Vehicle frame structure, vehicle rear structure, and vehicle

Abstract

This vehicle skeletal structure (101) can be arranged at the front or rear of the vehicle, and is a hollow tubular vehicle skeletal structure (101) having one end (103) and the other end (104) spaced apart along the longitudinal direction, and is provided with a first portion (101A) including the one end (103), a second portion (101B) including the other end (104), and an intermediate portion (101C) arranged between the first portion (101A) and the second portion (101B), and at least the first portion (101A) of the vehicle skeletal structure (101) is provided with a bead portion (120) that is continuous along the direction of the tube axis of the first portion (101A), and one longitudinal end portion (121) of the bead portion (120) is spaced apart from the one end (103) of the vehicle skeletal structure (101).

Description

[Technical Field]

[0001] The present invention relates to a vehicle frame structure, a vehicle rear structure, and a vehicle. This application claims priority based on Japanese Patent Application No. 2024-061667, filed on April 5, 2024, the contents of which are incorporated herein by reference. [Background technology]

[0002] Conventionally, there have been vehicles that have an energy absorbing section in the front straight section of the vehicle skeletal structure of the front structure of the vehicle, or in the rear straight section of the vehicle skeletal structure of the rear structure of the vehicle, that deforms due to the load input through the bumper during a front or rear collision, and absorbs the collision energy (for example, Patent Document 1).

[0003] Vehicle frame structures in the front or rear structure of a vehicle generally have a closed cross-section structure, and the rear rail of Patent Document 1 has a rear straight section, a front straight section whose tube axis position is different from that of the rear straight section, and a bent section located between the rear straight section and the front straight section. Patent Document 1 discloses a technology that can appropriately absorb collision energy in a rear collision by making the product of the material strength and plate thickness at the bent section greater than the product of the material strength and plate thickness at the rear straight section.

[0004] As a deformation mode of the energy absorption section (hereinafter, sometimes referred to as the EA section) for ensuring energy absorption performance, so-called bellows deformation is preferable, which can ensure a large amount of plastic deformation throughout the entire EA section before fracture of the material forming the EA section progresses. For this reason, Patent Document 1 also employs a structure that promotes bellows deformation by arranging multiple geometric deformation sections 25 along the vertical direction perpendicular to the load input direction on the wall surface corresponding to the EA section.

[0005] Here, if the rigidity of the portion adjacent to the downstream side of the EA section in the load input direction in the rear straight section, i.e., the portion adjacent to the front side of the EA section, is different, the degree of deformation of that portion will be different during a rear-end collision, and as a result, the deformation pattern of the EA section during a rear-end collision may be different.

[0006] However, in the structure of the rear straight section of the rear rail in Patent Document 1, no special measures are taken in the section adjacent to the front side of the EA section, which may result in insufficient rigidity in that section and prevent the EA section from deforming favorably in a rear-end collision. In other words, when the EA section deforms in a rear-end collision, the section adjacent to the front may deform significantly, which may hinder the desired deformation of the EA section. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2022-547492 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a vehicle skeletal structure, a vehicle rear structure, and a vehicle that are less likely to inhibit deformation that is considered desirable when absorbing collision energy and can fully ensure energy absorption performance. [Means for solving the problem]

[0009] The vehicle frame structure of an embodiment is a hollow tubular vehicle frame structure that can be arranged at the front or rear of a vehicle and has one end and the other end spaced apart along a longitudinal direction, The vehicle frame structure includes: a first portion that can be disposed forward of the front portion or rearward of the rear portion of the vehicle and includes the one end; a second portion that can be disposed near the center of the vehicle, has a tube axis positioned at a position different from the tube axis of the first portion, and includes the other end; an intermediate portion disposed between the first portion and the second portion and connecting the first portion and the second portion; a bead portion that is continuous along a pipe axis direction of the first portion is provided in at least the first portion of the vehicle frame structure, One longitudinal end of the bead portion is spaced apart from the one end of the vehicle frame structure. In addition, the vehicle rear structure of the embodiment includes a pair of hollow tubular vehicle frame structures arranged along the front-rear direction of the vehicle; a hollow tubular cross bar arranged along the left-right direction of the vehicle and connecting the pair of vehicle frame structures, The pair of vehicle frame structures are the vehicle frame structures described above. Moreover, the vehicle of the embodiment includes the above-described vehicle rear structure. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a vehicle frame structure, a vehicle rear structure, and a vehicle that are less likely to be hindered by the deformation that is considered desirable when absorbing collision energy, and that can fully ensure the expected energy absorption performance. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic perspective view showing a vehicle rear structure according to a first embodiment of the present invention; [Figure 2] 1 is a schematic plan view showing a vehicle rear structure according to a first embodiment of the present invention; [Figure 3] 2 is a diagram showing a vehicle rear structure according to a first embodiment of the present invention, and is a cross-sectional schematic view corresponding to the line AA in FIG. 1. [Figure 4] 1 is a cross-sectional view showing a vehicle rear structure according to a first embodiment of the present invention, the cross-sectional view corresponding to line BB in FIG. 1; [Figure 5]1 is a cross-sectional view showing a vehicle rear structure according to a first embodiment of the present invention, taken along line CC in FIG. 1; [Figure 6] 1 is a schematic plan view showing a vehicle frame structure provided in a vehicle rear structure according to a first embodiment of the present invention; [Figure 7A] 3 is a diagram showing a vehicle frame structure provided in a vehicle rear structure according to a first embodiment of the present invention, and is an enlarged schematic plan view showing the main parts of FIGS. 1 and 2. FIG. [Figure 7B] 7B is a schematic cross-sectional view taken along line DD in FIG. 7A. [Figure 8A] 3 is a diagram showing a vehicle frame structure provided in the vehicle rear structure according to the first embodiment of the present invention, and is an enlarged schematic side view showing the main parts of FIGS. 1 and 2. FIG. [Figure 8B] 8B is a schematic cross-sectional view taken along line EE in FIG. 8A. [Figure 9] FIG. 4 is a schematic plan view showing a vehicle rear structure according to a second embodiment of the present invention. [Figure 10] FIG. 10 is a schematic plan view showing a vehicle rear structure according to a third embodiment of the present invention. [Figure 11] FIG. 10 is a schematic diagram showing a vehicle equipped with a vehicle rear structure according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The vehicle frame structure, the vehicle rear structure, and the vehicle according to the embodiments of the present invention have the configurations described in the following [1] to

[18] .

