JP2021178592A - Columnar member - Google Patents

Abstract

To provide a columnar member which can absorb more energy during a collision without increasing its weight.SOLUTION: A columnar member 100 includes a hat shaped member 10 having: an upper wall 12 extending along a main axis; vertical walls 14, 16 extending along both side edge parts 12a, 12b of the upper wall 12; and flange parts 18, 20 extending along edges parts 14a, 16b, which are opposite to the upper wall 12, of the vertical walls 14, 16, the hat shaped member 10 having a cross section which is perpendicular to the main axis and presents a substantially hat shape. The columnar member 100 includes: a bending induction part 22 which is provided at the upper wall 12 and serves as a starting point of bending of the columnar member 100 when the columnar member 100 receives a compression load in a direction of the main axis; and bead parts 14b, 16b provided at positions corresponding to the bending induction part 22 in the direction of the main axis on the vertical walls 14, 16 and having a shape spreading to the bending induction part 22.SELECTED DRAWING: Figure 2

Description

The present invention relates to a columnar member.

In an automobile, in order to reduce the weight and increase the rigidity of the vehicle, columnar members formed by plastically deforming a thin plate so as to have a so-called hat-shaped cross section are welded to each other to form a vehicle body. Further, in order to secure a living space in the passenger cabin in the event of a car collision, such columnar members are required to increase the maximum reaction force and absorbed energy at the time of bending deformation.

For example, Patent Document 1 describes an upper wall extending along a predetermined main axis, a side wall extending along both side edges of the upper wall, and an edge of the side wall opposite to the upper wall. In a columnar member having a flange portion extending along the portion and having a substantially hat-shaped cross section perpendicular to the axis, a plane perpendicular to the upper wall and the main axis and the side wall surface. At least a pair of bead portions arranged line-symmetrically with respect to the axis defined by the line of intersection are formed on the side wall, and the bead portions are 20 to 75 ° in the surface of the side wall with respect to the axis. A columnar member extending along a central axis inclined at an angle is disclosed.

Japanese Patent No. 6445230

In order to achieve both the collision safety required for the vehicle and the weight reduction, various ideas are required not only for the materials applied to the vehicle but also for the design. Above all, there is a strong demand for compactness and high efficiency of members such as front side members, rear side members, and center pillars that mainly absorb energy in the event of a collision. These members absorb impact due to bending deformation, but the members are rapidly weakened due to bending deformation. Therefore, it is often considered to add a reinforcing member to these members, but the addition of the reinforcing member increases the weight. In addition, there is a problem that the reinforcing portion becomes too strong due to the reinforcing member, the expected deformation mode is not achieved, and conversely, the impact absorption performance is significantly deteriorated.

Further, in recent years, the drive source of an automobile is shifting from the conventional internal combustion engine to a smaller drive source such as an electric motor (motor). When the drive source of an automobile is miniaturized, the degree of freedom of the vehicle body structure, which has been restricted by the existence of the internal combustion engine, increases. For example, the space where the internal combustion engine used to exist can be used as the cabin space, and it is possible to design a vehicle that meets the needs of users who want to make the cabin wider.

On the other hand, the space in which the internal combustion engine exists is used to ensure collision safety because it does not affect the occupants in the cabin even if it collapses in the event of a collision. For this reason, if the space where the internal combustion engine used to exist is used as a passenger compartment, the collapse of the vehicle body that occurs in the event of a collision may directly affect the occupants in the passenger compartment, making it impossible to ensure safety in the event of a collision. There is.

As described above, if the cabin is made wider by using the space where the internal combustion engine existed, the space originally used to ensure collision safety will be reduced, so collision energy will be used in a narrower space. It is desirable to absorb it.

The technique described in Patent Document 1 provides a columnar member having a hat-shaped cross section in which the maximum stress for bending deformation and the amount of absorbed energy are increased with a simple configuration, but absorbs collision energy in a narrower space. There is room for further improvement if it is assumed that this will be done.

Therefore, an object of the present invention is to provide a columnar member capable of absorbing more energy at the time of a collision without increasing the weight.

The gist of this disclosure is as follows.

(1) An upper wall extending along the main axis, a vertical wall extending along both side edges of the upper wall, and a vertical wall along the edge opposite to the upper wall. A columnar member having an extended flange portion and a hat-shaped member having a cross section perpendicular to the main axis having a substantially hat shape, which is provided on the upper wall and compressed in the direction of the main axis. When a load is applied, the bending-inducing portion that is the starting point of bending of the columnar member is provided at a position corresponding to the bending-inducing portion in the direction of the main axis on the vertical wall, and the bending-inducing portion is provided. A columnar member having a bead portion having a shape that spreads toward it.

(2) The columnar member according to (1) above, wherein the bead portion projects to the outside of the vertical wall.

(3) The columnar member according to (2) above, wherein the length of the bead portion in the direction along the main axis is less than 0.5 times the height of the vertical wall.

(4) The columnar member according to (2) or (3) above, wherein the height of the bead portion is less than 0.75 times the height of the vertical wall.

(5) The columnar member according to any one of (1) to (4) above, wherein the position of the upper end of the bead portion is located below the R portion connecting the upper wall and the vertical wall.

(6) The columnar column according to any one of (1) to (5) above, wherein the bending-inducing portion is provided on the upper wall and is composed of recesses or holes extending in a direction orthogonal to the main axis. Element.

(7) The columnar member according to any one of (1) to (6) above, which constitutes the front side member or the rear side member of the vehicle.

