WO2013161339A1

WO2013161339A1 - Impact-absorbing structure

Info

Publication number: WO2013161339A1
Application number: PCT/JP2013/051841
Authority: WO
Inventors: 修久奥田; 三浦　寿久
Original assignee: トヨタ車体株式会社
Priority date: 2012-04-24
Filing date: 2013-01-29
Publication date: 2013-10-31
Also published as: JP2015155704A

Abstract

An impact-absorbing structure provided with: timber (12) that is compressed in the fiber direction when subjected to an impact load and crushed to absorb the impact; a cylindrical member (20) formed in the shape of a square tube, the cylindrical member (20) accommodating the timber such that the fiber direction is consistent with the axial direction of the square tube shape; and a receiving member (32) for receiving one axial-direction end of the timber (12) and the cylindrical member. The cylindrical member (20) splits from the one end along a ridgeline (23r) of the square tube when the timber (12) is crushed.

Description

Shock absorption structure

The present invention relates to an impact absorbing structure for absorbing an impact received on a vehicle at the time of a collision or the like.

Japanese Unexamined Patent Publication No. 2001-182769 discloses a technique related to an impact absorbing structure for absorbing an impact received on a vehicle, and a similar structure is also shown in FIG. The shock absorbing member 100 is used for a bumper reinforcement attaching portion to a vehicle body, and includes a rectangular metal hollow member 102 and a piece of wood 105 accommodated in the hollow member 102. The impact load F input to the bumper reinforcement at the time of the collision of the automobile is applied to the impact absorbing member 100, and the hollow member 102 and the wood piece 105 are crushed as shown in FIG.

Since the wooden piece 105 is confined in the hollow member 102, the crushed wooden piece 105 starts to be densified next, and it becomes difficult to absorb the impact any more. Therefore, it is necessary to delay the start of the densification stage of the wooden piece 105 and to secure a large amount of crushing as the entire shock absorbing member 100.

According to one aspect of the present invention, wood that absorbs an impact by being compressed and crushed in the fiber direction when subjected to an impact load, and an axial direction of the square tube shape that is formed in a rectangular tube shape. Thus, an impact absorbing structure including a cylindrical member that accommodates the wood and a receiving member that receives one end in the axial direction of the cylindrical member and the wood is obtained. The cylindrical member is torn along the ridgeline of the square tube from the one end when the wood is crushed.

It is a schematic plan view of a vehicle front part provided with the impact absorption structure which concerns on the 1st Embodiment of this invention. It is a plane sectional view showing the shock absorption structure of FIG. It is a perspective view of the cylindrical member and wood which comprise the shock absorption structure of FIG. It is a perspective view showing a mode before a cylindrical member and wood are crushed by an impact load. It is a perspective view showing a mode that a cylindrical member and wood are crushed by an impact load. It is a perspective view showing a mode that a cylindrical member and wood are crushed by an impact load. It is a perspective view showing a mode that a cylindrical member and wood are crushed by an impact load. It is a perspective view showing a mode that a cylindrical member and wood are crushed by an impact load. It is a schematic cross section of the cylindrical member and wood which comprise the said shock absorption structure. It is a schematic cross section showing a mode that a cylindrical member and wood are crushed by an impact load. It is a schematic cross section showing a mode that a cylindrical member and wood are crushed by an impact load. It is a graph showing the relationship between the impact load added to the impact-absorbing structure of FIG. 1, and the amount of collapse of a cylindrical member and wood. It is a perspective view which shows the form of the convex member which concerns on 2nd Embodiment. It is a perspective view which shows the impact-absorbing structure using the convex member of FIG. It is a perspective view which shows a mode that a cylindrical member is torn and expands by a convex member. It is a perspective view which shows a mode that the crushed wood is discharged | emitted from the inside of a cylindrical member. It is a graph which shows the relationship between compression load and the amount of crushing. It is a figure which shows the deformation | transformation form of a convex member. It is a figure which shows another modification of a convex member. It is a schematic cross section of a conventional impact absorbing member. It is a schematic cross section showing a mode that the impact-absorbing member of FIG. 20 is crushed. It is a graph showing the relationship between the impact load added to the impact-absorbing member of FIG. 21, and the amount of collapse of a cylindrical member and wood.

