set corresponding to the left first wall surface portions 53b and 56b. Further, a left protruding portion 10 d is formed on the left surface portion 10 c of the hat-shaped protruding portion corresponding to the left convex portion 55 of the crash can 50.

  Further, in FIG. 2, the outer member 12 of the front side frame 10 corresponds to the first wall surfaces 53 b and 56 b on the right side of the upper convex portion 53 and the lower convex portion 56 of the crash can 50 at the front end portion thereof. , Its position is set. Further, a right protruding portion 10 e is formed corresponding to the right convex portion 54 of the crash can 50.

  Further, in FIG. 2, the shape of the right protruding portion 10 e of the outer member 12 of the front side frame 10 is set corresponding to the second wall surface portions 57 a and 58 a of the first recess 57 and the second recess 58 of the crash can 50. The shape of the left protruding portion 10d of the inner member 11 of the front side frame 10 is set corresponding to the third concave portion 59 of the crash can 50 and the second wall surface portions 59a, 60a of the fourth concave portion 60.

  As described above, the front end portion of the front side frame 10 and the crush can 50 have substantially the same contour when viewed from the front.

  Thereby, when the crash load is received, the crash can 50 is firmly supported by the front end portion of the front side frame 10 in the direction of the buckling axis P1, so that the crash can 50 is against the compressive load in the direction of the buckling axis P1. Therefore, the buckling deformation of the crash can 50 is promoted in the most balanced manner, and the energy absorption at the initial stage of the collision by the crash can 50 is surely performed.

  Next, the operation of this embodiment will be described. Assume that a collision load is applied to the bumper beam 70 from the front. At the initial stage of the collision, the crash can 50 is buckled and deformed in a bellows shape in the direction of the buckling axis P <b> 1, whereby the collision energy at the initial stage of the collision is absorbed by the crash can 50.

  At this time, there are 16 cross-sectional ridge lines of the crash can 50, and the cross-section ridge lines are increased compared to the case where the second wall surface portions 57a to 60a are not formed. It has improved. As a result, the amount of collision energy that can be absorbed by the crash can 50 is maintained or increased, and the possibility that the crash can 50 is completely crushed and the collision energy directly acts on the side frame 10 is reduced. Alternatively, even when the collision energy acts directly on the side frame 10, the amount of energy is reduced. And since the total extension of the cross-sectional ridgeline is shorter than when the second wall surface portions 57a to 60a are not formed, the weight of the crash can 50 is reduced. It promotes weight reduction and contributes to vehicle weight reduction.

  In addition, since the entire shape of the crash can 50 with respect to the buckling axis P1 is highly symmetric, even if it receives an offset load, the collapse deformation is suppressed, the buckling deformation is promoted, and the crash Energy absorption by the can 50 is performed smoothly.

  Furthermore, since the crash can 50 and the front end portion of the front side frame 10 to which the crash can 50 is connected have the same cross-sectional shape and the same contour in front view, the buckle deformation of the crash can 50 is prevented. This is also promoted.

  In the above embodiment, the basic convex polygon for setting the shape of the crash can 50 is a convex octagon, but there is no particular limitation as long as it is an even convex polygon that is a hexagon or more. As an example, FIG. 3 shows a case where the basic convex polygon is a convex hexagon. In this case, the crash can 150 has a dodecagonal closed cross-sectional shape on a surface orthogonal to the buckling axis P1. The crash can 150 is a dodecagon having twelve vertices and twelve cross-sectional ridge lines. The crash can 150 has a closed cross-sectional shape in which three convex portions 153 to 155 and three concave portions 157 to 159 are alternately arranged at equal intervals in the circumferential direction at an allocation angle of 60 °.

  In FIG. 3, the lengths of the top sides 153 a to 155 a of the convex portions 153 to 155 are longer than the lengths of the first wall surface portions 153 b to 155 b, but are not limited thereto. The lengths of the top sides 153a to 155a of the convex portions 153 to 155 and the lengths of the first wall surface portions 153b to 155b may be substantially the same. You may make it shorter than the length of the 1st wall surface parts 153b-155b. The same applies to the crash can 50 having a substantially cross-sectional shape shown in FIG.