According to the present invention, there is provided a columnar member capable of absorbing more energy at the time of a collision without increasing the weight.

It is a schematic diagram for demonstrating the structure of the vehicle body floor of the automobile which concerns on this embodiment, and is the top view which looked at the body floor from above. It is the figure which looked at the car body floor from the bottom. It is a perspective view which shows the structure of the columnar member which concerns on one Embodiment of this invention. It is sectional drawing which shows the cross section (cross section) which cut in the plane perpendicular to the longitudinal direction which is the direction of the main axis of a columnar member at the fold induction bead position. It is a perspective view which shows the structure of the columnar member of the base member model which does not provide a bead portion. It is a schematic diagram which shows in time series how the bending deformation of a columnar member progresses when a compression load is applied to a columnar member in the direction of a main axis. It is a schematic diagram which shows in time series how the bending deformation of a columnar member progresses when a compression load is applied to a columnar member in the direction of a main axis. It is a schematic diagram which shows in time series how the bending deformation of a columnar member progresses when a compression load is applied to a columnar member in the direction of a main axis. FIG. 6 is a schematic view showing a state in which the vicinity of the breakage-inducing bead on the upper wall of the columnar member is viewed from above at the timing shown in FIG. 6C. When a compression load is applied to the columnar member of the present embodiment in which the bead portion is provided on the vertical wall under the same conditions as those in FIGS. 6A to 6C, the upper wall of the columnar member is broken at the same timing as in FIG. 6C. It is a schematic diagram which shows the state which looked at the vicinity of the induction bead from the top. A characteristic diagram showing the relationship between the stroke (horizontal axis) and the reaction force (vertical axis) when a compression load is applied to the columnar member and the columnar member of the base member model according to the present embodiment in the direction of the main axis Om. Is. In the characteristics of the stroke and the reaction force shown in FIG. 9, it is a figure which shows the state of bending deformation of a columnar member at each timing of a stroke S1, S2, S3. In the characteristics of the stroke and the reaction force shown in FIG. 9, it is a figure which shows the state of bending deformation of a columnar member at each timing of a stroke S1, S2, S3. In the characteristics of the stroke and the reaction force shown in FIG. 9, it is a figure which shows the state of bending deformation of a columnar member at each timing of a stroke S1, S2, S3. In the characteristics of the stroke and the reaction force shown in FIG. 9, it is a figure which shows the state of bending deformation of a columnar member at each timing of a stroke S1, S2, S3. In the characteristics of the stroke and the reaction force shown in FIG. 9, it is a figure which shows the state of bending deformation of a columnar member at each timing of a stroke S1, S2, S3. It is a schematic diagram which shows the bead portion 14b provided in the vertical wall 14 in detail. It is a schematic diagram which shows the bead part in detail when the columnar member is seen from the direction of the main axis. It is a characteristic diagram which shows the relationship between a stroke and a reaction force for each variation of the shape of a bead portion. It is a characteristic diagram which shows the relationship between the length I of a bead part and the energy absorption amount ratio. It is a characteristic diagram which shows the relationship between the height h of a bead part and the energy absorption amount ratio. It is a characteristic diagram which shows the relationship between a vertical wall angle and an energy absorption amount ratio. Similar to FIG. 12, it is a schematic diagram showing in detail the bead portion provided on the vertical wall, and is a diagram showing an example in which a space is provided between the position of the upper end of the bead portion and the position of the lower end of the R portion. be. Similar to FIG. 14, it is a characteristic diagram showing the relationship between the stroke of the columnar member and the reaction force, and is a characteristic showing the characteristics of the columnar member having the interval s of 5 mm shown in FIG. 16 together with the characteristics C1 and C2 of FIG. It is a figure. It is a perspective view which shows the example which the bending-inducing part was composed of the hole provided in the upper wall. FIG. 3 is a perspective view showing an example in which a bending-inducing portion is composed of four concave beads extending in the direction of the main axis. It is a schematic diagram which shows the example which the columnar member was composed of two hat-shaped members, and is the schematic diagram which shows the cross section along the direction orthogonal to the direction of the main axis of a columnar member.

Hereinafter, the columnar member according to the embodiment of the present invention will be described with reference to the drawings. First, with reference to FIGS. 1 and 2, the configuration of the vehicle body floor 110 to which the columnar member according to the embodiment of the present invention is applied will be described. FIG. 1 is a schematic view for explaining the structure of the vehicle body floor 110 of the automobile according to the present embodiment, and is a plan view of the vehicle body floor 110 as viewed from above. FIG. 2 is a view of the vehicle body floor 110 as viewed from below.

As shown in FIG. 1, the vehicle body floor 110 includes a floor panel 112, floor cross members 114a to 114f, a front bumper 115, front side members 116a and 116b, rear side members 117a and 117b, a rear bumper 119, and a side sill 120. There is.

The side sill 120 extends in the front-rear direction (vehicle length direction) of the automobile along the left and right side surfaces of the automobile. The floor cross members 114a to 114f extend in the left-right direction (vehicle width direction) of the automobile. Each of the floor cross members 114a to 14f is joined to each of the left and right side sills 120 at both ends by welding, riveting, bolting or the like (hereinafter referred to as welding or the like).

The floor cross members 114b to 114e are arranged so as to extend in the vehicle width direction in the area surrounded by the left and right side sills 120, the floor cross member 114a, and the floor cross member 114f.

Floor panels 112 are arranged under the floor cross members 114b to 114e. The floor panel 112 is fixed to the floor cross members 114a to 114f and the side sill 120 by welding or the like.

