JP2021067291A - Shock absorbing member for vehicle - Google Patents

Abstract

To provide a shock absorbing member for a vehicle capable of obtaining a characteristic that a load is substantially fixed when shock is applied.SOLUTION: The shock absorbing member for a vehicle has a cylinder part having a cylindrical shape and a top surface part formed so as to close one opening in an axial direction of the cylindrical part, and absorbs shock energy by compressing and deforming in the axial direction with a shock load input to the top surface part. At least one rib for supporting a load at the time of shock inside the cylindrical part is connected to the top surface part, and is provided apart from the cylindrical part.SELECTED DRAWING: Figure 1

Description

The present invention relates to a shock absorbing member for a vehicle, and more particularly to a shock absorbing member for a vehicle which has been improved so as to be able to advantageously absorb input impact energy together with effective realization of weight reduction.

It is desirable to provide shock absorbing members at each part of the vehicle in preparation for contact between a person and a vehicle, particularly an automobile, or a head-on collision, a side collision, or a rear collision between vehicles. While such a vehicle shock absorbing member is required to absorb sufficient energy, if the shock load applied to a pedestrian or an occupant is too large, it may cause injury to a person. In order to secure the amount of energy absorption while keeping the load below a certain load, it is desirable to keep the load substantially constant (load-displacement diagram at the time of collision is a rectangular wave).

Under such circumstances, it is composed of an integrally resin molded product having a tubular shape as a whole and a pressure receiving portion formed so as to close one opening in the axial direction thereof, and is lighter than metal. By adopting a resin material, a shock absorbing member (Patent Document 1) that can advantageously achieve sufficient weight reduction, or a reduction in harmfulness to other vehicles and sufficient shock energy without increasing the installation space. A shock absorbing member and a bumper (Patent Document 2) that can achieve both absorption and absorption have been proposed.

Japanese Patent No. 6441034 JP-A-2002-155981

However, as described above, at present, it is difficult to keep the impact load substantially constant in order to secure the energy absorption amount while suppressing the impact load to a certain load or less at the time of collision.

For example, in Patent Document 1, a stepped tubular portion having a similar shape in which the outer shape gradually increases is provided, and inside the tubular portion, there are a plurality of plate shapes extending to the end surface of the end portion on the opposite side of the pressure receiving portion. A structure for arranging the ribs of is proposed. However, as shown in FIG. 7 of Patent Document 1, the load is extremely reduced at the timing when the stepped tubular portion is compressed and buckling occurs, and the load cannot be made substantially constant. In addition, since the internal ribs are connected to the stepped tubular portion, the internal ribs are also compressed and deformed in the same manner as the tubular portion, so that the internal ribs behave mechanically independently of the tubular portion. It is not possible to expect the function of increasing the load by aiming at the timing when the load drops. Therefore, it is not suitable for the purpose of making the load of the load-displacement diagram constant. Further, in Patent Document 2, although high energy absorption characteristics can be obtained even if the deformation progresses, the energy absorption characteristics are improved by increasing the load as the deformation progresses, so that the load in the load-displacement diagram is changed. It is not suitable for the purpose of making it almost constant.

As described above, the conventional technique has a problem that it is not possible to obtain the characteristic that the load is substantially constant while ensuring the energy absorption characteristic in the state where the deformation is advanced.

Therefore, an object of the present invention is, in particular, to provide a vehicle shock absorbing member capable of obtaining a characteristic that the load becomes substantially constant when an impact is applied.

In order to solve the above problems, the present invention has a tubular portion having a tubular shape and a top surface portion formed so as to close one opening in the axial direction thereof, and is input to the top surface portion. For a vehicle shock absorbing member that absorbs shock energy by compressing and deforming in the axial direction with a shock load, to support at least one or more shock load inside the tubular portion. Provided is a vehicle shock absorbing member characterized in that the rib is connected to the top surface portion and is provided apart from the tubular portion.

In such a vehicle shock absorbing member according to the present invention, the rib length indicating the length from the top surface side to the opposite end of the rib is shorter than the axial length of the tubular portion. Is preferable.

Further, the rib length is preferably 50 to 99% of the axial length of the tubular portion.

Further, the vehicle shock absorbing member according to the present invention may be provided with a plurality of the ribs.

Further, regarding the rib length indicating the length from the top surface portion side to the tip end portion on the opposite side of the rib, the rib length of at least one rib may be different from the rib length of the other ribs.

