Vehicular framework structure, vehicular rear structure, and vehicle

Abstract

A vehicular framework structure (101) can be disposed in the front portion or the rear portion of a vehicle, and is in the shape of a hollow tube that has one end (103) and the other end (104) separated in the longitudinal direction. The vehicular framework structure (101) comprises: a first portion (101A) including the one end (103); a second portion (101B) including the other end (104); and a middle portion (101C) disposed between the first portion (101A) and the second portion (101B). At least the first portion (101A) of the vehicular framework structure (101) is provided with a bead part (120) that is continuous in the direction of the tubular axis of the first portion (101A). One end section (121) of the bead part (120) in the longitudinal direction is separated from the one end (103) of the vehicular framework structure (101).

Description

Vehicle frame structure, vehicle rear structure, and vehicle

[0001] This application claims priority to Japanese Patent Application No. 2024-061667, filed on April 5, 2024, the contents of which are incorporated herein by reference.

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

[0003] The vehicle frame structure in the front or rear structure of a vehicle generally has 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 of 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, a 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 EA section downstream in the load input direction in the rear straight section, i.e., the portion adjacent to the EA section forward, 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 straight section on the rear side 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.

[0007] Special Publication No. 2022-547492

[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.

[0009] The vehicle skeletal structure of one embodiment is a hollow tubular vehicle skeletal structure that can be arranged at the front or rear of a vehicle and has one end and the other end spaced apart along the longitudinal direction, wherein the vehicle skeletal structure comprises: a first portion that can be arranged toward the front of the front portion or toward the rear of the rear portion of the vehicle and includes the one end; a second portion that can be arranged toward the center of the vehicle, the position of the tube axis being different from the position of the tube axis of the first portion and including the other end; and an intermediate portion that is arranged between the first portion and the second portion and connects the first portion and the second portion, wherein at least the first portion of the vehicle skeletal structure is provided with a bead portion that is continuous along the direction of the tube axis of the first portion, and one longitudinal end of the bead portion is spaced apart from the one end of the vehicle skeletal structure. A vehicle rear structure according to an embodiment includes a pair of hollow tubular vehicle frame structures arranged along the longitudinal direction of the vehicle, and a hollow tubular crossbar arranged along the transverse direction of the vehicle and connecting the pair of vehicle frame structures, wherein the pair of vehicle frame structures are the vehicle frame structures described above. A vehicle according to an embodiment includes the vehicle rear structure described above.

[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.

[0011] 7A is a schematic perspective view showing a vehicle rear structure according to a first embodiment of the present invention; FIG. 7B is a schematic plan view showing a vehicle rear structure according to a first embodiment of the present invention; FIG. 8A is a schematic cross-sectional view showing a vehicle rear structure according to a first embodiment of the present invention, taken along line A-A in FIG. 1; FIG. 8B is a schematic cross-sectional view showing a vehicle rear structure according to a first embodiment of the present invention, taken along line B-B in FIG. 1; FIG. 8C is a schematic cross-sectional view showing a vehicle rear structure according to a first embodiment of the present invention, taken along line CC in FIG. 1; FIG. 8A is a schematic cross-sectional view showing a vehicle skeleton structure provided in the vehicle rear structure according to the first embodiment of the present invention; FIG. 8B is an enlarged schematic plan view showing a vehicle skeleton structure provided in the vehicle rear structure according to the first embodiment of the present invention, taken along line D-D in FIG. 7A; FIG. 8B is an enlarged schematic side view showing a vehicle skeleton structure provided in the vehicle rear structure according to the first embodiment of the present invention, taken along line E-E in FIG. 8A. 1 is a schematic plan view showing a vehicle rear structure according to a second embodiment of the present invention, a schematic plan view showing a vehicle rear structure according to a third embodiment of the present invention, and a schematic view showing a vehicle equipped with a vehicle rear structure according to a fourth embodiment of the present 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 [1] to

[18] below.