The floor cross members 114a to 114f may be made of a hat material (cross-section hat-shaped member). Further, the floor cross members 114a to 114f may be composed of a hollow tubular member, or may have a rectangular cross section orthogonal to the longitudinal direction.

Two front side members 116a and 116b extend in the vehicle length direction inside the side sill 120 in the vehicle width direction. The rear ends of the front side members 116a and 116b are in contact with the floor cross member 114f and are fixed to the floor cross member 114f by welding or the like.

The upper surfaces of the front side members 116a and 116b may be in contact with the floor panel 112, or may be fixed to the floor panel 112 by welding or the like.

Two rear side members 117a and 117b extend in the vehicle length direction behind the floor cross member 114f. The front ends of the rear side members 117a and 117b are fixed to the floor cloth member 114f by welding or the like. A rear bumper 119 is fixed to the rear end of the rear side members 117a and 117b. Further, a cross member 117c that connects the rear side member 117a and the rear side member 117b is arranged in the middle of the rear side members 117a and 117b in the front-rear direction. The end portion of the cross member 117c is fixed to each of the rear side member 117a and the rear side member 117b by welding or the like.

As described above, members such as front side members 116a and 116b, rear side members 117a and 117b, or center pillars, which are mainly responsible for energy absorption during a collision, mainly absorb energy during a collision when a vehicle collides. It is a member that bears the burden, and there is a strong demand for compactness and high efficiency.

The present inventors have found that a relatively small bead portion is installed in a portion close to a bending-inducing portion of these members in order to eliminate the weakening of the member due to bending deformation and to avoid an increase in weight. According to the present invention, it is possible to reduce the weakening of these members due to bending deformation without adding reinforcing members.

FIG. 3 is a perspective view showing the configuration of the columnar member 100 according to the embodiment of the present invention. The columnar member 100 is particularly suitable for application to the front side members 116a and 116b or the rear side members 117a and 117b among the members constituting the vehicle body floor 110. The columnar member 100 may be applied to other components of the vehicle body floor 110 shown in FIG. 1, such as the floor cross members 114a to 114f or the side sill 120. Further, the columnar member 100 may be applied to components other than the vehicle body floor 110 such as the center pillar, the A pillar, and the B pillar of the vehicle.

As shown in FIG. 3, the columnar member 100 has a hat-shaped member 10 and a plate-shaped member 30. The hat-shaped member 10 and the plate-shaped member 30 are formed of, for example, a steel plate.

The hat-shaped member 10 includes a flat plate-shaped upper wall 12 extending along a linear main axis Om, and vertical walls 14 and 16 extending along both side edges 12a and 12b of the upper wall 12, respectively. It includes flanges 18 and 20 extending along the opposite edges 14a and 16a of the vertical walls 14 and 16.

A bending-inducing portion 22 is formed on the upper wall 12 of the hat-shaped member 10. Further, a bead portion 14b is formed on the vertical wall 14. Similarly, a bead portion 16b is formed on the vertical wall 16. The bending inducing portion 22 and the bead portions 14b and 16b are formed at the same position in the direction along the main axis Om.

FIG. 4 is a cross-sectional view showing a cross section (cross section) cut in a plane perpendicular to the longitudinal direction, which is the direction of the main axis Om of the columnar member 100, at the position of the bending inducing portion 22. More specifically, FIG. 4 shows a cross section along the alternate long and short dash line II-II'shown in FIG. 3, and at the positions of the bead portions 14b and 16b described later, along the longitudinal direction of the bead portions 14b and 16b. The cross section is shown. As shown in FIG. 4, the cross section of the hat-shaped member 10 is substantially hat-shaped. The plate-shaped member 30 is joined to the flange portions 18 and 20 of the hat-shaped member 10 by spot welding, line welding, or the like.

The bending-inducing portion 22 is composed of a bending-inducing bead (recess) in which the front side (upper side of the upper wall 12 in FIG. 1) of the upper wall 12 is concave. The bending-inducing portion 22 is formed by pressing a steel plate which is a base material of the hat-shaped member 10. The bending-inducing portion 22 may be formed at the same time as the forming of the hat-shaped member 10 at the time of press working in which the steel plate is bent and the hat-shaped member 10 is press-formed.

The front side members 116a, 116b or the rear side members 117a, 117b constituting the vehicle body floor 110 receive a large impact force in the vehicle length direction and are compressed and deformed when an automobile collides. When the columnar member 100 is applied to the front side members 116a, 116b or the rear side members 117a, 117b, when a large impact force is applied in the vehicle length direction due to a collision, a compression load is applied in the direction of the main axis Om of the columnar member 100. The columnar member 100 is bent and deformed. The energy of the collision is absorbed by the bending deformation of the columnar member 100.

The bending-inducing portion 22 is formed to provide a portion easily broken in the columnar member 100, and becomes a starting point of bending of the columnar member 100 when the columnar member 100 receives a compression load in the direction of the main axis Om. As a result, when a compression load is applied to the columnar member 100, the columnar member 100 is bent and deformed in a predetermined deformation mode assumed in advance. Therefore, when a compression load is applied to the columnar member 100, the columnar member 100 is suppressed from being unexpectedly deformed, and safety is ensured.

The bead portions 14b and 16b are formed so that the front side of the vertical walls 14 and 16 is convex, and protrudes more convexly than the surfaces of the surrounding vertical walls 14 and 16. Further, the planar shape of the bead portion 14b is a V-shape, and the shape is such that the bead portion 14b expands toward the bending-inducing portion 22.

