JP5056191B2 - Energy absorbing member - Google Patents

Description

  The present invention relates to an energy absorbing member that absorbs energy by plastic deformation when a compressive load is input.

  For example, Patent Document 1 discloses an energy absorbing member that constitutes a part of a vehicle frame and is used to absorb an impact load at the time of a collision. The energy absorbing member includes a cylindrical main body and a concavo-convex portion formed at an intermediate position in the cylinder axis direction on the outer peripheral surface of the main body. In this energy absorbing member, when a compressive load in the cylinder axis direction is input to the main body, the main body is bent and deformed relatively large in the cylinder axis direction starting from the uneven portion, thereby absorbing energy. I am doing so.

For example, Patent Document 2 discloses an energy absorbing member that includes a large number of cavities as a panel-shaped energy absorbing member and absorbs energy by collapsing the cavities when an impact is input.
JP 2005-29064 A JP 2004-306682 A

  By the way, the conventional energy absorbing member disclosed in Patent Document 1 has a relatively large bending deformation of the main body, and therefore, a portion other than the deforming portion, that is, most of the main body is hardly involved in energy absorption. For this reason, there exists a problem that the amount of energy absorption (weight efficiency of energy absorption) with respect to a member weight is comparatively low.

  Due to such low weight efficiency, when the energy absorbing member is used to constitute a part of the vehicle frame, for example, the fuel consumption is deteriorated as the vehicle weight increases.

  This invention is made | formed in view of this point, The place made into the objective is to provide the energy absorption member with high weight efficiency of energy absorption.

  According to an aspect of the present invention, the energy absorbing member includes a cylindrical main body having a peripheral wall, and the peripheral wall has an inner wall positioned radially inward as viewed in a longitudinal section thereof, and a radially outer side. And a plurality of structures including an outer wall facing the inner wall at a predetermined interval and stacked in the cylinder axis direction, and compressed in the cylinder axis direction with respect to the main body When a load is input, at least one of the inner wall and the outer wall in each structure is buckled.

  According to this configuration, since the peripheral wall of the cylindrical main body is configured by laminating a plurality of structures including the inner wall and the outer wall in the cylindrical axis direction, a compressive load in the cylindrical axis direction is applied to the main body. When is inputted, at least one of the inner wall and the outer wall in each structure is buckled and deformed. As a result, a large number of fine bucklings occur in the cylinder axis direction, so that deformation occurs over a wide range of the energy absorbing member, and the amount of energy absorbed by complicated deformations occurring stably. Will also increase. As a result, this energy absorbing member greatly improves the weight efficiency of energy absorption.

Each structure, the inner wall and while being partitioned by an outer wall, further including a liquid chamber the liquid is sealed therein.

  By doing so, since the stress (buckling stress) when buckling occurs in each structure increases, the amount of energy absorbed by the energy absorbing member increases.

According to another aspect of the present invention, the load of the body - such displacement characteristic has a predetermined characteristic, the configuration of the structure that have been modified by stacking position of the cylinder axis.

  In other words, since this energy absorbing member has a structure in which a plurality of structures are stacked in the cylinder axis direction, the structure of each structure is changed according to the position in the cylinder axis direction where the structures are arranged. The load-displacement characteristic of the main body can be easily changed.

Then, the rigidity of the input side of the compressive load in the body, that is set lower than the rigidity of the opposite side.

  In this way, when the compressive load is input, the compressive load input side of the main body becomes buckled and deformed relatively easily. Therefore, in the load-displacement characteristics of the main body, the initial load peak value (the main body undergoes plastic deformation). It is possible to reduce the load value when starting.

  The height of each structural body in the cylinder axis direction may be gradually lowered from the compression load input side toward the opposite side.

  By doing so, on the compression load input side of the main body, the length of the inner wall and the outer wall of each structure in the cylinder axis direction is relatively long, so that the buckling stress is reduced. That is, the rigidity on the input side of the compression load in the main body is lower than the rigidity on the opposite side.

  Moreover, each structure on the input side of the compressive load may have a slit extending in a direction perpendicular to the cylinder axis on the outer wall or the inner wall. In addition, the slit may penetrate the outer wall or the inner wall in the thickness direction, or may not penetrate. By forming such slits, the rigidity on the input side of the compression load in the main body becomes lower than the rigidity on the opposite side.

According to still another aspect of the present invention, the thickness of the inner wall and the thickness of the outer wall in each structure are different from each other, and the structure has a cylindrical shaft formed by a relatively thin wall between the outer wall and the inner wall. that is stacked so as to alternate in direction.

