JP5776522B2 - Shock absorber for vehicle - Google Patents

Description

  The present invention relates to a shock absorbing member for a vehicle, and more specifically, includes a quadrangular columnar timber and a hollow cylindrical metal frame that surrounds the outer peripheral surface of the timber, and the impact at the time of collision is compressed in the axial direction. The present invention relates to a shock absorbing member of a vehicle received as

  An impact absorbing member of this type of vehicle is disclosed in Patent Document 1, for example. In the shock absorbing member of Patent Document 1, the compression load as a reaction force is generated when the shock absorbing member is displaced by receiving a shock by inserting the wood into the aluminum hollow material as a frame body substantially tightly or slightly tightly. It is said that the shock energy absorption performance can be improved by suppressing the fluctuation. Furthermore, the amount of impact energy absorbed is increased by making the fiber direction of the wood coincide with the axial direction of the frame.

JP 2001-182769 A

  Certainly, wood is originally porous and the fibers are aligned in one direction. Therefore, if the fiber direction matches the compression direction and can be compressed straight, it will effectively suppress fluctuations in the compression load. The amount of impact energy absorbed can be improved. However, in the conventional shock absorbing member, the frame body buckles and deforms in a bellows shape due to a compressive load. In this case, if the amplitude of the bellows is large, the frame body bites into the piece of wood, and the deformation direction of the fibers of the wood is locally inclined, so that the original characteristics of the wood cannot be fully utilized. In this case, the compressive load varies due to the local inclination of the fibers. In Patent Document 1, since the frame body and the wood are in close contact, the frame body is easy to bite deeply into the wood, and the fibers of the wood are easy to tilt.

  Therefore, an object of the present invention is to provide an impact absorbing member for a vehicle with a stable compression load by suppressing the frame body from biting into the wood at the time of compressive deformation and properly exhibiting the original function of the wood.

The present invention includes a rectangular columnar wood having a fiber direction as an axial direction and a hollow cylindrical metal frame surrounding the outer peripheral surface of the wood, and receives a shock at the time of a collision as a compressive load in the axial direction. In the shock absorbing member, at least a pair of ribs projecting at right angles from a pair of opposing surfaces are formed over the entire length of the frame body from end to end along the axial direction. A shock absorbing member for a vehicle characterized by the above.

  According to such an impact absorbing member, when the frame body is deformed into a bellows shape under the axial compressive load, the amplitude of the bellows is reduced by setting the rib. Thereby, it can suppress that a frame cuts into wood.

  It is desirable that the rib has a (projected height dimension / thickness) ratio of 5 to 20. In this case, it is possible to more effectively reduce the amplitude of the bellows when the frame body is deformed into a bellows shape, and to more effectively suppress the frame body from biting into the wood. It is also preferable to have a gap between the wood and the frame. In this case, the frame body can be prevented from biting into the wood by allowing the bellows wave of the frame body to be allowed in the gap. The rib can project to the outside of the frame. Moreover, it can also project inside.

  According to the shock absorbing member of the present invention, when the axial compressive load is received, the frame body is deformed in a bellows while being finely waved, so that it is difficult to bite into the wood. Therefore, the original characteristics of wood can be utilized to the maximum, and a vehicle impact absorbing member with a stable compression load can be provided.