[0013] [1] A hollow tubular vehicle frame structure that can be disposed at the front or rear of a vehicle and has one end and the other end spaced apart along a longitudinal direction, The vehicle frame structure includes: a first portion that can be disposed forward of the front portion or rearward of the rear portion of the vehicle and includes the one end; a second portion that can be disposed near the center of the vehicle, has a tube axis positioned at a position different from the tube axis of the first portion, and includes the other end; an intermediate portion disposed between the first portion and the second portion and connecting the first portion and the second portion; a bead portion that is continuous along a pipe axis direction of the first portion is provided in at least the first portion of the vehicle frame structure, One longitudinal end of the bead portion is spaced apart from the one end of the vehicle frame structure. [2] The vehicle frame structure has an opening formed therein for connecting a hollow cylindrical crossbar extending along the left-right direction of the vehicle, The vehicle frame structure according to [1], wherein the opening is formed between the position of the one end of the bead portion in the longitudinal direction and the position of the other end of the bead portion in the longitudinal direction. [3] The vehicle frame structure according to [2], wherein the opening is in the first portion of the vehicle frame structure. [4] A vehicle frame structure according to any one of [1] to [3], wherein the bead portion is provided continuously between the first portion and the intermediate portion, and the other longitudinal end of the bead portion is located at least in the intermediate portion. [5] A vehicle frame structure according to any one of [1] to [4], wherein a gradual change section is provided on the one end side of the bead section, in which one or both of the bead width and the bead height become smaller toward the one end. [6] The first portion of the vehicle frame structure is provided with a first region located on the side of the intermediate portion and a second region located on the side of the one end of the vehicle frame structure relative to the first region, a thickness of the vehicle frame structure in the second region is smaller than a thickness of the vehicle frame structure in the first region, The vehicle frame structure according to [5], wherein the second region includes the gradually changing portion and the one end portion of the bead portion. [7] The first portion of the vehicle frame structure is provided with a first region located on the side of the intermediate portion and a second region located on the side of the one end of the vehicle frame structure relative to the first region, the yield strength and the wall thickness of the vehicle frame structure in the second region are smaller than the yield strength and the wall thickness of the vehicle frame structure in the first region, The vehicle frame structure according to [5] or [6], wherein the second region includes the gradually changing portion and the one end of the bead portion. [8] The first portion of the vehicle frame structure is provided with a first region located on the side of the intermediate portion and a second region located on the side of the one end of the vehicle frame structure relative to the first region, For each of the first region and the second region, when the difference (Hm-Hs) between the hardness Hm at the center in the thickness direction in a cross section perpendicular to the tube axis direction of the first portion and the hardness Hs at the surface layer in the thickness direction in the cross section is defined as the hardness difference, The hardness difference in the second region is greater than the hardness difference in the first region, The vehicle frame structure according to any one of [5] to [7], wherein the second region includes the gradually changing portion and the one end portion of the bead portion. [9] The vehicle frame structure according to any one of [1] to [8], wherein the vehicle frame structure is provided with an upper wall portion, and the bead portion is provided on the upper wall portion.

[10] At least two or more bead portions are provided on the vehicle frame structure, The vehicle frame structure according to any one of [1] to [9], wherein the two bead portions are arranged at positions facing each other across the tube axis of the first portion.

[11] The vehicle skeletal structure described in

[10] , wherein the vehicle skeletal structure has an upper wall portion and a lower wall portion, and the two bead portions arranged in opposing positions across the pipe axis of the first part are provided on the upper wall portion and the lower wall portion.

[12] The vehicle frame structure according to

[10] , wherein the frame structure has a side wall portion, and one of the bead portions is provided on the side wall portion.

[13] A rear structure for a vehicle, comprising the vehicle frame structure according to any one of [1] to

[12] .

[14] A pair of hollow tubular vehicle frame structures arranged along the front-rear direction of the vehicle; a hollow tubular cross bar arranged along the left-right direction of the vehicle and connecting the pair of vehicle frame structures, A rear structure for a vehicle, wherein the pair of vehicle frame structures are the vehicle frame structures according to any one of [1] to

[12] .

[15] The pair of vehicle frame structures and the crossbar each have an upper wall portion facing upward of the vehicle and a lower wall portion facing downward of the vehicle,

[14] A vehicle rear structure as described in

[14] , wherein the heights of the respective upper wall portions and the respective lower wall portions are the same at the connection position between the vehicle skeletal structure and the crossbar.

[16] The vehicle frame structure and the crossbar are composed of an upper member located on the upper side of the vehicle and a lower member located on the lower side of the vehicle, the upper member and the lower member are provided with upper and lower rails that constitute the vehicle frame structure, The upper rail and the lower rail each have a first region that forms a connection with the crossbar, a second region that is closer to one end of the vehicle frame structure than the first region, and a third region that is closer to the other end of the vehicle frame structure than the first region,

[14] or

[15] , wherein the first region, the second region, and the third region are each joined via a welded joint that does not have a heat-affected zone.

[17] A vehicle equipped with the vehicle frame structure according to any one of [1] to

[12] .

[18] A vehicle equipped with the vehicle rear structure according to any one of

[14] to

[15] .

[0014] Hereinafter, a vehicle frame structure and a vehicle rear structure according to an embodiment of the present invention will be specifically described.

[0015] (First embodiment) First, a vehicle rear structure 100 according to a first embodiment of the present invention will be described. The vehicle rear structure 100 according to this embodiment, shown in the perspective view of FIG. 1 and the plan view of FIG. 2, is configured to include a pair of hollow tubular vehicle skeletal structures 101 arranged along the longitudinal direction of the vehicle, and a hollow tubular crossbar 102 arranged along the lateral direction of the vehicle and connecting the pair of vehicle skeletal structures 101. The vehicle rear structure 100 shown in FIGS. 1 and 2 may also include a bumper beam 110 joined to one end 103 of the pair of vehicle skeletal structures 101, as shown by the dashed dotted line in FIG. 2. As can be seen from the arrangement of the bumper beam 110, in the vehicle rear structure 100 shown in FIGS. 1 and 2, the one end 103 of the pair of vehicle skeletal structures 101 is on the rear side of the vehicle, and the other end 104 of the pair of vehicle skeletal structures 101 is on the center side of the vehicle.

[0016] 3 to 5 show schematic cross-sectional views taken along lines AA, BB, and CC in FIG. 2, respectively. As shown in FIGS. 3 to 5, the pair of vehicle skeletal structure 101 and crossbar 102 are both hollow tubular members with a closed cross-sectional structure. However, at the connection portion between the vehicle skeletal structure 101 and the crossbar 102, the hollow portion of the vehicle skeletal structure 101 and the hollow portion of the crossbar 102 are configured to communicate with each other. Accordingly, an opening is provided in the vehicle skeletal structure 101 at the connection position of the crossbar 102. The opening will be described later.

[0017] As shown in FIGS. 3 to 5, the vehicle rear structure 100 of this embodiment is formed by integrally joining an upper member 100A located on the upper side of the vehicle and a lower member 100B located on the lower side of the vehicle. The upper member 100A and the lower member 100B are each formed, for example, by a hot stamping method after a steel plate is processed into a predetermined shape to form a blank. As is clear from the cross sections taken along lines AA, BB, and CC in FIG. 2, each of the upper member 100A and the lower member 100B has a cross-sectional shape consisting of web portions 100a, 100b, a vertical wall portion 100c, and a flange portion 100d. The vehicle rear structure 100 of this embodiment is integrated by joining the flange portions 100d of the upper member 100A and the lower member 100B together. Spot welding, for example, can be used as a joining method. Furthermore, spot welding can also be used in combination with a structural adhesive.

[0018] 3 to 5, the upper member 100A is further provided with an upper rail 101U and an upper crossbar 102U. The upper rail 101U constitutes the vehicle frame structure 101 of the vehicle rear structure 100 when the upper member 100A is joined integrally with the lower member 100B from above and below. The upper crossbar 102U constitutes the crossbar 102 of the vehicle rear structure 100.

[0019] Similarly, the lower member 100B is provided with a lower rail 101D and a lower crossbar 102D. The lower rail 101D, together with the upper rail 101U, constitutes the vehicle frame structure 101 of the vehicle rear structure 100. The lower crossbar 102D, together with the upper crossbar 102U, constitutes the crossbar 102 of the vehicle rear structure 100.

[0020] The upper rail 101U and upper crossbar 102U that make up the upper member 100A are integrally formed by hot stamping. Similarly, the lower rail 101D and lower crossbar 102D that make up the lower member 100B are integrally formed by hot stamping. The hot stamping method refers to a method in which a steel sheet that will become a blank is heated and softened, and the heated blank is formed using a forming die and then heat is removed by the die to process the blank into a desired shape. The heating temperature of the blank should be set to the Ac3 point or higher. The Ac3 point is the temperature at which ferrite disappears in the metal structure of the blank. The metal structure after processing by the hot stamping method becomes a structure mainly composed of martensite.