  In this way, when a compressive load is input, the inner wall and the outer wall of each structure are alternately buckled in the cylinder axis direction, and the main body is stably crushed in the cylinder axis direction. As a result, the load fluctuation in the load-displacement characteristic of the main body (the fluctuation of the load while the main body is compressively deformed) is reduced.

  The main body has an inner cylinder and an outer cylinder arranged coaxially with each other, and a longitudinal section between the inner cylinder and the outer cylinder extends in a cylinder axis direction in a corrugated manner, and an outer peripheral surface of the inner cylinder and an inner circumference of the outer cylinder It is good also as being comprised by mutually joining the corrugated sheet which contact | abuts alternately with respect to a surface.

  The main body has a plurality of annular joints in which an inner cylinder and an outer cylinder, each having a wall thickness periodically changed in the cylinder axis direction, are arranged coaxially with each other and at a predetermined interval in the cylinder axis direction. The inner cylinder and the outer cylinder may be joined to each other through a portion.

  With these configurations, it is possible to easily manufacture a main body (energy absorbing member) in which structures are laminated so that relatively thin walls alternate between the outer wall and the inner wall in the cylinder axis direction. Become.

  The main body is arranged so that a cylinder axis direction thereof coincides with a vehicle front-rear direction and constitutes a part of a front frame of the vehicle, and a collision load input to the vehicle is applied to an inner wall of each structure and Absorption may be achieved by buckling deformation of at least one of the outer walls.

  As described above, since this energy absorbing member has a high energy absorption weight efficiency, when used as a vehicle frame member, there is an advantage that the vehicle weight is reduced.

  As described above, according to the present invention, an energy absorbing member is produced by generating a lot of fine buckling when a compressive load in the cylinder axis direction is input to a main body configured by laminating a plurality of structures. Over a wide range, complicated deformations occur stably, and the weight efficiency of energy absorption can be greatly improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

(Embodiment 1)
FIG. 2 shows the energy absorbing member 10 according to the first embodiment of the present invention. As shown in FIG. 1, the energy absorbing member 10 is, for example, in the vehicle front-rear direction at the vehicle width direction both side positions at the front of the vehicle. Are used as a crush can 92 interposed between the front end portion of the front side frame 91 and the front end of the front side frame 91 and the bumper reinforcement.

  The energy absorbing member 10 includes a cylindrical main body 11 constituted by a peripheral wall 12. The main body 11 is a cylinder in the present embodiment, but is not limited to a cylinder. For example, the cross-sectional shape of the main body 11 can be appropriately set such as an elliptical shape or a rectangular shape.

  As shown in FIG. 3 in an enlarged manner, the peripheral wall 12 is formed by laminating a large number of tubes 13 having a substantially rectangular cross section in the cylinder axis direction. In other words, the peripheral wall 12 of the main body 11, when viewed in its longitudinal section, is located radially inward with the inner wall 14 positioned radially outward and spaced apart from the inner wall by a predetermined distance. And a plurality of structures (tubes 13, hereinafter also referred to as structures 13) including the opposing outer walls 15 are stacked in the cylinder axis direction. The structure 13 is not limited to a substantially rectangular cross section and can be set as appropriate. For example, as shown in FIG. 4, it may have a circular cross section. In this case, the boundary between the inner wall and the outer wall of the structure 13 is not always clear, but in the structure 13 having a circular cross section, the inner part corresponds to the inner wall and the outer part corresponds to the outer wall.

  The energy absorbing member 10 having the above-described configuration can be manufactured by various molding methods. As an example, as shown in FIGS. 4 (a) and 4 (b), the long tube 13 is wound around the outer peripheral surface of a core material 81 having a circular cross section without any gap, and the stacked tubes 13 are brazed together. It is possible to manufacture by bonding together by a technique such as bonding with an adhesive (note that the core material 81 is removed before or after the tube 13 is bonded).

  Although not shown, the cylindrical energy absorbing member can also be formed by winding a long tube around a relatively thin cylindrical base material (skin material) and joining them together. 10 can be manufactured.

  In addition, although not shown in the figure, the long tube is not wound, but the tube-shaped tube is stacked so as to be coaxial and then joined to each other. The energy absorbing member 10 can be manufactured.

  The annular tube does not necessarily have to be endless. In other words, the annular tube may be substantially C-shaped with a cut. When stacking the C-shaped tubes, it is preferable to stack the tubes while shifting the circumferential position of the cuts so that the cuts do not continue in the cylinder axis direction.