It is a perspective view of the impact-absorbing member which concerns on Embodiment 1 of this invention. It is a figure corresponding to the II-II section of the shock-absorbing member shown in Drawing 1, and showing the state after modification typically. It is a figure which picks up a part of frame and shows typically about a modification of a frame which constitutes an impact-absorbing member concerning Embodiment 1 of the present invention. It is a perspective view of the impact-absorbing member which concerns on Embodiment 2 of this invention. 6 is a graph according to Test Example 1; It is a graph which shows the relationship between the displacement of an impact-absorbing member, and the compressive load as a reaction force about 1 impact-absorbing member. 6 is a graph according to Test Example 1; It is a graph which shows the relationship between the displacement of an impact-absorbing member, and the compressive load as a reaction force about 2 impact-absorbing members. 6 is a graph according to Test Example 1; 3 is a graph showing the relationship between the displacement of the shock absorbing member and the compressive load as a reaction force for the shock absorbing member 3; No. of Test Example 1 It is a photograph which shows the external appearance after compression about the one impact-absorbing member as the state which looked at one wall surface from the front. No. of Test Example 1 It is the photograph which cut | disconnects the axial direction after compression about 1 shock-absorbing member, and shows the cut surface. No. of Test Example 1 It is a photograph which shows the external appearance after compression about the shock absorption member of 2 as the state seen from the diagonal direction. No. of Test Example 1 It is a photograph which shows the external appearance after compression about the shock absorption member of 3 as the state seen from the diagonal direction. No. of Test Example 1 3 is a photograph showing the cut surface of the impact absorbing member 3 cut in the axial direction after compression. It is a graph which concerns on the test example 2, and is a graph which shows the relationship between the (overhang height dimension / thickness) ratio of a rib, and the number of the waves formed in the frame part. It is a graph which concerns on the test example 3, and is a graph which shows the relationship between the displacement of an impact-absorbing member, and the compressive load as a reaction force about the impact-absorbing member whose rib (overhang height dimension / thickness) ratio is 4. It is a graph which concerns on the test example 3, and is a graph which shows the relationship between the displacement of an impact-absorbing member, and the compressive load as a reaction force about the impact-absorbing member whose rib (projection height dimension / thickness) ratio is 5.

<Embodiment 1>
An embodiment of the present invention will be described with reference to FIGS. The impact absorbing member 11 of the present embodiment is a member that is installed in a vehicle such as an automobile and absorbs impact energy at the time of collision. As shown in FIG. 1, the shock absorbing member 11 includes a square columnar wood 21 having a square cross section orthogonal to the axial direction and a metal frame 31 surrounding the outer peripheral surface of the wood 21. Is received as an axial compressive load.

  The wood 21 is made into a square column shape so that the fiber direction is parallel to the compression load (axial direction). The kind of wood 21 is not specifically limited, For example, conifers, such as a cedar, a cypress, and a pine, and broad-leaved trees, such as a zelkova and a beech, can be used. Wood with a high specific gravity is excellent in strength, and wood with a low specific gravity has a high porosity, so that the crash stroke (displacement due to compression) is long. Considering this point, it is desirable to select wood having an appropriate specific gravity according to the installation position of the vehicle. Use of wood having a specific gravity of 0.2 to 0.4 is preferable because it can increase the amount of impact energy absorbed by having a certain degree of strength while sufficiently securing the crash stroke. Examples of the wood having a specific gravity of 0.2 to 0.4 include cedar, hinoki and pine.

  The frame body 31 includes a hollow rectangular tube-shaped frame portion 33 formed by four wall surfaces 41 to 44 facing the side surface of the wood 21. The frame 31 can support the wood 21 and can be deformed together with the wood 21 by receiving an axial compressive load. For example, the frame 31 is made of a metal such as aluminum, copper, or iron. The frame portion 33 accommodates the wood 21 with a slight gap S formed between the side surface of the wood 21 and the entire outer peripheral surface of the wood 21 is covered by the frame portion 33 without excess or deficiency.

  Each of the four wall surfaces 41 to 44 forming the frame portion 33 is provided with ribs 41r to 44r. The ribs 41r to 44r are plate-like and project outward from the wall surfaces 41 to 44 at a right angle. The ribs 41r to 44r are formed over the entire length in the axial direction along the axial direction at the center in the width direction of the wall surfaces 41 to 44, and the protruding height dimension (projection amount) is equal throughout the entire length. When the ribs 41r to 44r are subjected to an axial compressive load, the ribs 41r to 44r can allow the wall surfaces 41 to 44 of the frame portion 33 to buckle and deform so as to be undulated while themselves buckling and deforming. . The action function will be described in more detail while explaining the action function of the shock absorbing member 11 when a compressive load due to a collision is applied.