The impact absorbing structure described below is a structure that is provided in a vehicle and can absorb an impact load received during a vehicle collision. The shock absorbing structure 10 can be disposed, for example, between the left and right side members 5 constituting the frame of the vehicle 2 and the bumper reinforcement 3 of the front bumper (not shown) as shown in FIG. The front and rear and the left and right shown in the following description and the drawings correspond to the front and rear and the left and right of the vehicle provided with the shock absorbing structure as shown in FIG.

[First Embodiment]
As shown in FIGS. 2 and 3, the shock absorbing structure 10 according to the first embodiment is provided at the tip of the cylindrical member 20, the wood 12 accommodated in the cylindrical member 20, and the side member 5. And a receiving member 30 that receives an impact load F through the wood 12 and the tubular member 20. The cylindrical member 20 is made of, for example, an aluminum alloy by extrusion molding, and a cross section perpendicular to the axis is formed in a regular hexagonal shape as shown in FIG. Furthermore, on the base end side (rear end side) of the cylindrical member 20, a cut 23 is formed from the end surface of the cylindrical member 20 along the ridge line 23r. The length of the cylindrical member 20 in the axial direction is set to about 70 mm, the width (diameter of the hexagonal circumscribed circle) is set to about 28 mm, and the wall thickness is set to about 0.8 mm. Further, the length dimension of the notch 23 is set to about 5 mm, and the width dimension is set to about 1.5 mm. The length dimension of the notch 23 is preferably set to 3 to 20% of the length dimension of the cylindrical member 20 in the axial direction.

As shown in FIGS. 2 and 3, the wood 12 constituting the shock absorbing structure 10 has a hexagonal column shape having a cross-sectional shape equal to the cross-sectional shape (cross-sectional shape) perpendicular to the axis of the cylindrical member 20. It is formed and is set to a length dimension (about 70 mm) substantially equal to the length dimension of the cylindrical member 20 in the axial direction. The wood 12 is formed in a hexagonal column shape so that the axial center direction of the annual ring 12k extends in the longitudinal direction (axial direction). For this reason, when the wood 12 is housed in the tubular member 20, the axial center direction of the annual ring 12 k of the wood 12 becomes substantially coincident with the axial direction of the tubular member 20. That is, the wood 12 is accommodated in the cylindrical member 20 so that the axial center direction of the annual ring 12k is along the axial direction of the cylindrical member 20. For this reason, the strength of the wood 12 in the axial direction increases, and a large impact load F can be received by the wood. As the wood 12, for example, cedar is preferably used. The width dimension of the wood 12 (diameter dimension of the hexagonal circumscribed circle) is set to a value (about 28 mm) at which the clearance between the outer peripheral surface of the wood 12 and the inner peripheral surface of the tubular member 20 is about 0.25 mm. ing.

As shown in FIG. 2, the receiving member 30 constituting the shock absorbing structure 10 receives a load from wood and a cylindrical member on a flat receiving surface 32 provided on the front side. The receiving member 30 of the present embodiment is a flat plate member having a large thickness. The receiving members 30 are attached to the front ends of the left and right side members 5 of the vehicle 2 so that the receiving surface 32 faces the back surface 3 b of the bumper reinforcement 3.
The end surface of the cylindrical member 20 and the wood 12 on the rear end side (the notch 23 side) abuts on the receiving surface 32 of the receiving member 30. Here, as shown in FIG. 2, the receiving member 30 is formed with a plurality of screw holes 35 (one in the figure) penetrating to the position where the end face of the wood 12 abuts. The wood 12 is fixed to the receiving member 30 by screws 37 from the side member 5 side using 35.

Furthermore, the front end side in the axial direction of the cylindrical member 20 is fixed to the back surface 3b of the bumper reinforcement 3 by, for example, welding. Specifically, the receiving member 30 is attached to the front end of the side member 5, the rear end side of the wood 12 is fixed to the receiving member 30 with a screw 37, and the front end side of the tubular member 20 is connected to the back surface 3 b of the bumper reinforcement 3. The shock absorbing structure 10 is installed between the bumper reinforcement 3 of the vehicle 2 and the left and right side members 5 by welding or the like.