The bead portions 14b and 16b are formed by pressing a steel plate which is a base material of the hat-shaped member 10. Since the bead portion 14b is formed by stamping a steel plate from the back side by press working, the back side of the bead portions 14b and 16b is a recess when viewed from the back side of the vertical walls 14 and 16. The bead portions 14b and 16b may be formed at the same time as the formation of the hat-shaped member 10 at the time of press working in which the steel plate is bent and the hat-shaped member 10 is press-formed.

By providing the bending-inducing portion 22, when a compression load is applied to the columnar member 100 in the direction of the main axis Om, bending deformation occurs in the columnar member 100 at the position of the bending-inducing portion 22, and the position of the bending-inducing portion 22 The columnar member 100 bends at. The reaction force in the direction of the main axis Om of the columnar member 100 when a compression load is applied increases until the columnar member 100 bends due to bending deformation, and decreases when the columnar member 100 bends.

When the columnar member 100 bends, a groove-shaped recess in the direction orthogonal to the main axis Om is formed on the upper wall 12 at the position of the bending inducing portion 22. As the deformation of the columnar member 100 progresses and the bending becomes larger, the width of the groove-shaped dent becomes narrower, and the distance between the inner walls facing the groove-shaped dent becomes shorter. Then, when the inner walls facing the groove-shaped dents collide with each other, the columnar member 100 temporarily stops bending, and the reduced reaction force starts to increase.

The bead portions 14b and 16b provided on the vertical wall 14.16 gradually generate groove-shaped dents in the process of bending and deforming the columnar member 100, and the groove-shaped dents face each other at an early stage of bending deformation. It is provided so as to collide with the inner wall and increase the reaction force from the early stage of bending deformation. By providing the bead portions 14b and 16b, after the columnar member 100 is bent and deformed at the position of the bending inducing portion 22, the inner walls facing each other of the groove-shaped dents collide stepwise, so that the reaction force is reduced. It is suppressed and the amount of collision energy absorbed increases.

In order to explain the difference in reaction force depending on the presence or absence of the bead portions 14b and 16b, the present invention relates to the columnar member 102 of the base member model in which the bead portions 14b and 16b are not provided and the present embodiment in which the bead portions 14b and 16b are provided. This will be described in comparison with the columnar member 100. FIG. 5 is a perspective view showing the configuration of the columnar member 102 of the base member model in which the bead portions 14b and 16b are not provided. The structure of the columnar member 102 shown in FIG. 5 is the same as that of the columnar member 100 according to the present embodiment shown in FIG. 3, except that the bead portions 14b and 16b are not provided.

6A to 6C show a state in which the columnar member 102 of the base member model is viewed from the side surface, and when a compression load is applied to the columnar member 102 in the direction of the main axis Om, the columnar member 102 is bent and deformed. It is a schematic diagram which shows the progress in time series. In FIGS. 6A to 6C, the position of the alternate long and short dash line indicates the position of the bending-inducing portion 22.

FIG. 6A shows a jig 40 for applying a compression load to the columnar member 102. In order to analyze how the bending deformation progresses in the columnar member 102, the rotation axis is inserted into the holes 42 of the jig 40 at both ends of the columnar member 102, and the deformation when the rotation axes are brought close to each other is analyzed.

FIG. 6A shows a state in which a compression load is started to be applied in the longitudinal direction of the columnar member 102. In this state, the columnar member 102 is not yet bent.

Next, as shown in FIG. 6B, when the rotation axes inserted into the holes 42 approach each other, a compression load is applied in the longitudinal direction of the columnar member 102, and the columnar member 102 begins to bend at the position of the bending inducing portion 22. , Wrinkle-shaped bulges 14c and 16c are formed on the vertical walls 14 and 16, and dents 13a are formed on the upper wall 12 at the position of the bending inducing portion 22.

Next, as shown in FIG. 6C, when the rotation axis inserted into the hole 42 gets closer, the columnar member 102 further bends and the recess 13a becomes groove-shaped. The timing shown in FIG. 6C is the timing when T has elapsed from FIG. 6A for a certain period of time. When the columnar member 102 is further bent from the state shown in FIG. 6C, the inner walls facing each other of the groove-shaped recesses 13a collide with each other.

FIG. 7 is a schematic view showing a state in which the vicinity of the bending-inducing portion 22 of the upper wall 12 of the columnar member 102 is viewed from above at the timing shown in FIG. 6C. As shown in FIG. 7, a groove-shaped recess 13a having a width d2 is formed on the upper wall 12. When the columnar member 102 is further bent after the state shown in FIG. 7, the inner walls 13b of the groove-shaped recesses 13a facing each other collide with each other.

When a compression load is applied to the columnar member 100 of the present embodiment provided with the bead portions 14b and 16b under the same conditions as those in FIGS. 6A to 6C, the columnar member 100 basically becomes the columnar member 102 of the base member model. It bends and deforms in the same way as. However, in the columnar member 100 of the present embodiment, due to the action of the bead portions 14b and 16b, the inner walls facing the groove-shaped dents collide with each other at an early stage of bending deformation, so that the decrease in reaction force is suppressed.

FIG. 8 is the same as FIG. 6C when a compression load is applied to the columnar member 100 of the present embodiment in which the bead portions 14b and 16b are provided on the vertical walls 14 and 16 under the same conditions as those in FIGS. 6A to 6C. It is a schematic diagram which shows the state which looked at the vicinity of the bending induction part 22 of the upper wall 12 of a columnar member 100 from the top at the timing (after the elapse of a certain time T from the start of applying a compression load).