  The impact absorbing member 11 is installed so that the axial direction (fiber direction) of the wood 21 and the collision direction of the vehicle are parallel to each other. When an axial compressive load is applied to the shock absorbing member 11 in accordance with the collision, the frame portion 33 of the frame body 31 surrounding the wood 21 is axially bent in a bellows shape as schematically shown in FIG. After being crushed, the wood 21 is prevented from being overturned by the frame 31 and is directly compressed and deformed in the axial direction.

  At this time, the ribs 41r to 44r are buckled and deformed so as to hit a wave while being curved in a direction perpendicular to the direction of the bellows of each of the wall surfaces 41 to 44. That is, the deformation mode of the ribs 41r to 44r will be described by taking up the wall surface 41 with reference to FIG. 3, and the wall surface 41 is buckled so as to wave inward and outward of the frame 33 as indicated by an arrow A. On the other hand, as indicated by an arrow B, the rib 41r is crushed in the axial direction while buckling so as to strike a wave in a direction perpendicular to the buckling direction of the wall surface 41. Here, basically, the frame portion 33 tends to be deformed so that the corner portions 45 to 48 having relatively high strength are buckled, and the flat surfaces (wall surfaces 41 to 44) between them are undulated. . However, the wall surfaces 41 to 44 are provided with ribs 41r to 44r, and the ribs 41r to 44r are crushed in the axial direction, so that the wall surfaces 41 to 44 are deformed bellows while being largely bent in the middle in the width direction. Is acceptable. For this reason, the ribs 41r to 44r also serve as base points for bellows deformation on the wall surfaces 41 to 44, and the corrugated wave shapes formed on the wall surfaces 41 to 44 are divided at the ribs 41r to 44r. In other words, the corrugations are formed in small surface shape units divided by the ribs 41r to 44r in the respective wall surfaces 41 to 44. Since the narrow surface shape unit tries to buckle while attracting each other with the adjacent surface shape unit, the large shape is restricted, and each surface shape unit is deformed while forming a wave shape with a small amplitude.

  In order to effectively divide the wave shape in each of the wall surfaces 41 to 44, the ribs 41r to 44r are subjected to a compressive load so that the ribs 41r to 44r are crushed in the axial direction while being buckled and deformed. The thickness is adjusted as appropriate. Here, although the ribs 41r to 44r reinforce the wall surfaces 41 to 44 to some extent, it is not preferable to reinforce the entire wall surfaces 41 to 44 and prevent the bellows deformation of the wall surfaces 41 to 44. In addition, it is not preferable that the wall surfaces 41 to 44 are so brittle that the wall surfaces 41 to 44 wave in the inner and outer directions and undulate in the inner and outer directions. When the ribs 41r to 44r have a (projection height dimension / thickness) ratio of 5 to 20, the ribs 41r to 44r receive a compressive load so that the ribs 41r to 44r wave in the front and back surfaces of the plate-like shape. This is preferable in that it can be buckled and effectively divide the corrugated corrugations of the wall surfaces 41 to 44 into finer waveforms. In setting such a ratio (overhang height dimension / thickness), the thickness of the ribs 41r to 44r can be set to 5 mm or less, for example. In this case, it is easy to form a fine waveform by effectively dividing the wave shapes of the wall surfaces 41 to 44 in balance with the overhang height dimension.

  According to the shock absorbing member 11, when an axial compressive load is applied, the frame portion 33 of the frame body 31 surrounding the wood 21 is bellows deformed and crushed in the axial direction, so that the wood 21 does not fall down in the fiber direction. Along the line, it compresses straight. Therefore, there is little fluctuation of the compressive load as stress. Here, since the frame portion 33 of the frame body 31 is deformed into a bellows shape with a small waveform amplitude, the frame portion 33 is not greatly bent inward, is difficult to bite into the wood 21, and the fibers of the wood 21 are partially tilted by the bite. It is difficult to cause the fluctuation of the compression load due to. The provision of the gap S between the frame 31 and the wood 21 also contributes to suppression of biting. However, since the frame portion 33 of the frame body 31 is not greatly curved inward, the biting suppression effect can be enhanced by setting the gap S very slightly, and the wood 21 of the frame portion 33 is held straight. Function can be secured. The gap S is preferably 1 mm or less, and more preferably 0.5 mm or less. In this shock absorbing member 11, since the frame body is finely deformed into a bellows shape and the biting of the frame body into the wood is suppressed, there is no need for the gap S, and the dimension of the gap S The lower limit of is not particularly limited.