[0021] The upper member 100A and the lower member 100B may also be formed by hot stamping a so-called tailored blank. A tailored blank is formed by welding together multiple types of steel plates with different yield strengths and thicknesses. The upper member 100A and the lower member 100B formed from such a tailored blank have partially different yield strengths or thicknesses. For example, the upper rail 101U and the lower rail 101D can each be composed of multiple regions (first and second regions described below) with different yield strengths or thicknesses, as described below.

[0022] When forming a tailored blank by hot stamping, the tailored blank can be heated to the Ac3 point or higher, thereby eliminating the heat-affected zone of the weld that remained when the tailored blank was manufactured.

[0023] The pair of vehicle skeletal structures 101 and crossbars 102 of the vehicle rear structure 100 of this embodiment each have upper wall portions 101a, 102a facing the upper side of the vehicle and lower wall portions 101b, 102b facing the lower side of the vehicle. In the vehicle rear structure 100 of this embodiment, at the connection position between the vehicle skeletal structure 101 and the crossbar 102, it is preferable that the heights of the upper wall portions 101a, 102a are the same, and the heights of the lower wall portions 101b, 102b are the same. This makes it less likely that bending will occur at the connection position between the vehicle skeletal structure 101 and the crossbar 102 when collision energy is applied.

[0024] Next, a pair of vehicle skeletal structures 101 that are part of the vehicle rear structure 100 of this embodiment will be described in detail. Fig. 6 shows a schematic plan view of the vehicle skeletal structure 101 of this embodiment. Fig. 7A shows a schematic plan view of a part of the vehicle skeletal structure 101, and Fig. 7B shows a schematic longitudinal cross-sectional view taken along line DD in Fig. 7A. Fig. 8A shows a schematic cross-sectional view of a part of the side of the vehicle skeletal structure 101, and Fig. 8B shows a schematic longitudinal cross-sectional view taken along line EE in Fig. 8A. Note that, as described with reference to Figs. 1 to 5, the vehicle skeletal structure 101 of this embodiment can be disposed in the rear of the vehicle, but the position of the vehicle skeletal structure 101 of this embodiment is not limited to the rear of the vehicle and can also be disposed in the front of the vehicle.

[0025] 6, the vehicle skeletal structure 101 of this embodiment is a hollow tubular member having one end 103 and the other end 104 spaced apart along the longitudinal direction. The vehicle skeletal structure 101 includes a first portion 101A including the one end 103, a second portion 101B including the other end 104 of the vehicle skeletal structure 101, and an intermediate portion 101C disposed between the first portion 101A and the second portion 101B.

[0026] The first portion 101A, the second portion 101B and the intermediate portion 101C are all hollow tubular, and the hollow portions of each are in communication with each other.

[0027] The first portion 101A, the second portion 101B, and the middle portion 101C constituting the vehicle frame structure 101 each have an upper wall portion 101a disposed on the upper side of the vehicle, a lower wall portion 101b disposed on the lower side of the vehicle, and a side wall portion 101c connecting the upper wall portion 101a and the lower wall portion 101b. The upper wall portion 101a and the lower wall portion 101b correspond to the web portion 100a in the upper member 100A and the lower member 100B described above. The side wall portion 101c corresponds to the vertical wall portion 100c in the upper member 100A and the lower member 100B.

[0028] Here, when external stress is input due to a collision, the vehicle skeletal structure 101 of this embodiment is designed to absorb the collision energy by deforming only a portion of the first portion 101A while leaving the second portion 101B and the middle portion 101C unchanged. More specifically, a region of the first portion 101A near one end 103 of the vehicle skeletal structure 101 is deformed to absorb the collision energy. Meanwhile, a region of the first portion 101A near the other end 104 of the vehicle skeletal structure 101 is not deformed. In this way, deformation due to a collision is prevented from occurring at the intended connection position between the vehicle skeletal structure 101 and the crossbar 102 or in the middle portion 101C, which is located closer to the center of the vehicle than the first portion 101A. The first portion 101A, the second portion 101B, and the middle portion 101C will be described below.

[0029] The first portion 101A can be disposed near the front of the vehicle or near the rear of the vehicle, and is a portion that includes one end 103 of the vehicle skeletal structure 101. When the bumper beam 110 is attached to the vehicle skeletal structure 101, it is attached to this first portion 101A. The tube axis of the first portion 101A is made substantially linear. That is, the first portion 101A extends along the longitudinal direction of the vehicle skeletal structure 101. More specifically, the first portion 101A extends substantially linearly along the longitudinal direction of the vehicle skeletal structure 101.

[0030] A crossbar 102 can be connected to the first portion 101A. The vehicle skeletal structure 101 of this embodiment has a closed cross-sectional structure as a whole, but when the crossbar 102 is connected to the vehicle skeletal structure 101, an opening 150 is provided in the side wall portion 101c of the vehicle skeletal structure 101 at the connection position, as shown in Fig. 8A. The opening 150 is configured to allow communication between the hollow portion of the vehicle skeletal structure 101 and the hollow portion of the crossbar 102.

[0031] The second portion 101B can be disposed closer to the center of the vehicle, and the position of its tube axis is different from the position of the tube axis of the first portion 101A. The second portion 101B is a portion that includes the other end 104 of the vehicle skeleton structure 101. The other end 104 of the vehicle skeleton structure 101 can be joined to another structure that constitutes the cabin of the vehicle.

[0032] The intermediate portion 101C is disposed between the first portion 101A and the second portion 101B and is provided to connect the first portion 101A and the second portion 101B. If the first portion 101A and the second portion 101B were disposed in a straight line without the intermediate portion 101C, the first portion 101A may interfere with the wheel wells that house the front or rear wheels of the vehicle, the engine, the battery, the axles, etc. Therefore, the intermediate portion 101C serves to position the tube axis of the first portion 101A at a position different from the position of the tube axis of the second portion 101B.

[0033] Next, the bead portion 120 will be described. As shown in FIGS. 1, 2, 4, and 6 to 8B, the bead portion 120 is formed on the upper wall portion 101a of the first portion 101A of the vehicle skeleton structure 101 of this embodiment. The bead portion 120 is provided continuously from one end 121 to the other end 122 in the longitudinal direction of the bead portion 120 along the pipe axis direction of the first portion 101A. That is, like the first portion 101A, the bead portion 120 as a whole extends along the front-rear direction of the vehicle of the vehicle skeleton structure 101. More specifically, like the first portion 101A, the bead portion 120 as a whole extends in an approximately linear manner along the front-rear direction of the vehicle of the vehicle skeleton structure 101. One end 121 of the bead portion 120 is located on the side of one end 103 of the vehicle frame structure 101, and the other end 122 is located on the side of the other end 104 of the vehicle frame structure 101. The intended connection position of the crossbar 102 is located between the one end 121 and the other end 122 of the bead portion 120. By providing the bead portion 120, the rigidity of the first portion 101A is partially increased.

[0034] As shown in Figures 1, 2, 4, and 6 to 8B, the bead portion 120 may be a groove-shaped concave bead that protrudes inward from the vehicle skeletal structure 101, or a convex bead that protrudes outward from the vehicle skeletal structure 101.

[0035] The other end 122 of the bead portion 120 in the longitudinal direction is located at least in the intermediate portion 101C. That is, the bead portion 120 is present at least in the intermediate portion 101C. By extending the bead portion 120 beyond the intended connection position of the crossbar 102 and reaching the intermediate portion 101C, the rigidity of the first portion 101A is improved in the area where the bead portion 120 is formed, thereby reliably preventing deformation of the intended connection position of the crossbar 102 and the intermediate portion 101C during a collision. Note that the other end 122 of the bead portion 120 may extend to the second portion 101B. That is, the bead portion 120 may be present in the second portion 101B.