Further, the rib in the present invention may be composed of a plurality of ribs extending radially with respect to the central axis of the tubular portion.

Further, the ribs may be separated from each other at the central portion of the tubular portion.

Further, the wall thickness of the rib decreases from the top surface side toward the rib tip side opposite to the top surface portion, and the wall thickness is the maximum on the top surface portion side. May be good.

Further, the shock absorbing member for a vehicle of the present invention may be integrally molded as a whole.

Further, the material constituting the shock absorbing member for a vehicle of the present invention is not particularly limited, and for example, it can be composed of a thermoplastic resin composition or a thermosetting resin composition.

Further, the thermoplastic resin composition or the thermosetting resin composition constituting the shock absorbing member for a vehicle of the present invention is a thermoplastic resin or a thermosetting resin, and at least one of glass fiber, carbon fiber, and metal fiber. It may be composed of a fiber-reinforced resin mixed with fibers.

Further, in the present invention, on the mounting surface on the vehicle structure side on which the shock absorbing member for a vehicle is installed as described above, the portion corresponding to the extension portion of the rib on the rib tip end side opposite to the top surface portion. It is also possible to provide a shock absorbing structure for a vehicle provided with a non-slip for preventing the rib tip from slipping.

According to the shock absorbing member for a vehicle of the present invention, it is possible to obtain a load characteristic in which the load becomes substantially constant when an impact is applied, so that it is possible to exhibit highly efficient shock energy absorbing characteristics.

The shock absorbing member for a vehicle according to the first embodiment of the present invention is shown, (A) is a schematic perspective view, (B) is a schematic perspective view seen from a different angle from FIG. 1 (A), (C). Is a bottom view. It is a schematic block diagram of the front part of an automobile which shows the example of attaching the shock absorbing member for a vehicle which concerns on this invention to an automobile. It is a schematic cross-sectional view of the shock absorbing member for a vehicle in the cross section AA shown in FIG. 1 (C). It is explanatory drawing which shows typically the compression deformation behavior of a tubular part and a rib when the weight drop test was performed on the shock absorbing member for a vehicle shown in FIG. 1, and (A) is a weight and a ceiling. The state before contact with the surface portion, (B) is the state where the weight is in contact with the top surface portion, the tubular portion is compressed and deformed, and the ribs are beginning to contact the mounting surface on the vehicle structure side, and (C) is the cylinder. It shows a state in which the compression deformation of the shape portion further progresses and the ribs are also compression deformation. It is the schematic sectional drawing of the comparative example 1 which removed the rib of the shock absorbing member for a vehicle shown in FIG. FIG. 5 is a schematic cross-sectional view of Comparative Example 2 in which the rib of the vehicle shock absorbing member shown in FIG. 1 is connected to the tubular portion. The vehicle shock absorbing member of the first embodiment shown in FIG. 1, the vehicle shock absorbing member of Comparative Example 1 shown in FIG. 5, and the vehicle shock absorbing member of Comparative Example 2 shown in FIG. 6, respectively. It is a graph which shows roughly the load-displacement characteristic when the drop weight test was performed on the vehicle. It is a schematic perspective view of the shock absorbing member for a vehicle which concerns on 2nd Embodiment of this invention. FIG. 8 is an explanatory view schematically showing the compression deformation behavior of the tubular portion and the rib when the weight drop test is performed on the shock absorbing member for a vehicle shown in FIG. The state before contact with the surface portion, (B) is the state where the weight is in contact with the top surface portion, the tubular portion is compressed and deformed, and the ribs are beginning to contact the mounting surface on the vehicle structure side, and (C) is the cylinder. It shows a state in which the compression deformation of the shape portion further progresses and the ribs are also compression deformation. FIG. 5 is a schematic cross-sectional view of Comparative Example 3 in which the ribs of the vehicle shock absorbing member shown in FIG. 8 are removed. Load-displacement characteristics when a drop weight test is performed on each of the vehicle shock absorbing member of the second embodiment shown in FIG. 8 and the vehicle shock absorbing member of Comparative Example 3 shown in FIG. It is a graph which shows roughly.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a vehicle shock absorbing member according to the first embodiment of the present invention. In FIG. 1, 100 indicates a vehicle shock absorbing member, and the vehicle shock absorbing member 100 receives a collision energy 200 input at the time of a collision at the front portion of an automobile body, for example, as shown in FIG. It is preferably used so that it can be absorbed. However, this structure can be suitably used for a rear portion or a side surface portion other than the front portion of the vehicle body, and is not limited to the front portion of the automobile vehicle body.

