JP7568928B2 - Shock absorbing materials - Google Patents

Description

This disclosure relates to shock absorbing components for vehicle bodies.

Conventionally, a monocoque structure has been widely adopted as the body structure of an automobile. A monocoque body is formed by connecting multiple structural members. The structural members include, for example, bumper reinforcement, front side members, rear side members, crash boxes, pillars, side sills, cross members, floor panels, roof panels, etc. Each structural member functions as an impact absorbing member that absorbs impact when an automobile crashes, either alone or in combination with other structural members.

Patent Document 1 discloses an impact absorbing member having a side sill extending in the vehicle length direction and a cross member extending in the vehicle width direction and connected to the side sill. The side sill, for example, bends and deforms when a collision load is input from the side, to absorb collision energy. The side sill in Patent Document 1 is hollow and has a substantially rectangular cross section. The side sill has multiple lateral ribs that connect the outer side wall and the inner side wall in the vehicle width direction. At least one of these lateral ribs is provided so as to be continuous with the upper surface of the cross member when viewed from the longitudinal direction of the side sill. The side sill further has multiple vertical ribs that connect any of the multiple lateral ribs to the upper wall or the lower wall.

The side sill in Patent Document 1 has a constant cross-sectional shape over its entire length. Therefore, when a collision load is input to the side sill, the side sill cannot bend and deform at the desired location.

In response to this, Patent Document 2 proposes an impact absorbing member capable of controlling the bending deformation mode. Patent Document 2 discloses a rear side member disposed on a floor panel as an example of an impact absorbing member. The rear side member in Patent Document 2 includes a top plate, a pair of vertical walls protruding downward from both side edges of the top plate, and a pair of flanges protruding outward from the lower ends of these vertical walls. A recess extending in the up-down direction is formed in each vertical wall. The recess in one vertical wall is disposed away from the recess in the other vertical wall in the longitudinal direction of the rear side member. According to Patent Document 2, when a collision load is input to the rear side member in the longitudinal direction, bending deformation originating from the recess occurs stably in the rear side member, and the collision energy can be efficiently absorbed.

JP 2018-192871 A JP 2016-199187 A

Impact absorbing components are required to have excellent impact energy absorption performance. When incorporating a means for controlling the bending deformation mode into an impact absorbing component, it is preferable to minimize the effect on the rigidity of the entire vehicle body.

The objective of this disclosure is to provide an impact absorbing member that can improve collision energy absorption performance while minimizing the impact on the rigidity of the entire vehicle body.

The impact absorbing member according to the present disclosure is an impact absorbing member for a vehicle body. The impact absorbing member includes a first structural member and a reinforcing member. The first structural member includes a pair of first vertical walls, a first top plate, and a pair of first ridges. The pair of first vertical walls face each other. The first top plate connects the edges of the first vertical walls. The pair of first ridges constitute a corner between the first vertical walls and the first top plate. The reinforcing member includes a pair of second vertical walls, a second top plate, and a pair of second ridges. The pair of second vertical walls are disposed along the first vertical walls on the inside of the first structural member. The second top plate faces the first top plate on the inside of the first structural member. The second top plate connects the edges of the second vertical walls. The pair of second ridges constitute a corner between the second vertical walls and the second top plate. The reinforcing member is joined to the first structural member. One side of the second ridge line has a first recess. The first recess is provided so as to recess a portion of the second ridge line into the inside of the reinforcing member. The first recess reaches partway into each of the one side of the second vertical wall and the second top plate. The other side of the second ridge line has a second recess. The second recess is provided so as to recess a portion of the second ridge line into the inside of the reinforcing member. The second recess is disposed at a position opposite the first recess. The second recess reaches partway into each of the other side of the second vertical wall and the second top plate.

The impact absorbing member disclosed herein can improve the collision energy absorption performance while minimizing the impact on the rigidity of the entire vehicle body.

FIG. 1 is a perspective view that illustrates a shock absorbing member according to an embodiment. FIG. 2 is a cross-sectional view of the impact absorbing member shown in FIG. 1 taken along line II-II. FIG. 3 is a view of the structural members and reinforcing members included in the impact absorbing member shown in FIG. 1 as viewed from the top plate side. FIG. 4 is a cross-sectional view of the impact absorbing member shown in FIG. 1 taken along line IV-IV. FIG. 5 is a diagram showing another example of the cross section of the impact absorbing member shown in FIG. FIG. 6 is a diagram showing another example of the cross section of the impact absorbing member shown in FIG. FIG. 7 is a diagram showing another example of the cross section of the impact absorbing member shown in FIG. FIG. 8 is a diagram showing another example of the cross section of the impact absorbing member shown in FIG. FIG. 9 is a diagram showing another example of the cross section of the impact absorbing member shown in FIG. FIG. 10 is a diagram showing a schematic state in which structural members are connected to each other in the impact absorbing member according to the embodiment. FIG. 11 is a perspective view that shows a schematic diagram of a modified example of the reinforcing member included in the impact absorbing member according to the embodiment. FIG. 12 is a perspective view that illustrates a shock absorbing member used as Comparative Example 1 in an analysis of an offset frontal collision of an automobile. FIG. 13 is a perspective view that illustrates a shock absorbing member used as Comparative Example 2 in an analysis of an offset frontal collision of an automobile. FIG. 14 is a graph showing the relationship between the vehicle stroke (intrusion amount) and the amount of absorbed energy for Comparative Example 1 and Example 3 in an offset frontal collision analysis of an automobile.