In the columnar member 100 of the present embodiment, when the columnar member 100 starts to bend at the position of the bending inducing portion 22, the bead portions 14b and 16b are formed, so that the vertical walls 14 and 16 are easily deformed to the outside. .. Therefore, the vertical walls 14 and 16 have bulges 14d and 16d, and the upper wall 12 has dents 13d at an earlier stage than the columnar member 102 of the base member model.

More specifically, the bead portions 14b and 16b are provided at expected positions where the bulges 14d and 16d are formed along the contour where the bulges 14d and 16d are formed. If the bead portions 14b and 16b are provided in advance at the positions where the bulges 14d and 16d are formed, buckling occurs at the positions of the two bead portions 14b and 16b when the columnar member 100 is bent. As shown by the two-dot chain line E2 in 8, acute-angled bulges 14d and 16d are formed on the vertical walls 14 and 16, and the formation of the bulges 14d and 16d on the vertical walls 14 and 16 is promoted. On the other hand, as shown in FIG. 7, in the columnar member 102 of the base member model, buckling by the bead portions 14b and 16b does not occur, so that the bulges 14c and 16c are arcuate as shown by the alternate long and short dash line E1. The bulges 14c and 16c do not occur as significantly as the columnar member 100 of the embodiment. Therefore, in the columnar member 100 of the present embodiment, the vertical walls 14 and 16 are bulged 14d and 16d earlier than the columnar member 102 of the base member model, and the dent 13d is formed in the upper wall 12 earlier.

Therefore, as shown in FIGS. 7 and 8, the width d1 of the groove-shaped recess 13d formed in the upper wall 12 of the columnar member 100 of the present embodiment is formed in the columnar member 102 of the base member model at the same timing. It becomes narrower than the width of the groove-shaped recess 13a to be formed. Therefore, when the bead portions 14b and 16b are provided, the inner walls 13e facing the groove-shaped recesses 13d collide at an earlier stage than when the bead portions 14b and 16b are not provided.

FIG. 9 shows the stroke (horizontal axis) and reaction force (vertical axis) when a compression load is applied to the columnar member 100 and the columnar member 102 of the base member model according to the present embodiment in the direction of the main axis Om. It is a characteristic diagram which shows the relationship of. In FIG. 9, the characteristic C1 shown by the solid line shows the characteristics of the stroke and the reaction force in the columnar member 100 of the present embodiment in which the bead portions 14b and 16b are provided on the vertical walls 14 and 16. Further, the characteristic C2 shown by the broken line indicates the characteristics of the stroke and the reaction force in the columnar member 102 of the base member model.

Further, FIGS. 10A and 10B, and FIGS. 11A to 11C show the bending deformation states of the columnar members 100 and 102 at the respective timings of the strokes S1, S2 and S3 in the stroke and reaction force characteristics shown in FIG. It is a figure which shows. 10A and 10B show the bending deformation state of the columnar member 100 of the present embodiment. 11A to 11C show the bending deformation state of the columnar member 102 of the base member model. 10A and 10B, and FIGS. 11A to 11C show a state in which the columnar member 100 is broken along the alternate long and short dash line I-I'shown in FIGS. 3 and 5.

10A and 11A show the bending deformation state of the columnar members 100 and 102 at the timing of the stroke S1 shown in FIG. Further, FIGS. 10B and 11B show the bending deformation state of the columnar members 100 and 102 at the timing of the stroke S2 shown in FIG. Further, FIG. 11C shows a state of bending deformation of the columnar member 102 at the timing of the stroke S3 shown in FIG.

As shown in FIG. 9, when a compressive load is applied to the columnar members 100 and 102 in the direction of the main axis Om, the reaction force increases as the stroke increases until the stroke reaches S0. When the stroke reaches S0, the columnar members 100 and 102 bend at the position of the bending inducing portion 22.

After the stroke S0, the bending deformation of the columnar member 100 progresses, and the reaction force decreases as the stroke increases. Further, in the columnar member 100 of the present embodiment, a groove-shaped recess 13d is formed in the upper wall 12, and in the columnar member 102 of the base member model, a groove-shaped recess 13a is formed in the upper wall 12. Until the stroke reaches S1, there is no significant difference between characteristic C1 and characteristic C2.

When the stroke reaches S1, in the columnar member 100 of the present embodiment, as shown in FIG. 10A, the inner walls 13e facing the groove-shaped recesses 13d collide with each other (first collision). As a result, in the solid line characteristic C1 shown in FIG. 9, the reaction force temporarily increases after the stroke S1. After that, the reaction force of the characteristic C1 gradually decreases until the stroke S2.

On the other hand, in the columnar member 100 of the base member model, as shown in FIG. 11A, even if the stroke reaches S1, the inner walls 13b facing each other of the groove-shaped recesses 13a do not collide, and the inner walls 13b facing each other do not collide with each other. There is a large space. Therefore, in the characteristic C2 of the broken line shown in FIG. 9, the reaction force continues to decrease even after the stroke S1.

When the stroke reaches S2, in the columnar member 100 of the present embodiment, as shown in FIG. 10B, the inner wall 13e facing the groove-shaped recess 13d collides again on the inner wall 13e that collided with the stroke S1 (second). collision). As a result, in the solid line characteristic C1 shown in FIG. 9, the reaction force temporarily increases after the stroke S2. After that, the reaction force of the characteristic C1 becomes a substantially constant value even if the stroke increases.