[0013] [1] A hollow tubular vehicle skeleton 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 skeleton structure comprising: a first portion that can be arranged toward the front of the front portion or toward the rear of the rear portion of the vehicle and includes the one end; a second portion that can be arranged toward the center of the vehicle, the position of the tube axis being different from the position of the tube axis of the first portion and including the other end; and an intermediate portion that is arranged between the first portion and the second portion and connects the first portion and the second portion, wherein at least the first portion of the vehicle skeleton structure is provided with a bead portion that is continuous along the direction of the tube axis of the first portion, and one longitudinal end of the bead portion is spaced apart from the one end of the vehicle skeleton structure. [2] The vehicle skeleton structure according to [1], wherein an opening is formed in the vehicle skeleton structure to allow connection of a hollow cylindrical crossbar extending along the left-right direction of the vehicle, and the opening is formed at a position between the one longitudinal end of the bead portion and the other longitudinal end of the bead portion. [3] The vehicle skeleton structure according to [2], wherein the opening is in the first portion of the vehicle skeleton structure. [4] The vehicle skeleton 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] The vehicle skeleton structure according to any one of [1] to [4], wherein a gradually changing portion is provided on the one end side of the bead portion, 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 skeletal structure has a first region on the side of the intermediate portion and a second region on the side of the one end of the vehicle skeletal structure relative to the first region, the thickness of the vehicle skeletal structure in the second region is smaller than the thickness of the vehicle skeletal structure in the first region, and the gradually changing portion and the one end of the bead portion are located in the second region. [5] A vehicle skeletal structure as described in [5].[7] The first portion of the vehicle skeletal structure has a first region on the side of the intermediate portion and a second region on the side of the one end of the vehicle skeletal structure relative to the first region, the yield strength and thickness of the vehicle skeletal structure in the second region being smaller than the yield strength and thickness of the vehicle skeletal structure in the first region, and the gradual change portion and the one end of the bead portion are located in the second region. [8] A vehicle skeletal structure as described in [5] or [6]. [8] The vehicle skeleton structure according to any one of [5] to [7], wherein the first portion of the vehicle skeleton structure is provided with a first region on the side of the intermediate portion and a second region on the side of the one end of the vehicle skeleton structure relative to the first region, and wherein, for each of the first region and the second region, when a difference (Hm-Hs) between a hardness Hm at a center in a wall thickness direction in a cross section perpendicular to a tube axis direction of the first portion and a hardness Hs at a surface layer in the wall thickness direction in the cross section is defined as a hardness difference, the hardness difference in the second region is larger than the hardness difference in the first region, and the gradually changing portion and the one end of the bead portion are located in the second region. [9] The vehicle skeleton structure according to any one of [1] to [8], wherein the vehicle skeleton structure is provided with an upper wall portion, and the bead portion is provided in the upper wall portion.

[10] The vehicle skeleton structure according to any one of [1] to [9], wherein at least two or more of the bead portions are provided in the vehicle skeleton structure, and the two bead portions are respectively arranged in positions opposing each other across the tube axis of the first portion.

[11] The vehicle skeleton structure according to

[10] , wherein the vehicle skeleton structure is provided with an upper wall portion and a lower wall portion, and the two bead portions arranged in positions opposing each other across the tube axis of the first portion are provided on the upper wall portion and the lower wall portion.

[12] The vehicle skeleton structure according to

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

[13] A vehicle rear structure including the vehicle skeleton structure according to any one of [1] to

[12] .

[14] A vehicle rear structure comprising: a pair of hollow tubular vehicle skeletal structures arranged along the longitudinal direction of the vehicle; and a hollow tubular crossbar arranged along the lateral direction of the vehicle and connecting the pair of vehicle skeletal structures, wherein the pair of vehicle skeletal structures is the vehicle skeletal structure described in any one of [1] to

[12] .

[15] The pair of vehicle skeletal 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, and at a connection position between the vehicle skeletal structures and the crossbar, the heights of the respective upper wall portions and the heights of the respective lower wall portions are the same.

[16] The vehicle rear structure according to

[14] or

[15] , wherein the vehicle skeletal structure and the crossbar are composed of an upper member located above the vehicle and a lower member located below the vehicle, the upper member and the lower member are respectively provided with upper and lower rails that constitute the vehicle skeletal structure, the upper rail and the lower rail are each provided with a first region that forms a connection with the crossbar, a second region that is closer to one end of the vehicle skeletal structure than the first region, and a third region that is closer to the other end of the vehicle skeletal structure than the first region, and the first region, the second region, and the third region are each joined via a weld that does not have a heat-affected zone.

[17] A vehicle comprising the vehicle skeletal structure according to any one of [1] to

[12] .