[0036] It is preferable that one longitudinal end 121 of the bead portion 120 is as close as possible to one end 103 of the vehicle skeleton structure 101. The distance between one end 121 of the bead portion 120 and one end 103 of the vehicle skeleton structure 101 is at least equal to or less than a distance equivalent to 1 / 5 of the total length of the vehicle skeleton structure 101. More preferably, it is equal to or less than a distance equivalent to 1 / 10 of the total length of the vehicle skeleton structure 101.

[0037] In the region of the first portion 101A where the bead portion 120 is provided, the buckling resistance load against a load input in the axial direction of the first portion 101A is relatively high. On the other hand, the buckling resistance load of the region of the first portion 101A where the bead portion 120 is not formed is lower than the buckling resistance load of the region where the bead portion 120 is formed. The range of the region where the bead portion 120 is not formed, i.e., the region where the buckling resistance load is relatively low, expands as the distance between the one end 103 of the vehicle skeletal structure 101 and the one end 121 of the bead portion 120 increases. This allows buckling deformation that occurs when collision energy is input to occur over a wide range, which is advantageous for absorbing collision energy. However, if the distance between the one end 103 of the vehicle skeletal structure 101 and the one end 121 of the bead portion 120 is too long, the range of deformation during a collision will expand, and the deformation may extend to the intermediate portion 101C or the crossbar 102. In particular, if the deformation reaches the intended connection position of the crossbar 102 in the vehicle skeletal structure 101, the deformation range due to the collision may extend to the crossbar 102. Therefore, as described above, the distance between one end 103 of the vehicle skeletal structure 101 and one end 121 of the bead portion 120 is preferably equal to or less than a distance equivalent to 1 / 5 of the total length of the vehicle skeletal structure 101. More preferably, it is equal to or less than a distance equivalent to 1 / 10 of the total length of the vehicle skeletal structure 101.

[0038] Furthermore, the bead portion 120 The end 121 on the side of the end 103 isIt is preferable to provide a gradually changing portion 123 in which one or both of the bead width and the bead height decrease toward the end of the bead portion 120. Note that the bead height is the groove depth in the case of a concave bead and the protruding height in the case of a convex bead. The gradually changing portion 123 is located on the side of the one end 121 of the bead portion 120. In other words, the gradually changing portion 123 of the bead portion is located on the side where the collision load is input. In the gradually changing portion 123, the cross-sectional shape of the bead portion 120 gradually decreases as it approaches the one end 121 of the bead portion 120, i.e., toward the side where the collision load is input. Meanwhile, the bead width and bead height of the portion of the bead portion 120 other than the gradually changing portion 123 are constant along the longitudinal direction of the bead portion 120. In the following description, the portion with constant bead width and bead height is referred to as a constant portion 124. In FIG. 7A, the boundary between the gradually changing portion 123 and the constant portion 124 is indicated by a dashed line F. By providing such gradual-change portion 123, the buckling resistance load of first portion 101A gradually decreases from near the boundary between steady portion 124 and gradual-change portion 123 toward one end 121. Note that the buckling resistance load of steady portion 124 of first portion 101A is increased by steady portion 124 and remains constant. Therefore, when collision energy during a collision is input to first portion 101A, the portion of first portion 101A where bead portion 120 is not provided buckles and collapses in an accordion-like manner, the buckling collapse is smaller in the portion where gradual-change portion 123 is provided, and the buckling collapse is even smaller in the portion where gradual-change portion 123 is provided. As a result, by placing one end 121 of the bead portion 120 as close as possible to one end 103 of the vehicle skeletal structure 101, even if collision energy is input to the first part 101A during a collision, the first part 101A will buckle and collapse in an accordion-like manner starting from the one end 103 side of the vehicle skeletal structure 101, thereby maximizing the amount of energy absorption.

[0039] The first portion 101A may be divided into a first region 131 located closer to the intermediate portion 101C and a second region 132 located closer to the one end 103 of the vehicle skeletal structure 101 than the first region 131 based on differences in thickness, yield strength, or hardness. The vehicle skeletal structure 101 may also have a third region 133 located closer to the other end 104 of the vehicle skeletal structure 101 than the first region 131. The third region 133 includes the intermediate portion 101C and the second portion 101B. As shown in FIGS. 6, 7A, and 8A, the first region 131 occupies a region of the first portion 101A that is adjacent to the intermediate portion 101C and includes a position where the crossbar 102 is to be formed. The second region 132 occupies a region that is adjacent to the first region 131 and includes the one end 103 of the vehicle skeletal structure 101.

[0040] First region 131, second region 132, and third region 133 are joined, for example, via welds. First region 131, second region 132, and third region 133 are provided, for example, when upper member 100A and lower member 100B are manufactured using a tailored blank as described above. Note that when upper member 100A and lower member 100B are manufactured using a single steel plate as the material, it is not possible to have differences in local thickness or yield strength, so the divisions into first region 131, second region 132, and third region 133 are not provided.

[0041] When the first region 131 and the second region 132 are provided in the first portion 101A, it is preferable that the thicknesses of the upper wall portion 101a, the lower wall portion 101b, and the side wall portion 101c that constitute the second region 132 are smaller than the respective thicknesses of the first region 131. In addition, it is preferable that the gradually changing portion 123 and one end portion 121 of the bead portion 120 are positioned in the second region 132. As a result, when collision energy is input to the first portion 101A, the first region 131 is not deformed, and the second region 132 is deformed preferentially.

[0042] Furthermore, when the first region 131 and the second region 132 are provided in the first portion 101A, the yield strength and thickness of the upper wall portion 101a, the lower wall portion 101b, and the side wall portion 101c that constitute the second region 132 may be smaller than the yield strength and thickness of the first region 131. In addition, the gradually changing portion 123 and one end portion 121 of the bead portion 120 may be positioned in the second region 132. This prevents the first region 131 from deforming when collision energy is input to the first portion 101A, and the second region 132 is more likely to deform preferentially.

[0043] Furthermore, when the first portion 101A is provided with the first region 131 and the second region 132, it is preferable to adjust the hardness difference in the thickness direction of the upper wall 101a, the lower wall 101b, and the side wall 101c. Specifically, it is preferable to make the hardness difference in the second region 132 larger than the hardness difference in the first region 131.

[0044] The hardness difference refers to the difference (Hm-Hs) between the hardness Hm at the center of the thickness direction in a cross section perpendicular to the tube axis of the first portion 101A in the upper wall portion 101a, the lower wall portion 101b, and the side wall portion 101c, and the hardness Hs at the surface layer in the thickness direction in the same cross section. The surface layer in the thickness direction refers to a position 50 μm deep from the surface, where t is the thickness of the upper wall portion 101a, the lower wall portion 101b, and the side wall portion 101c. The hardness Hs and Hm may be Vickers hardnesses measured under the same conditions. Therefore, the hardness difference is the difference in Vickers hardness.

[0045] When the upper wall portion 101a, the lower wall portion 101b, and the side wall portion 101c are made of steel, the surface that is the reference for measuring the Vickers hardness refers to the surface of the steel. When the upper wall portion 101a, the lower wall portion 101b, and the side wall portion 101c are made of plated steel, the surface that is the reference for measuring the Vickers hardness refers to the interface between the plated layer and the steel. Plated steel refers to steel on which a plated layer is formed.