  As described above, when the energy absorbing member is manufactured using the tube 13, the material of the main body 11 may be any material as long as it is a material capable of manufacturing the tube 13. Therefore, the material of the main body 11 can be appropriately selected from various materials used as members constituting a vehicle frame, such as steel and aluminum.

  When the main body 11 is made of aluminum, the tube 16 wound around the core 81 is made of a relatively high melting point aluminum material 16a and a relatively low melting point aluminum material 16b as shown in FIG. You may comprise what is called a clad material. By doing so, joining of the tubes 16 is facilitated, so that the energy absorbing member can be easily manufactured.

  As shown in FIG. 6, when a compressive load is input to the energy absorbing member 10 having the above configuration (see the white arrow in FIG. 6), the inner wall 14 and the outer wall 15 of each structure 13 are buckled and deformed. As a result (see the black arrow in FIG. 6), many fine buckling deformations occur. That is, in the energy absorbing member 10, complicated deformation occurs over a wide range of the main body 11 when a compression load is input. As a result, the energy absorbing member 10 can improve the weight efficiency of energy absorption compared to the conventional case.

  In addition, you may make a surrounding wall into a double structure according to the energy absorption amount requested | required of an energy absorption member. For example, as shown in FIG. 7, it is possible to manufacture an energy absorbing member having a peripheral wall with a double structure by winding the long tube 13 around the core material 81 twice. By doing so, the amount of energy that can be absorbed by the energy absorbing member can be increased.

(Embodiment 2)
FIG. 8 shows an energy absorbing member 20 according to the second embodiment. In the energy absorbing member 20, the same components as those in the energy absorbing member 10 shown in FIG. In the energy absorbing member 20, a space in the tube 13 is sealed, and a liquid chamber 17 is configured by filling the space with a liquid.

  When a compressive load is input to one end of the energy absorbing member 20 in the cylinder axis direction, the inner wall 14 and the outer wall 15 of each structure (tube 13) are buckled and deformed, similarly to the energy absorbing member 10. However (see FIG. 6), the liquid (that is, incompressible fluid) is sealed in the liquid chamber 17, so that the buckling stress increases. For this reason, the energy absorption amount of the energy absorption member 20 can be increased correspondingly.

(Embodiment 3)
FIG. 9 shows an example of load-displacement characteristics of the energy absorbing member. The characteristics required when the energy absorbing member is applied to the vehicle front side frame 91 or the like as described above are as follows: (1) Peak value of initial load (starting plastic deformation) (2) The load fluctuation (the fluctuation of the load while the main body is compressively deformed) is small, (3) The target average load is obtained, (4) Crushing There are roughly four characteristics: a long stroke. Among these, (1) and (2) are mainly for suppressing large load fluctuations from acting on the vehicle occupant, and (3) and (4) are mainly set according to the specifications of the vehicle. This is related to the design value of the energy absorbing member.

  FIG. 10 shows a configuration of the energy absorbing member 30 according to the third embodiment, and this energy absorbing member 30 is mainly intended to reduce the peak value of the initial load in the load-displacement characteristics shown in FIG. . Note that the same components as those of the energy absorbing member 10 shown in FIG. 3 and the like are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

  Specifically, in this energy absorbing member 30, the rigidity of the load input side (upper side in FIG. 10) portion of the main body 31 is relatively lowered. That is, the portion on the load input side, in the illustrated example, the upper two-stage structure (tube) 33 is formed with a lateral slit 35a penetrating the inside and outside of the outer wall 35 thereof. With this lateral slit 35a, the buckling stress of the structure 33 constituting the load input side portion is reduced. Therefore, when a compressive load is input to the main body 31, the load input side portion of the main body 31 is buckled and deformed relatively easily, so that the peak value of the initial load is lowered.

  In addition, what is necessary is just to set suitably the step number of the structure 33 in which the horizontal slit 35a was formed. Even if the lateral slit does not penetrate the outer wall 35 or is only recessed from the outer surface of the outer wall 35, the buckling stress of the structure can be reduced. Further, the lateral slit may be formed in the inner wall 34, or may be formed in both the outer wall 35 and the inner wall 34.

(Embodiment 4)
Since the energy absorbing member is configured by stacking a plurality of structures in the cylinder axis direction, as shown in FIG. 11, the height (a), the width (b), and the thickness of the inner wall 44 in the structure 43. By appropriately adjusting the dimensions of (c) and the thickness (d) of the outer wall 45, it is possible to change the load-displacement characteristics (see FIG. 9) of the energy absorbing member and obtain desired characteristics. .