  In FIG. 3, the bottoms of the recesses 157 to 159, that is, the second wall surface portions 157 a to 159 a form an angle of approximately 150 ° with the two first wall surface portions in each of the recesses 157 to 159. .

  In the above embodiment, the angle formed by the second wall surface portion with the first wall surface portion is the same between the two first wall surface portions, or the two first wall surfaces sandwiching the second wall surface portion. Although the length of the wall surface portion is the same, it is not limited to this, and various changes may be made according to the situation.

  If the basic convex polygon for setting the shape of the crash can is an even convex polygon that is a hexagon or more, whether or not it is a regular polygon with the same side length is the problem. Don't be.

  Dimensions of each part of the crash can, for example, the ratio of the length of the top side of the convex portion to the length of the first wall surface portion, the length of the second wall surface portion, or the second wall surface portion is the first wall surface portion As for the angle to make, and the number of convex parts, the number of concave parts, etc., compared with the case where the second wall surface part is not formed, the degree of weight reduction of the crash can and the yield strength of the crash can increase or It is preferable to set the degree of decrease by comparative consideration.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

[Crash can production]
Using a cold-rolled steel plate (SPC material) with a plate thickness of 1.4 mm, as shown in FIG. 4A, the length of the top side is 40 mm, the length (L) of the first wall surface portion is 40 mm, A crush can having a length of 80 mm in the buckling axis direction and not forming the second wall portion and having a closed cross-sectional shape with a substantially cross-sectional shape was prepared as Comparative Example 1.

  In contrast to the comparative example 1, as shown in FIG. 4B, a second wall surface portion was formed as an example. In that case, the length of the first embodiment, 10 mm, in which the two first wall surfaces are connected to each other at a position on the outer side of the polygon by a length of 5 mm from the intersection (O) between the first wall surfaces. As shown in the second embodiment, the position of the second wall surface is changed in increments of 5 mm, and the outer side of the polygon is 35 mm long. What was connected in the position of this was set as Example 7.

  Then, as shown in FIG. 4C, a reference example 1 was used in which the first wall surface portion was not formed, the convex portion and the concave portion were not formed, and the cross-sectional shape was a convex octagon.

[Energy absorption test]
About each crush can of Examples 1-7, the comparative example 1, and the reference example 1, the energy absorption test was done. As shown in FIG. 5, one end X of the crash can is constrained, a rigid wall Z is applied to the other end Y, and the rigid wall Z is directed toward the one end X of the crash can at a speed of 0.5 m / sec. It was moved in the buckling axis direction until the crash can was crushed. The distance traveled by the rigid wall Z (crash stroke, amount of deformation of the crash can) and the load were measured, and the energy absorption amount of each crash can until the crash can was crushed was determined from the results. The results are shown in FIGS. FIG. 6 shows only the results of Comparative Example 1 and Examples 2 to 4. FIG. 7 shows the amount of energy absorbed by all crash cans.

  In FIG. 7, the number in parentheses (%) indicates the intersection (O) between the first wall surfaces and the second wall surface with respect to the length (L = 40 mm) of the first wall surface in Comparative Example 1. It is the ratio of the length (5 mm in the first embodiment, 10 mm in the second embodiment,...) Between the portions connecting the first wall portions.

[Consideration of results]
As is clear from FIG. 7, in Examples 1 to 7 in which the second wall surface portion is formed, the energy of the crush can is reduced compared to Comparative Example 1 in which the second wall surface portion is not formed. The degree of decrease in the amount of absorption was limited, and generally good proof stress was maintained.

  In particular, in Examples 2 to 4, in which the second wall surface portion connects the first wall surface portions at a position on the outer side of the polygon by a length of 0.25 L to 0.5 L from the intersection point, the energy absorption amount is small. It was maintained at the same level with almost no decrease from Comparative Example 1. Furthermore, among these, Examples 2 and 3 in which the second wall surface portion connects the first wall surface portions at a position on the outer side of the polygon by a length of 0.25 L to 0.38 L from the intersection point. On the contrary, the amount of energy absorption was improved more than that of Comparative Example 1.