When the vehicle 2 collides forward and an impact load F is applied to the wood 12 and the cylindrical member 20 of the impact absorbing structure 10 from the axial direction via the bumper reinforcement 3, the impact load F is applied as shown in FIG. When the allowable value H is exceeded, the wood 12 and the tubular member 20 are crushed in the axial direction. Here, FIG. 12 shows the crushing amount [mm] between the wood 12 and the cylindrical member 20 of the shock absorbing structure 10 as the horizontal axis, and the impact load F [N] applied to the wood 12 and the like from the axial direction as the vertical axis. It is the graph represented to.

Specifically, as shown in FIGS. 4 to 5 (FIGS. 9 and 10) due to the impact load F exceeding the allowable value H, the rear end side of the wood 12 in contact with the receiving surface 32 of the receiving member 30 is in the axial direction. The wall portion 20b divided by the notch 23 is deformed so as to bulge outward in the radial direction in the vicinity of the end surface on the rear end portion side of the tubular member 20 (see FIG. 5). Then, as the crushing of the wood 12 and the tubular member 20 proceeds, the bulging portion of the wall portion 20b of the tubular member 20 is crushed into a bowl shape as shown in FIG. Will come into contact. In other words, the wall portions 20b of the cylindrical member 20 that are divided by the notches 23 tend to expand in a direction away from each other. As a result, a force is applied to the ridge line 23r of the tubular member 20 to tear the ridge line 23r from the notch 23.

From this state, when the crushing of the wood 12 and the cylindrical member 20 proceeds, the ridge line 23r of the cylindrical member 20 is torn starting from the notch 23 as shown in FIGS. Further, the crushed portion 12c of the wood 12 moves radially outward along the receiving surface 32 of the receiving member 30, and presses the cylindrical member 20 radially outward from the inside. As a result, the divided wall portion 20 b of the cylindrical member 20 is pushed by the crushed portion 12 c of the wood 12, and expands radially outward along the receiving surface 32 of the receiving member 30.

Further, as the crushing of the wood 12 and the tubular member 20 further proceeds, as shown in FIGS. 8 and 11, the tear of the ridge line 23r of the tubular member 20 is increased, and the tubular member 20 is divided. The wall portion 20b extends in the radial direction along the receiving surface 32 so that the wall portion 20b is spirally wound. Further, the crushed portion 12 c of the wood 12 is discharged to the outside in the radial direction of the tubular member 20 along the receiving surface 32.

According to the present embodiment, the tubular member 20 is such that the wall portion 20b is torn along the ridge line 23r from one end that contacts the receiving surface 32 due to the impact load F. Further, the wood 12 crushed by the impact load F inside the cylindrical member 20 tends to move radially outward along the receiving surface 32. For this reason, the divided wall portion 20b of the cylindrical member 20 is pushed by the crushed wood 12 and spreads radially outward by tearing. Therefore, as the crushed wood 12 progresses, the crushed wood 12 protrudes radially outward of the tubular member 20 along the receiving surface 32. As a result, the crushed wood 12 is less likely to be clogged in the tubular member 20, and the densification of the wood 12 in the tubular member 20 is delayed. As a result, as compared with the conventional case, a large amount of deformation can be secured with the wood 12 having the same length and the amount of shock absorption is increased. In the structure actually manufactured according to this embodiment, the entire length of 70 mm was crushed by about 50 mm as shown in FIG. On the other hand, in the conventional structure, as shown in FIG. 22, the cylindrical member 20 is deformed without bellows and the crushed portion 12c of the wood 12 is confined in the cylindrical member 20, so that the total length of 70 mm is about 40 mm. Only deforms.

In addition, since the wall portion 20b of the tubular member 20 is torn along the ridge line 23r from one end of the tubular member 20 with a simple structure by the notch 23, the impact absorbing performance can be improved without much cost increase.

