JP7420666B2 - Shock absorbing member - Google Patents

Description

The present invention relates to a shock absorbing member that absorbs shock energy generated during a vehicle collision and suppresses transmission to the vehicle body.

There is a structure between the front and rear bumper reinforcements of the vehicle and the vehicle body that deforms when a large impact is applied during a collision, reducing the impact energy transmitted to the vehicle body and protecting the occupants. A shock absorbing member, also referred to as a protective crash box, is provided.
This impact absorbing member is required to have a deformation load lower than that of the vehicle body frame in response to an impact compressive load in the axial direction, and to have an axial crushing property that causes plastic deformation due to continuous buckling during a collision.

As such a shock absorbing member, for example, there is one described in Patent Document 1. This shock absorbing member has a cylindrical shape such as a square as a whole, and is provided with a trigger portion formed by deforming a part of the side wall into a convex or concave shape, and deforms starting from the trigger portion during a collision. Configured to get started. In this case, a first side wall including a first trigger part, a second side wall including a second trigger part disposed closer to the vehicle body than the first trigger part, and a through hole in the vicinity of the first trigger part. and a third side wall having an odd number of side walls between the first side wall and the second side wall. In the event of a collision, the first trigger portion deforms first. At this time, since the rigidity of the position near the first trigger part is reduced by the through hole, the peak load at the start of deformation can be reduced. It is described that the presence of the two side walls suppresses a sudden drop in load when the second trigger portion deforms.

JP2015-68475A

By the way, recent collision requirements require collision performance in offset collisions in which the vehicle collides with the center of the vehicle, with a smaller amount of overlap (the amount of overlap in the width direction of the vehicle with the other party in the collision) than in the past. be. If the amount of overlap is small, the collision surface near the end of the bumper reinforcement is inclined with respect to the vehicle width direction, so the load at the time of collision acts largely not only in the longitudinal direction of the vehicle but also in the lateral direction of the vehicle. For this reason, in the cylindrical impact absorbing member described in Patent Document 1, there is a risk that the impact absorbing member (crash box) may fall down due to the load in the lateral direction of the vehicle in the event of an offset collision with a small amount of overlap.
In order to absorb the impact without collapsing the impact-absorbing member, it is necessary to increase the width of the impact-absorbing member, but if the aspect ratio of the cross-sectional external dimensions of the impact-absorbing member increases, ideal axial crushing characteristics can be obtained. things become difficult.
Therefore, it is desired to increase the strength against loads in the lateral direction of the vehicle without impairing the axial crushing characteristics.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a shock absorbing member that can obtain an ideal axially collapsed state even when a load is applied in the lateral direction of the vehicle due to an offset collision.

The shock absorbing member of the present invention is a shock absorbing member having a cylindrical body that is provided between a bumper reinforcement and a vehicle body and deforms into an axially collapsed state by an axial impact compressive load, the cylindrical body comprising: It has a polygonal cross-sectional shape having a plurality of plate-shaped side walls, and connects the first side wall that becomes the upper surface when attached to the vehicle body, the second side wall that becomes the lower surface, and the first side wall and the second side wall. and a plurality of trigger parts bent in the shape of grooves along a direction intersecting the axial direction of the cylinder on both sides of the first side wall and the second side wall. The trigger portions are formed at intervals in the axial direction of the body, and are alternately formed on each side wall through the center in the width direction, and are vertically opposed to each other on the first side wall and the second side wall. A third side wall is formed at approximately the same position as shown in FIG. At least one easily deformable portion is formed on the fourth side wall to be arranged so as to be lined up at approximately the same position as any of the trigger portions disposed on the side of the connecting portion with these side walls.

A plurality of trigger parts provided on the first side wall and the second side wall disposed on the upper and lower surfaces of the vehicle body promote the axial collapse state in the event of a collision. The strength of the side wall and the fourth side wall to prevent it from collapsing is maintained. In this case, since the middle wall is provided between the first side wall and the second side wall, even if the first side wall and the second side wall are made wide (the distance between the third side wall and the fourth side wall is large), The first side wall and the second side wall can be formed so that the length of each side partitioned by the middle wall is approximately equal to that of the third side wall and the fourth side wall, and has desired axial strength (buckling strength). Further, since the easily deformable portions are formed on the third side wall and the fourth side wall, axial crushing is less likely to be inhibited.
In this way, this shock absorbing member has ideal axial crushing characteristics due to the synergistic action of each element.