[18] A vehicle comprising 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, includes 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 located on the rear side of the vehicle, and the other end 104 of the pair of vehicle skeletal structures 101 is located on the central side of the vehicle.

[0016] Figures 3 to 5 show schematic cross-sectional views taken along lines A-A, B-B, and C-C in Figure 2, respectively. As shown in Figures 3 to 5, the pair of vehicle skeletal structures 101 and crossbar 102 are both hollow tubular members with a closed cross-sectional structure. However, at the connection 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 with 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 configured 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 processing a steel plate into a predetermined shape to form a blank, followed by hot stamping. As is apparent from the cross sections taken along lines A-A, B-B, and C-C 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 the upper crossbar 102U that make up the upper member 100A are integrally formed by hot stamping. Similarly, the lower rail 101D and the 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 plate that will become a blank is heated and softened, and the heated blank is formed in 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 is Ac ３ It is recommended to set it to 1 point or more. ３ The temperature at which ferrite disappears from the metal structure of the blank is the temperature at which 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 may have partially different yield strengths or thicknesses. For example, the upper rail 101U and the lower rail 101D may 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 is ３ By heating to above this point, it is possible to eliminate 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 upward of the vehicle and lower wall portions 101b, 102b facing downward 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 D-D 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 E-E in FIG. 8A. As described in 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 intermediate 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 in the intended connection position between the vehicle skeletal structure 101 and the crossbar 102 and in the intermediate 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 intermediate 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 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 first portion 101A has a substantially linear tube axis. 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. A hollow portion of the vehicle skeletal structure 101 and a hollow portion of the crossbar 102 are configured to communicate with each other via the opening 150.

[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 that 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 first portion 101A of the vehicle skeleton structure 101 of this embodiment has a bead portion 120 formed on its upper wall portion 101a. 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 tube axis direction of the first portion 101A. That is, like the first portion 101A, the bead portion 120 extends entirely along the front-to-rear direction of the vehicle skeleton structure 101. More specifically, like the first portion 101A, the bead portion 120 extends entirely in a substantially linear manner along the front-to-rear direction 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 part 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 longitudinal end 122 of the bead portion 120 is located at least in the intermediate portion 101C. That is, the bead portion 120 exists at least in the intermediate portion 101C. By extending the bead portion 120 beyond the intended connection position of the crossbar 102 and into 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 exist 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 end 103 of the vehicle skeletal structure 101 and the 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 end 103 of the vehicle skeletal structure 101 and the 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 extends to 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, it is preferable that the distance between the one end 103 of the vehicle skeletal structure 101 and the one end 121 of the bead portion 120 is 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, a gradually changing portion 123 is preferably provided on the one end 121 side of the bead portion 120, in which one or both of the bead width and the bead height decrease toward the one end 121. The bead height is the groove depth in the case of a concave bead, and the protrusion height in the case of a convex bead. The gradually changing portion 123 is located on the one end 121 side 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. On the other hand, 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 where the bead width and bead height are constant is referred to as a constant portion 124. 7A , the boundary between the gradually changing portion 123 and the steady portion 124 is indicated by a dashed dotted line F. By providing such a gradually changing portion 123, the buckling resistance load of the first portion 101A gradually decreases from near the boundary between the steady portion 124 and the gradual changing portion 123 toward the one end 121. Note that the buckling resistance load of the steady portion 124 of the first portion 101A is increased by the steady portion 124 and remains constant. Therefore, when collision energy during a collision is input to the first portion 101A, the portion of the first portion 101A that does not have the bead portion 120 buckles and collapses in an accordion-like manner, the buckling collapse is smaller in the portion where the gradual changing portion 123 is provided, and the buckling collapse is even smaller in the portion where the gradual changing 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 adjacent to the intermediate portion 101C and including a position where the crossbar 102 is to be formed. The second region 132 occupies a region adjacent to the first region 131 and including the one end 103 of the vehicle skeletal structure 101.

[0040] The first region 131, the second region 132, and the third region 133 are joined, for example, via welds. The first region 131, the second region 132, and the third region 133 are provided, for example, when the upper member 100A and the lower member 100B are manufactured using a tailored blank as described above. Note that when the upper member 100A and the lower member 100B are manufactured using a single steel plate, differences in local thickness or yield strength cannot be imparted, and therefore the divisions into the first region 131, the second region 132, and the third region 133 are not provided.