Furthermore, the wood 12 accommodated in the cylindrical member 20 is formed so that the outer peripheral surface thereof is in contact with the inner peripheral surface of the cylindrical member 20 over the entire circumference. Therefore, when the timber 12 is crushed, the divided wall portion 20b of the cylindrical member 20 is pushed by this and easily spreads outward in the radial direction.

As a modification of the present embodiment, instead of providing the notch 23, it is also possible to provide a thin portion (for example, about 0.4 mm) thinner than the surrounding portion from one end of the cylindrical member 20 along the ridge line 23r. . The thin-walled portion also functions as a fragile portion serving as a starting point at which the cylindrical member tears in the same manner as the cut 23.

[Second Embodiment]
In the second embodiment, a convex member is provided between one end of the tubular member 20 and the receiving member 30 in the direction of the ridge line 23r of the tubular member 20. The convex member can be constituted by a plurality of wedge-shaped bodies 41 as shown in FIG. 13, for example, and these are provided for each ridge line 23r of the cylindrical member 20 as shown in FIG. The wedge-shaped body 41 is formed integrally with the receiving surface 32 of the receiving member 30. The wedge-shaped body 41 can be formed of metal. As shown in FIG. 14, the wedge-shaped body 41 is formed so that an end edge 43 facing the ridge line 23 r of the tubular member 20 intersects the tubular member 20 and becomes narrower toward the end edge 43. ing. The wedge-shaped body 41 may have a trapezoidal cross section in which the edge 43 is chamfered, a wedge having a sharp triangular cross section, or an intermediate cross sectional shape in which the edge 43 is rounded. .

While the wood 12 is compressed, the wedge-shaped body 41 continues to apply a force to the ridge line 23r of the cylindrical member 20 at its edge 43, and the cylindrical member 20 is moved from the one end along the ridge line 23r as shown in FIG. Split into a plurality of wall portions 20b. Since each wedge-shaped body 41 is tapered toward the end edge 43 while forming inclined surfaces 45 on both sides, the wall portion 20b divided by splitting slides the inclined surfaces 45 of the two wedge-shaped bodies 41 sandwiching the wall portions 20b in the radial direction. Expand outward. A part of the crushed wood 12 is discharged out of the tubular member 20 from between the expanded wall portion 20b and the receiving member as shown in FIG. The discharging action of the wood 12 delays the densification of the crushed wood 12 as in the first embodiment, and ensures a large amount of deformation of the entire shock absorbing member. In the shock absorbing structure 10 of the first embodiment, the bellows deformation occurred in the later stage of deformation of the cylindrical member 20 as can be seen from the load fluctuation of FIG. On the other hand, when an experiment was performed with a sample manufactured according to the second embodiment, a flat load variation was confirmed as shown in the results of FIG. 17, and the deformation of the cylindrical member 20 was progressing only by spreading. I understood. As the proportion of the expansion deformation increases with respect to the bellows deformation, the wood 12 is more easily discharged and a large amount of deformation is ensured, and the shock absorbing performance is improved.

Also, the shape of the wedge-shaped body 41 bites into the crushed wood 12 firmly. In other words, the crushed wood 12 enters a gap having a complicated shape formed by the wedge-shaped body 41 therebetween. Thereby, the timber 12 and the receiving member are fixed to each other, and the shock absorbing structure 10 is hardly decomposed. Therefore, according to this shock absorbing structure 10, even if the structure is deformed to some extent by the first collision, it is possible to cope with further collision that may occur subsequently.

As a modification of the present embodiment, the convex member can be constituted by a ridge line 53 of a pyramid 51 provided with the top 57 facing the wood 12 as shown in FIG. If the cylindrical member 20 is a hexagonal cylinder shape as shown in the figure, the pyramid 51 may be a hexagonal pyramid. Further, the pyramid 51 may be changed to a truncated pyramid having a chamfered top 57 or an intermediate form in which the top 57 is rounded. Since the pyramid 51 has a slope 55 extending radially from the top 57, the crushed piece of wood slides in the radial direction when it receives a further compressive load, and pushes the torn tubular member 20 to expand outward. While being opened, the crushed piece of wood itself is easily discharged out of the cylindrical member 20.