In this shock absorbing member, the easily deformable portion may be a through hole. The easily deformable part may have any shape as long as it can be easily deformed by a collision load, and can be easily formed by forming a through hole.

In this shock absorbing member, the cylindrical body is attached at an angle with respect to the longitudinal direction of the vehicle body, and the mounting surface of the cylindrical body to the bumper reinforcement is fixed when attached to the bumper reinforcement. The trigger portion may be inclined so as to be arranged along the width direction of the vehicle body.

Both ends of the bumper reinforcement are slanted toward the vehicle body, and by attaching it to the bumper reinforcement with a mounting surface that is sloped to match the slope, the trigger part can be placed along the width direction of the vehicle body. It is possible to effectively exhibit the axial crushing characteristics in the event of a collision.

In this shock absorbing member, a notch portion is disposed on an extension of one of the trigger portions in at least one of the first side wall and the second side wall to expose a connecting edge of the inner wall to the side wall. It would be good if it was done.

The trigger part starts to deform at the part where this notch is formed, and is crushed while being linked to other trigger parts. Therefore, by appropriately arranging this notch, more ideal axial crushing characteristics can be exhibited.

In this shock absorbing member, it is preferable that the distance between the third side wall and the fourth side wall be larger than the distance between the first side wall and the second side wall. When attached to the vehicle body, the horizontal dimension becomes larger than the vertical dimension, which prevents the vehicle from collapsing against the lateral load caused by an offset collision, and effectively exhibits the axial crushing characteristic.

In this shock absorbing member, the thickness of the third side wall is preferably greater than the thickness of the fourth side wall. The deformation load on the third side wall disposed inside the vehicle body is increased to suppress the third side wall from collapsing due to the lateral load caused by an offset collision. In this case, the easily deformable part of the third side wall is preferably easier to deform than the easily deformable part of the fourth side wall, and if the easily deformable part is a through hole, the through hole of the fourth side wall is more easily deformed than the easily deformable part of the fourth side wall. It is preferable to form the through hole large. Since the thickness is large, the easily deformable portion of the third side wall is made more deformable than the easily deformable portion of the fourth side wall, thereby making it possible to evenly cause axial collapse of both side walls.

In this shock absorbing member, a reinforcing portion formed by bending the third side wall into a concave groove shape in the thickness direction is provided at the end of the third side wall on the side where it is attached to the vehicle body. It would be good if it was formed as follows. Although the cylindrical body is axially crushed during a collision, the buckling strength of the third side wall is locally increased by a reinforcing part at the end on the side where it is attached to the vehicle body, and this reinforcing part remains without buckling. As a result, the collapse against the lateral load is maintained until the final stage of axial collapse, and an ideal axial collapse state can be maintained.

According to the shock absorbing member of the present invention, an ideal axially collapsed state can be obtained even when a load is applied in the lateral direction of the vehicle due to an offset collision.

FIG. 2 is a perspective view showing a state in which a shock absorbing member according to an embodiment of the present invention is attached to a bumper reinforcement. FIG. 2 is a perspective view showing the bumper rinse force from FIG. 1 as a virtual line. FIG. 3 is a plan view of FIG. 2 with the bumper rinsing force facing upward; FIG. 2 is a perspective view of the shock absorbing member used in FIG. 1. FIG. 5 is a view of the shock absorbing member viewed from the direction of arrow A in FIG. 4. FIG. 5 is a view of the shock absorbing member viewed from the direction of arrow B in FIG. 4. FIG. 6 is a view of the shock absorbing member viewed from the direction of arrow J in FIG. 5. FIG. 6 is a view of the shock absorbing member viewed from the direction of arrow K in FIG. 5. FIG. It is a graph showing an energy absorption state.

Embodiments of the shock absorbing member according to the present invention will be described below with reference to the drawings.
FIG. 1 shows a pair of shock absorbing members 1A and 1B attached to a front bumper reinforcement 3 of a vehicle body 2 (see FIG. 3). In this case, the bumper reinforcement 3 is bent so that both ends thereof are inclined toward the rear of the vehicle body 2, and the inclined portions at both ends in the width direction of the vehicle body 2 are larger than the bent portions 31. At 32, shock absorbing members 1A and 1B are provided. Both inclined portions 32 of the bumper reinforcement 2 are not necessarily limited, but in the illustrated example, the inclined angle θ1 with respect to the width direction (vehicle width direction) of the vehicle main body 2 is set to 20°.