The vehicle shock absorbing member 100 of FIG. 1 has a tubular shape in order from the fixing portion 101 for fixing to the vehicle member (not shown) by fastening and the fixing portion 101 toward the collision direction (FIG. 1 (A) Z direction). It has a top surface portion 103 formed so as to close one opening of the portion 102 and the tubular portion 102, and a rib for supporting at least one or more impact load inside the tubular portion 102. 110 is provided. Further, the fastening hole 104 may be provided in the fastening portion 101 so that it can be easily attached to another vehicle member.

Here, as shown in FIG. 1, the vehicle shock absorbing member 100 has a tubular portion 102 having a side surface portion having a substantially dodecagonal cross section perpendicular to the axis in the collision direction (FIG. 1 (A) Z direction). However, the shape of this cross-sectional structure is not particularly limited, and other shapes such as a circle, a substantially quadrangle, and a substantially hexagon may be used.

More specifically, as shown in FIG. 3, the rib 110 in FIG. 1 is connected to the top surface portion 103 and is provided apart from the tubular portion 102. Reference numeral 301 in FIG. 3 indicates a bumper, and reference numeral 300 indicates a collision energy.

Here, the effect of the structure of the vehicle shock absorbing member 100 will be described based on the result of simulating the drop weight test by the finite element method. The dimensions of the vehicle shock absorbing member 100 are 81 mm × 81 mm for the fixed portion 101 and 77 mm for the height. The total wall thickness is 3 mm. In this test, in the state where the vehicle shock absorbing member 100 is erected as shown in FIG. 4A, the fastening hole 104 is restrained on the fixed surface 402, and the predetermined weight 401 is subjected to the collision energy 400 from above. A method of dropping in the direction and crushing the shock absorbing member 100 for a vehicle in the axial direction is adopted. As various conditions of this weight drop test, the weight of the weight is 20 kg and the height of the weight is 1 m, the compression deformation behavior of the vehicle shock absorbing member 100 is observed, and the compression deformation of the vehicle shock absorbing member 100 is started. The displacement and the load generated by such compressive deformation were output. As the resin used for the vehicle shock absorbing member 100, 8207X01B (elastic modulus: 1.8 GPa, strength: 135 MPa) manufactured by Toray Industries, Inc. was used.

Regarding the simulation of the drop weight test as described above, first, Comparative Example 1 in which the rib 110 of the vehicle shock absorbing member 100 of the first embodiment shown in FIG. 5 was deleted was carried out. As a result, a load-displacement diagram like 700 in FIG. 7 was obtained. Immediately after the deformation, the load gradually increases, but the load suddenly drops from the point where the target load is exceeded due to the buckling of the tubular portion 102. As the deformation progresses, the tubular portion 102 is further crushed and sandwiched between the fixed surface 402 and the weight 401, so that the load increases. As described above, in the structure of Comparative Example 1 without the rib 110, the load characteristic undulates as the deformation progresses, and the generated load does not change substantially constant in the vicinity of the target load.

Further, FIG. 703 of FIG. 7 shows a simulation result of Comparative Example 2 in which the rib 110 of the vehicle shock absorbing member 100 of the first embodiment shown in FIG. 6 is connected to the tubular portion 102 as the rib 600. Since the rib 600 is connected to the tubular portion 102, the rigidity is improved as a whole and a high load is generated, but the rigidity is too high so that the tubular portion 102 does not buckle and is compressed. With almost no deformation, the load-displacement diagram is such that only a high peak load is generated, and the generated load does not change substantially constant near the target load. Further, in Comparative Example 2, since the target load is significantly exceeded, an excessive impact force is generated, which may cause damage to other parts or cause a great deal of damage to the pedestrian in the event of a collision with the pedestrian. ..

Next, the deformed state of the vehicle shock absorbing member 100 according to the first embodiment of the present invention at the time of simulation is shown in FIGS. 4 (B) and 4 (C), and the load-displacement diagram is shown in 701 of FIG. Immediately after the deformation, the load gradually increases, but as shown in FIG. 4 (B), the rib 110 has a fixed surface 402 at the timing when the load starts to decrease from around the point where the target load is exceeded due to buckling of the tubular portion 102. Can support the load from the weight 401 instead of the tubular portion 102 as shown in 701 of FIG. The vehicle shock absorbing member 100 of the first embodiment is an effect generated because the rib 110 can be deformed independently of the deformation of the tubular portion 102 because the rib 110 is separated from the tubular portion 102. .. This can be seen from the fact that for 700 and 701 in FIG. 7, the same load-displacement diagram transition is shown up to the first peak of the load, and the subsequent load difference 702 appears as an effect of the rib 110. it is obvious.