[0046] The plating layer is not particularly limited, but examples thereof include hot-dip galvanizing, alloyed hot-dip galvanizing, electrogalvanizing, Zn-Ni plating (electroalloy galvanizing), Sn plating, Al-Si plating, alloyed electrogalvanizing, hot-dip zinc-aluminum alloy plating, hot-dip zinc-aluminum-magnesium alloy plating, hot-dip zinc-aluminum-magnesium-Si alloy plating, and zinc-vapor-deposited Al plating.

[0047] By making the hardness difference in the second region 132 greater than the hardness difference in the first region 131, when collision energy is input to the first portion 101A and the second region 132 is deformed, the surface layers of the upper wall portion 101a, the lower wall portion 101b and the side wall portion 101c of the second region 132 undergo plastic deformation, making it less likely for cracks to occur.This prevents the first portion 101A from breaking and makes it possible to maintain the energy absorption capacity of the vehicle skeletal structure 101 until the collision energy is eliminated.

[0048] The thickness, yield strength, and hardness difference of the third region 133 are not particularly limited, and may be the same as the thickness, yield strength, and hardness difference of the first region 131, for example.

[0049] The thickness of the first region 131 is preferably in the range of 1.4 to 2.0 mm, for example, and the thickness of the second region 132 is preferably in the range of 0.8 to 1.2 mm, for example.

[0050] The yield strength (0.2% proof stress) of the first region 131 is preferably in the range of 1100 to 1800 MPa, for example. The yield strength (0.2% proof stress) of the second region 132 is preferably in the range of 800 to 1150 MPa, for example.

[0051] The hardness difference of the first region 131 is preferably in the range of, for example, −50 to 50 HV, and the hardness difference of the second region 132 is preferably in the range of, for example, 100 to 150 HV.

[0052] Vickers hardness measurements can be performed, for example, in accordance with JIS Z 2244-1:2020. Measurements are taken at a measurement position at least 10 mm away from each part, excluding areas where hardness changes locally, such as bent or welded parts. Specifically, a cut surface parallel to the thickness direction is created at the measurement position, and Vickers hardness measurements are taken at five points along a line perpendicular to the thickness direction at 2 mm measurement intervals, at the center of the thickness and at a depth of 50 μm from the surface on the cut surface. The test force used to measure the Vickers hardness Hm at the center of the thickness is 9.807 N. The test force used to measure the Vickers hardness Hs at a depth of 50 μm from the surface is 0.1961 N. The average values ​​of these five points are taken as the Vickers hardness Hm and Hs for the same part. The case where Vickers hardness is measured on plated steel will be described later.

[0053] Yield strength refers to the maximum stress that can be applied to a material without causing plastic deformation, and in this embodiment, yield strength refers to 0.2% proof stress. 0.2% proof stress can be measured in accordance with JIS Z 2241:2011. When evaluating the magnitude relationship between the yield strengths of the first region 131 and the second region 132, it is naturally desirable to use the same sample shape and the same test conditions.

[0054] The shape of the yield strength test specimen shall be a plate-shaped test specimen (thickness: original thickness of the first region 131 and the second region 132) as specified in ASTM A370-22. As long as the test specimen conforms to the above standard, either a subsize test specimen or a standard test specimen may be used. Subsize specimens of rectangular tension test specimens are particularly preferred. The test specimen should be taken from a location where the above-mentioned flat test specimens can be taken. The case where the yield strength is measured on plated steel will be described later. The test conditions are as follows: the tensile test should be performed at a tension rate (strain rate) of 0.015±0.003 / min. The tensile test should be performed three times, and the arithmetic mean of the three measurement results is taken as the yield strength.

[0055] When the measurement target for yield strength and Vickers hardness Hm, Hs is a plated steel material with a plating layer, this paper describes how to specify the "surface" that serves as the reference for measuring Vickers hardness Hm, Hs, and the "thickness" of the yield strength test piece.

[0056] The thickness of the plating layer on the plated steel material is measured using a high-frequency glow discharge optical emission surface analyzer (GDS). The specific measurement method is described below.

[0057] Three measurement positions are arbitrarily determined on the plating layer. At each measurement point, the concentration of each element (Fe, Mn, Zn, Si, Al, O, Cr, Ni, Mg, Cu, Sn) is measured while sputtering from the surface of the plating layer.

[0058] The content of each element is analyzed in the depth direction, and the depth at which the Fe concentration first reaches 90 mass% or greater is determined. This depth is designated as the interface between the steel material and the coating layer. The average depth at each measurement point is then calculated, and this average is used as the coating layer thickness. Note that if the Fe concentration does not reach 90 mass% or greater up to the depth analyzed in a single GDS measurement, i.e., if the coating layer thickness is greater than the measurable depth, a portion of the coating layer equivalent to 80-90% of the previously measured depth is removed by polishing at a different location within the same area. The depth of the coating layer removed by polishing is determined from the change in plate thickness before and after polishing, and a new GDS analysis is then performed on the polished surface. The thickness of the coating layer is then measured by combining the results of the first and subsequent measurements.

[0059] Regarding yield strength, when the yield strength measurement target is a plated steel material, the tensile strength is measured using a test piece in a plated state, and "thickness: original thickness of the first region 131 and the second region 132" refers to the thickness of the steel material portion obtained by subtracting the thickness of the plating layer from the total thickness of the plated steel material. In other words, the original cross-sectional area of ​​the test piece used to calculate the yield strength is the original cross-sectional area of ​​the steel material portion excluding the plating layer.

[0060] Regarding Vickers hardness, when the object to be measured for Vickers hardness is plated steel, the Vickers hardness measurement is performed using a test piece in its plated state. A cut surface of the plated steel is formed parallel to the thickness direction at the position where the Vickers hardness is measured. The thickness of the steel portion is then determined by subtracting the thickness of the plating layer from the total thickness of the plated steel. Vickers hardness measurements are taken at a total of five points, at measurement intervals of 2 mm, along a line perpendicular to the thickness direction at the center of the steel portion and at a depth of 50 μm from the surface of the steel portion (the interface between the plating layer and the steel). The average values ​​of these five points are then used to determine the Vickers hardness Hm and Hs of the same area.

[0061] Furthermore, it is preferable that the welds joining the first region 131, the second region 132, and the third region 133 do not have a heat-affected zone. As described above, when the upper member 100A and the lower member 100B are manufactured from tailored blanks by the hot stamping method, the heat-affected zone is eliminated in the welds joining the first region 131, the second region 132, and the third region 133 by heating to the Ac3 point or higher.

[0062] Furthermore, in the present embodiment, the case where the bead portion 120 is provided on the upper wall portion 101a of the vehicle skeleton structure 101 has been described, but the present embodiment is not limited to this, and the bead portion 120 may be provided on both the upper wall portion 101a and the lower wall portion 101b of the vehicle skeleton structure 101. That is, the two bead portions 120 may be disposed at positions facing each other across the tube axis of the first portion 101A. This prevents the first portion 101A from warping or bending upward or downward when collision energy is input, and the first portion 101A is deformed so as to be compressed in the tube axis direction of the first portion 101A.

[0063] In this embodiment, a bead portion may also be provided on the side wall portion 101c of the first portion 101A of the vehicle skeleton structure 101. In this case, the bead portion may be provided on the outer side of the vehicle skeleton structure 101, i.e., on the side where the crossbar 102 is not provided. The bead portion provided on the side wall portion 101c may also be provided on the middle portion 101C, similar to the bead portion 120 provided on the upper wall portion 101a. By providing a bead portion on the side wall portion 101c, when collision energy is input, the first portion 101A does not bend, but is deformed so as to be compressed in the tube axis direction of the first portion 101A.