  The installation location of the impact absorbing member 11 is not particularly limited as long as it is a location where collision energy should be absorbed in order to protect passengers, pedestrians, and the like. For example, between fender panels and body panels, between bumper in hoses and side members, between door panels and door trims, between pillars and pillar trims, between ceiling panels and roof liners, between floor panels and carpets. It can be installed in between. The method for fixing the shock absorbing member 11 to the vehicle is not particularly limited. For example, the frame body 31 may be fixed to the vehicle by welding or adhesion, or may be fixed to the vehicle via a bracket.

<Embodiment 2>
With reference to FIG. 4, another embodiment of the present invention will be described. The shock absorbing member 51 of the present embodiment is composed of a quadrangular prism-shaped wood 61 and a metal frame 71 surrounding the outer peripheral surface of the wood 61, and is installed in a vehicle such as an automobile so that an impact at the time of collision can be reduced in the axial direction. It is a member for receiving as a compressive load. The shock absorbing member 51 has the same function as that of the first embodiment, but is different from the first embodiment in that the ribs 81r to 84r formed on the frame 71 project inward from the structure. It is.

  The wood 61 is made into a square pillar shape so that its fiber direction is parallel to the compression load (axial direction), and notches 63a to 63d into which the ribs 81r to 84r of the frame 71 are inserted are formed on each side surface. ing.

  The frame 71 includes a hollow rectangular tube-shaped frame portion 73, and plate-like ribs 81 r to 84 r projecting at right angles to the inside are provided on each of the four wall surfaces 81 to 84 forming the frame portion 73. It has been. The ribs 81r to 84r are formed over the entire length in the axial direction along the axial direction at the center in the width direction of the wall surfaces 81 to 84, and the protruding height dimension (projection amount) is equal throughout the entire length. The frame 71 accommodates the wood 61 in the frame portion 73 with the ribs 81r to 84r inserted into the cuts 63a to 63d of the wood 61, and covers the entire outer peripheral surface of the wood 61 without excess or deficiency.

  When the ribs 81r to 84r receive an axial compressive load, the ribs 81r to 84r themselves collapse in the axial direction while buckling and deforming, and allow the wall surfaces 81 to 84 of the frame portion 73 to buckle and deform so as to wave. It can be done. The overhang height dimension of the ribs 81r to 84r is appropriately adjusted within a dimension range in which the ribs 81r to 84r do not divide the wood 61. This is because, when the wood 61 is divided by the ribs 81r to 84r, the wood 61 is likely to fall down when receiving an axial compressive load. The ribs 81r to 84r preferably have a (projected height dimension / thickness) ratio of 5 to 20. In this case, the corrugated wave shape can be effectively divided on each of the wall surfaces 81 to 84 to obtain a finer waveform. The thickness of the ribs 81r to 84r is not limited in setting the ratio (overhang height dimension / thickness), but for example, 5 mm or less can be used as a guide. In this case, it is easy to form a fine waveform by effectively dividing the wave shapes of the wall surfaces 81 to 84 in balance with the overhang height dimension.

  The present invention is not limited to the above embodiment, and various modifications can be considered. For example, the ribs of the frame body may be provided on at least two opposing wall surfaces. Taking the shock absorbing member 11 shown in FIG. 1 as an example, ribs may be provided on at least one set of wall surfaces 41, 43 or 42, 44 facing each other. Further, the plane cross section orthogonal to the axial direction of the shock absorbing member may be rectangular. In that case, it is preferable to provide ribs on the two wall surfaces having the larger area. Further, in one shock absorbing member, a rib projecting outward as in the first embodiment and a rib projecting outward as in the second embodiment may be mixed.