Here, when the rib 110 starts to come into contact with the fixed surface 402 at the timing when the tubular portion 102 starts to be deformed and buckles and the load starts to decrease, the load-displacement diagram can be more effectively changed near the target load. Therefore, when the length from the top surface portion 103 to the opposite tip portion 111 (shown in FIG. 3) is taken as the rib length, the rib length of the rib 110 is shorter than the collision direction length of the tubular portion 102. Better. Further, it is more preferable that the length of the tubular portion 102 in the collision direction is 50 to 99%.

Further, it is more preferable to arrange a plurality of ribs 110 so that the ribs 110 can efficiently bear the load borne by the load of the tubular portion 102.

When a plurality of ribs 110 are arranged, the rib length of the rib 110 is different from the rib length of at least one rib 110, so that the tubular portion 102 is compressively deformed and each rib is deformed. By shifting the timing at which 110 starts to touch the fixed surface 402, the transition of the load load becomes smooth, and the load-displacement diagram becomes more likely to change in the vicinity of the target load to be substantially constant, which is preferable.

Further, it is preferable to use a plurality of ribs 110 extending radially with respect to the central axis of the tubular portion 102 because the ribs 110 can be efficiently arranged in the space, and further, the ribs 110 are separated from each other at the central portion. This is more preferable because each rib 110 in which the rib 110 is compressively deformed can be deformed independently, so that a load can be borne instead of the tubular portion 102 while preventing an excessive load increase. In particular, when the rib lengths of the ribs 110 are different, it is more effective to separate the ribs 110 at the center.

Next, as a second embodiment, FIG. 8 shows a shape in which a hole 800 is formed in the tubular portion 102 of the vehicle shock absorbing member 100. In the second embodiment, as shown in FIG. 9A, the rib length before the deformation is different between the rib 110a and the rib 110b. Then, the deformation state at the time of simulation of the second embodiment is shown in FIGS. 9 (B) and 9 (C), and the load-displacement diagram is shown in 1101 of FIG. Further, similarly to Comparative Example 1, a simulation was also carried out for Comparative Example 3 in which the rib 110 of the vehicle shock absorbing member 100 of the second embodiment shown in FIG. 10 was deleted, and a load-displacement diagram was shown in FIG. 1100.

In Comparative Example 3, the load gradually increases immediately after the deformation, but the load drops sharply from the point where the target load is exceeded due to the buckling of the upper portion of the tubular portion 102. As the deformation progresses, the upper part of the tubular part 102 is crushed and the lower part of the tubular part 102 supports the load, so that the load rises once, and then the lower part of the tubular part 102 buckles, and the load decreases. Further, when the tubular portion 102 is crushed and sandwiched between the fixed surface 402 and the weight 401, the load increases. As described above, as in the structure of Comparative Example 3 without the rib 110, a plurality of waviness of the load characteristic may occur.

Next, regarding the result of the second embodiment, as shown in FIG. 9, the load gradually increases immediately after the deformation, but as shown in FIG. 9B, the target is due to the buckling of the upper part of the tubular portion 102. The rib 110b starts to come into contact with the fixed surface 402 at the timing when the load starts to decrease from around the point where the load is exceeded, and the contacted rib 110b receives the load from the weight 401 instead of the tubular portion 102 as shown in 1101 of FIG. It can support only the load difference 1102 (first difference). As the deformation further progresses, the rib 110a starts to come into contact with the fixed surface 402 at the timing when the load starts to decrease due to the buckling of the lower portion of the tubular portion 102 as shown in FIG. 9C, and the cylinder as shown in 1101 of FIG. Instead of the shape portion 102, the load from the weight 401 can be supported by the load difference 1103 (second difference), and the generated load changes near the target load, making it possible to keep the load substantially constant. Become. As described above, when a plurality of waviness of the load characteristic occurs as in the structure of Comparative Example 3, if the rib 110a and the rib 110b having different rib lengths are provided, the effect of the rib can be effectively utilized.

Further, since the impact collecting member 100 for a vehicle is molded by injection molding in many cases, the wall thickness decreases from the top surface portion 103 toward the tip end portion 111 on the opposite side, and the maximum meat thickness on the top surface portion 103 side. It is preferable that the thickness is increased because the moldability is improved. Further, it is more preferable to integrally mold the shock absorbing member 100 for a vehicle by injection molding because it can be molded efficiently.