[0041] When the first portion 101A is provided with the first region 131 and the second region 132, 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 be 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 be 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. 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 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 portion 101a, the lower wall portion 101b, and the side wall portion 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 101 a, the lower wall portion 101 b, and the side wall portion 101 c 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 101 a, the lower wall portion 101 b, and the side wall portion 101 c 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-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 disappears.

[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 may be performed, for example, in accordance with JIS Z 2244-1:2020. Measurements are made at measurement positions at least 10 mm away from each portion, excluding areas where hardness changes locally, such as bent or welded sections. Specifically, a cut surface parallel to the thickness direction is formed at the measurement positions, and Vickers hardness measurements are taken at a total of five points, at 2 mm measurement intervals, along a line perpendicular to the thickness direction 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 used to determine the Vickers hardness Hm and Hs of the same portion. The case where Vickers hardness is measured on a plated steel material 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 test under the same conditions.

[0054] The shape of the yield strength test specimen is a plate-shaped test specimen (thickness: original thickness of the first region 131 and the second region 132) specified in ASTM A370-22. As long as the test specimen conforms to the above standard, either a subsized test specimen or a standard test specimen may be used. Subsized specimens of the Rectangular Tension Test Specimens are particularly preferred. The test specimen is preferably taken from a location where the above-mentioned flat test specimens can be taken. The case where the yield strength is measured on a plated steel material will be described later. The test conditions are that the tensile test be performed at a tension rate (strain rate) of 0.015±0.003 / min. The tensile test is 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 having a plating layer, a method for specifying the "surface" that serves as the reference for measuring Vickers hardness Hm, Hs and the "thickness" of the yield strength test piece will be described.

[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). A specific measurement method is described below.

[0057] Three arbitrary measurement positions are determined on the plating layer. At each measurement point, the concentrations of the elements Fe, Mn, Zn, Si, Al, O, Cr, Ni, Mg, Cu, and Sn are 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% by mass or more 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 designated as the thickness of the coating layer. Note that if the Fe concentration does not reach 90% by mass or more up to the depth that can be analyzed in a single GDS measurement, i.e., if the thickness of the coating layer is greater than the measurable depth, a portion of the coating layer equivalent to 80 to 90% of the previously measured depth is removed by polishing at an arbitrary position other than the previously measured position in the same region. 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 performed from the polished surface. The thickness of the coating layer is measured by combining the results of the first and subsequent measurements.

[0059] Regarding yield strength, when the yield strength is to be measured on a plated steel material, the tensile strength is measured using a test piece in a plated state, and the "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 a plated steel material, the Vickers hardness is measured using a test piece in a plated state. A cut surface of the plated steel material is formed parallel to the thickness direction at the Vickers hardness measurement position. The thickness of the steel material portion is then determined by subtracting the thickness of the plating layer from the total thickness of the plated steel material. Vickers hardness measurements are taken at five points, at measurement intervals of 2 mm, along a line perpendicular to the thickness direction at the center of the steel material portion and at a depth of 50 μm from the surface of the steel material portion (the interface between the plating layer and the steel material). The average values ​​of these five points are then used to determine the Vickers hardness Hm and Hs of the same portion.

[0061] Furthermore, it is preferable that the welded portion joining the first region 131, the second region 132, and the third region 133 does not have a heat-affected zone. ３ By heating to a temperature above this point, the heat-affected zone disappears in the welded portion joining the first region 131, the second region 132, and the third region 133 together.

[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. Furthermore, 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 skeleton structure 101 of this embodiment, the upper wall portion 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 portion 121 of this bead portion 120 is located as close as possible to the one end 103 of the vehicle skeleton 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 portion 121 of the bead portion 120 and the one end 103 of the vehicle skeleton structure 101. Furthermore, the range where the rigidity is relatively decreased is located closer to the one end 103 of the vehicle skeleton 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, thereby suppressing the propagation of deformation toward the center of the vehicle.

[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 at a position 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 may 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 part 101A, the crossbar 102 may also be deformed due to the collision energy during 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 intermediate portion 101C in addition to the first portion 101A can be suppressed, and propagation of deformation toward the center of the vehicle can be suppressed.

