Vehicle impact absorbing components

Abstract

This reduces the number of welding points and, furthermore, achieves a cross-sectional shape that is less prone to tipping over while enhancing impact absorption performance. [Solution] A vehicle shock-absorbing member having a box cross-section is provided, which is in the form of a roll-formed product formed from a single sheet material to have a box cross-section, has only one welded joint surface, and the box cross-section has a convex portion that protrudes outward from the outside of the box cross-section, and two straight lines or approximate straight lines along the shape of the convex portion form an acute angle.

Description

Technical Field

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[0001] The present disclosure relates to a vehicle impact absorbing member.

Background Art

[0002] There is known a technique of disposing a vehicle impact absorbing member having a box cross-sectional shape in a front-rear direction view of the vehicle between a bumper liner hose extending in the vehicle width direction and a front end of a side member extending in the vehicle front-rear direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, since a vehicle impact absorbing member provided in this type of vehicle has a box cross-sectional shape, it is generally formed by welding pieces of two press-worked products having a hat cross-sectional shape. However, in such a configuration of the prior art, there are problems that the degree of freedom in shape regarding the details of the cross-sectional shape is low and the number of welding points increases. Due to the low degree of freedom in shape regarding the details of the cross-sectional shape, it is impossible to realize a cross-sectional shape that is difficult to tip over while enhancing the impact absorption performance.

[0005] Therefore, on one side, the present disclosure aims to reduce the number of welding points and further realize a cross-sectional shape that is difficult to tip over while enhancing the impact absorption performance in a vehicle impact absorbing member.

Means for Solving the Problems

[0006] On one side, a vehicle impact absorbing member having a box cross-sectional shape, It is a roll-formed product formed from a single sheet of material to have a box cross-section, and has only one welded joint surface. The box cross-sectional shape has a convex portion that protrudes outward from the outside of the box cross-section, A vehicle impact-absorbing member is provided, wherein two straight lines or approximate straight lines that follow the shape of the convex portion form an acute angle. [Effects of the Invention]

[0007] In one respect, according to this disclosure, the number of welding points in a vehicle impact absorbing member can be reduced, and furthermore, a cross-sectional shape that is less prone to lateral tilting can be achieved while improving impact absorption performance. [Brief explanation of the drawing]

[0008] [Figure 1] This is a plan view showing the front section of a vehicle, such as an automobile. [Figure 2] This is a perspective view showing the Crash Box in its standalone state. [Figure 3] Figure 2 is a cross-sectional view of the main body passing through the area where the protrusion is formed. [Figure 4] Figure 2 is a cross-sectional view of the main body passing through the area where no protrusions are formed. [Figure 5] This is an explanatory diagram of the main dimensions that characterize the cross-sectional shape. [Figure 6] This is an enlarged view of one corner of Figure 5. [Figure 7] This is an explanatory diagram of a box cross-section using a comparative example, and corresponds to Figure 5, which shows this embodiment. [Figure 8] This is an explanatory diagram of a vehicle tipping over, and is a plan view showing the behavior of the front part of the vehicle during a collision, from the same view as Figure 1 mentioned above. [Figure 9] This figure shows the box cross-sectional shape in a comparative example. [Figure 10] This figure shows two variations of this embodiment and a comparison of their effects (performance). [Modes for carrying out the invention]

[0009] Hereinafter, each embodiment will be described in detail with reference to the attached drawings. Note that the dimensional ratios in the drawings are merely examples and are not limited thereto, and the shapes and the like in the drawings may be exaggerated partially for convenience of explanation. Also, in the drawings, for ease of viewing, only some of the parts having the same attribute existing in plurality may be provided with reference numerals.

[0010] FIG. 1 is a plan view showing a front portion of a vehicle such as an automobile.

[0011] As shown in FIG. 1, a pair of side members 11 are disposed on both sides in the vehicle width direction. The side member 11 is made of, for example, a metal plate, has a hollow structure with a substantially square cross section, and extends in the vehicle longitudinal direction. The pair of side members 11 form part of the body.

[0012] A crash box 12 as a vehicle impact absorber is provided at the front end of each side member 11. The crash box 12 may be fastened to the side member 11 by fasteners such as bolts and nuts.

[0013] The front end of the crash box 12 is coupled to a bumper in hose 16. The bumper in hose 16 extends in the vehicle width direction. The bumper in hose 16 is formed of, for example, a metal plate. The crash box 12 may be fastened to the bumper in hose 16 by fasteners such as bolts and nuts.

[0014] FIG. 2 is a perspective view showing the crash box 12 in a single state. Hereinafter, one of the pair of crash boxes 12 will be described, but the other crash box 12 may be substantially the same and symmetric about the left and right.

[0015] Regarding the following description of the cross section of the crash box 12, unless otherwise particularly mentioned, it relates to the cross section viewed in the vehicle longitudinal direction.

[0016] The crash box 12 includes a lid 121, a main body 122, and a pedestal 123.

[0017] The lid 121 is provided at the front end of the main body 122. The lid 121 is provided with respect to the main body 122 in a manner that closes the box cross-section (described later) of the main body 122. The lid 121 may be joined to the main body 122 by welding. In addition, a weld bolt BT1 for connection with the bumper inlet hose 16 may be attached to the lid 121.

[0018] The main body 122 has a box cross-section (described later) and extends in the front-rear direction. The characteristics of the box cross-section of the main body 122 will be described later.

[0019] The pedestal 123 is provided at the rear end of the main body 122. The pedestal 123 may be joined to the main body 122 by welding. In addition, a weld bolt BT2 for connection with the side member 11 may be attached to the pedestal 123.

[0020] FIG. 3 and FIG. 4 are explanatory views of the box cross-section of the main body 122 of the crash box 12. FIG. 3 is a cross-sectional view passing through the convex portion formation range S1 in the main body 122 of FIG. 2, and FIG. 4 is a cross-sectional view passing through the non-convex portion formation range S2 in the main body 122 of FIG. 2. FIG. 5 is an explanatory view of the main dimensions characterizing the cross-sectional shape, and FIG. 6 is an enlarged view of one corner of FIG. 5. In FIG. 5, the symbol SP indicates a spot weld point.

[0021] Hereinafter, the outside of the box cross-section refers to the outside with respect to the inside surrounded by the box cross-section, and the inside of the box cross-section refers to the inner side surrounded by the box cross-section.

[0022] In this embodiment, the main body 122 is formed by a roll forming method (also called roll forming) which uses rolls to form a metal plate. The main body 122 is a roll-formed product that has a box cross-section. The main body 122 is formed by welding a single metal plate that has a box cross-section at a joint surface 1229. That is, the main body 122 can be manufactured by a manufacturing method that includes the steps of forming a roll-formed product having a box cross-section with one joint surface 1229 from a single metal plate (plate material) using a roll forming method, and welding the joint surface.

[0023] In this case, the main body 122 can be formed from a single piece of material. Therefore, a more efficient structure can be achieved compared to the case where two press-formed metal plates are welded together. Furthermore, when two press-formed metal plates are welded together, two welding surfaces are created, whereas in this embodiment, only one welding surface is created. This significantly reduces the number of welding points and the corresponding welding time (for example, by half). For example, in this embodiment, the number of spot welds can be halved compared to the case where two press-formed metal plates are welded together.

[0024] Furthermore, by forming the main body 122 using a roll molding method, the degree of freedom in the shape of the box cross-section of the main body 122 is increased, making it easy to form the characteristic cross-sectional shapes described later.

[0025] As shown in Figure 3, the box cross-sectional shape of the main body 122 has a convex portion 70 that protrudes outward from the outside of the box cross-section. The convex portion 70 forms a convex ridge on the outside of the box cross-section. In this embodiment, multiple convex portions 70 are formed. Specifically, the multiple convex portions 70 are a convex portion 71 formed at the mating surface, a convex portion 72 formed at the location opposite to the convex portion 71, four convex portions 73 formed at the four corners, and two convex portions 74 formed between pairs of adjacent convex portions 73. Hereinafter, unless otherwise specified, the convex portions 71 to 74 will be referred to as convex portions 70.

[0026] The main body 122 may have protrusions 70 along its entire length in the front-to-back direction, but in this embodiment, some sections do not have protrusions 70. Specifically, the entire front-to-back range of the main body 122 includes a protrusion-forming range S1 in which protrusions 70 are formed, and a protrusion-non-forming range S2 in which some protrusions 70 (specifically protrusions 73 and 74) are not formed. There are four protrusion-non-forming ranges S2, but the number of such ranges is arbitrary. In this case, when subjected to a compressive impact, it becomes easier to deform by contracting in the front-to-back direction in a bellows-like manner, resulting in good shock absorption performance (energy absorption efficiency) of the crash box 12.

[0027] As shown in Figure 5, the convex portion 70 has two straight lines L1 and L2 that follow the shape of the convex portion, forming an acute angle α. Note that the slope of the convex portion 70 does not necessarily have to be a plane; in this case, instead of the two straight lines L1 and L2, two approximate straight lines (equivalent to tangents) that follow the shape of the convex portion form an acute angle α. The range of the acute angle α is arbitrary, but for example, it is between 45 degrees and 75 degrees, and preferably within the range of 55 to 65 degrees.

[0028] Preferably, the box cross-sectional shape of the main body 122 has recesses 77 on both sides of the convex portion 70 that are recessed inward into the box cross-section, as shown in Figure 6. In other words, the convex portion 70 protrudes outward from the box cross-section in a protruding manner such that recesses 77 are formed on both sides thereof. In this case, the impact absorption performance is good. However, the recesses 77 are formed so as not to cause a significant decrease in the second moment of area due to the reduction in the outer diameter of the cross-sectional shape. That is, as can be seen from Figure 6, the recesses 77 are formed to be very shallow and obtuse (the angle between two approximate straight lines along the shape of the recess).

[0029] In this embodiment, the radius of the corner at the tip of the protrusion is preferably 1.5 mm or less, and more preferably about 1 mm. Although such a relatively small radius of corner is difficult to form by press working, it can be formed relatively easily by the roll forming method. By using such a relatively small radius of corner, the impact absorption performance can be effectively enhanced.

[0030] Here, the characteristics of the box cross-section of this embodiment will be further explained in comparison with the comparative example shown in Figure 7.

[0031] Figure 7 is an explanatory diagram of a box cross-section using a comparative example, and corresponds to Figure 5 which shows this embodiment. In Figure 7, the symbol SP indicates a spot welding point.

[0032] The box cross-section in the comparative example is a cross-section that can be formed by press working, and differs from that of this embodiment in that it does not have the protrusion 70. In addition, in the box cross-section of the comparative example, at the four corners, two approximate straight lines along the corner shape form an obtuse angle (for example, 93 degrees), and the corner radius is 3 mm.

[0033] In such comparative examples, since there is no protrusion 70, the impact absorption performance is inferior to that of this embodiment. Furthermore, the box cross section in the comparative example is formed from two pieces, resulting in two joint surfaces, which leads to a large number of spot welding points, as mentioned above. In other words, this embodiment can reduce the number of spot welding points and improve impact absorption performance compared to such comparative examples.

[0034] Next, the effects of this embodiment regarding lateral tilting will be explained with reference to Figures 8 and 9.

[0035] Figure 8 is an explanatory diagram of a vehicle lying on its side, and is a plan view that schematically shows the behavior of the front part of the vehicle during a collision, from the same view as Figure 1 mentioned above. Figure 9 is a diagram showing a box cross-sectional shape according to a comparative example. Here, a crash box 12' having a polygonal box cross-sectional shape as shown in Figure 9 is assumed.

[0036] As shown in Figure 8, assume that a load F is applied to the crash box 12' from an oblique angle relative to its axial direction (vehicle longitudinal direction), such as when a vehicle collides obliquely with an obstacle S. In this case, the crash box 12' becomes more prone to tipping over laterally, with the base end (root side), which is the side member 11 side, as the second moment of area decreases due to the reduction in the outer diameter of the cross-sectional shape associated with polygonalization. Furthermore, local deformation is more likely to occur due to the imbalance in the cross-sectional shape, making tipping over even more likely. Note that the reduction in the outer diameter of the cross-sectional shape refers to the degree of reduction relative to the area of ​​a rectangular cross-section that is circumscribing the box cross-sectional shape.

[0037] In contrast, according to this embodiment, as described above, by providing the protrusion 70, it is possible to achieve diversification while minimizing the reduction in the outer diameter of the cross-sectional shape. For example, as shown in Figure 5, according to this embodiment, the box cross-sectional shape can be maintained as substantially rectangular while providing the protrusion 70. This effectively prevents tipping over. Hereinafter, this function of preventing tipping over will also be referred to as "resistance to tipping over."

[0038] Next, we will refer to Figure 10 to explain various modifications and a comparison of their effects.

[0039] Figure 10 is a table-like diagram showing two modifications of this embodiment and a comparison of their effects (performance). Here, the effects relate to impact absorption performance (energy absorption efficiency) and resistance to lateral tipping.

[0040] Modification 1 and Modification 2 differ from this embodiment in the number (and consequently, arrangement) of the protrusions 70. Specifically, Modification 1 has five protrusions 70, while Modification 2 has seven protrusions 70. Thus, although the number of protrusions 70 is arbitrary, as explained below, a larger number of protrusions 70 is desirable.

[0041] As shown in Figure 10, the more protrusions 70 there are, the higher the impact absorption performance. This is because the more protrusions 70 there are, the shorter the length of the straight sections in the box cross-section shape becomes. On the other hand, the resistance to tipping over is not substantially affected by the number of protrusions 70, and each modified example is equivalent to that of this embodiment. In other words, this embodiment can enhance impact absorption performance while ensuring the necessary resistance to tipping over.

[0042] In this embodiment, as well as in Modification 1 and Modification 2, the protrusion 70 is basically formed symmetrically. Therefore, local deformation due to imbalance in the cross-sectional shape is unlikely to occur.

[0043] Although each embodiment has been described in detail above, the invention is not limited to any particular embodiment, and various modifications and changes are possible within the scope described in the claims. Furthermore, it is possible to combine all or more of the components of the embodiments described above.

[0044] For example, the above-described embodiment relates to a crash box 12 between the side member 11 and the bumper reinforcement 16, but it is applicable to other impact-absorbing members for vehicles.

[0045] Furthermore, in a configuration in which a pair of crash boxes are provided between the side member 11 and the bumper reinforcement 16, the configuration of this embodiment may be applied to both or only one of the pair of crash boxes. [Explanation of Symbols]

[0046] 11...Side member, 12...Crash box (vehicle impact absorbing component), 1229...Mating surface, 16...Bump reinforcement, 70...Convex part, 77...Concave part

Claims

1. A vehicle shock-absorbing member having a box cross-sectional shape, It is a roll-formed product formed from a single sheet of material to have a box cross-section, and has only one welded joint surface. The box cross-sectional shape has a convex portion that protrudes outward from the outside of the box cross-section, A vehicle impact-absorbing member in which two straight lines or approximate straight lines that follow the shape of the aforementioned protrusion form an acute angle.

2. The box cross-sectional shape has recesses on both sides of the convex portion that are recessed inward from the box cross-section, as described in claim 1 for the vehicle impact absorbing member.

3. The aforementioned protrusions are provided in four or more locations different from the mating surface. The vehicle impact absorbing member according to claim 1, wherein the radius of the corner of the tip of the protrusion is 1.5 mm or less.

4. A vehicle impact absorbing member according to any one of claims 1 to 3, wherein the member is positioned between a bumper reinforcement extending in the vehicle width direction and the front end of a side member extending in the vehicle longitudinal direction, with its cross-section in the vehicle longitudinal direction being the box cross-section.

5. A method for manufacturing a vehicle shock-absorbing member having a box cross-sectional shape, A process for forming a roll-formed product having a box cross-section with one joint surface from a single sheet of material using a roll forming method, The process includes welding the aforementioned mating surfaces, The box cross-sectional shape has a convex portion that protrudes outward from the outside of the box cross-section, A method in which two straight lines or approximate straight lines that follow the shape of the convex portion form an acute angle.

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