Further, it is preferable that the vehicle shock absorbing member 100 is made of a thermoplastic resin composition or a thermosetting resin composition because a lighter weight effect and a shock absorbing property can be obtained. Furthermore, by using a fiber-reinforced resin in which at least one fiber of glass fiber, carbon fiber, or metal fiber is mixed with a thermoplastic resin or a thermosetting resin, it is possible to effectively cope with a high target load. ,preferable.

Further, on the mounting surface on the vehicle structure side on which the vehicle shock absorbing member 100 is installed, the rib tip portion 111 slides on a portion corresponding to the extension portion of the rib 110 on the rib tip portion 111 side opposite to the top surface portion 103. It is preferable that the non-slip is provided to prevent the rib 110 from supporting the load more efficiently. The non-slip structure is not particularly limited, and it is sufficient that the rib tip 111 can be prevented from slipping.

The shock absorbing member for a vehicle of the present invention can be applied to any part of a vehicle in which shock absorption is desired, and in particular, can be suitably applied to a rear portion and a side surface portion in addition to the front portion of an automobile body.

100 Impact absorbing member for vehicle according to the first embodiment 101 Fixed portion 102 Cylindrical portion 103 Top surface portion 104 Fastening hole 110, 110a, 110b Rib 111 Rib tip portion 200, 300, 400 Collision energy 301 Bumper 401 Weight 402 Fixed surface 600 Rib 700 Load-Displacement Diagram 701 of Comparative Example 1 Load-Displacement Diagram 702 Difference between Load of Comparative Example 1 and First Embodiment 703 Load-Displacement Diagram of Comparative Example 2 Hole 1100 Comparative Example 3 Load-Displacement Diagram 1101 Load-Displacement Diagram 1102 First difference between the load of Comparative Example 3 and the second embodiment 1103 Second difference between the load of Comparative Example 3 and the second embodiment

Claims (12)

Along with a tubular portion having a tubular shape, it has a top surface portion formed so as to close one opening in the axial direction thereof, and is compressed and deformed in the axial direction by an impact load input to the top surface portion. With respect to the impact absorbing member for a vehicle that absorbs impact energy, ribs for supporting at least one or more impact load are connected to the top surface portion inside the tubular portion, and the above-mentioned A shock absorbing member for a vehicle, characterized in that it is provided apart from the tubular portion. The vehicle shock absorption according to claim 1, wherein the rib length indicating the length from the top surface side to the opposite end of the rib is shorter than the axial length of the tubular portion. Element. The vehicle shock absorbing member according to claim 2, wherein the rib length is 50 to 99% of the axial length of the tubular portion. The vehicle shock absorbing member according to any one of claims 1 to 3, wherein a plurality of the ribs are provided. 4. The rib length indicating the length from the top surface side to the opposite tip of the rib is characterized in that the rib length of at least one rib is different from the rib length of the other ribs. The vehicle shock absorbing member described. The vehicle shock absorbing member according to claim 4 or 5, wherein the rib is composed of a plurality of ribs extending radially with respect to the central axis of the tubular portion. The vehicle shock absorbing member according to any one of claims 4 to 6, wherein the ribs are separated from each other at a central portion of the tubular portion. The claim is characterized in that the wall thickness of the rib decreases from the top surface portion side toward the rib tip portion side opposite to the top surface portion, and the wall thickness is the maximum on the top surface portion side. Item 4. The shock absorbing member for a vehicle according to any one of Items 1 to 7. The vehicle shock absorbing member according to any one of claims 1 to 8, wherein the entire body is integrally molded. The vehicle shock absorbing member according to any one of claims 1 to 9, which is composed of a thermoplastic resin composition or a thermosetting resin composition. The thermoplastic resin composition or the thermosetting resin composition is composed of a fiber-reinforced resin in which at least one fiber of glass fiber, carbon fiber, or metal fiber is mixed with the thermoplastic resin or the thermosetting resin. The vehicle shock absorbing member according to claim 10. On the mounting surface on the vehicle structure side on which the vehicle shock absorbing member according to any one of claims 1 to 11 is installed, a portion corresponding to an extension portion of the rib on the rib tip end side opposite to the top surface portion. , A shock absorbing structure for a vehicle, characterized in that a non-slip is provided to prevent the tip of the rib from slipping.

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