[0064] As described above, in the vehicle skeletal structure 101 of this embodiment, the upper wall 101a of the hollow cylindrical first portion 101A is provided with the bead portion 120 that is continuous along the axial direction of the first portion 101A, and one longitudinal end 121 of this bead portion 120 is located as close as possible to one end 103 of the vehicle skeletal structure 101. Therefore, the rigidity is increased in the range of the first portion 101A where the bead portion 120 is provided, while the rigidity is relatively decreased in the range where the bead portion 120 is not provided, i.e., the range between the one end 121 of the bead portion 120 and the one end 103 of the vehicle skeletal structure 101. Furthermore, the range where the rigidity is relatively decreased is located closer to the one end 103 of the vehicle skeletal structure 101 than the range where the rigidity is increased by the bead portion 120, i.e., on the side where a load is input. As a result, when a load is input due to a collision or the like, the area of ​​the first portion 101A where the bead portion 120 is not provided is deformed so as to be compressed along the pipe axis, thereby absorbing the collision energy. On the other hand, the area where the bead portion 120 is provided is less likely to deform, and propagation of deformation toward the center of the vehicle can be suppressed.

[0065] In addition, the vehicle skeletal structure 101 of this embodiment may have an opening 150 formed therein to enable connection of the crossbar 102. In this case, the opening 150 is formed between the position of one longitudinal end 121 of the bead portion 120 and the position of the other longitudinal end 122 of the bead portion 120. Therefore, even if there is concern that the presence of the opening 150 will reduce the rigidity of the vehicle skeletal structure 101, the rigidity near the opening 150 can be reinforced by the bead portion 120, thereby suppressing deformation at the intended connection position with the crossbar 102.

[0066] Furthermore, in the vehicle skeletal structure 101 of this embodiment, when the above-mentioned opening 150 is located in the first portion 101A, the crossbar 102 may also be deformed due to the collision energy at the time of a collision. However, the bead portion 120 can reinforce the rigidity near the opening 150, thereby suppressing deformation at the intended connection position with the crossbar 102.

[0067] Furthermore, in the vehicle skeletal structure 101 of this embodiment, the bead portion 120 is provided continuously from the first portion 101A to the intermediate portion 101C, and the other longitudinal end portion 122 of the bead portion 120 is located in the intermediate portion 101C. Therefore, when a load such as a collision is input, deformation of the first portion 101A as well as the intermediate portion 101C can be suppressed, and propagation of deformation toward the center of the vehicle can be suppressed.

[0068] In addition, the vehicle frame structure 101 of this embodiment has a bead portion 120. At one end 121 on the side of one end 103, A gradually changing portion 123 may be provided in which one or both of the bead width and the bead height become smaller toward the center of the vehicle. This makes it difficult for stress to concentrate on one end 121 of the bead portion 120 when a collision load is input to the vehicle frame structure 101, and there is no possibility of breakage of the first portion 101A occurring near the boundary between the range where the bead portion 120 is provided and the range where the bead portion 120 is not provided, so that absorption of the collision energy by the first portion 101A is not hindered, and propagation of deformation toward the center of the vehicle can be suppressed.

[0069] In addition, the first part 101A of the vehicle skeletal structure 101 of this embodiment is formed with a first region 131 and a second region 132 which is located closer to one end 103 of the vehicle skeletal structure 101 than the first region 131 and has a smaller thickness than the first region 131, and this second region 132 has the gradual change portion 123 and one end 121 of the bead portion 120, so that in the event of a collision, the first region 131 is less likely to deform, while the second region 132 is more likely to deform, and the collision energy can be absorbed in the second region 132.

[0070] In addition, the first part 101A of the vehicle skeletal structure 101 of this embodiment is formed with a first region 131 and a second region 132 which is located closer to one end 103 of the vehicle skeletal structure 101 than the first region 131 and has a smaller yield strength and thickness than the first region 131, and since this second region 132 has the gradually changing portion 123 and one end 121 of the bead portion 120, during a collision the first region 131 is less likely to deform, while the second region 132 is more likely to deform, and the collision energy can be absorbed in the second region 132.

[0071] In addition, the first part 101A of the vehicle skeletal structure 101 of this embodiment is formed with a first region 131 and a second region 132 which is located closer to one end 103 of the vehicle skeletal structure 101 than the first region 131 and has a smaller hardness difference than the first region 131, and since this second region 132 has the gradually changing portion 123 and one end 121 of the bead portion 120, in the event of a collision, the surface layers of the upper wall portion 101a, lower wall portion 101b and side wall portion 101c which constitute the second region 132 are less likely to crack, and the second region 132 can sufficiently absorb the collision energy, thereby preventing deformation of the first region 131.

[0072] Furthermore, the vehicle skeletal structure 101 of this embodiment may be provided with bead portions 120 not only on the upper wall portion 101a of the vehicle skeletal structure 101 but also on both the upper wall portion 101a and the lower wall portion 101b of the vehicle skeletal structure 101, thereby ensuring that the first portion 101A can be deformed so as to be compressed along its axial direction when collision energy is input, thereby suppressing propagation of deformation toward the center of the vehicle. Furthermore, in order to compress and deform the first portion 101A along its axial direction, a bead portion may also be provided on the side wall portion 101c of the vehicle skeletal structure 101 of this embodiment.

[0073] The vehicle rear structure 100 of this embodiment is equipped with a pair of vehicle skeletal structures 101, and since this vehicle skeletal structure 101 is the vehicle skeletal structure 101 of this embodiment in which a bead portion 120 is provided in the first portion 101A, the first portion 101A can be deformed so as to be compressed along its pipe axis direction, and propagation of deformation toward the center of the vehicle can be suppressed.

[0074] Furthermore, the vehicle rear structure 100 of this embodiment is equipped with a pair of vehicle skeletal structures 101 and a crossbar 102, and since this vehicle skeletal structure 101 is the vehicle skeletal structure 101 of this embodiment in which a bead portion 120 is provided in the first portion 101A, the first portion 101A can be deformed so as to be compressed along its axial direction, and further, since the connection portion between the vehicle skeletal structure 101 and the crossbar 102 does not deform during a collision, the range of deformation can be reduced and the propagation of deformation toward the center of the vehicle can be suppressed.

[0075] Furthermore, in the vehicle rear structure 100 of this embodiment, at the connection position between the vehicle skeletal structure 101 and the crossbar 102, the heights of the upper wall portion 101a of the vehicle skeletal structure 101 and the upper wall portion 102a of the crossbar 102 are the same, and the heights of the lower wall portion 101b of the vehicle skeletal structure 101 and the lower wall portion 102b of the crossbar 102 are the same. Therefore, when collision energy is applied, bending is less likely to occur at the connection portion between the vehicle skeletal structure 101 and the crossbar 102, and the propagation of deformation toward the center of the vehicle can be suppressed.

[0076] Furthermore, the vehicle skeletal structure 101 of the vehicle rear structure 100 of this embodiment is provided with a first region 131 that forms a connection portion with the crossbar 102, a second region 132 at one end 103 of the vehicle skeletal structure 101, and a third region 133 at the other end 104 of the vehicle skeletal structure 101, and each of these is joined via a welded portion that does not have a heat-affected zone, so that the strength near the welded portion is not partially reduced and the occurrence of cracks originating from the welded portion is suppressed. This allows the first portion 101A to be deformed so as to be compressed along its axial direction, and the propagation of deformation toward the center of the vehicle can be suppressed.