[Test Example 1]
In Test Example 1, No. 1 with a different rib configuration was used. 1 to 3 impact absorbing members were used. No. No. 1 has the same configuration as that of the first embodiment, and the rib projects outward. 2 has the same configuration as that of the second embodiment, and the ribs project inward. No. Reference numeral 3 denotes a comparative shock absorbing member which is composed of only a frame portion without ribs. No. In the impact absorbing members 1 to 3, a cedar square member having an outer size of 39.3 mm square and an axial length of 70 mm was used for the wood. In addition, aluminum (A5052) is used for the frame body, the frame portion has an inner size of 40 mm square x an axial length of 70 mm and a thickness of 0.5 mm, and a gap of 0.35 mm on one side is formed between the frame and the wood. Housed wood. Table 1 shows the structure of the rib of each impact absorbing member.

  No. of the said structure. Displacement and compressive load (reverse force) when the impact absorbing members 1 to 3 are installed in a compression tester (Autograph AG-100KNE type) manufactured by Shimadzu Corporation and compressed in the axial direction at 2 mm / min. Force). The results are shown in FIGS. Moreover, about each impact-absorbing member, the state after compression is shown with a photograph to FIGS. FIG. No. 1 is a photograph showing a state of one wall surface as viewed from the front, and FIG. It is a photograph which cut | disconnects the impact-absorbing member of 1 in an axial direction, and shows a part of cut surface. FIG. It is a photograph which shows the state which looked at the impact-absorbing member of 2 from the diagonal direction. FIG. 3 is a photograph showing a state in which the shock absorbing member 3 is viewed from an oblique direction. 3 is a photograph showing a part of the cut surface of the shock absorbing member 3 cut in the axial direction.

  Referring to the graphs of FIGS. 5 to 7 showing the relationship between the displacement of the shock absorbing member and the compressive load (reaction force), after the compressive load rises at the initial displacement, No. 1 having no rib. Compared to No. 3, No. 3 having ribs. It became clear that 1 and 2 were more linear and more stable. Here, when attention was paid to the deformation of the shock absorbing member, no. In any of 1 to 3, the frame portion of the frame body was crushed in the axial direction while being bellows deformed, and the wood inside was compressed and deformed straight without falling down. However, the number of bellows waves formed in the frame portion is No. with no ribs. No. 3 having 3 ribs, whereas No. 3 having ribs. 1 and 2 were five, the amplitude of the bellows was smaller, and it was deformed finely. No. In No. 3, the bellows peaks (valleys) of the frame portion were continuous from end to end in the width direction of the wall surface (see FIG. 11), whereas No. 3 having ribs. In 1 and 2, it was divided at the position of the rib (see FIGS. 8 and 10). Here, when attention was paid to the ribs, the ribs were crushed without following the bellows deformation of the frame portion. That is, in FIG. As well shown in the photograph of 1, the ribs were crushed so as to wave in a direction perpendicular to the bellows deformation of the frame portion. Therefore, when the rib is provided, the middle wall of the frame portion is suppressed from being bent greatly, and the rib and the wall surface are buckled and deformed in directions orthogonal to each other. It is thought that it was transformed into a shape. No. with ribs In 1 and 2, the frame portion was finely bellows deformed, and as a result, the frame did not bite into the wood (see FIG. 9). As a result, the compressive load is considered to be stable. On the other hand, no. 3, as shown in FIG. 12, the wall surface of the frame portion greatly oscillates and deforms into a bellows shape and bites into the wood.

[Test Example 2]
In Test Example 2, the configuration is the same as in Embodiment 1 above, the material and dimensions of the wood and the frame portion are the same as in Test Example 1, the rib thickness is constant at 0.5 mm, and the overhang Using a shock absorbing member in which the height dimension was changed and the ratio of rib height (overhang height dimension / thickness) was 4, 5, 10, 20, 22 was compressed in the same manner as in Test Example 1, and the shock absorbing member was The number of waves formed on the frame part of the frame body was counted by visual observation. The results are shown in FIG. 13 as a graph showing the relationship between the ratio of rib height (overhang height dimension / thickness) and the number of waves.