  As an example, FIG. 12 shows a configuration of the energy absorbing member 40 in which the peak value of the initial load decreases. In this energy absorbing member 40, the structure (tube) 43 stacked in the cylinder axis direction so as to form the main body 41 is opposite to the compression load input side (upper side in FIG. 12) (lower side in FIG. 12). The height (a) (see FIG. 11) gradually decreases toward the end.

  By doing this, in the portion of the main body 41 on the input side of the compressive load, the height of the outer wall 45 and the inner wall 44 of the structure 43 is relatively high, so that the buckling stress is lowered, while the non-input side of the main body 41 In the portion, since the height of the outer wall 45 and the inner wall 44 of the structure 43 is relatively low, the buckling stress becomes high. Accordingly, the peak value of the initial load is lowered.

  As another example, FIG. 13 shows a configuration of an energy absorbing member 50 that reduces the load fluctuation. The energy absorbing member 50 has different thicknesses (c) and (d) (see FIG. 11) between the outer wall 55 and the inner wall 54 of each structure (tube) 53, and the thinner wall is The outer wall 55 and the inner wall 54 are set alternately in the cylinder axis direction.

  When the thicknesses of the outer wall 55 and the inner wall 54 in each structure 53 are different, when a compressive load is input, the relatively thin wall is more likely to buckle. In the energy absorbing member 50, since the walls that are easily buckled and deformed are alternately arranged in the cylinder axis direction, the structures 53 are surely buckled and deformed in order in the cylinder axis direction. . As a result, the entire energy absorbing member 50 (main body 51) is stably buckled and the weight efficiency of energy absorption is increased.

  As shown in FIG. 13, such an energy absorbing member 50 is manufactured by stacking a large number of annular tubes 53 formed so that the inner wall 54 and the outer wall 55 have different thicknesses in the cylinder axis direction as described above. It is possible.

  Unlike this, for example, as shown in FIG. 14, a relatively thin inner cylinder 56 and an outer cylinder 57 are prepared and arranged coaxially, and a longitudinal section is formed in a waveform between them. An energy absorbing member having the same configuration and the same function as described above can be obtained by arranging a corrugated plate 58 having a constant thickness and joining the corrugated plate 58 and the inner tube 56 or the outer tube 57 by welding or the like. It is possible to manufacture. That is, in this configuration, the portion where the inner tube 56 or the outer tube 57 and the corrugated plate 58 are joined is a relatively thick wall, and the opposite side is the inner tube 56 or the outer tube 57, The portion where the corrugated plate 58 is not joined becomes a relatively thin wall, and the thin wall is alternately arranged between the outer wall 55 and the inner wall 54 in the cylinder axis direction.

  Further, as shown in FIG. 15, for example, by joining two cylindrical members 61 and 62 formed in a predetermined shape by extrusion molding, energy having the same configuration and the same function as described above. It is possible to manufacture an absorbent member.

  That is, the inner cylinder 61 in which the relatively thick wall portions 61a and the relatively thin wall portions 61b are alternately arranged in the cylinder axis direction, and similarly the thick wall portion 62a and the thin wall portion. An outer cylinder 62 configured by alternately arranging 62b in the cylinder axis direction is prepared. An annular joint 61c that protrudes outward in the radial direction from the outer peripheral surface is integrally formed at the boundary portion where the thickness changes in the inner cylinder 61, and the thickness changes in the outer cylinder 62. An annular joint 62c that protrudes inward in the radial direction from the inner peripheral surface is integrally formed at the boundary portion. Then, when the inner cylinder 61 and the outer cylinder 62 are arranged coaxially, the thick portion 61a and the thin portion 62b, and the thin portion 61b and the thick portion 62a are respectively opposed in the radial direction, The joining portions 61c and 62c are joined together using an appropriate method such as brazing. By doing so, an energy absorbing member having the same structure as described above and having the same function is completed.

  As described above, since the weight efficiency of the energy absorbing member is improved, the present invention is useful, for example, as an energy absorbing member for constituting a part of a vehicle frame, particularly a front or rear frame.