[0068] Furthermore, the vehicle frame structure 101 of this embodiment may be provided with a gradually changing portion 123 on the one end 121 side of the bead portion 120, in which one or both of the bead width and the bead height decrease toward the one end 121. This makes it difficult for stress to concentrate on the 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. This does not hinder absorption of collision energy by the first portion 101A, and it is possible to suppress propagation of deformation toward the center of the vehicle.

[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 gradual change portion 123 and one end 121 of the bead portion 120, 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.

[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 gradual change 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 101 a of the vehicle skeletal structure 101 but also on both the upper wall portion 101 a and the lower wall portion 101 b of the vehicle skeletal structure 101, thereby ensuring that, when collision energy is input, the first portion 101A can be deformed so as to be compressed along its axial direction, 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 101 c of the vehicle skeletal structure 101 of this embodiment.

[0073] The vehicle rear structure 100 of this embodiment has 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 the propagation of deformation toward the center of the vehicle can be suppressed.

[0074] In addition, 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 suppresses the propagation of deformation toward the center of the vehicle.

[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 located on the side of one end 103 of the vehicle skeleton structure 101, and the other end 122 is located 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 intermediate 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. Furthermore, the distance is equal to or less than two-thirds of the distance between the one end 103 of the vehicle skeleton structure 101 and the intended connection position of the crossbar 102.

[0080] As in the first embodiment, it is preferable that a gradually changing portion 223 be provided on the one end 221 side of the bead portion 220, in which one or both of the bead width and the bead height become smaller toward the one end 221.

[0081] As in 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 framework 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 along the pipe axis direction of the first part 101A from one end 321 to the other end 322 in the longitudinal direction of the bead portion 120. The one end 321 of the bead portion 320 is located on the side of the 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 longitudinal end 321 of the bead portion 320 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 one-fifth of the total length of the vehicle skeleton structure 101. Also, the distance is equal to or less than two-thirds 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 the present 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 region with relatively lower rigidity is located closer to the one end 103 of the vehicle skeletal structure 101, i.e., closer to the load input side, than the region with increased rigidity due to the bead portion 320. As a result, when a load is input due to a collision or the like, the region 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] Furthermore, in this embodiment, as in the first embodiment, it is preferable that a gradually changing portion 323 be provided on one end 321 side of the bead portion 320, in which one or both of the bead width and bead height become smaller toward the one end 321.

[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 framework 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 of the vehicle, the vehicle skeletal structure 101 absorbs the collision energy, preventing the passenger compartment from deforming due to the collision and ensuring the safety of the occupants.

[0091] An upper member and a lower member were manufactured by forming a tailored blank by 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 FIG. 2 , FIG. 9 , or FIG. 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 having a plate thickness of 1.6 mm and a yield strength of 1105 to 1498 MPa. The second region was made of steel material having a plate thickness of 1.0 mm and a yield strength of 900 to 1105 MPa.

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

[0093] [Evaluation criteria] ◎...One end portion of the first region of the vehicle skeletal structure was crushed in an accordion-like manner, but no deformation was observed in the connection portion with the crossbar. ◯...One end portion of the first region of the vehicle skeletal structure was crushed in an accordion-like manner, and slight deformation was observed in the connection portion with the crossbar. △...One end portion of the first region of the vehicle skeletal structure did not crush, but the other portion was crushed, and slight deformation was observed in the connection portion with the crossbar. ×...Significant deformation was observed in the connection portion with the crossbar of the first portion of the vehicle skeletal structure, and the other portions, including the one end portion, did not crush.

[0094] The results are shown in Table 1.

[0095]

[0096] As shown in Table 1, the vehicle rear structure satisfying the present invention performed better than the comparative example.

[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.

[0098] DESCRIPTION OF SYMBOLS 100...Vehicle rear structure 100A...Upper member 100B...Lower member 101...Vehicle skeleton structure 101a...Upper wall portion 101b...Lower wall portion 101c...Side wall portion 101A...First portion 101B...Second portion 101C...Intermediate portion 101U...Upper rail 101D...Lower rail 102...Crossbar 102U...Upper crossbar 102D...Lower crossbar 103...One end of vehicle skeleton structure 104...Other end of vehicle skeleton structure 110...Bumper beam 120, 220, 320...Bead portion 121, 221, 321...One end portion 122, 222, 322...Other end portion 123, 223, 323...Gradually changing portion 124...Steady portion 131...First region portion 132...Second area part 133...Third area part 150...Opening part