The shock absorbing members 1A, 1B are formed by a cylinder 10 and a mounting plate 40 fixed to one end of the cylinder 10 and attached to the vehicle body 2. In this case, the impact absorbing members 1A and 1B are attached to the inclined portion 32 of the bumper reinforcement 3 and receive loads in the lateral direction of the vehicle at the time of an offset collision, so they are inclined with respect to the center line C in the width direction of the vehicle body 2. It is attached. Specifically, as shown in FIGS. 1 to 3, the tips of the impact absorbing members 1A and 1B are fixed to the vehicle body side of both the left and right inclined portions 32 of the bumper reinforcement 3, and The absorbing members 1A and 1B are inclined in such a direction that the distance between them gradually decreases toward the rear of the vehicle main body 2. Since the mounting surface 2a of the vehicle main body 2 to which the shock absorbing members 1A and 1B are attached is formed along the left-right direction (vehicle width direction), both the front end surface and the rear end surface of the cylinder 10 are formed as inclined surfaces. and both inclined surfaces are inclined in different directions. If the front end surface of the cylindrical body 10 is the bumper side mounting surface 11 and the rear end surface is the vehicle body side mounting surface 12, then, for example, the inclination angle θ2 of the bumper side mounting surface 11 is 12 degrees, and the inclination angle θ3 of the vehicle body side mounting surface 12 is 8 degrees. (see Figure 5).

The direction of the vehicle body 2 is the left-right direction (or vehicle width direction), the vertical direction (or vehicle height direction), and the front-rear direction (or vehicle length direction). Since it is arranged at a slight inclination with respect to the front-back direction, the description will be made not in the front-back direction but in the axial direction (or length direction) of the cylindrical body 10. Furthermore, the direction orthogonal to the axial direction of the cylinder 10 is defined as the width direction (horizontal direction) of the cylinder 10, but since this direction is slightly different from the width direction (vehicle width direction or left-right direction) of the vehicle body 2, It is distinguished as the width direction (or left-right direction) of the cylinder 10, the width direction (or left-right direction) of the vehicle body 2, or the vehicle width direction.
In addition, in the examples shown in FIGS. 1 to 3, the side where the bumper reinforcement 3 is arranged is the front of the vehicle body 2, and hereinafter, the shock absorbing members 1A and 1B are provided on the bumper reinforcement 3 in front of the vehicle body 2. The shock absorbing member may be attached to the bumper reinforcement at the rear of the vehicle main body 2, and in that case, it is provided front-to-back symmetrically with the example shown in FIGS. 1 to 3.

As shown in FIG. 3, both shock absorbing members 1A and 1B provided on the left and right sides of the bumper reinforcement 3 are formed symmetrically with respect to the widthwise center line C of the vehicle body 3, and the cylindrical bodies 10 have the same shape. The left and right parts are installed in different mounting positions (upside down). In the following explanation, one of the shock absorbing members 1A and 1B, 1A, will be explained in the mounting posture shown in FIGS. 1 to 3.

[Configuration of cylinder 10]
As shown in FIGS. 4 to 8, the cylindrical body 10 has a first side wall 13 that becomes an upper surface when attached to the vehicle body 2, a second side wall 14 that becomes a lower surface, and the first side wall 13 and the second side wall 14. As shown in FIG. The overall shape can be said to be a closed cross-sectional shape with a rectangular frame shape in cross section, but the connecting portions between the first side wall 13, the third side wall 15, and the fourth side wall 16, the second side wall 14, the third side wall 15, and the fourth side wall 16 Since both the connecting portions are formed as inclined corner portions 18 which are inclined in a chamfered manner with a slight width, in a cross section, if the surface of these inclined angle portions 18 is taken as one side, the cross section is formed into an octagonal shape. ing. Furthermore, since it has a central inner wall 17, it is formed in a cross section shaped like the Chinese character "Japanese character".