It is a partially broken side view showing a front frame of a vehicle to which an energy absorbing member is applied. It is a perspective view which shows the energy absorption member which concerns on Embodiment 1. FIG. It is an expanded sectional view of the energy absorption member. It is explanatory drawing which shows an example of the manufacturing method of the said energy absorption member. It is explanatory drawing which shows an example of another manufacturing method of the said energy absorption member. It is explanatory drawing which shows a mode that the said energy absorption member deform | transforms. It is sectional drawing which shows the energy absorption member which concerns on the modification of Embodiment 1. 6 is an enlarged cross-sectional view of an energy absorbing member according to Embodiment 2. FIG. It is an example of the load-displacement characteristic of an energy absorption member. It is sectional drawing of the energy absorption member which concerns on Embodiment 3. FIG. It is sectional explanatory drawing which shows the dimensional relationship of a structure. It is sectional drawing which shows the energy absorption member which concerns on Embodiment 4. 6 is a cross-sectional view showing an energy absorbing member according to another example of Embodiment 4. FIG. It is sectional drawing which shows an example of the manufacturing method of the said energy absorption member. It is sectional drawing which shows another example of the manufacturing method of the said energy absorption member.

10, 20, 30, 40, 50 Energy absorbing member 11, 31, 41, 51 Main body 12 Peripheral wall 13, 16, 33, 43, 53 Structure 14, 34, 44, 54 Inner wall 15, 35, 45, 55 Outer wall 35a Slits 56, 61 Inner cylinder 57, 62 Outer cylinder 58 Corrugated plates 61c, 62c Annular joint 91 Front side frame (front frame)
92 Crash Can (front frame)

Claims (8)

A cylindrical body having a peripheral wall is provided,
The peripheral wall includes an inner wall located radially inward when viewed in the longitudinal section, and an outer wall located radially outward and facing the inner wall with a predetermined interval therebetween. It is configured by laminating a plurality of structures in the cylinder axis direction,
When a compressive load in the cylindrical axis direction is input to the main body, at least one of the inner wall and the outer wall in each structure is buckled and deformed ,
Each structure is defined by the inner wall and the outer wall, and further includes a liquid chamber in which a liquid is sealed . A cylindrical body having a peripheral wall is provided,
The peripheral wall includes an inner wall located radially inward when viewed in the longitudinal section, and an outer wall located radially outward and facing the inner wall with a predetermined interval therebetween. It is configured by laminating a plurality of structures in the cylinder axis direction,
When a compressive load in the cylindrical axis direction is input to the main body, at least one of the inner wall and the outer wall in each structure is buckled and deformed,
The configuration of the structure is changed by the stacking position in the cylinder axis direction so that the load-displacement characteristic of the main body becomes a predetermined characteristic,
An energy absorbing member in which the rigidity on the input side of the compression load in the main body is set lower than the rigidity on the opposite side . A cylindrical body having a peripheral wall is provided,
The peripheral wall includes an inner wall located radially inward when viewed in the longitudinal section, and an outer wall located radially outward and facing the inner wall with a predetermined interval therebetween. It is configured by laminating a plurality of structures in the cylinder axis direction,
When a compressive load in the cylindrical axis direction is input to the main body, at least one of the inner wall and the outer wall in each structure is buckled and deformed,
The configuration of the structure is changed by the stacking position in the cylinder axis direction so that the load-displacement characteristic of the main body becomes a predetermined characteristic,
The thickness of the inner wall and the thickness of the outer wall in each structure are different from each other,
The structure is an energy absorbing member in which relatively thin walls are laminated such that an outer wall and an inner wall are alternately arranged in a cylinder axis direction . The energy absorbing member according to claim 2 ,
The energy absorbing member in which the height in the cylinder axis direction of each structure is gradually lowered from the compression load input side toward the opposite side. The energy absorbing member according to claim 2 ,
Each structure on the input side of the compression load is an energy absorbing member in which a slit extending in a direction perpendicular to the cylinder axis is formed on an outer wall or an inner wall. The energy absorbing member according to claim 3 ,
The main body has an inner cylinder and an outer cylinder arranged coaxially with each other, and a longitudinal section between the inner cylinder and the outer cylinder extends in a cylinder axis direction in a wavy shape, and an outer peripheral surface of the inner cylinder and an inner circumference of the outer cylinder An energy absorbing member constituted by joining corrugated plates alternately in contact with a surface to each other. The energy absorbing member according to claim 3 ,
The main body has an inner cylinder and an outer cylinder, the thickness of which is periodically changed in the cylinder axis direction, arranged coaxially with each other, and a plurality of annular joints arranged at predetermined intervals in the cylinder axis direction. An energy absorbing member configured by joining the inner cylinder and the outer cylinder to each other. In the energy absorption member according to any one of claims 1 to 7 ,
The main body is arranged so that a cylinder axis direction thereof coincides with a vehicle front-rear direction and constitutes a part of a front frame of the vehicle, and a collision load input to the vehicle is applied to an inner wall of each structure and An energy absorbing member that absorbs by buckling deformation of at least one of the outer walls.

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