On the other hand, in the columnar member 102 of the base member model, as shown in FIG. 11B, even when the stroke reaches S2, the facing inner walls 13b of the groove-shaped recesses 13a still do not collide, and there is a space between the facing inner walls 13b. Exists. Therefore, in the characteristic C2 of the broken line shown in FIG. 9, the reaction force continues to decrease even after the stroke S2.

When the stroke reaches S3, in the columnar member 102 of the base member model, as shown in FIG. 11C, the inner walls 13b facing the groove-shaped recesses 13a finally collide with each other. As a result, in the characteristic C2 of the broken line shown in FIG. 8, the reaction force increases after the stroke S3, and thereafter, the reaction force becomes a substantially constant value even if the stroke increases, as in the characteristic C1 of the solid line.

As described above, in the characteristic C1 of the columnar member 100 according to the present embodiment, the inner wall 13e collides twice in total at the timing of the stroke S1 and the stroke S2, so that the decrease in the reaction force after the stroke S1 is suppressed. .. As a result, a large reaction force can be generated with a small stroke, so that energy can be absorbed at the time of a collision in a smaller space.

On the other hand, in the columnar member 102 of the base member model, since the inner walls 13b facing each other do not collide until the stroke S3 is reached, the reaction force continues to decrease until the inner walls 13b collide. Therefore, in the columnar member 102 of the base member model, the reaction force generated at the same stroke is further reduced as compared with the columnar member 100 of the present embodiment, and the same collision energy as that of the columnar member 100 of the present embodiment is absorbed. More space is needed.

The area of the region surrounded by the characteristic C1 or the characteristic C2 and the horizontal axis indicates the magnitude of the collision energy absorbed by the columnar member 100 being bent and deformed. According to the characteristic C1 of the columnar member 100 of the present embodiment in which the bead portions 14b and 16b are provided on the vertical walls 14 and 16, the columnar columns of the base member model in which the bead portions 14b and 16b are not provided on the vertical walls 14 and 16. Compared to the characteristic C2 of the member 102, a larger collision energy is absorbed by the area indicated by the hatching.

In the above-described embodiment, the bead portions 14b and 16b are convex toward the outside of the vertical wall 14, but the bead portions 14b and 16b are convex toward the inside of the vertical wall 14. There may be.

Further, in the above-described embodiment, the bending-inducing portion 22 made of a concave bead is shown, but the bending-inducing portion 22 may be a portion that is the starting point of bending of the columnar member 100, and is provided on the upper wall 12. It may be composed of a convex portion, a hole, or a change point of the curvature of the columnar member 100. Further, the bending-inducing portion 22 may be composed of a portion where the material strength of the columnar member 100 is locally reduced.

For example, FIG. 18 is a perspective view showing an example in which the bending inducing portion 22 is composed of a hole provided in the upper wall 12. Further, FIG. 19 is a perspective view showing an example in which the bending inducing portion 22 is composed of four concave beads extending in the direction of the main axis Om. The flexural rigidity of the columnar member 100 is determined by the shape of the cross section orthogonal to the main axis Om. Bending deformation is likely to occur at the change point of the moment of inertia of area, and in both the examples of FIGS. 18 and 19, the provision of the bending inducing portion 22 causes the moment of inertia of area of the cross section orthogonal to the main axis Om to bend. Since it changes depending on the position of the induced portion 22, the bent induced portion 22 becomes the starting point of bending when a compression load is applied in the direction of the main axis Om of the columnar member 100. FIG. 18 is an example in which the moment of inertia of area changes high in the bending-inducing portion 22, and FIG. 19 shows an example in which the moment of inertia of area changes low in the bending-inducing portion 22.

Further, in the above-described embodiment, the example in which the bending-inducing portion 22 is provided on the upper wall 12 is shown, but the bending-inducing portion 22 may be provided on the plate-shaped member 30 on the opposite side of the upper wall 12. .. In this case, the bead portions 14b and 16b have an inverted V shape that spreads toward the bending-inducing portion 22 provided on the plate-shaped member 30.

Further, in the above-described embodiment, the columnar member 100 is composed of the hat-shaped member 10 and the plate-shaped member 30, but the columnar member 100 may be composed of two hat-shaped members. FIG. 20 is a schematic view showing an example in which the columnar member 100 is composed of the hat-shaped member 10 and the hat-shaped member 50, and shows a cross section along a direction orthogonal to the direction of the main axis Om of the columnar member 100. It is a schematic diagram which shows. In the columnar member 100 shown in FIG. 20, the flange portions 52 and 54 of the plate-shaped member 50 are joined to the flange portions 18 and 20 of the hat-shaped member 10 by spot welding, line welding, or the like. The upper wall 56 of the plate-shaped member 50 may be located on the hat-shaped member 10 side, or may be located on the opposite side of the hat-shaped member 10. Note that FIG. 20 shows a cross section at a position where no recess or hole is provided in the direction of the main axis Om.

As described above, according to the present embodiment, the bead portions 14b and 16b are provided on the vertical wall 14 at the position of the bending inducing portion 22, and the shapes of the bead portions 14b and 16b are made to expand toward the bending inducing portion 22. As a result, when a compression load is applied to the columnar member 100, a decrease in reaction force due to bending deformation is suppressed. This improves the impact absorption performance of the columnar member 100 without increasing the weight.

Hereinafter, specific examples of this embodiment will be described.