  The present invention is widely used in the technical field of a front body structure of a vehicle in which a crash can is provided between a front side frame and a bumper beam so that the collision energy at the initial stage of the collision is absorbed by the crash can. Industrial applicability is expected.

DESCRIPTION OF SYMBOLS 10 Front side frame 10a Upper surface part 10b Lower surface part 10c Left surface part 10d Left protrusion part 10e Right protrusion part 11 Inner member 12 Outer member 20 Fixing plate 30 Mounting plate 50 Crash can 51 Inner member 52 Outer member 53 Upper convex part 54 Right convex part 55 Left convex part 56 Lower convex part 53a-56a Top side 53b-56b 1st wall surface part 57-60 1st-4th recessed part 57a-60a 2nd wall surface part (bottom side)
70 Bumper beam 71 Beam member 72 Beam plate L Length from the top edge to the intersection O Intersection P1 Buckling axis P2 Center axis

Claims (5)

A front side frame extending in the vehicle front-rear direction, a cylindrical crush can connected to the front end portion of the front side frame and extending in the vehicle front-rear direction, and a side end portion connected to the front end portion of the crash can in the vehicle width direction A vehicle front body structure with a bumper beam extending to
The cross-sectional shape of the crash can in the plane perpendicular to the buckling axis of the crash can is a closed cross-sectional shape in which four convex portions having a top side and four concave portions having a bottom side are alternately arranged at equal intervals in the circumferential direction. Yes,
This closed cross-sectional shape is
Extending every other side of the convex octagon as the apex side of the convex part from the both ends of the apex side to the inward side of the polygon,
The second wall surface portion that connects the first wall surface portions at a position on the outer side of the polygon from the intersection when the adjacent first wall surface portions extending from different top sides intersect with each other. A front body structure of a vehicle, which is set by forming the bottom of the recess. A front side frame extending in the vehicle front-rear direction, a cylindrical crush can connected to the front end portion of the front side frame and extending in the vehicle front-rear direction, and a side end portion connected to the front end portion of the crash can in the vehicle width direction A vehicle front body structure with a bumper beam extending to
The cross-sectional shape of the crash can in the plane perpendicular to the buckling axis of the crash can is a closed cross-sectional shape in which convex portions having a top side and concave portions having a bottom side are alternately arranged in the circumferential direction,
This closed cross-sectional shape is
Hexagonal or more even convex polygons every other side of the convex portion as the top side of the convex portion, the first wall surface portion is extended from both ends of the top side to the inward side of the polygon,
The second wall surface portion that connects the first wall surface portions at a position on the outer side of the polygon from the intersection when the adjacent first wall surface portions extending from different top sides intersect with each other. It is set by forming as the bottom of the recess,
A front body structure of a vehicle, wherein a front end portion of the front side frame has a cross-sectional shape corresponding to a crash can, and the front end portion of the front side frame and the crash can overlap in a front view . The first wall portion extends perpendicularly to the top side,
The front body structure of a vehicle according to claim 1 , wherein the second wall surface portion forms an angle of 135 ° with each of the two first wall surface portions.   The second wall surface portion is a polygon having a length of 0.25L to 0.5L from the intersection point, where L is the total length of the first wall surface portion when the first wall surface portions intersect each other. The front body structure of a vehicle according to claim 3, wherein the first wall surfaces are connected to each other at a position on the outer side. A front side frame extending in the vehicle front-rear direction, a cylindrical crush can connected to the front end portion of the front side frame and extending in the vehicle front-rear direction, and a side end portion connected to the front end portion of the crash can in the vehicle width direction A vehicle front body structure with a bumper beam extending to
The cross-sectional shape of the crash can in the plane perpendicular to the buckling axis of the crash can is a closed cross-sectional shape in which three convex portions having a top side and three concave portions having a bottom side are alternately arranged at equal intervals in the circumferential direction. Yes,
This closed cross-sectional shape is
Extending every other side of the convex hexagon as the apex side of the convex part, the first wall surface part extends from both ends of the apex side to the inward side of the polygon,
The second wall surface portion that connects the first wall surface portions at a position on the outer side of the polygon from the intersection when the adjacent first wall surface portions extending from different top sides intersect with each other. A front body structure of a vehicle, which is set by forming the bottom of the recess .

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