  As is clear from the results of FIG. 13, when the (overhang height dimension / thickness) ratio of the ribs is 5 to 20, the number of waves increases, and the frame portion deforms bellows while forming a finer waveform. Became clear. When the compressed frame is observed, the rib appears to wave in a direction orthogonal to the bellows deformation of the frame portion in any case where the ratio of the ribs (projected height dimension / thickness) is 5, 10, or 20. It was crushed. On the other hand, when the (overhang height dimension / thickness) ratio of the rib was 4, it was also found that the number of waves was reduced. When the compressed frame body was observed, the rib was deformed following the deformation of the wall surface of the frame portion into a waveform. It has also been found that the number of waves is reduced when the (overhang height dimension / thickness) ratio of the ribs is 22. When the compressed frame was observed, it was deformed so that the rib collapsed and was caught in the wall surface. From the above, it is preferable that the (overhang height dimension / thickness) ratio of the ribs is 5 to 20 because the frame portion can be effectively suppressed from biting into the wood due to finer bellows deformation. Became clear.

  Further, as an additional test of Test Example 2, the rib thickness is kept constant at 1 mm, the overhang height dimension is changed, and the (overhang height dimension / thickness) ratio of the rib is adjusted, and the same method as in Test Example 2 The relationship between the ratio of rib height (overhang height dimension / thickness) and the number of waves formed in the frame was examined. As a result, it was confirmed that the same behavior as when the rib thickness was 0.5 mm was exhibited.

[Test Example 3]
In Test Example 3, No. 1 in Test Example 1 was obtained. In the shock absorbing member of No. 2, the shock absorbing member in which only the protruding height dimension of the rib was changed and the rib protruding (height height dimension / thickness) ratio was 4, 5, and 20 was used in the same manner as in Test Example 1 above. Compressed.

  As a result, when the (overhang height dimension / thickness) ratio of the rib was 4, the rib was wound so as to be involved in the bellows deformation of the frame portion. As is clear from the graph showing the relationship between the displacement and the compressive load (reaction force) shown in FIG. 14, the change in the compressive load after the compressive load rose at the initial displacement was large. However, when the (overhang height dimension / thickness) ratio of the rib is 5, the No. No. of the rib (overhang height dimension / thickness) is 10. As is clear from the graph showing the relationship between the displacement and the compressive load (reaction force) shown in FIG. After the compression load rose at the initial displacement, it changed linearly. In addition, even when the (overhang height dimension / thickness) ratio of the rib is 20, the bellows peak (valley) of the frame portion is divided at the position of the rib and finely bellows deformed, and the compression load rises at the initial displacement. After that, it was confirmed that the transition was linear. From the above results, even when the ribs are projecting inward, the ratio of the ribs (projection height dimension / thickness) is set to 5 to 20, so that the frame portion is deformed more finely and effectively bites into the wood. It has become clear that it can be suppressed. As a result, it became clear that the transition after the rising of the compressive load at the initial displacement can be further stabilized.

11 Shock Absorbing Member 21 Wood 31 Frame 33 Frame 41r to 44r Rib 51 Shock Absorbing Member 61 Wood 71 Frame 73 Frame 81r to 84r Rib S Gap

Claims (5)

A shock-absorbing member for a vehicle, comprising: a rectangular columnar wood having an axial direction in the fiber direction; and a hollow cylindrical metal frame surrounding the outer peripheral surface of the wood, and receiving an impact at the time of collision as a compressive load in the axial direction Because
The frame has a rib that protrudes at a right angle from at least a pair of opposing surfaces, and is formed over the entire length from end to end of the frame along the axial direction. Element. The vehicle impact absorbing member according to claim 1,
A shock absorbing member for a vehicle, wherein the rib has a (projected height dimension / thickness) ratio of 5 to 20. The impact absorbing member for a vehicle according to claim 1 or 2,
A vehicle impact absorbing member having a gap between the wood and the frame. The impact absorbing member for a vehicle according to any one of claims 1 to 3,
The impact-absorbing member for a vehicle, wherein the rib projects to the outside of the frame. The impact absorbing member for a vehicle according to any one of claims 1 to 3,
A shock absorbing member for a vehicle, wherein the rib protrudes inside the frame.