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KR-20260065896-A - Shock-absorbing members, and vehicle body

KR20260065896AKR 20260065896 AKR20260065896 AKR 20260065896AKR-20260065896-A

Abstract

The shock absorbing member is provided on the vehicle body and includes a closed section formed along a predetermined longitudinal direction, wherein the cross section perpendicular to the longitudinal direction has a closed cross-sectional shape. The shock absorbing member comprises a low-strength section, a high-strength section aligned with the low-strength section and having a central portion in the plate thickness direction having a Vickers hardness higher than that of the central portion in the plate thickness direction of the low-strength section, and a joint that joins the low-strength section and the high-strength section. The maximum bending angle of the high-strength section is set according to the maximum bending angle of the low-strength section.

Inventors

  • 오노 아쓰시

Assignees

  • 닛폰세이테츠 가부시키가이샤

Dates

Publication Date
20260511
Application Date
20241016
Priority Date
20231018

Claims (16)

  1. A shock-absorbing member provided on a vehicle body, formed along a predetermined length direction, and comprising a portion having a closed cross-section shape with a cross-section perpendicular to the length direction, low-strength section, and A low-strength section and a high-strength section arranged in the longitudinal direction having a central section in the plate thickness direction having a Vickers hardness higher than the Vickers hardness of the central section in the plate thickness direction of the low-strength section, A joint that joins the above low-strength part and the above high-strength part Equipped with, The maximum bending angle of the high-strength part is set according to the maximum bending angle of the low-strength part, in a shock-absorbing member.
  2. In claim 1, A shock-absorbing member in which the difference between the maximum bending angle of the high-strength part and the maximum bending angle of the low-strength part is 100 degrees or less.
  3. In claim 1, A shock-absorbing member having a Vickers hardness of 500 HV or higher at the center of the plate thickness direction of the high-strength portion.
  4. In claim 3, A shock-absorbing member having a Vickers hardness of 150 HV or higher at the center of the plate thickness direction of the low-strength portion.
  5. In claim 3, A shock-absorbing member having a ratio of HV 1/HV 2 between the Vickers hardness HV 1 of the central part in the plate thickness direction of the high-strength part and the Vickers hardness HV 2 of the central part in the plate thickness direction of the low-strength part, such that HV 1 /HV 2 is 1.3 or higher.
  6. In claim 1, A shock-absorbing member having a difference of 30 degrees or less between the maximum bending angle of the low-strength portion and the maximum bending angle of the high-strength portion.
  7. In any one of claims 1 to 6, The shock-absorbing member is a center pillar having a pillar inner and a pillar outer and arranged along the vertical direction of the vehicle body, and The above filler outer comprises the low-strength portion, the joint portion, and the high-strength portion, and A shock-absorbing member having a high-strength portion positioned above the low-strength portion.
  8. In claim 7, A pair of upper and lower brackets are installed on the center pillar to support a door installed at the rear of the center pillar, and The above joint is a shock-absorbing member positioned at a height lower than the lower height of the upper bracket.
  9. In claim 8, The above joint is a shock-absorbing member positioned at a height higher than the upper height of the bracket on the lower side.
  10. In claim 8, The above joint is a shock-absorbing member positioned at a height lower than the lower height of the bracket on the lower side.
  11. In claim 7, The vehicle body further comprises a side sill that is joined to the lower part of the center pillar, arranged along the front-rear direction of the vehicle body, and has a closed cross-sectional shape in a cross-section perpendicular to the front-rear direction. The above side sill has an outer wall disposed on the outer side in the width direction of the vehicle body in the above side sill, and The lower part of the center pillar has an overlapping portion arranged to cover the side sill at the connection point with the side sill, and The above-mentioned overlapping portion is a shock-absorbing member that extends downward from a height position that is halfway up and down the outer wall of the side seal.
  12. In claim 1, An impact absorbing member having a Vickers hardness at the surface of the high-strength portion in the plate thickness direction that is at least 100 HV lower than the Vickers hardness at the center of the high-strength portion in the plate thickness direction.
  13. In claim 12, The above high-strength part has a high-strength part softening layer installed from the surface in the direction of the plate thickness, and In the above high-strength part, the Vickers hardness of the central portion in the plate thickness direction in the part where the high-strength part softening layer is installed is 500 HV or higher, and The thickness of the high-strength softening layer is 80 μm or more, and is 5% or more and 20% or less of the plate thickness in the part where the high-strength softening layer is installed. The Vickers hardness of the high-strength softening layer on the above surface is 0.5 times or more and less than 0.9 times the Vickers hardness of the central part in the plate thickness direction in the part where the high-strength softening layer is installed, and The high-strength softening layer has, in the plate thickness direction, a first hardness change region which is an area from the surface to 40% of the thickness of the high-strength softening layer, and a second hardness change region which is an area of the high-strength softening layer that is not the first hardness change region. An impact absorbing member in which the absolute value ΔHV1 of the hardness change in the plate thickness direction in the first hardness change region is greater than the absolute value ΔHV2 of the hardness change in the plate thickness direction in the second hardness change region.
  14. In claim 1, A shock-absorbing member having a Vickers hardness at the surface of the low-strength portion in the plate thickness direction that is at least 100 HV lower than the Vickers hardness at the center of the low-strength portion in the plate thickness direction.
  15. In claim 14, The above low-strength portion has a low-strength portion softening layer installed from the surface in the direction of the plate thickness, and In the above low-strength portion, the Vickers hardness of the central portion in the plate thickness direction in the part where the low-strength portion softening layer is installed is 150 HV or higher, and The thickness of the low-strength softening layer is 80 μm or more, and is 5% or more and 20% or less of the plate thickness in the portion where the low-strength softening layer is installed. The Vickers hardness of the low-strength softening layer on the above surface is 0.5 times or more and less than 0.9 times the Vickers hardness of the central part in the plate thickness direction in the portion where the low-strength softening layer is installed, and The low-strength softening layer has, in the plate thickness direction, a first hardness change region which is an area from the surface to 40% of the thickness of the low-strength softening layer, and a second hardness change region which is an area of the low-strength softening layer that is not the first hardness change region. An impact absorbing member in which the absolute value ΔHV1' of the hardness change in the plate thickness direction in the first hardness change region is greater than the absolute value ΔHV2' of the hardness change in the plate thickness direction in the second hardness change region.
  16. It comprises a center pillar and a side seal joined to the lower part of the center pillar, and A vehicle body in which at least one of the center pillar and the side sill is a shock-absorbing member as described in claim 1.

Description

Shock-absorbing members, and vehicle body The present invention relates to a shock-absorbing member and a vehicle body. While automobiles are required to reduce CO2 emissions, crash safety standards are becoming stricter. Consequently, lightweighting and improved crash safety are required for automobile components, such as impact absorbers, making the material selection and structural design of impact absorbers critical. In particular, for the center pillar, which is a critical component for protecting occupants during a side collision, a more advanced level of material selection and structural design expertise is required. Since the upper part of the center pillar requires high tolerance to prevent deformation for occupant protection, the application of high-strength materials is effective. On the other hand, since the lower part of the center pillar is required to absorb energy, a material with a good balance of strength and fracture resistance is required. Therefore, for the sake of lightweighting, a tail weld blank (TWB), which allows two different materials to be placed in a single blank, is useful as a material for the center pillar. As a TWB material, the TWB material described in Patent Document 1 can be exemplified. FIG. 1 is a schematic left side view showing a main part of a vehicle body to which a shock-absorbing member according to one embodiment of the present invention is applied. FIG. 2 is a cross-sectional view perpendicular to the vertical direction of the closed cross-section of the center pillar along line II-II of FIG. 1, and the illustration of the inside of the cross-section is omitted. FIG. 3 is a schematic cross-sectional view of a main part to explain the combined state of the side sill outer and the center pillar outer along line III-III of FIG. 1, and shows a cross-section perpendicular to the front-rear direction of the vehicle body. FIGS. 4A and FIGS. 4B are schematic diagrams for explaining a bending test, FIG. 4A is a plan view of the test specimen before the test, and FIG. 4B shows the test specimen, punch, and roll. FIG. 5 is a longitudinal cross-sectional view along the plate thickness direction and the up-down direction for the filler outer near the joint in Variation Example 1, and the inside of the cross-section is omitted. Figure 6 is an image illustrating an example of a method for measuring the boundary between the high-strength softened layer and the central part. Figure 7 is an image illustrating an example of a change in Vickers hardness in a softened layer. FIG. 8 is a longitudinal cross-sectional view along the plate thickness direction and the up-down direction for the filler outer near the joint in Variation Example 2, and the inside of the cross-section is omitted. FIG. 9 is a schematic left side view for explaining Variant Example 3, in which no reinforcing member is installed in the side seal. FIG. 10 is a schematic cross-sectional view of the main part of deformation example 4 regarding a deformation example of an overlapping part of a filler outer, and shows a cross-section perpendicular to the front-rear direction. Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, an impact-absorbing member applied to an automobile will be described. FIG. 1 is a schematic left side view showing a main part of a vehicle body (1) to which a shock-absorbing member according to one embodiment of the present invention is applied. FIG. 2 is a cross-sectional view perpendicular to the vertical direction (Z) with respect to a closed cross-sectional part (46) of a center pillar (4) along line II-II of FIG. 1, and the inside of the cross-section is omitted. FIG. 3 is a schematic cross-sectional view of a main part to explain the combined state of a side sill outer (15) and a pillar outer (41) of a center pillar (4) along line III-III of FIG. 1, and shows a cross-section perpendicular to the front-rear direction (X) of the vehicle body (1). In the following, unless otherwise noted, FIG. 1 to FIG. 3 will be appropriately illustrated. The vehicle body (1) is part of the vehicle, and the vehicle can be an automobile. An example of an automobile is a passenger car. Examples of the above passenger car include a sedan-type passenger car, a coupe-type passenger car, a hatchback-type passenger car, a minivan-type passenger car, and an SUV (Sport Utility Vehicle)-type passenger car. In addition, in this embodiment, a configuration in which the vehicle is a BEV (Battery Electric Vehicle) is described as an example. In this embodiment, the vehicle body (1) is formed from a material including a steel plate. As the steel plate, an aluminum-plated steel plate may be exemplified, but other steel types such as a galvanized steel plate may also be used. The plating on the plated steel plate is not particularly limited, but examples include hot-dip galvanizing, alloyed hot-dip galvanizing, electro-galvanizing, Zn-Ni plating (elect