The columnar member 100 is a structure in which a hat-shaped member 10 including a bending-inducing portion 22 and bead portions 14b and 16b and a plate-shaped member 30 are spot-welded at flange portions 18 and 20. The hat-shaped member 10 was made of a steel plate having a tensile strength of 1180 MPa and having a plate thickness of 1.6 mm, and the plate-shaped member 30 was made of a steel plate having a tensile strength of 980 MPa and having a plate thickness of 1.2 mm.

The point welding pitch was 30 mm, and the welding diameter of spot welding was 6 mm. The member length (L1 shown in FIG. 6A) is 340 mm, the height of the hat-shaped member 10 (H shown in FIG. 4) is 72 mm, and the width of the plate-shaped member 30 (W shown in FIG. 4) is 160 mm. It is common to the columnar member 100 and the columnar member 102 of the base member model.

As a result of diligent studies by the present inventors, the reaction force and the amount of energy absorption with respect to the base member model may differ depending on the shapes of the bead portions 14b and 16b and the angles of the vertical walls 14 and 16 (θ shown in FIG. 4). found.

FIG. 12 is a schematic view showing in detail the bead portion 14b provided on the vertical wall 14. Further, FIG. 13 is a schematic view showing the bead portion 14b in detail when the columnar member 100 is viewed from the direction of the main axis Om. In FIGS. 12 and 13, h1 indicates the distance from the surface of the upper wall 12 to the lower end of the R portion 15 formed at the boundary between the upper wall 12 and the vertical walls 14 and 16. The positions of the upper ends of the bead portions 14b and 16b substantially coincide with the positions of the lower ends of the R portion 15 which is the distance from the upper wall 12 to h1. In FIG. 12, the shape of the bead portion 16b is determined by the length I [mm] and the height h [mm] in the direction of the main axis Om. If the bead portion 14b protrudes from the surface of the vertical wall 14 as much as possible, the above-mentioned effect can be obtained. Preferably, the amount s of the bead portion 14b protruding from the surface of the vertical wall 14 shown in FIG. 13 is equal to or larger than the plate thickness of the hat-shaped member 10.

(Relationship between the shape of the bead and the reaction force)
First, the results of examining the relationship between the variation in the shapes of the bead portions 14b and 16b according to the length I and the height h and the reaction force are shown. The reaction force with the columnar member 100 of the example of the present invention shown in FIG. 3 is based on the columnar member 102 of the base member model in which the bending inducing portion 22 is formed in the center of the longitudinal direction of the web surface as shown in FIG. The comparison was carried out by CAE.

In the examination of the reaction force, a plurality of variations were prepared for the length I [mm] of the bead portions 14b and 16b in the direction of the main axis Om and the height h [mm] of the bead portions 14b and 16b shown in FIG. For each of the size variations of the portions 14b and 16b, the same characteristics as in FIG. 9 showing the relationship between the stroke and the reaction force were obtained.

At this time, similarly to FIG. 6A, the deformation when the rotation axes inserted into the holes 42 of the jig 40 at both ends of the columnar member 102 were brought close to each other was analyzed. In FIG. 6A, the width direction of the columnar member 102 is the axis with respect to the hole 42 provided at the position of L2 = 67 mm from the end in the longitudinal direction of the columnar member 102 and L3 = 15 mm from the upper wall 12 in the height direction. The rotating shafts were inserted, and forced displacement was applied by bringing these rotating shafts closer to each other at a speed of 500 mm / s, and bending deformation of the columnar members 100 and 102 was analyzed.

FIG. 14 is a characteristic diagram showing the relationship between the stroke and the reaction force for each variation of the shapes of the bead portions 14b and 16b. As variations in the shapes of the bead portions 14b and 16b, a plurality of those having different lengths I [mm] and height h [mm] in the direction of the main axis Om are prepared, and the stroke and reaction force characteristics C1 to those shown in FIG. 14 are prepared. C4 was measured. In the characteristics C1 to C4, the ratios of the length I [mm] and the height h [mm] to the height H are as follows. The characteristics C1 and C2 shown in FIG. 14 are the same as the characteristics C1 and C2 shown in FIG.

As shown in FIG. 14, in the comparison with the base member model (characteristic C2), the reaction force of the characteristic C1 was the largest, followed by the characteristic C3 and the characteristic C4 in that order.

(Energy absorption)
Further, forced displacement is applied to the columnar member 100 under the same conditions as described above, and the relationship between the sizes (length I, height h) of the bead portions 14b and 16b and the energy absorption performance of the columnar member 100 is determined by the energy in the base member model. It was examined by comparing with the amount of absorption. Further, the relationship between the angles θ of the vertical walls 14 and 16 of the columnar member 100 and the energy absorption performance was also derived in the same manner.

Similar to the above, the sizes of the bead portions 14b and 16b are expressed by the ratio of the vertical walls 14 and 16 to the height H, and the ratios of the length I and the height h are 0.1, 0.2 and 0.25, respectively. , 0.33, 0.4, 0.5, 0.75, 1.0 variations were prepared. There were four types of vertical wall angle variations: 50 [deg], 60 [deg], 70 [deg], and 80 [deg].

When the length I was examined, the ratio of the height h to the height H was set to 0.33, and the vertical wall angle was set to 80 [deg]. When considering the height h, the ratio of the length I to the height H was set to 0.33, and the vertical wall angle was set to 80 [deg]. When examining the vertical wall angle, the ratio of the height h to the height H was set to 0.33, and the ratio of the length I to the height H was set to 0.33. Each level is shown in Table 2 below.

The examination results are shown in FIGS. 15A to 15C. In FIGS. 15A to 15C, the vertical axis shows the ratio of the energy absorption amount of the columnar member 100 to be examined (energy absorption amount ratio) to the energy absorption amount in the base member model. When this ratio is larger than 1, the amount of energy absorbed is larger than that of the base member model.

FIG. 15A shows the relationship between the length I of the bead portions 14b and 16b and the energy absorption amount ratio. In FIG. 15A, the horizontal axis indicates the ratio I / H of the length I [mm] to the height H. As shown in FIG. 15A, when the I / H was less than 0.5, the energy absorption ratio to the base member was larger than 1.

FIG. 15B shows the relationship between the height h of the bead portions 14b and 16b and the energy absorption amount ratio. In FIG. 15A, the horizontal axis indicates the ratio h / H of the height h [mm] to the height H. As shown in FIG. 15B, when h / H was less than 0.75, the energy absorption ratio with respect to the base member was larger than 1.

FIG. 15C shows the relationship between the vertical wall angle and the energy absorption ratio. In FIG. 15C, the horizontal axis indicates the vertical wall angle. As shown in FIG. 15C, when the vertical wall angle exceeded 50 [deg], the energy absorption ratio with respect to the base member model was larger than 1.

In addition, in FIGS. 15A and 15B, the data of the energy absorption amount ratio when the ratio (I / H, h / H) on the horizontal axis is 0.0 is the data of the base member not provided with the bead portions 14b and 16b. The result of is shown.

(Distance from R part to the upper end of bead part)
When the columnar member 100 receives a compressive load in the direction of the main axis Om, a relatively large reaction force is generated in the R portion 15. Therefore, when the bead portions 14b and 16b penetrate to the R portion 15, the reaction force generated in the R portion 15 decreases, and the collision energy absorption capacity of the columnar member 100 decreases. Therefore, it is preferable that the upper ends of the bead portions 14b and 16b are located below the R portion 15.

More preferably, the positions of the upper ends of the bead portions 14b and 16b coincide with the positions of the lower ends of the R portion 15 which is the distance from the upper wall 12 to h1. According to this configuration, when a compressive load is applied to the columnar member 100, a large reaction force can be generated in the R portion 15 and the inner walls 13e facing the recesses 13d can be collided at an early stage.

On the other hand, even when the position of the upper end of the bead portions 14b and 16b is located below the position of the lower end of the R portion 15, it is possible to increase the reaction force against the base member model.

FIG. 16 is a schematic view showing in detail the bead portion 14b provided on the vertical wall 14, as in FIG. 12, between the positions of the upper ends of the bead portions 14b and 16b and the positions of the lower ends of the R portion 15. An example in which an interval s is provided is shown.

FIG. 17 is a characteristic diagram showing the relationship between the stroke and the reaction force of the columnar members 100 and 102 as in FIG. 14, and the interval s shown in FIG. 16 is set to 5 mm together with the characteristics C1 and C2 of FIG. The characteristic C5 in the columnar member 100 is shown.

As shown in FIG. 17, the characteristic C5 of the columnar member 100 having a gap of 5 mm between the positions of the upper ends of the bead portions 14b and 16b and the positions of the lower ends of the R portion 15 has a reaction force higher than that of the characteristic C1. Although it decreases, the reaction force greatly exceeds the characteristic C2 of the base member model. Therefore, as shown in FIG. 16, a gap s may be provided between the positions of the upper ends of the bead portions 14b and 16b and the positions of the lower ends of the R portion 15. In this case, since the positions of the upper ends of the bead portions 14b and 16b and the positions of the lower ends of the R portion 15 do not necessarily match, the degree of freedom in designing the bead portions 14b and 16b is increased and the manufacturing cost is reduced. Is expected.

10,50 Hat-shaped member 12,56 Upper wall 12a Side edge 13a, 13d Indentation 13b, 13e Inner wall 14 Vertical wall 14a, 16a Edge 14b, 16b Bead 15 R 16 Vertical wall 18, 20, 52, 54 Flange Part 22 Bending-inducing part 30 Plate-shaped member 40 Jig 42 Hole 100, 102 Columnar member 110 Body floor

Claims (7)

The upper wall extending along the main axis and
A vertical wall extending along both side edges of the upper wall,
A flange portion extending along the edge of the vertical wall opposite to the upper wall, and a flange portion.
A columnar member comprising a hat-shaped member having a substantially hat-shaped cross section perpendicular to the main axis.
A bending-inducing portion provided on the upper wall and serving as a starting point for bending of the columnar member when a compression load is applied in the direction of the main axis.
On the vertical wall, a bead portion provided at a position corresponding to the bending-inducing portion in the direction of the main axis and having a shape extending toward the bending-inducing portion, and a bead portion.
A columnar member having. The columnar member according to claim 1, wherein the bead portion projects to the outside of the vertical wall. The columnar member according to claim 2, wherein the length of the bead portion in the direction along the main axis is less than 0.5 times the height of the vertical wall. The columnar member according to claim 2 or 3, wherein the height of the bead portion is less than 0.75 times the height of the vertical wall. The columnar member according to any one of claims 1 to 4, wherein the position of the upper end of the bead portion is located below the R portion connecting the upper wall and the vertical wall. The columnar member according to any one of claims 1 to 5, wherein the bending-inducing portion is provided on the upper wall and is composed of recesses or holes extending in a direction orthogonal to the main axis. The columnar member according to any one of claims 1 to 6, which constitutes the front side member or the rear side member of the vehicle.

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