Claims

1. A hollow tubular vehicle frame structure that can be placed at the front or rear of a vehicle and has one end and the other end spaced apart along the longitudinal direction, the vehicle frame structure comprising: a first portion that can be placed towards the front of the front portion or towards the rear of the rear portion of the vehicle and includes the one end; a second portion that can be placed towards the center of the vehicle, the position of the tube axis being different from the position of the tube axis of the first portion and includes the other end; and an intermediate portion that is placed between the first and second portions and connects the first and second portions, wherein at least the first portion of the vehicle frame structure is provided with a bead portion that is continuous along the direction of the tube axis of the first portion, and one longitudinal end of the bead portion is spaced apart from the one end of the vehicle frame structure.

2. A vehicle frame structure as described in claim 1, wherein an opening is formed in the vehicle frame structure to enable connection of a hollow cylindrical cross bar along the left-right direction of the vehicle, and the opening is formed at a position between the position of 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 of claim 2, wherein the opening is in the first portion of the vehicle frame structure.

4. A 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 longitudinal end of the bead portion is located at least in the intermediate portion.

5. A vehicle frame structure as set forth in claim 1, wherein a gradually changing portion is provided on the one end side of the bead portion, in which one or both of the bead width and bead height become smaller toward the one end.

6. A vehicle skeletal structure as described in claim 5, wherein the first portion of the vehicle skeletal structure is provided with a first region located on the side of the intermediate portion and a second region located closer to the one end of the vehicle skeletal structure than the first region, the thickness of the vehicle skeletal structure in the second region is smaller than the thickness of the vehicle skeletal structure in the first region, and the gradually changing portion and the one end of the bead portion are located in the second region.

7. A vehicle skeletal structure as set forth in claim 5, wherein the first portion of the vehicle skeletal structure is provided with a first region located on the side of the intermediate portion and a second region located closer to the one end of the vehicle skeletal structure than the first region, the yield strength and thickness of the vehicle skeletal structure in the second region being smaller than the yield strength and thickness of the vehicle skeletal structure in the first region, and the gradually changing portion and one end of the bead portion being located in the second region.

8. A vehicle skeleton structure as set forth in claim 5, wherein the first portion of the vehicle skeleton structure is provided with a first region located on the side of the intermediate portion and a second region located closer to the one end of the vehicle skeleton structure than the first region, and wherein, 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 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, and the gradually changing portion and the one end of the bead portion are located in the second region.

9. 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.

10. A vehicle frame structure as described in claim 1, wherein at least two or more bead portions are provided on the vehicle frame structure, and the two bead portions are respectively positioned opposite each other across the tube axis of the first portion.

11. A vehicle frame structure as described in claim 10, 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, and are arranged at positions opposite each other across the tube axis of the first portion.

12. The vehicle frame structure according to claim 10, 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.

13. A rear structure for a vehicle comprising the vehicle frame structure according to any one of claims 1 to 12.

14. A rear structure for a vehicle comprising: a pair of hollow tubular vehicle skeletal structures arranged along the longitudinal direction of the vehicle; and a hollow tubular crossbar arranged along the lateral direction of the vehicle and connecting the pair of vehicle skeletal structures, wherein the pair of vehicle skeletal structures are the vehicle skeletal structures defined in any one of claims 1 to 12.

15. A vehicle rear structure as set forth in claim 14, wherein the pair of vehicle frame structures and the crossbar each have an upper wall portion facing the upper side of the vehicle and a lower wall portion facing the lower side of the vehicle, and at the connection position between the vehicle frame structures and the crossbar, the heights of the respective upper wall portions and the heights of the respective lower wall portions are the same.

16. A vehicle rear structure as set forth in claim 14, wherein the vehicle skeletal structure and the crossbar are composed of an upper member located above the vehicle and a lower member located below the vehicle, the upper member and the lower member are each provided with an upper rail and a lower rail that constitute the vehicle skeletal 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 skeletal structure than the first region, and a third region that is closer to the other end of the vehicle skeletal structure than the first region.

17. A vehicle equipped with a vehicle frame structure according to any one of claims 1 to 12.

18. A vehicle equipped with the rear structure for a vehicle according to claim 14.

Images