[0077] (Second embodiment) Next, a vehicle rear structure 200 according to a second embodiment of the present invention will be described. The vehicle rear structure 200 according to this embodiment shown in Fig. 9 has substantially the same structure as the vehicle rear structure 100 according to the first embodiment. The difference between the vehicle rear structure 200 according to this embodiment and the vehicle rear structure 100 according to the first embodiment is the range in which the bead portion is provided.

[0078] As in the first embodiment, the bead portion 220 of the vehicle rear structure 200 of this embodiment is provided continuously from one end 221 to the other end 222 in the longitudinal direction of the bead portion 120 along the pipe axis direction of the first part 101A. The one end 221 of the bead portion 220 is on the side of one end 103 of the vehicle skeleton structure 101, and the other end 122 is on the side of the other end 104 of the vehicle skeleton structure 101. The intended connection position of the cross bar 102 is located between the one end 121 and the other end 222 of the bead portion 220.

[0079] As in the first embodiment, the other longitudinal end 222 of the bead portion 220 is located in the middle portion 101C. On the other hand, one longitudinal end 221 of the bead portion 220 is located further away from one end 103 of the vehicle skeleton structure 101 than in the first embodiment. As in the first embodiment, the distance between one end 221 of the bead portion 220 and one end 103 of the vehicle skeleton structure 101 is equal to or less than one-fifth of the total length of the vehicle skeleton structure 101. In addition, the distance is equal to or less than two-thirds of the distance between one end 103 of the vehicle skeleton structure 101 and the intended connection position of the crossbar 102.

[0080] As in the first embodiment, the bead portion 220 The end 221 on the side of the end 103 is It is preferable to provide a gradually changing portion 223 in which one or both of the bead width and the bead height become smaller toward the center.

[0081] Furthermore, similarly to the first embodiment, the first portion 101A of this embodiment may be divided into a first region 131 located on the side of the intermediate portion 101C and a second region 132 located closer to the one end 103 of the vehicle frame structure 101 than the first region 131, based on differences in thickness, yield strength, or hardness. In addition, the gradually changing portion 223 and one end 221 of the bead portion 220 may be positioned in the second region 132.

[0082] As described above, the vehicle rear structure 200 of this embodiment and the vehicle frame structure 101 provided in the vehicle rear structure 200 can achieve the same effects as those of the first embodiment.

[0083] (Third embodiment) Next, a vehicle rear structure 300 according to a third embodiment of the present invention will be described. The vehicle rear structure 300 according to this embodiment shown in Fig. 10 has substantially the same structure as the vehicle rear structure 100 according to the first embodiment. The difference between the vehicle rear structure 300 according to this embodiment and the vehicle rear structure 100 according to the first embodiment is the range in which the bead portion is provided.

[0084] As in the first embodiment, the bead portion 320 of the vehicle rear structure 300 of this embodiment is provided continuously from one end 321 to the other end 322 in the longitudinal direction of the bead portion 120 along the pipe axis direction of the first part 101A. The one end 321 of the bead portion 320 is located on the side of one end 103 of the vehicle skeleton structure 101, and the other end 322 is located on the side of the other end 104 of the vehicle skeleton structure 101.

[0085] As in the first embodiment, one end 321 of the bead portion 320 in the longitudinal direction is located away from one end 103 of the vehicle skeleton structure 101. As in the first embodiment, the distance between one end 221 of the bead portion 320 and one end 103 of the vehicle skeleton structure 101 is equal to or less than 1 / 5 of the total length of the vehicle skeleton structure 101. Also, the distance is equal to or less than 2 / 3 of the distance between the one end 103 of the vehicle skeleton structure 101 and the intended connection position of the crossbar 102.

[0086] On the other hand, in this embodiment, the other longitudinal end 322 of the bead portion 320 does not extend to the intended connection position of the crossbar 102. That is, the bead portion 320 is not formed at the intended connection position of the crossbar 102. Therefore, the rigidity at the intended connection position of the crossbar 102 is lower than that of the first or second embodiment. However, as in the first and second embodiments, the longitudinal end 321 of the bead portion 320 is located away from the one end 103 of the vehicle skeletal structure 101. Therefore, a range where the rigidity is relatively lower is located closer to the one end 103 of the vehicle skeletal structure 101, i.e., closer to the load input side, than the range where the rigidity is increased by the bead portion 320. As a result, when a load is input due to a collision or the like, the range of the first portion 101A where the bead portion 120 is not provided can be deformed so as to be compressed along the tube axis, thereby absorbing the collision energy, as in the first and second embodiments.

[0087] In this embodiment, similarly to the first embodiment, the bead portion 320 The end 321 on the side of the end 103 isIt is preferable to provide a gradually changing portion 323 in which one or both of the bead width and the bead height become smaller toward the center.

[0088] Furthermore, in this embodiment, similarly to the first embodiment, the first portion 101A may be divided into a first region 131 located on the side of the intermediate portion 101C and a second region 132 located closer to the one end 103 of the vehicle frame structure 101 based on differences in thickness, yield strength, or hardness. In addition, the gradually changing portion 323 and one end 321 of the bead portion 320 may be positioned in the second region 132.

[0089] As described above, the vehicle rear structure 300 of this embodiment and the vehicle frame structure 101 provided in the vehicle rear structure 300 can achieve the same effects as those of the first embodiment.

[0090] (Fourth embodiment) FIG. 11 is a schematic diagram of a vehicle according to a fourth embodiment of the present invention. As shown in FIG. 11, the vehicle of this embodiment includes a vehicle rear structure 300. The vehicle rear structure 300 is disposed rearward of the vehicle cabin. A vehicle skeletal structure 101 constituting the vehicle rear structure 300 is used as a rear side member RM. One end of the vehicle skeletal structure 101 is disposed so as to face rearward of the vehicle. The vehicle skeletal structure 101 functions as an impact absorbing material for the vehicle. As a result, even if a collision load is applied from the rear side of the vehicle, the vehicle skeletal structure 101 absorbs the collision energy, so that the vehicle cabin is not deformed by the collision and the safety of the occupants can be ensured. [Example]

[0091] An upper member and a lower member were manufactured by forming a tailored blank using a hot press method, and the upper member and the lower member were joined by spot welding to manufacture a vehicle rear structure having the structure shown in Figure 2, Figure 9, or Figure 10. A bumper beam was joined to one end of the vehicle skeleton structure. The vehicle skeleton structure constituting the vehicle rear structure had a first region, a second region, and a third region. The first region and the third region were made of steel material with a plate thickness of 1.6 mm and a yield strength of 1105 to 1498 MPa. The second region was made of steel material with a plate thickness of 1.0 mm and a yield strength of 900 to 1105 MPa.

[0092] A CAE analysis was conducted in which a rigid barrier of 1,100 kgf was crashed head-on from behind at a full wrap at 50 km / h against the bumper beam of the resulting rear structure for a vehicle. However, a boundary condition was set to completely restrain the boundary between 101B and 101C. The state of deformation of the vehicle rear structure was evaluated according to the following evaluation criteria.

[0093] [Evaluation criteria] ◎...One end of the first region of the vehicle frame structure was crushed like an accordion, but no deformation was observed at the connection with the crossbar. 〇...One end of the first region of the vehicle skeletal structure was crushed like an accordion, and slight deformation was also observed at the connection with the crossbar. △: One end of the first region of the vehicle frame structure was not crushed, but the other parts were crushed, and slight deformation was also observed in the connection with the crossbar. ×: Significant deformation was observed in the first portion of the vehicle frame structure at the connection with the crossbar, but the other portions, including the portion on one end, did not collapse.

[0094] The results are shown in Table 1.

[0095] [Table 1]

[0096] As shown in Table 1, the vehicle rear structure satisfying the present invention was superior to the comparative example. [Industrial Applicability]

[0097] The present invention has industrial applicability, as it is possible to provide a vehicle skeletal structure, a vehicle rear structure, and a vehicle that are less likely to inhibit deformation, which is considered desirable when absorbing collision energy, and that can sufficiently ensure energy absorption performance. [Explanation of symbols]

[0098] 100...Rear structure for vehicle 100A...Upper member 100B...Lower member 101...Vehicle frame structure 101a...Top wall part 101b…Lower wall part 101c...Side wall part 101A…Part 1 101B…Second part 101C…middle part 101U...Upper rail 101D...lower rail 102...Crossbar 102U...Upper crossbar 102D...Lower crossbar 103...One end of vehicle frame structure 104...other end of vehicle frame structure 110...Bumper beam 120, 220, 320...Bead section 121, 221, 321...One end 122, 222, 322...Other end 123, 223, 323...gradually changing part 124...Stationary section 131...First area part 132…Second area part 133…Third area part 150...Opening

Claims

1. A hollow tubular vehicle framework structure that can be disposed at the front or rear of a vehicle and has one end and the other end spaced apart along a longitudinal direction, The vehicle frame structure includes: a first portion that can be disposed forward of the front portion or rearward of the rear portion of the vehicle and that includes the one end; a second portion that can be disposed near the center of the vehicle, has a tube axis positioned at a position different from the tube axis of the first portion, and includes the other end; an intermediate portion disposed between the first portion and the second portion and connecting the first portion and the second portion; a bead portion that is continuous along a pipe axis direction of the first portion is provided in at least the first portion of the vehicle frame structure, an end portion of the bead portion on the side of the one end in the longitudinal direction thereof is spaced apart from the one end of the vehicle frame structure; a gradually changing portion is provided at the one end of the bead portion, in which one or both of the bead width and the bead height become smaller toward the one end, the first portion is provided with a first region located on the side of the intermediate portion and a second region located on the side of the one end of the vehicle frame structure relative to the first region, a thickness of the vehicle frame structure in the second region is smaller than a thickness of the vehicle frame structure in the first region, The vehicle frame structure, wherein the second region includes the gradually changing portion and the one end portion of the bead portion.

2. A hollow tubular vehicle framework structure that can be disposed at the front or rear of a vehicle and has one end and the other end spaced apart along a longitudinal direction, The vehicle frame structure includes: a first portion that can be disposed forward of the front portion or rearward of the rear portion of the vehicle and that includes the one end; a second portion that can be disposed near the center of the vehicle, has a tube axis positioned at a position different from the tube axis of the first portion, and includes the other end; an intermediate portion disposed between the first portion and the second portion and connecting the first portion and the second portion; a bead portion that is continuous along a pipe axis direction of the first portion is provided in at least the first portion of the vehicle frame structure, an end portion of the bead portion on the side of the one end in the longitudinal direction thereof is spaced apart from the one end of the vehicle frame structure; a gradually changing portion is provided at the one end of the bead portion, in which one or both of the bead width and the bead height become smaller toward the one end, the first portion is provided with a first region located on the side of the intermediate portion and a second region located on the side of the one end of the vehicle frame structure relative to the first region, the yield strength and the wall thickness of the vehicle frame structure in the second region are smaller than the yield strength and the wall thickness of the vehicle frame structure in the first region, The vehicle frame structure, wherein the second region includes the gradually changing portion and the one end portion of the bead portion.

3. A hollow tubular vehicle framework structure that can be disposed at the front or rear of a vehicle and has one end and the other end spaced apart along a longitudinal direction, The vehicle frame structure includes: a first portion that can be disposed forward of the front portion or rearward of the rear portion of the vehicle and that includes the one end; a second portion that can be disposed near the center of the vehicle, has a tube axis positioned at a position different from the tube axis of the first portion, and includes the other end; an intermediate portion disposed between the first portion and the second portion and connecting the first portion and the second portion; a bead portion that is continuous along a pipe axis direction of the first portion is provided in at least the first portion of the vehicle frame structure, an end portion of the bead portion on the side of the one end in the longitudinal direction thereof is spaced apart from the one end of the vehicle frame structure; a gradually changing portion is provided at the one end of the bead portion, in which one or both of the bead width and the bead height become smaller toward the one end, the first portion is provided with a first region located on the side of the intermediate portion and a second region located on the side of the one end of the vehicle frame structure relative to the first region, For each of the first region and the second region, when the difference (Hm-Hs) between the hardness Hm at the center in the thickness direction in a cross section perpendicular to the tube axis direction of the first portion and the hardness Hs at the surface layer in the thickness direction in the cross section is defined as a hardness difference, The hardness difference in the second region is greater than the hardness difference in the first region, The vehicle frame structure, wherein the second region includes the gradually changing portion and the one end portion of the bead portion.

4. an opening is formed in the vehicle frame structure to allow connection of a hollow cylindrical cross bar extending along the left-right direction of the vehicle; 4. The vehicle frame structure according to claim 1, wherein the opening is formed between the one end of the bead portion in the longitudinal direction and the other end of the bead portion in the longitudinal direction.

5. The vehicle frame structure of claim 4 , wherein the opening is in the first portion of the vehicle frame structure.

6. 4. The vehicle frame structure according to claim 1, wherein the bead portion is provided continuously between the first portion and the intermediate portion, and the other end of the bead portion in the longitudinal direction is located at least in the intermediate portion.

7. 4. The vehicle frame structure according to claim 1, wherein the vehicle frame structure is provided with an upper wall portion, and the bead portion is provided on the upper wall portion.

8. At least two or more of the bead portions are provided on the vehicle frame structure, 4. The vehicle frame structure according to claim 1, wherein the two bead portions are arranged at positions facing each other across the tube axis of the first portion.

9. 9. The vehicle frame structure according to claim 8, wherein the vehicle frame structure has an upper wall portion and a lower wall portion, and the two bead portions are provided on the upper wall portion and the lower wall portion, the two bead portions being arranged at positions opposite each other across the tube axis of the first portion.

10. 9. The vehicle frame structure according to claim 8, wherein the vehicle frame structure is provided with a side wall portion, and one of the bead portions is provided on the side wall portion.

11. A rear structure for a vehicle, comprising the vehicle frame structure according to any one of claims 1 to 3.

12. a pair of hollow tubular vehicle frame structures arranged along the front-rear direction of the vehicle; a hollow tubular cross bar arranged along the left-right direction of the vehicle and connecting the pair of vehicle frame structures, A rear structure for a vehicle, wherein the pair of vehicle frame structures are the vehicle frame structures according to any one of claims 1 to 3.

13. The pair of vehicle frame structures and the cross bar each have an upper wall portion facing upward of the vehicle and a lower wall portion facing downward of the vehicle, 13. The vehicle rear structure according to claim 12, wherein at a connection position between the vehicle frame structure and the crossbar, the heights of the respective upper wall portions and the heights of the respective lower wall portions are the same.

14. the vehicle frame structure and the crossbar are composed of an upper member located on an upper side of the vehicle and a lower member located on a lower side of the vehicle, the upper member and the lower member are provided with upper and lower rails that constitute the vehicle frame structure, Each of the upper rail and the lower rail is provided with a first region that forms a connection portion with the crossbar, a second region that is closer to one end of the vehicle frame structure than the first region, and a third region that is closer to the other end of the vehicle frame structure than the first region, The vehicle rear structure according to claim 12, wherein the first region, the second region, and the third region are joined together via welds that do not have a heat-affected zone.

15. A vehicle comprising the vehicle frame structure according to any one of claims 1 to 3.

16. A vehicle comprising the rear structure for a vehicle according to claim 12.

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