The width W1 of the first side wall 13 and the second side wall 14 is larger than the width W2 of the third side wall 15 and the fourth side wall 16. Therefore, the overall width W3 of the cylindrical body 10 is larger than the vertical dimension H1, for example, approximately twice as large. On both sides of the first side wall 13 and second side wall 14, a plurality of trigger parts 51 formed by bending the side walls 13 and 14 into a groove shape are arranged mutually in the axial direction (lengthwise direction) of the cylinder body 10. They are formed at intervals. As shown in FIG. 5, each trigger portion 51 is formed such that the length direction of the groove is parallel to the vehicle body side mounting surface 12 of the cylindrical body 10, and the vehicle body side mounting surface 12 of the first side wall 13 and the second side wall 14. The length is slightly shorter than half of the length of the side along the . One end of the groove is open to both side edges of the first side wall 13 and the second side wall 14, and the other end is disposed toward the center of the cylindrical body 10 in the width direction.

In this case, the end of the trigger part 51 disposed on the widthwise center side of the first side wall 13 and the second side wall 14 does not reach the connecting part 17a of the middle wall 17 on the first side wall 13 and the second side wall 14. not reached. Further, in each of the first side wall 13 and the second side wall 14, the trigger portions 51 are formed alternately across the center of the cylindrical body 10 in the width direction. On the other hand, as shown in FIGS. 7 and 8, the trigger part 51 provided on the first side wall 14 and the trigger part 51 provided on the second side wall 14 are located at the same position so as to face each other in the thickness direction (vertical direction). It is located in In the example shown in FIG. 5 and the like, three trigger parts 51 are formed on each side of the first side wall 14 and three on each side of the second side wall 14.
Note that the concave groove shape of the trigger portion 51 is such that, for example, the bottom thereof is formed as a concave circular arc portion 51a, and an inclined surface portion 51b that slopes outward so as to widen the groove width from the periphery of the concave circular arc portion 51a, The peripheral edge of the inclined surface portion 51b is connected to the surfaces of the first side wall 13 and the second side wall 14 by a convex arc surface portion 51c.

Of the third side wall 15 and the fourth side wall 16, the third side wall 15 that is disposed on the inner side in the width direction of the vehicle body body 2 when attached to the vehicle body body 2 is smaller than the fourth side wall 16 located on the outer side in the width direction. The axial length is large. The third side wall 15 and the fourth side wall 16 have easily deformable portions 52 formed of slot-shaped through holes along the width direction of the side walls 15 and 16, which are arranged in the axial direction (length direction) of the cylinder 10. Multiple formations are formed.

In the example shown in FIG. 7, five easily deformable parts 52 are formed on the third side wall 15, and among these, the first, third, and fifth easily deformable parts 52 counting from the vehicle body side mounting surface 12 are It is provided at approximately the same axial position as each trigger part 51 of the first side wall 13 and the second side wall 14 which are arranged on the side of the connection part with the third side wall 15 . On the other hand, as shown in FIG. 8, four easily deformable parts 52 are formed on the fourth side wall 16, of which the second and fourth easily deformable parts 52 counting from the vehicle body side mounting surface 12 are the fourth easily deformable parts 52. It is provided at the same axial position as two of the three trigger parts 51 of each of the first side wall 13 and the second side wall 14 which are arranged on the side of the connection part with the side wall 16. There is. That is, when the trigger part 51 deforms, the easily deformable part 52 also deforms at the same axial position, so that axial crushing is not inhibited.

Note that the third side wall 15 located on the inside in the width direction of the vehicle body 2 is formed to have a larger thickness than the fourth side wall 16 located on the outside to prevent it from collapsing against lateral loads caused by offset collisions. ing. Therefore, the through hole that becomes the easily deformable part 52 is smaller than the through hole provided in the fourth side wall 16 so that the both side walls 15 and 16 are axially crushed evenly (without collapsing) due to the deformation in the easily deformable part 52. The through hole provided in the third side wall 15 is formed to be large, and the easily deformable portion 52 of the third side wall 15 is formed to be more deformable than the easily deformable portion 52 of the fourth side wall 16.

Moreover, in the first side wall 13 and the second side wall 14, one of the plurality of trigger parts 51, in the example shown in FIG. In the three trigger parts 51 lined up on the outer side of the trigger part 51, a round hole is formed almost on the extension of the first trigger part 51) so as to expose the connecting edge of the inner wall 17 to the side walls 13 and 14. A notch 53 is formed. This notch 53 is for specifying one trigger part 51 that becomes the starting point of buckling when receiving an impact load, and the trigger part 51 in the vicinity where this notch 53 is provided is 51 (the second trigger part 51 counting from the bumper-side mounting surface 11) is set to deform first.