The impact absorbing member according to the embodiment is an impact absorbing member for a vehicle body. The impact absorbing member includes a first structural member and a reinforcing member. The first structural member includes a pair of first vertical walls, a first top plate, and a pair of first ridges. The pair of first vertical walls face each other. The first top plate connects the edges of the first vertical walls. The pair of first ridges form corners between the first vertical walls and the first top plate. The reinforcing member includes a pair of second vertical walls, a second top plate, and a pair of second ridges. The pair of second vertical walls are arranged along the first vertical walls on the inside of the first structural member. The second top plate faces the first top plate on the inside of the first structural member. The second top plate connects the edges of the second vertical walls. The pair of second ridges form corners between the second vertical walls and the second top plate. The reinforcing member is joined to the first structural member. One side of the second ridge line has a first recess. The first recess is provided so as to recess a portion of the second ridge line into the inside of the reinforcing member. The first recess reaches partway into one of the second vertical walls and the second top plate. The other side of the second ridge line has a second recess. The second recess is provided so as to recess a portion of the second ridge line into the inside of the reinforcing member. The second recess is disposed at a position opposite the first recess. The second recess reaches partway into the other of the second vertical wall and the second top plate (first configuration).

In the impact absorbing member according to the first configuration, at least a portion of the first structural member is reinforced from the inside by a reinforcing member, increasing its rigidity. Therefore, for example, when a collision load is input to the impact absorbing member in its longitudinal direction, deformation of the first structural member can be suppressed. This improves the impact energy absorption performance of the impact absorbing member.

In the first configuration, the reinforcing member improves the impact energy absorption performance of the impact absorbing member. Therefore, for example, when a collision load is input to the impact absorbing member in its longitudinal direction, the amount by which the impact absorbing member intrudes into the inside of the vehicle (vehicle intrusion amount) is reduced. This makes it possible to shorten the length of the impact absorbing member, which is determined according to the vehicle intrusion amount. As a result, it is possible to reduce the weight of the impact absorbing member and the vehicle body in which the impact absorbing member is used.

In the first configuration, in the reinforcing member disposed inside the first structural member, recesses are formed in the second ridges that form the corners between the second vertical wall and the second top plate, reaching halfway through the second vertical wall and halfway through the second top plate. Therefore, for example, when a collision load is input to the impact absorbing member in its longitudinal direction and deformation occurs in the first structural member, the first structural member can be bent starting from these recesses. In other words, the bending deformation mode of the first structural member can be controlled.

In the shock absorbing member according to the first configuration, the first structural member is usually connected to other structural members to form the vehicle body. On the other hand, the reinforcing member is a member for reinforcing the first structural member, and is not connected to other structural members. A recess, which is a means for controlling the bending deformation mode, is provided in this reinforcing member. Therefore, when a force such as bending or twisting is input to the vehicle body, the recess does not impede the transmission of force between the structural members. Therefore, the recess does not substantially affect the rigidity of the entire vehicle body.

The shock absorbing member may further include a second structural member. The second structural member is arranged in series with the first structural member and is connected to the first structural member. The second structural member preferably includes a cylindrical member body and a rib. The member body extends in the arrangement direction of the first structural member and the second structural member. The rib is provided within the member body. The rib traverses the space within the member body and extends in the axial direction of the member body (second configuration).

According to the second configuration, the second structural member is connected in series to the first structural member. The rigidity of the second structural member is increased by ribs provided in the member body. This makes it possible to suppress deformation of the second structural member in an unintended deformation mode. Therefore, for example, when a collision load is input from the second structural member side to the impact absorbing member, the second structural member can be stably crushed in the axial direction of the member body. On the other hand, the first structural member is at least partially reinforced by incorporating a reinforcing member. Therefore, after the second structural member is crushed, the first structural member can be bent and deformed. At this time, bending deformation of the first structural member can be caused starting from a recess provided in the second ridge portion of the reinforcing member.

In the second structural member, a groove may be formed in the peripheral wall of the member body. The groove, for example, has a concave shape toward the inside of the member body and extends in the axial direction of the member body (third configuration).

According to the third configuration, the second structural member is connected in series to the first structural member. The rigidity of the second structural member is increased by a groove provided in the peripheral wall of the member body. In this case, it is also possible to suppress deformation of the second structural member in an unintended deformation mode. Therefore, for example, when a collision load is input from the second structural member side to the impact absorbing member, the second structural member can be stably crushed in the axial direction of the member body. On the other hand, the first structural member is at least partially reinforced by incorporating a reinforcing member. Therefore, after the second structural member is crushed, the first structural member can be bent and deformed. At this time, bending deformation of the first structural member can be caused starting from a recess provided in the second ridge portion of the reinforcing member.

The reinforcing member may have a thickness of, for example, less than 2.0 mm (fourth configuration).

The first recess and the second recess may be located in the longitudinal center of the reinforcing member (fifth configuration).

When designing the first structural member, the location where the bending deformation is to begin, i.e., the location where the recess of the reinforcing member is to be located, is determined, and the area that needs reinforcement to bear the collision load is determined with the recess at the center. Therefore, if the reinforcing member has a configuration in which one side is long and the other side is short across the recess, one side of the reinforcing member may also reinforce areas of the first structural member that do not particularly need reinforcement. In contrast, in the fifth configuration, the recess is located in the center of the longitudinal direction of the reinforcing member. Therefore, only the areas of the first structural member that need reinforcement can be efficiently reinforced by the reinforcing member.

At least one of the surfaces of the first recess and the second recess may be a curved surface that is concave toward the inside of the reinforcing member as a whole (sixth configuration).

The reinforcing member may be formed from a steel plate having a tensile strength of 780 MPa or more (seventh configuration).

Embodiments of the present disclosure will be described below with reference to the drawings. In each drawing, the same or equivalent components are given the same reference numerals, and the same description will not be repeated.

[Configuration of impact absorbing member]
1 is a perspective view showing a shock absorbing member 100 according to the present embodiment. The shock absorbing member 100 is used in the body of an automobile. The shock absorbing member 100 has an elongated shape. When the shock absorbing member 100 is installed in the vehicle body, it extends, for example, generally in the front-rear direction (vehicle length direction) of the vehicle body. As shown in FIG. 1, the shock absorbing member 100 includes structural members 10 and 20 and a reinforcing member 30.

The structural member 10 is, for example, a side member. The structural member 10 is used, for example, as a front side member. The structural member 10 has an elongated shape. The structural member 10 extends generally in the vehicle length direction. The structural member 10 includes a pair of vertical walls 11, 12, a top plate 13, and a pair of ridge portions 14, 15. The structural member 10 further includes a pair of flanges 16, 17, and a pair of ridge portions 18, 19.

The structural member 20 is, for example, a crash box. The structural member 20 is arranged in series with the structural member 10 in the vehicle length direction and is connected to the structural member 10. However, in FIG. 1, the structural members 10 and 20 are shown in an exploded state. The structural member 20 includes a cylindrical member body 21 and ribs 22 and 23. The member body 21 extends in the arrangement direction of the structural members 10 and 20, i.e., roughly in the vehicle length direction. The ribs 22 and 23 are provided within the member body 21.

The reinforcing member 30 is a member for reinforcing the structural member 10. The reinforcing member 30 is disposed within the structural member 10 and joined to the structural member 10. Like the structural member 10, the reinforcing member 30 also extends generally in the vehicle length direction. However, the reinforcing member 30 is typically shorter than the structural member 10. The reinforcing member 30 includes a pair of vertical walls 31, 32, a top plate 33, and a pair of ridge portions 34, 35. The ridge portions 34, 35 have recesses 341, 351, respectively.

Figure 2 is a cross-sectional view of the shock absorbing member 100 shown in Figure 1 taken along line II-II. Figure 2 shows cross sections of the structural member 10 and the reinforcing member 30 of the shock absorbing member 100. The cross section refers to a cross section obtained by cutting the member along a plane that is substantially perpendicular to the longitudinal direction of the shock absorbing member 100.

Referring to FIG. 2, the structural member 10 has a substantially hat-shaped cross section. The vertical walls 11, 12 of the structural member 10 face each other. The vertical walls 11, 12 are arranged such that one side of each wall faces each other, for example, in the vertical direction (vehicle height direction) of the vehicle body. In a cross-sectional view of the structural member 10, the vertical walls 11, 12 extend generally in the left-right direction (vehicle width direction) of the vehicle body.

The edges of the vertical walls 11, 12 in the vehicle width direction are connected to each other by a top plate 13. The top plate 13 is disposed on the inside or outside of the vertical walls 11, 12 in the vehicle width direction. In a cross-sectional view of the structural member 10, the top plate 13 extends from one edge of the vertical wall 11 to one edge of the vertical wall 12, generally in the vehicle height direction. One vertical wall 11 is connected to the top plate 13 via a ridge portion 14. The other vertical wall 12 is connected to the top plate 13 via a ridge portion 15. The ridge portions 14, 15 form corners between the vertical walls 11, 12 and the top plate 13, respectively. Each of the ridge portions 14, 15 has a substantially arc shape, for example, in a cross-sectional view of the structural member 10.

Flanges 16, 17 are connected to the other end edges of the vertical walls 11, 12 in the vehicle width direction. The flanges 16, 17 are arranged on the opposite side of the vertical walls 11, 12 from the top plate 13, and protrude outward from the vertical walls 11, 12. One flange 16 is connected to the vertical wall 11 via a ridge portion 18. The other flange 17 is connected to the vertical wall 12 via a ridge portion 19. The ridge portions 18, 19 form corners between the vertical walls 11, 12 and the flanges 16, 17, respectively. Each of the ridge portions 18, 19 has a substantially arc shape, for example, when viewed in cross section of the structural member 10.

In this embodiment, the impact absorbing member 100 further includes a closing plate 40. The closing plate 40 closes the opening of the structural member 10, which has a substantially hat-shaped cross section, and forms a closed cross section together with the structural member 10. The closing plate 40 extends generally in the vehicle length direction, similar to the structural member 10. The closing plate 40 is joined to the flanges 16, 17 of the structural member 10, for example, by welding.

With continued reference to FIG. 2, the reinforcing member 30 is housed within a space defined by the structural member 10 and the closing plate 40.

In the reinforcing member 30, a pair of vertical walls 31, 32 are arranged to face each other on the inside of the structural member 10. One vertical wall 31 is arranged along one vertical wall 11 of the structural member 10. The other vertical wall 32 is arranged along the other vertical wall 12 of the structural member 10. The vertical walls 31, 32 can be joined to the vertical walls 11, 12 of the structural member 10 by, for example, welding.

One end edge of the vertical walls 31, 32 in the vehicle width direction is connected by a top plate 33. The other end edge of the vertical walls 31, 32 in the vehicle width direction is an open edge. In a cross-sectional view of the reinforcing member 30, the top plate 33 extends from one end edge of the vertical wall 31 toward one end edge of the vertical wall 32, generally in the vehicle height direction. The top plate 33 faces the top plate 13 of the structural member 10 on the inside of the structural member 10. The top plate 33 is arranged along the top plate 13 of the structural member 10.

The top plates 13, 33 may be in contact with each other or may be slightly spaced apart in the vehicle width direction. When the top plates 13, 33 are in contact, they can be joined by, for example, welding. When the top plates 13, 33 are spaced apart, the size of the gap between the top plates 13, 33 in the vehicle width direction can be, for example, 10% or less of 1/2 the height of the structural member 10 (1/2 the length in the vehicle width direction).

One vertical wall 31 is connected to the top plate 33 via a ridge portion 34. The other vertical wall 32 is connected to the top plate 33 via a ridge portion 35. The ridge portions 34 and 35 form corners between the vertical walls 31 and 32 and the top plate 33, respectively. The ridge portions 34 and 35 have a substantially arc shape when viewed in cross section of the reinforcing member 30.

Recesses 341, 351 are formed on the ridges 34, 35, respectively. Recess 341 is provided on ridge 34 so as to recess a portion of one ridge 34 toward the inside of the reinforcing member 30. Recess 351 is provided on ridge 35 so as to recess a portion of the other ridge 35 toward the inside of the reinforcing member 30. Recess 351 on ridge 35 is disposed at a position opposite recess 341 on ridge 34. That is, in the longitudinal direction (vehicle length direction) of reinforcing member 30, the positions of recesses 341, 351 are substantially the same.

The recess 341 in the ridge portion 34 reaches partway up one of the vertical walls 31. The recess 341 also reaches partway up the top plate 33. The surface of the recess 341 is generally a curved surface that is concave toward the inside of the reinforcing member 30. The surface of the recess 341 is, for example, composed of a part of a sphere, an ellipsoid of revolution, a paraboloid of revolution, etc. It is preferable that the outline of the recess 341 is generally composed of a curve. The recess 341 can be formed in the ridge portion 34 by, for example, a round embossing process.

The recess 351 in the ridge portion 35 reaches halfway into the other vertical wall 32. The recess 351 also reaches halfway into the top plate 33. However, the recess 351 does not reach the recess 341. That is, the recesses 341 and 351 are not connected at the top plate 33. The surface of the recess 351 is a curved surface that is concave toward the inside of the reinforcing member 30 as a whole. The surface of the recess 351 is composed of, for example, a part of a sphere, a spheroid, a paraboloid, etc. It is preferable that the contour of the recess 351 is composed of a curve as a whole. The recess 351 can be formed in the ridge portion 35 by, for example, a round embossing process.

In this embodiment, the recesses 341, 351 have a symmetrical shape with respect to a plane including the center line CL of the reinforcing member 30 in the vehicle height direction. However, the recesses 341, 351 may have an asymmetrical shape with respect to the plane including the center line CL.

The recess 341 has a height H1. The height H1 is the maximum length of the region of the recess 341 that extends to the vertical wall 31, and refers to the distance from the outer surface of the top plate 33 to the end of the recess 341 on the vertical wall 31 side. On the other hand, the recess 351 has a height H2. The height H2 is the maximum length of the region of the recess 351 that extends to the vertical wall 32, and refers to the distance from the outer surface of the top plate 33 to the end of the recess 351 on the vertical wall 32 side. The ratio of each of the heights H1 and H2 to the height H of the reinforcing member 30 is less than 1 (H1/H<1, H2/H<1). That is, the heights H1 and H2 of the recesses 341 and 351 are both smaller than the overall height H of the reinforcing member 30. Therefore, the ends of the recesses 341 and 351 on the vertical wall 31 and 32 side do not reach the open edge of the vertical walls 31 and 32.

The heights H1 and H2 of the recesses 341 and 351 can each be 20 mm or more. In this embodiment, the height H1 of the recess 341 is equal to the height H2 of the recess 351. However, the height H1 of the recess 341 may be different from the height H2 of the recess 351.

The recess 341 has a width W1. The width W1 is the maximum length of the region of the recess 341 that extends to the top plate 33, and refers to the distance from the outer surface of the vertical wall 31 to the end of the recess 341 on the top plate 33 side. The recess 351 has a width W2. The width W2 is the maximum length of the region of the recess 351 that extends to the top plate 33, and refers to the distance from the outer surface of the vertical wall 32 to the end of the recess 351 on the top plate 33 side. When the width of the reinforcing member 30, that is, the length from the outer surface of the vertical wall 31 to the outer surface of the vertical wall 32, is W, the widths W1 and W2 of the recesses 341 and 351 satisfy, for example, (W1 + W2) / W ≧ 0.5. It is preferable that the widths W1 and W2 are set to satisfy (W1 + W2) / W ≦ 0.8. It is also preferable that the widths W1 and W2 are set to satisfy W - (W1 + W2) ≧ 14 [mm].

The widths W1 and W2 of the recesses 341 and 351 can each be 20 mm or more. In this embodiment, the width W1 of the recess 341 is equal to the width W2 of the recess 351. However, the width W1 of the recess 341 may be different from the width W2 of the recess 351.

Figure 3 is a view of the structural member 10 and the reinforcing member 30 as seen from the top plate 13, 33 side. In Figure 3, the structural member 10 is shown by a solid line, and the reinforcing member 30 within the structural member 10 is shown by a dashed line.

As shown in FIG. 3, recesses 341, 351 are provided in portions of the ridges 34, 35 in the longitudinal direction of the reinforcing member 30. In this embodiment, the recesses 341, 351 are disposed in the center of the reinforcing member 30 in the longitudinal direction. The recesses 341, 351 have lengths L1, L2, respectively, in the longitudinal direction of the reinforcing member 30.

It is preferable that the length L1 of the recess 341 is set to satisfy the relationship L1/W≧0.3 with respect to the width W of the reinforcing member 30. It is preferable that the length L1 is set to satisfy the relationship L1/W≦0.9 with respect to the width W of the reinforcing member 30.

When the length of the entire reinforcing member 30 in the longitudinal direction is L, it is preferable that the length L1 of the recess 341 is set to satisfy L-L1 ≧ 50 [mm]. It is also preferable that the length L1 is set to satisfy L-L1 ≦ 150 [mm]. L-L1 is the longitudinal length of the portion of the reinforcing member 30 excluding the recess 341.

Similarly, it is preferable that the length L2 of the recess 351 is set to satisfy the relationship L2/W≧0.3 with respect to the width W of the reinforcing member 30. It is preferable that the length L2 is set to satisfy the relationship L2/W≦0.9 with respect to the width W of the reinforcing member 30.

The length L2 of the recess 351 is preferably set to satisfy L-L2≧50 [mm]. Also, the length L2 is preferably set to satisfy L-L2≦150 [mm]. L-L2 is the longitudinal length of the portion of the reinforcing member 30 excluding the recess 351. In this embodiment, the length L2 of the recess 351 is equal to the length L1 of the recess 341. However, the length L2 of the recess 351 may be different from the length L1 of the recess 341.

In the longitudinal direction of the structural member 10 and the reinforcing member 30, the length L of the reinforcing member 30 is typically smaller than the length of the structural member 10. The length L of the reinforcing member 30 is, for example, 1/2 or less of the length of the structural member 10. The longitudinal position of the reinforcing member 30 relative to the structural member 10 can be determined as appropriate.

The structural member 10, closing plate 40, and reinforcing member 30 shown in Figures 1 to 3 are typically made of metal. The materials of the structural member 10, closing plate 40, and reinforcing member 30 may be the same or different. The structural member 10 and reinforcing member 30 are formed, for example, by pressing a metal plate. The reinforcing member 30 can be formed, for example, from a steel plate having a tensile strength of 780 MPa or more. The structural member 10 and closing plate 40 are formed, for example, from a steel plate having a tensile strength equal to or less than the tensile strength of the steel plate used for the reinforcing member 30.

The thickness (plate thickness) of the reinforcing member 30 is preferably less than 2.0 mm. The thickness (plate thickness) of each of the structural member 10 and the closing plate 40 can be, for example, equal to or less than the thickness of the reinforcing member 30. However, the thickness of each of the structural member 10 and the closing plate 40 may be greater than the thickness of the reinforcing member 30. The thickness of the structural member 10 may be the same as or different from the thickness of the closing plate 40.

Figure 4 is a cross-sectional view of the shock absorbing member 100 shown in Figure 1 taken along line IV-IV. Figure 4 shows a cross section of the structural member 20 included in the shock absorbing member 100.

Referring to FIG. 4, the member body 21 of the structural member 20 includes a peripheral wall 211. The peripheral wall 211 is hollow and has a substantially square shape in a cross-sectional view of the structural member 20. The peripheral wall 211 includes an upper wall 211a, a lower wall 211b, and side walls 211c and 211d. The upper wall 211a and the lower wall 211b are disposed one above the other in the vehicle height direction. The side walls 211c and 211d connect the upper wall 211a and the lower wall 211b.

The ribs 22 and 23 are provided in the member body 21. The ribs 22 and 23 are each plate-shaped. The rib 22 crosses the space within the member body 21 generally in the vehicle height direction. The rib 22 extends in the axial direction of the member body 21 while crossing the space within the member body 21 in the vehicle height direction. The rib 22 is connected to the upper wall 211a and the lower wall 211b of the member body 21.

The rib 23 crosses the space inside the member body 21 generally in the vehicle width direction. The rib 23 extends in the axial direction of the member body 21 while crossing the space inside the member body 21 in the vehicle width direction. The rib 23 is connected to the side walls 211c and 211d of the member body 21. The rib 23 intersects with the rib 22. For example, the ribs 22 and 23 are perpendicular to each other. The member body 21 may further include ribs other than the ribs 22 and 23. For example, the member body 21 may include a rib that intersects with at least one of the ribs 22 and 23, or a rib that connects the peripheral wall 211 to one of the ribs 22 and 23.

The structure of the structural member 20 is not limited to the example shown in FIG. 4. In FIG. 5 to FIG. 9, cross sections of structural members that can be applied to the impact absorbing member 100 according to this embodiment instead of the structural member 20 are shown.

In the structural member 20A shown in FIG. 5, the peripheral wall 211A of the member body 21A is hollow and has a substantially rectangular cross section. Ribs 22A and 23A that do not intersect with each other are provided within the member body 21A. In a cross-sectional view of the structural member 20A, the ribs 22A and 23A each cross the space within the member body 21A in the short direction of the member body 21A. In the example shown in FIG. 5, two ribs 22A and 23A are provided within the member body 21A, but a single rib or three or more ribs may be provided within the member body 21A.

In the structural member 20B shown in FIG. 6, multiple grooves 24 are provided in the peripheral wall 211B of the member body 21B. Similarly, in the structural member 20C shown in FIG. 7, multiple grooves 24 are provided in the peripheral wall 211C of the member body 21C. Each of the grooves 24 has a concave shape toward the inside of the member bodies 21B, 21C, and extends in the axial direction of the member bodies 21B, 21C.

6 and 7, the imaginary polygon inscribed by the peripheral walls 211B, 211C of the member bodies 21B, 21C in the cross-sectional view of the structural members 20B, 20C is shown by a two-dot chain line. A groove 24 is provided in at least one corner of this imaginary polygon. In the example shown in FIG. 6, in the imaginary hexagon inscribed by the peripheral wall 211B in the cross-sectional view of the structural member 20B, grooves 24 are provided in four of the six corners. In the example shown in FIG. 7, in the imaginary quadrangle inscribed by the peripheral wall 211C in the cross-sectional view of the structural member 20C, grooves 24 are provided in each corner.

In the structural members 20D and 20E shown in Figs. 8 and 9, similar to the structural members 20B and 20C shown in Figs. 6 and 7, multiple grooves 24 are provided in the peripheral walls 211D and 211E of the member main bodies 21D and 21E. In the example shown in Figs. 8 and 9, the grooves 24 are provided on at least one side of the imaginary polygon in which the peripheral walls 211D and 211E are inscribed in the cross section of the structural members 20D and 20E. In the structural member 20D shown in Fig. 8, the grooves 24 are provided on the long sides of the imaginary long octagon in which the peripheral wall 211D is inscribed in the cross section. In the structural member 20E shown in Fig. 9, the grooves 24 are provided on each side of the imaginary rectangle in which the member main body 21E is inscribed in the cross section.

The structural members 20, 20A to 20E are typically made of metal. The structural member 20 can be made of, for example, a steel plate. The member bodies 21, 21A to 21E are made of, for example, a steel plate having a tensile strength equal to or less than that of the steel plate used in the reinforcing member 30 (FIGS. 1 to 3). The thickness (plate thickness) of the member bodies 21, 21A to 21E may be equal to or less than that of the reinforcing member 30, or may be greater than that of the reinforcing member 30. The tensile strength of the steel plate used in the member bodies 21, 21A to 21E may be the same as or different from that of the steel plate used in the structural member 10 (FIGS. 1 to 3). The thickness of the member bodies 21, 21A to 21E may be the same as or different from that of the structural member 10. However, when the thickness of the member bodies 21, 21A to 21E is t ₂ , the tensile strength of the member bodies 21, 21A to 21E is TS ₂ , the thickness of the structural member 10 is t ₁ , and the tensile strength of the structural member 10 is TS ₁ , it is preferable that t ₂ ×TS ₂ ≦t ₁ ×TS ₁ is satisfied. The material and thickness of the ribs 22, 23, 22A, 23A may be the same as or different from those of the member body 21.

The structural members 20, 20A to 20E are connected to the structural member 10 that incorporates the reinforcing member 30. Figure 10 is a schematic diagram showing the state in which the structural member 20 is connected to the structural member 10.

As shown in FIG. 10, the structural member 20 is attached to the structural member 10 via set plates 51, 52. The member body 21 of the structural member 20 is joined to the set plate 51. One longitudinal end of the structural member 10 is joined to the set plate 52. The set plates 51, 52 are fixed to each other by a fastening member 53 such as a bolt. The structural members 20A to 20E shown in FIGS. 5 to 9 can be attached to the structural member 10 in the same manner as the structural member 20.

[effect]
In the impact absorbing member 100 according to this embodiment, at least a part of the structural member 10, which is, for example, a side member, is reinforced from the inside by the reinforcing member 30 to increase its rigidity. This makes it possible to suppress deformation of the structural member 10 when, for example, a collision load is input to the impact absorbing member 100 in its longitudinal direction. Therefore, it is possible to improve the impact energy absorption performance of the impact absorbing member 100.

In this embodiment, the reinforcing member 30 improves the impact energy absorption performance of the impact absorbing member 100, so that when a collision load is input to the impact absorbing member 100 in its longitudinal direction, the amount by which the impact absorbing member 100 intrudes into the inside of the vehicle body (vehicle intrusion amount) is reduced. Therefore, the length of the impact absorbing member 100, which is determined according to the vehicle intrusion amount, can be shortened. As a result, the impact absorbing member 100 and the vehicle body in which the impact absorbing member 100 is used can be made lighter.

In the impact absorbing member 100 according to this embodiment, recesses 341, 351 are formed on each of the ridges 34, 35 that form the corners between the vertical walls 31, 32 and the top plate 33 of the reinforcing member 30. The recesses 341, 351 are arranged at positions facing each other in the longitudinal direction of the reinforcing member 30, and reach halfway through the vertical walls 31, 32 and the top plate 33. Therefore, for example, when a collision load is input to the impact absorbing member 100 in its longitudinal direction with the top plate 13 of the structural member 10 and the top plate 33 of the reinforcing member 30 facing inward or outward in the vehicle width direction, the structural member 10 can be bent together with the reinforcing member 30 starting from the recesses 341, 351. In other words, the bending deformation mode of the impact absorbing member 100 can be controlled.

In the shock absorbing member 100 according to this embodiment, the structural member 10 is usually connected to other structural members to form the vehicle body. On the other hand, the reinforcing member 30 is a member that is not connected to other structural members. The recesses 341, 351, which are means for controlling the bending deformation mode, are provided in this reinforcing member 30. Therefore, when a force such as bending or twisting is input to the vehicle body, the recesses 341, 351 do not impede the transmission of force between the structural members. Therefore, the recesses 341, 351 do not substantially affect the rigidity of the entire vehicle body.

In this embodiment, the length L1 of the recess 341 is preferably set to satisfy the relationship L1/W≧0.3 with respect to the width W of the reinforcing member 30. The length L2 of the recess 351 is preferably set to satisfy the relationship L2/W≧0.3 with respect to the width W of the reinforcing member 30. This makes it possible to suppress local deformation of the structural member 10 and the reinforcing member 30 at the recesses 341, 351, and to stably generate bending deformation in the structural member 10 starting from the recesses 341, 351.

In this embodiment, the length L1 of the recess 341 is preferably set to satisfy the relationship L1/W≦0.9 with respect to the width W of the reinforcing member 30. The length L2 of the recess 351 is preferably set to satisfy the relationship L2/W≦0.9 with respect to the width W of the reinforcing member 30. This ensures a sufficient restraining effect on the structural member 10 by the peripheral portions of the recesses 341 and 351 of the reinforcing member 30. This makes it possible to suppress a decrease in the load that causes bending deformation in the structural member 10.

In this embodiment, the heights H1 and H2 of the recesses 341 and 351 are, for example, 20 mm or more. This allows sufficient stress concentration to occur in the recesses 341 and 351. This allows the recesses 341 and 351 to function stably as starting points for bending deformation of the structural member 10.

In this embodiment, the widths W1 and W2 of the recesses 341 and 351 are, for example, 20 mm or more. This allows sufficient stress concentration to occur in the recesses 341 and 351. This allows the recesses 341 and 351 to function stably as starting points for bending deformation of the structural member 10.

In this embodiment, it is preferable that the widths W1 and W2 of the recesses 341 and 351 are set to satisfy the relationship (W1+W2)/W≦0.8 with respect to the width W of the reinforcing member 30. In this case, the top plate 33 of the reinforcing member 30 can adequately support the top plate 13 of the structural member 10. As a result, it is possible to suppress a decrease in the load that causes bending deformation in the structural member 10.

In this embodiment, it is preferable that the widths W1 and W2 of the recesses 341 and 351 are set to satisfy the relationship W-(W1+W2) ≥ 14 mm with respect to the width W of the reinforcing member 30. In this case, the portion of the top plate 33 of the reinforcing member 30 between the recesses 341 and 351 can be easily joined to the top plate 13 of the structural member 10 by, for example, spot welding.

In this embodiment, the length L1 of the recess 341 is preferably set to satisfy the relationship L-L1 ≧ 50 mm with respect to the length L of the reinforcing member 30. The length L2 of the recess 351 is preferably set to satisfy the relationship L-L2 ≧ 50 mm with respect to the length L of the reinforcing member 30. This ensures a sufficient restraining effect on the structural member 10 by the portions of the reinforcing member 30 surrounding the recesses 341 and 351. This prevents the load that causes bending deformation in the structural member 10 from being suppressed.