As another modification, the convex member can be embedded in one end of the wood 12 in advance as shown in FIG. If the convex member is firmly embedded in the wood 12 so as to be fixed to the wood 12, the convex member does not need to be fixed to the receiving member. In this example, the wedge-shaped body 41 provided with respect to each ridgeline 23r of the cylindrical member 20 is integrally coupled at the center so as to form a star shape as a whole. Further, the convex member has an intermediate form between the pyramid 51 and the combined wedge-shaped body 41, that is, a form such as a grapefruit squeezer for providing a valley on the side surface between the ridges 53 of the pyramid 51. It can also be configured.

In addition to the convex member of the second embodiment, the fragile portion of the first embodiment may be provided on the ridge line 23r of the cylindrical member 20, so that the cylindrical member 20 is more easily torn.

[Example of change]
While embodiments of the present invention have been described with reference to the above aspects, it will be apparent to those skilled in the art that many substitutions, improvements, and modifications can be made without departing from the scope of the invention. Accordingly, embodiments of the invention may include all permutations, improvements and modifications that do not depart from the spirit and scope of the appended claims. The embodiment of the present invention is not limited to the specific aspect described above, and can be modified as follows, for example.

Instead of attaching the receiving member 30 to the front end of the side member 5, the side member 5 itself can be used as a receiving member, and the front end surface thereof can be used as a receiving surface. Further, the receiving member 30 may be provided on the bumper reinforcement 3 side, not on the vehicle frame side member such as the side member 5. In this case, a cut 23 or a thin portion is provided on the front end side of the cylindrical member 20. Moreover, although the example which forms the cylindrical member 20 and the timber 12 in a cross-sectional hexagon was shown, it is also possible to form in polygons other than a hexagon. Furthermore, although the example which uses the extrusion molding product of aluminum for the cylindrical member 20 was shown, the pultrusion molding product of aluminum may be sufficient. Moreover, you may form a cylindrical member from metals other than aluminum. Further, the shock absorbing structure 10 can be provided on a part of a vehicle frame.

Claims

Wood that absorbs impact by being compressed and crushed when subjected to impact load,
A cylindrical member that accommodates the wood so that the fiber direction is the axial direction of the rectangular tube formed in a rectangular tube shape;
A receiving member for receiving one end in the axial direction of the tubular member and the wood,
The cylindrical member is an impact absorbing structure that is torn along the square cylindrical ridge line from the one end when the wood is crushed.
The shock absorbing structure according to claim 1,
An impact absorbing structure in which the cylindrical member that is torn when the wood is crushed expands radially outward.
The shock absorbing structure according to claim 2,
An impact absorbing structure that is discharged to the outside of the cylindrical member from between the cylindrical member and the receiving member in which a part of the crushed wood is expanded.
The shock absorbing structure according to any one of claims 1 to 3,
A convex member provided toward the ridge line of the cylindrical member and formed so as to give the ridge line a force that the cylindrical member tears along the ridge line from the one end while the wood is being compressed. Shock absorbing structure with.
The shock absorbing structure according to claim 4,
The said convex member is an impact-absorbing structure formed so that an edge may be formed in the direction which crosses the said cylindrical member, and it may become thin toward this edge.
The shock absorbing structure according to claim 4 or 5, wherein
The shock absorbing structure is configured by a wedge-shaped body having a trapezoidal cross section or a triangular cross section provided for each ridgeline of the cylindrical member.
The shock absorbing structure according to claim 4 or 5, wherein
The convex member is a shock absorbing structure constituted by a pyramid or a ridge line of a truncated pyramid provided with the top facing the wood.
The shock absorbing structure according to any one of claims 4 to 7,
The impact absorbing structure in which the convex member is formed integrally with the receiving member.
The shock absorbing structure according to any one of claims 4 to 8,
The convex member is an impact absorbing structure embedded in one end of the wood.
The shock absorbing structure according to any one of claims 1 to 9,
The shock absorbing structure in which the tubular member is provided with a fragile portion along the ridge line of the rectangular tube shape from the one end.
The shock absorbing structure according to any one of claims 1 to 10,
The wood is an impact absorbing structure formed so that the outer peripheral surface of the wood is in contact with the inner peripheral surface of the cylindrical member over the entire periphery.