Further, a reinforcing portion 54 is formed at the end of the third side wall 15 on the side that becomes the vehicle body side mounting surface 12 . This reinforcing part 54 is formed by bending the end of the third side wall 15 into a concave groove shape similar to the trigger part 51, and is open to the vehicle body side mounting surface 12 of the third side wall part 15, and is attached to the cylindrical body. It is formed to extend in the axial direction (lengthwise direction) of 10. The buckling strength of the third side wall 15 is increased within the length range in which the reinforcing portion 54 is provided.

The material and dimensions of the cylindrical body 10 are not necessarily limited, but for example, the cylindrical body 10 may be made of aluminum alloy in the 6000 series or 7000 series, the width W3 of the cylindrical body 10 is 105 mm to 115 mm, and the height of the cylindrical body 10 is The length (vertical dimension) H1 is 45 mm to 55 mm, the length of the third side wall 15 is 30 mm to 40 mm, the thickness of each side wall from the first side wall 13 to the fourth side wall 16 is 1.5 mm to 2.5 mm, The thickness of the side wall 15 is 2 mm to 3 mm, the axial length of the third side wall 15 is 200 mm to 250 mm, the depth of the trigger part 51 is 2 mm to 4 mm, the groove width of the trigger part 51 is 10 mm to 20 mm, and the length of the third side wall 15 is 200 mm to 250 mm. The length is 35 mm to 45 mm, the arrangement pitch of the trigger part 51 is 40 mm to 60 mm, the slot width of the easily deformable part 52 is 5 mm to 10 mm, the slot length is 15 mm to 35 mm, the arrangement pitch of the easily deformable part 52 is 20 mm to 30 mm, The depth of the reinforcing portion is 3 mm to 5 mm, the length of the reinforcing portion is 30 mm to 40 mm, and the groove width of the reinforcing portion is 10 mm to 15 mm.

In the shock absorbing members 1A and 1B configured in this way, when an impact load is received between the bumper reinforcement 3 and the vehicle body 2, the cylindrical body 10 is axially crushed and absorbs the impact energy. protect the occupants by suppressing the transmission of impact energy to the vehicle.
In this case, in the trigger part 51 of the cylindrical body 10, the trigger part 51 in which the notches 53 are lined up begins to deform first, and then the other trigger parts 51 deform one after another so that the deformation propagates. . Since these trigger portions 51 are disposed perpendicular to the direction in which the impact load is applied (the longitudinal direction of the vehicle body 2), they are buckled and deformed so as to narrow their grooves. At this time, in the third side wall 15 and fourth side wall 16 of the cylindrical body 10, the easily deformable part 52 consisting of a through hole is also formed at almost the same position as the trigger part 51, so that the deformation of the trigger part 51 is promoted, Axial collapse is more likely to occur.
The amount of load required to cause axial collapse depends on the cross-sectional shape formed by the four side walls 13 to 16 and the middle wall 17, and the partial deformability of the trigger portion 51, easily deformable portion 52, and notch portion 53. You can adjust it accordingly.

On the other hand, when a large load is applied to the vehicle main body 2 in the lateral direction due to an offset collision, the cylindrical body 10 is difficult to collapse against the lateral load because the width W3 is larger than the vertical dimension H1. Moreover, since the thickness of the third side wall 15 disposed on the inner side in the width direction of the vehicle main body 2 is larger than the other side walls 13, 14, and 16, it is possible to suppress the third side wall 15 from collapsing due to a lateral load. . In this case, since the third side wall 15 and the fourth side wall 16 are provided with the easily deformable portions 52, axial crushing is not inhibited. Further, since the reinforcing portion 54 is formed on the third side wall 15 on the side of the vehicle body 2, the third side wall 15 is prevented from collapsing until the end of the shaft collapse, and an ideal shaft collapse state can be maintained. .

FIG. 9 is a graph schematically showing the relationship between the load required to deform the impact absorbing member and the deformation of the impact absorbing member in the event of an offset collision. A shock absorbing member is assumed, and FIG. 6(b) shows the shock absorbing member of this embodiment. The horizontal axis shows the displacement S, and the vertical axis shows the deformation load F.