The length L1 of the recess 341 is preferably set to satisfy L-L1 ≦ 150 mm. Similarly, the length L2 of the recess 351 is preferably set to satisfy L-L2 ≦ 150 mm. This makes it possible to prevent the length of the portion of the reinforcing member 30 other than the recesses 341 and 351 from becoming excessively long in the longitudinal direction of the reinforcing member 30. This makes it possible to prevent the weight of the impact absorbing member 100 from increasing too much due to the reinforcing member 30.

In this embodiment, the structural members 20 and 20A are connected in series to the structural member 10. The rigidity of the structural members 20 and 20A is increased by the ribs 22, 23, 22A, and 23A provided in the member main body 21 and 21A. This makes it possible to suppress the deformation of the structural members 20 and 20A in an unintended deformation mode, and to stably crush the structural members 20 and 20A in the axial direction of the member main body 21 and 21A. On the other hand, the structural member 10 is at least partially reinforced by incorporating the reinforcing member 30. Therefore, when a collision load is input to the impact absorbing member 100 from the structural member 20 and 20A side, the structural member 20 and 20A, which is, for example, a crash box, is crushed, and then the structural member 10, which is, for example, a side member, can be bent and deformed.

The structural members 20B-20E connected to the structural member 10 have their rigidity increased by grooves 24 provided in the peripheral walls 211B-211E of the member bodies 21B-21E. In this case, too, it is possible to prevent the structural members 20B-20E from deforming in an unintended deformation mode, and the structural members 20B-20E can be stably crushed in the axial direction of the member bodies 21B-21E. On the other hand, the structural member 10 is at least partially reinforced by incorporating the reinforcing member 30. Therefore, when a collision load is input to the impact absorbing member 100 from the structural members 20B-20E side, the structural members 20B-20E are crushed, and then the structural member 10 can be bent and deformed.

In this embodiment, the thickness of the reinforcing member 30 is preferably less than 2.0 mm. This allows the structural member 10 to be appropriately reinforced by the reinforcing member 30. In this case, when a collision load is input to the impact absorbing member 100 in its longitudinal direction, bending deformation starting from the recesses 341, 351 in the structural member 10 can be easily generated at an appropriate timing.

When designing the structural member 10, the location of the structural member 10 where bending deformation is to start, that is, the location where the recesses 341, 351 should be provided, is determined, and the area that needs reinforcement to bear the collision load is determined with the recesses 341, 351 as the center. Therefore, if the reinforcing member 30 is configured such that one side is longer and the other side is shorter across the recesses 341, 351, one side of the reinforcing member 30 may also reinforce areas of the structural member 10 that do not particularly need reinforcement. Therefore, in this embodiment, it is preferable that the recesses 341, 351 are located in the center of the longitudinal direction of the reinforcing member 30. This allows the reinforcing member 30 to efficiently reinforce only the areas of the structural member 10 that need reinforcement.

In this embodiment, the surfaces of the recesses 341 and 351 are generally curved surfaces that are concave toward the inside of the reinforcing member 30. In this case, the moldability of the reinforcing member 30 can be improved.

However, the surfaces of the recesses 341 and 351 do not necessarily have to be curved overall. The surfaces of the recesses 341 and 351 may include one or more planes. For example, as shown in FIG. 11, the recess 341A may have a curved surface 341a and a plane 341b connecting the curved surface 341a and the top plate 33. Similarly, the recess 351A may have a curved surface 351a and a plane 351b connecting the curved surface 351a and the top plate 33. In this case, the contour of the recesses 341A and 351A in the top plate 33 is rectangular. On the other hand, the contour of the recesses 341 and 351 in the vertical walls 31 and 32 is a convex arc shape, an elliptical arc shape, a parabola shape, or the like toward the open edge of the vertical walls 31 and 32. In the example shown in FIG. 11, the portion of the vertical wall 31 corresponding to the recess 341A bulges outward from the reinforcing member 30A compared to the other portions. However, the portion of the vertical wall 31 that corresponds to the recess 341A does not necessarily have to bulge.

The reinforcing member 30 shown in Figures 1 to 3 may be provided with one of the recesses 341A and 351A shown in Figure 11. For example, the reinforcing member 30 may be provided with a recess 341A instead of the recess 341. Also, the reinforcing member 30 may be provided with a recess 351A instead of the recess 351.

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

The present disclosure will be described in more detail below with reference to examples. However, the present disclosure is not limited to the following examples.

To confirm the effectiveness of the impact absorbing component disclosed herein, an offset frontal collision analysis of an automobile was performed using general-purpose structural analysis software (general-purpose dynamic explicit FEM solver LS-DYNA, manufactured by LSTC).

In this analysis, as Example 1, the amount of intrusion of the impact absorbing member into the inside of the vehicle (vehicle intrusion amount) was confirmed for a case in which the impact absorbing member (FIGS. 1 to 4) including the structural members 10 and 20, the closing plate 40, and the reinforcing member 30 was installed on the vehicle body. Also, as Example 2, the amount of intrusion of the vehicle was confirmed for a case in which the impact absorbing member (FIGS. 4 and 11) including the structural members 10 and 20, the closing plate 40, and the reinforcing member 30A was installed on the vehicle body. Furthermore, as Example 3, the amount of intrusion of the vehicle was confirmed for a case in which an impact absorbing member having the same shape as Example 1 but a reinforcing member 30 with a different thickness (plate thickness) from Example 1 was installed on the vehicle body. The thickness of the reinforcing member 30 in Example 1 was 2.0 mm, and the thickness of the reinforcing member 30 in Example 3 was 1.3 mm. The thickness of the reinforcing member 30 in Example 2 was 1.4 mm.

For comparison, the vehicle intrusion amount was also confirmed for cases (Comparative Examples 1 and 2) in which shock absorbing members of different configurations from those in each embodiment were provided on the vehicle body. As shown in FIG. 12, in Comparative Example 1, the structural member 10 does not incorporate a reinforcing member, and the structural member 80 connected to the structural member 10 does not have a rib in the member body 81. As shown in FIG. 13, in Comparative Example 2, the reinforcing member 90 in the structural member 10 has a recess 931 that crosses the top plate 93 from one vertical wall 91 to the other vertical wall 92.

The amount by which the cabin was set back (cabin setback amount) was also confirmed for each example and comparative example. In this analysis, structural member 10 is a front side member, and structural members 20 and 80 are crash boxes. In the analysis, a longitudinal collision load was input to each impact absorbing member from the structural member 20 or 80 side (the front of the vehicle). The results of the analysis are shown in Table 1.

In Table 1, Comparative Example 1 is used as a control example, and the vehicle intrusion amount and cabin setback amount are shown as the difference from Comparative Example 1. As shown in Table 1, in Comparative Example 2, the vehicle intrusion amount was reduced compared to Comparative Example 1, but bending deformation of structural member 10, which is a side member, occurred before structural member 20, which is a crash box, was crushed. In contrast, in Examples 1 to 3, in addition to the vehicle intrusion amount being reduced compared to Comparative Example 1, bending deformation of structural member 10 occurred after structural member 20 was crushed.

These results show that reinforcing members 30, 30A with recesses 341, 351, 341A, 351A on ridges 34, 35 allow structural member 10 to bend and deform at the appropriate time, and improves collision energy absorption performance. In addition, the length of the impact absorbing member can be reduced by the amount of vehicle intrusion reduced, making it possible to reduce the weight of the impact absorbing member and the vehicle body. Furthermore, structural member 20 (crash box), which is an easily replaceable bolt-on member, can be crushed preferentially, improving the repairability of the impact absorbing member.

Figure 14 is a graph showing the relationship between the vehicle stroke (intrusion amount) and the amount of energy absorbed by the structural member 10 (side member) for Comparative Example 1 and Example 3. The vertical axis in this graph is normalized by the maximum amount of absorbed energy for Comparative Example 1.

As shown in FIG. 14, the structural member 10 (side member) of Example 3 incorporating the reinforcing member 30 absorbed more energy than the structural member 10 of Comparative Example 1, which did not incorporate the reinforcing member 30. In Example 3, the amount of energy absorption increased with a short vehicle stroke. This shows that the reinforcing member 30 improves the collision energy absorption performance of the structural member 10 itself.

In Example 1, the thickness of the reinforcing member 30 is 2.0 mm, which is larger than in Examples 2 and 3, and the stiffness of the reinforcing member 30 is high. Therefore, in Example 1, bending deformation of the structural member 10 is relatively unlikely to occur, and the cabin retreat amount is larger than in Examples 2 and 3. Therefore, from the viewpoint of ensuring cabin space in the event of a collision, it is preferable that the thickness of the reinforcing members 30, 30A is less than 2.0 mm.

100: Impact absorbing member 10: Structural member 11, 12: Vertical wall 13: Top plate 14, 15: Ridge portion 20, 20A to 20E: Structural member 21, 21A to 21E: Main member 211, 211B to 211E: Peripheral wall 22, 23, 22A, 23A: Rib 24: Groove 30, 30A: Reinforcing member 31, 32: Vertical wall 33: Top plate 34, 35: Ridge portion 341, 341A, 351, 351A: Recess

Claims (6)

An impact absorbing member for a vehicle body,
a first structural member including a pair of first vertical walls facing each other, a first top plate connecting end edges of the first vertical walls, and a pair of first ridge portions constituting corners between the first vertical walls and the first top plate;
a reinforcing member joined to the first structural member, the reinforcing member including: a pair of second vertical walls arranged along the first vertical wall inside the first structural member; a second top plate facing the first top plate inside the first structural member and connecting edges of the second vertical walls; and a pair of second ridge portions constituting corners between the second vertical walls and the second top plate;
Equipped with
one of the second ridge lines includes a first recess provided to recess a part of the second ridge line toward the inside of the reinforcing member, the first recess reaching halfway through each of the one of the second vertical walls and the second top plate;
the other of the second ridge line portion is a second recess provided so as to recess a part of the second ridge line portion toward the inside of the reinforcing member, the second recess being disposed at a position facing the first recess and reaching halfway through the other of the second vertical wall and the second top plate ,
a surface of each of the first recess and the second recess is a curved surface that is concave toward the inside of the reinforcing member as a whole, and is formed of a part of any one of a sphere, an ellipsoid, and a paraboloid;
An impact absorbing member which satisfies 0.5≦(W1+W2)/W, where W1 is the maximum length of the area of the first recess which extends to the second top plate, W2 is the maximum length of the area of the second recess which extends to the second top plate, and W is the distance between the outer surfaces of the pair of second vertical walls . The impact absorbing member according to claim 1, further comprising:
a second structural member disposed in series with the first structural member and connected to the first structural member;
Equipped with
The second structural member is
a cylindrical member main body extending in an arrangement direction of the first structural member and the second structural member;
A rib is provided within the member body, traversing a space within the member body and extending in an axial direction of the member body;
A shock absorbing member comprising: The impact absorbing member according to claim 1, further comprising:
a second structural member disposed in series with the first structural member and connected to the first structural member;
Equipped with
the second structural member includes a tubular member main body extending in an arrangement direction of the first structural member and the second structural member,
An impact absorbing member, wherein a groove is formed in a peripheral wall of the member body, the groove having a concave shape toward the inside of the member body and extending in an axial direction of the member body. The impact absorbing member according to any one of claims 1 to 3,
The reinforcing member has a thickness of less than 2.0 mm. The impact absorbing member according to any one of claims 1 to 4,
The first recess and the second recess are disposed in a central portion of the reinforcing member in a longitudinal direction of the shock absorbing member. The impact absorbing member according to any one of claims 1 to 5 ,
The reinforcing member is formed of a steel plate having a tensile strength of 780 MPa or more.

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