As shown in FIG. 9(a), when the load P at the time of starting deformation is large, the cylindrical body is more likely to collapse than when it collapses axially, and when collapse occurs, the subsequent deformation load decreases as shown by the arrow, As a result, the absorbed energy E also becomes smaller.

On the other hand, in the case of this embodiment, the load P when the deformation starts is smaller than that shown in FIG. It sequentially buckles and becomes axially crushed, and as a result, the absorbed energy E also increases.
In this way, the shock absorbing member of this embodiment has a small load when it starts to deform, and then the trigger part undergoes chain buckling deformation and becomes axially crushed, and can absorb large impact energy.

Note that the present invention is not limited to the above embodiments, and changes can be made without departing from the spirit of the present invention.
For example, the number and arrangement of the trigger parts and easily deformable parts can be designed as appropriate. In this case, a plurality of trigger parts are required in order to cause continuous buckling, but at least one easily deformable part is required in order to prevent buckling of the trigger part by the third side wall and the fourth side wall. It is sufficient if there is one.
Moreover, although the cross-sectional shape of the cylinder is formed in the shape of the Chinese character "日", it may also be formed in the shape of the Chinese character "eye" by forming two parallel inner walls.

1A, 1B Shock absorbing member 2 Vehicle main body 2a Mounting surface 10 Cylindrical body 11 Bumper side mounting surface 12 Vehicle body side mounting surface 13 First side wall 14 Second side wall 15 Third side wall 16 Fourth side wall 17 Middle wall 18 Inclined angle part 3 Bumper Reinforcement 31 Bent part 32 Slanted part 40 Mounting plate 51 Trigger part 52 Easily deformable part 53 Notch part 54 Reinforcement part

Claims (8)

A shock absorbing member that is provided between a bumper reinforcement and a vehicle body and has a cylindrical body that is deformed into an axially collapsed state by an axial impact compressive load, the cylindrical body having a plurality of plate-shaped side walls. It has a polygonal cross-sectional shape, and includes a first side wall that becomes an upper surface when attached to the vehicle body, a second side wall that becomes a lower surface, and an intermediate wall that connects the first side wall and the second side wall, A plurality of trigger portions are formed on both sides of the first side wall and the second side wall and are bent in a groove shape along a direction intersecting the axial direction of the cylindrical body, and are spaced apart from each other in the axial direction of the cylindrical body. The trigger portions are formed alternately across the widthwise center of each side wall, and are formed at substantially the same position on the first side wall and the second side wall so as to face each other in the vertical direction. Further, the trigger portion of the first side wall opens one end of the groove to a side edge of the first side wall, and the trigger portion of the second side wall opens the one end of the groove to the side edge of the second side wall. A third side wall that is open to a side edge and is located on the inside in the width direction of the vehicle body when attached to the vehicle body between the first side wall and the second side wall, and a third side wall that is located on the outside in the width direction of the vehicle body. The fourth side wall is characterized in that at least one easily deformable portion is formed so as to be lined up at approximately the same position as any of the trigger portions disposed on the side portions on the connection portion side with these side walls. Shock absorbing member. The shock absorbing member according to claim 1, wherein the easily deformable portion is a through hole. The cylindrical body is attached obliquely with respect to the front-rear direction of the vehicle body, and the mounting surface of the cylindrical body to the bumper reinforcement is such that when attached to the bumper reinforcement, the trigger portion is attached to the vehicle body. The shock absorbing member according to claim 1 or 2, wherein the shock absorbing member is inclined so as to be arranged along the width direction of the main body. A notch portion is disposed on an extension of the trigger portion in at least one of the first side wall and the second side wall to expose a connecting edge of the middle wall to the side wall. The shock absorbing member according to any one of claims 1 to 3. The shock absorbing member according to any one of claims 1 to 4, wherein a distance between the third side wall and the fourth side wall is larger than a distance between the first side wall and the second side wall. . The shock absorbing member according to any one of claims 1 to 5, wherein the thickness of the third side wall is greater than the thickness of the fourth side wall. 7. The shock absorbing member according to claim 6, wherein the easily deformable portion of the third side wall is easier to deform than the easily deformable portion of the fourth side wall. A reinforcing portion formed by bending the third side wall into a concave groove shape in the thickness direction is formed along the length direction of the cylindrical body at the end of the third side wall on the side where the third side wall is attached to the vehicle body. The shock absorbing member according to any one of claims 1 to 7, characterized by: