Vehicle underbody structure

Abstract

To provide vehicle underbody structure technology that is highly resistant to collisions and can also increase productivity. [Solution] The vehicle body lower structure 10 extends in the longitudinal direction of the vehicle body and includes a vertical frame 20 with a U-shaped or hat-shaped cross-section having a bottom wall 21 and a vertical wall 22, a horizontal frame 30 with a U-shaped or hat-shaped cross-section extending in the vehicle width direction and intersecting the vertical wall 22 of the vertical frame 20, and a connecting portion 52 that forms a C-shaped opening 53 over the entire intersection portion 51 of the vertical frame 20 and the horizontal frame 30. A reinforcing member 70 is provided in the intersection portion 51 of the vertical frame 20. The reinforcing member 70 includes a partition wall 90 that closes the C-shaped opening 53. The partition wall 90 is positioned to be continuous with the vertical wall 22.

Description

Technical Field

[0001] The present invention relates to an improved technology for a vehicle body lower structure.

Background Art

[0002] A general vehicle body lower structure has a configuration in which a cross-frame is spanned between a pair of longitudinal frames extending in the vehicle body front-rear direction. Such a technology for a vehicle body lower structure is known, for example, from Patent Document 1 and Patent Document 2.

[0003] The vehicle body lower structure known from Patent Document 1 is such that a hat-shaped cross member (cross-frame) is abutted and joined to the side portion of a hat-shaped floor frame (longitudinal frame) extending in the vehicle body front-rear direction, and a bulkhead is provided inside the floor frame at the joining portion. According to Patent Document 1, it is possible to suppress the bending deformation of the floor frame that occurs when a side impact load is input due to a pole collision.

[0004] The vehicle body lower structure known from Patent Document 2 is such that a tailored blank obtained by joining a plurality of blanks is press-formed to integrate the vehicle body rear frame, thereby improving productivity. This vehicle body lower structure includes left and right side members (longitudinal frames) having a hat-shaped cross section extending in the vehicle body front-rear direction, and a hat-shaped cross member (cross-frame) spanned between these side members. When press-forming is performed using a T-shaped die and punch in plan view, a C-shaped opening is formed at the intersection of the side member and the cross member.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] In the vehicle underbody structure known from Patent Document 1, a cross member (horizontal frame) with a hat-shaped cross section is butted and joined to the side of a floor frame (vertical frame) with a hat-shaped cross section, and a bulkhead is provided inside the floor frame at the joint, resulting in high rigidity and resistance to collisions. However, since the vertical and horizontal frames are produced separately and then butted and joined, it is disadvantageous in terms of increasing the productivity of the vehicle underbody structure.

[0007] In the vehicle body understructure known from Patent Document 2, the rear frame of the vehicle body is integrated by press-forming a tailored blank formed by joining multiple blanks, which can increase the productivity of the vehicle body understructure. However, the intersection of the side members (vertical frames) and cross members (horizontal frames) forms a C-shaped opening, which is disadvantageous in terms of increasing the rigidity and strength of the vehicle body understructure.

[0008] The present invention aims to provide a technology for a vehicle underbody structure that is highly resistant to collisions and can also increase productivity. [Means for solving the problem]

[0009] According to this disclosure, A longitudinal frame extending in the front-to-rear direction of the vehicle body, having a bottom wall and vertical walls, and having a U-shaped or hat-shaped cross-section, A horizontal frame with a U-shaped or hat-shaped cross-section extends in the vehicle width direction and intersects the vertical wall of the vertical frame, It includes a connecting portion that forms a C-shaped opening over the entire intersection of the vertical frame and the horizontal frame, Reinforcement members are provided at the intersection portion of the aforementioned vertical frame. The reinforcing member includes a partition wall that closes the C-shaped opening, The bulkhead is provided as part of a vehicle body lower structure, which is positioned to be continuous with the vertical wall. [Effects of the Invention]

[0010] In this disclosure, the joints forming a C-shaped opening across the entire intersection of the longitudinal and transverse frames can be integrated, thereby increasing the productivity of the vehicle body understructure. Furthermore, the reduction in strength and rigidity of the C-shaped opening can be compensated for by providing reinforcing members at the intersections of the longitudinal frames. In particular, the reinforcing members include a bulkhead that closes the C-shaped opening, and by positioning the bulkhead to be continuous with the longitudinal wall, the axial load acting in the longitudinal direction of the longitudinal frame can be increased. Therefore, this disclosure can provide a vehicle body understructure technology that is highly resistant to collisions and can increase productivity. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view of the underbody structure of the vehicle according to Example 1. [Figure 2] This is an enlarged view of part 2 of Figure 1. [Figure 3] Figure 3A is a schematic diagram of a tailored blank material used to obtain the vehicle body understructure shown in Figure 2, and Figure 3B is a schematic diagram of press-forming the tailored blank material shown in Figure 3A to obtain the vehicle body understructure. [Figure 4] Figure 2 is a perspective view showing the intersection of the vehicle body's lower structure reinforced with reinforcing members. [Figure 5] Figure 4 is a disassembled perspective view of the reinforcing member shown. [Figure 6] This is a cross-sectional view along line 6-6 in Figure 4. [Figure 7] This is a cross-sectional view along line 7-7 in Figure 4. [Figure 8] Figure 4 is a diagram illustrating the operation of the vehicle's underbody structure. [Figure 9] This is an exploded view of the underbody structure of the vehicle according to Example 2 (corresponding to Figure 5). [Figure 10] Figure 9 is a plan view of the underbody structure of the vehicle. [Figure 11]Fig. 11A is a schematic view of a tailored blank material for obtaining the underbody structure shown in Fig. 9, and Fig. 11B is a schematic view of obtaining the underbody structure by pressing the tailored blank material shown in Fig. 11A. Fig. 11C is a schematic view of the underbody structure shown in Fig. 11B as viewed from the upside down direction. [Figure 12] It is a cross-sectional view along line 12-12 of Fig. 10. [Figure 13] It is a cross-sectional view of the underbody structure according to Example 3 (equivalent to Fig. 7). [Figure 14] It is a perspective view of the intersection of the underbody structure according to Example 4 (equivalent to Fig. 4). [Figure 15] It is an exploded view of the underbody structure shown in Fig. 14. [Figure 16] It is a cross-sectional view along line 16-16 of Fig. 14. [Figure 17] It is a plan view of the vehicle body according to Example 5.

Mode for Carrying Out the Invention

[0012] Embodiments of the present invention will be described below based on the accompanying drawings. Note that the embodiments shown in the accompanying drawings are examples of the present invention, and the present invention is not limited to such embodiments. In the description, front and rear are based on the traveling direction of the vehicle, left and right are based on the traveling direction of the vehicle, Fr in the figure indicates front, Rr indicates rear, Le indicates left, Ri indicates right, Up indicates up, and Dn indicates down.

[0013] [[ID=?]]<Example 1> The underbody structure 10 of Example 1 will be described while referring to Figs. 1 to 8.

[0014] (Regarding the underbody structure 10) Figure 1 shows one embodiment of the vehicle body understructure 10. This vehicle body understructure 10 comprises left and right longitudinal frames 20, 20 extending in the longitudinal direction of the vehicle body, and front and rear transverse frames 30, 30 extending in the width direction of the vehicle body. The vehicle body understructure 10 shown in Figure 1 exemplifies a rear structure 40 having left and right rear frames 41, 41 and front and rear rear cross members 42. The left and right longitudinal frames 20, 20 constitute the left and right rear frames 41, 41. The front and rear transverse frames 30, 30 constitute the front and rear rear cross members 42, 42. Rear bumper beams 44 are attached to the rear ends 43, 43 of the left and right longitudinal frames 20, 20.

[0015] The vehicle body lower structure 10 will be explained in detail below, using the left vertical frame 20 and the rear horizontal frame 30 as examples. Referring also to Figure 2, the vertical frame 20 has a U-shaped or hat-shaped cross-section (including a roughly U-shaped or hat-shaped cross-section) with a bottom wall 21 and a pair of vertical walls 22, 22 rising from the bottom wall 21. Of the pair of vertical walls 22, 22, the vertical wall 22 on the side of the vehicle width center CL is sometimes called the "inner vertical wall 22A," and the vertical wall 22 on the opposite side is sometimes called the "outer vertical wall 22B." The horizontal frame 30 has a U-shaped or hat-shaped cross-section (including a roughly U-shaped or hat-shaped cross-section) that intersects with the vertical wall 22 (inner vertical wall 22A) of the vertical frame 20. This horizontal frame 30 has a bottom wall 31 and a pair of vertical walls 32, 32 rising from the bottom wall 31. The vertical frame 20 and horizontal frame 30 shown in Figure 2 exemplify a hat-shaped cross-section configuration.

[0016] The T-shaped (including Y-shaped) intersection 51 of the vertical frame 20 and the horizontal frame 30 in plan view is connected to each other by a connecting portion 52. This connecting portion 52 forms a so-called C-shaped opening 53 that is open only at the top along the inner vertical wall 22A throughout the entire intersection 51. When viewing the vehicle body lower structure 10 from above, the area of ​​the intersection 51 (the area Ar1 of the C-shaped opening 53) is sometimes called the horizontal frame mounting area Ar1.

[0017] As shown in Figures 1 and 7, the bottom wall 31 of the horizontal frame 30 is configured to be one step higher than the bottom wall 21 of the vertical frame 20, so that a stepped portion 54 is provided between the bottom walls 21 and 31. This stepped portion 54 is formed over the entire intersection portion 51. In other words, even in the horizontal frame mounting area Ar1, the vertical wall 22A on the inside of the vertical frame 20 has a continuous portion 55 (lower portion 55) closer to the bottom wall 21. This compensates for the reduction in strength of the joint portion 52.

[0018] The vertical frame 20 and horizontal frame 30 are press-formed products of metal sheets such as steel plates or lightweight metal plates. More specifically, a composite frame, which integrates the vertical frame 20 and the horizontal frame 30, can be obtained by press-forming (hot stamping, etc.) a single tailored blank material (TWB), which is made by overlapping and welding the edges of multiple blank materials with different plate thicknesses and materials, into a predetermined frame shape. In Example 1, the composite frame straddles the C-shaped opening 53 and overlaps the vertical frame 20 and the horizontal frame 30.

[0019] Here, as an example of press forming, we will outline the forming method using spot-tailored blanks. First, as shown in Figure 3A, a portion of a second blank material 62, which represents a horizontal frame 30 (see Figure 3B), is superimposed on a first blank material 61, which represents a vertical frame 20 (see Figure 3B). A tailored blank material 65 is obtained by partially spot welding at least one point 64 in the center of the overlapping portion 63 (overlap portion 63) (temporary fixing step). The overlap portion 63 of this tailored blank material 65 has a fixed portion 66, which is spot-welded at least one point 64, and a movable portion 67 located around this fixed portion 66. The fixed portion 66 cannot be displaced relative to the plate surface because the two blank materials 61 and 62 are spot-welded to each other. The movable portion 67 is not welded, so the two blank materials 61 and 62 can be displaced relative to each other in the plate surface direction.

[0020] Next, the tailored blank material 65 is press-formed into the shape of the target part, that is, the shape of a composite frame 68 in which the vertical frame 20 and horizontal frame 30 are integrated, as shown in Figure 3B, using a press device (not shown) (forming process). During the press forming of the tailored blank material 65, relative sliding occurs between the blank materials 61 and 62 in the movable part 67. This relative sliding prevents the occurrence of wrinkles and cracks, and a press-formed product without wrinkles or cracks can be obtained.

[0021] Finally, a composite frame 68 is obtained by spot welding the remaining portion 69 of the overlapping portion 63, thereby integrating the vertical frame 20 and the horizontal frame 30 (fixing process). This forming method is called a "spot-tailored blank" because it obtains an integrated tailored blank material 65 by overlapping parts of each blank material 61, 62 and partially spot welding the overlapping portion 63. When forming a composite frame 68 using spot-tailored blanks, the radius of curvature of the corners (curved surfaces) of the joint 52 shown in Figure 2 can be reduced, thereby making the lateral frame mounting area Ar1 relatively narrower.

[0022] (Regarding the reinforcing member 70) As shown in Figures 4 and 5, a reinforcing member 70 is provided at the intersection 51 of the vertical frame 20. This reinforcing member 70 is composed of a vertical frame reinforcing section 80 that reinforces the vertical frame 20 and a partition wall 90 that reinforces the horizontal frame 30. In other words, the reinforcing member 70 includes a partition wall 90 that closes the C-shaped opening 53. The vertical frame reinforcing section 80 and the partition wall 90 are separate press-formed products, but they may be made as a single unit.

[0023] (Regarding the vertical frame reinforcement section 80) The vertical frame reinforcement section 80 is located in the space (inside) enclosed by the bottom wall 21 of the vertical frame 20 and the pair of vertical walls 22, 22, and is positioned to block the horizontal frame mounting area Ar1 (see Figure 2). In other words, the vertical frame reinforcement section 80 is longer in the front-to-rear direction of the vehicle body than the horizontal frame mounting area Ar1.

[0024] The vertical frame reinforcement section 80 is a press-formed metal plate. Referring also to Figure 6, when the vertical frame 20 is viewed from the vehicle width direction, the vertical frame reinforcement section 80 has an inverted U-shape (including a substantially inverted U-shape) configuration and is connected (joined) to the vertical frame 20 by fixing means such as spot welding. Preferably, the width of this vertical frame reinforcement section 80 is the same as (including substantially the same width) the inner width between the pair of vertical walls 22, 22 of the vertical frame 20.

[0025] More specifically, the vertical frame reinforcement section 80 is composed of a front wall 81 and a rear wall 82 extending upward from the bottom wall 21 of the vertical frame 20, and an upper wall 83 integrally formed with the upper ends of the front wall 81 and the rear wall 82. This upper wall 83 is parallel (including substantially parallel) to the bottom wall 21 of the vertical frame 20. The front flange 84 at the lower end of the front wall 81 and the rear flange 85 at the lower end of the rear wall 82 are joined to the bottom wall 31 of the vertical frame 20 by fixing means such as spot welding. Furthermore, side flanges 86, 86 are provided at both ends of the vertical frame reinforcement section 80 in the vehicle width direction, extending over the entire front wall 81, rear wall 82, and upper wall 83. These side flanges 86, 86 are joined to a pair of vertical walls 22, 22 of the vertical frame 20. The side flanges 86, 86 may be divided into the front wall 81, rear wall 82, and upper wall 83, respectively.

[0026] In this way, the vertical frame reinforcement section 80 is integrated with the vertical frame 20, thereby reinforcing the intersection portion 51 of the vertical frame 20. It should be noted that having through holes 87 in the front wall 81 and the rear wall 82 is optional and should be formed as needed.

[0027] The upper wall 83 of the vertical frame reinforcement portion 80 has at least one bead 88 formed on it that is long in the longitudinal direction of the vehicle body. Preferably, two beads 88 of the upper wall 83 are formed parallel to each other in the vehicle width direction. The beads 88 can increase the surface rigidity of the upper wall 83. The upper wall 83 with high surface rigidity can support the mounting member 100.

[0028] As shown in Figure 7, the mounting member 100 is a member that attaches a separate on-board component 111, which is located below the underbody structure 10, to the underbody structure 10, and is fixed to the upper wall 83. An example of an on-board component 111 is a subframe. The mounting member 100 is made up of a round bar-shaped member having a female thread 101 in the vertical direction, and is fixed to a through hole 89 in the upper wall 83 by a fixing means such as crimping. The on-board component 111 can be attached to the female thread 101 of the mounting member 100 by a bolt 112.

[0029] The upper wall 83 has increased surface rigidity due to the formation of the bead 88, which further enhances the support rigidity for supporting the mounting member 100. The lower part of the mounting member 100 extends downward through the bottom wall 21 of the vertical frame 20 and has a lower flange 102 at its lower end.

[0030] An outer reinforcing member 120 is positioned below the bottom wall 21 of the vertical frame 20. The lower flange 102 of the mounting member 100 is supported by the outer reinforcing member 120. This outer reinforcing member 120 is located on the opposite side of the reinforcing member 70 from the bottom wall 21 of the vertical frame 20, and reinforces the bottom walls 21, 31 and the stepped portion 54 by surrounding the bottom wall 21 of the vertical frame 20, the bottom wall 31 of the horizontal frame 30, and the stepped portion 54. This outer reinforcing member 120 is joined to the pair of vertical walls 22, 22 of the vertical frame 20 and the bottom wall 31 and the pair of vertical walls 32, 32 of the horizontal frame 30 by fixing means such as spot welding. Since this outer reinforcing member 120 covers the partition wall that closes the C-shaped opening from below, it can compensate for the reduction in strength caused by the C-shaped opening.

[0031] (Regarding partition wall 90) As shown in Figures 4, 5, and 7, the partition wall 90 is a press-formed metal plate. The strength of the partition wall 90 is greater than or equal to the strength of the vertical frame reinforcement 80. For example, the thickness of the partition wall 90 is set to be greater than the thickness of the vertical frame reinforcement 80. This partition wall 90 is positioned to be continuous with the inner vertical wall 22A of the vertical frame 20. This partition wall 90 is continuous with the upper wall 83 of the vertical frame reinforcement 80 and is connected to the horizontal frame 30 by fixing means such as spot welding.

[0032] More specifically, the partition wall 90 extends from the upper wall 83 of the vertical frame reinforcement section 80 through the C-shaped opening 53 into the space (interior) enclosed by the bottom wall 31 of the horizontal frame 30 and a pair of vertical walls 32, 32. Preferably, the width of this partition wall 90 is the same as (or approximately the same as) the inner width between the pair of vertical walls 32, 32 of the horizontal frame 30. This partition wall 90 is composed of a flat upper wall 91 superimposed on and joined to the upper wall 83 of the vertical frame reinforcement section 80, a vertical wall 92 that extends downward and inclined from this upper wall 91 to the bottom wall 31 of the horizontal frame 30, and a lower flange 93 provided at the lower end of this vertical wall 92 and joined to the bottom wall 31 of the horizontal frame 30. Side flanges 94, 94 are formed at both ends of the vertical wall 92 of the partition wall 90 that face the pair of vertical walls 32, 32 of the horizontal frame 30. These side flanges 94, 94 are joined to a pair of vertical walls 32, 32 of the horizontal frame 30.

[0033] The presence or absence of the lower flange 93 of the bulkhead 90 and the connection of the horizontal frame 30 to the bottom wall 31 are optional and can be provided as needed, taking into consideration the load transmission from the vertical frame 20 to the horizontal frame 30.

[0034] The upper wall 91 of the bulkhead 90 has at least one bead 95 (upper wall bead 95) that is long in the vehicle width direction. The upper wall bead 95 can increase the surface rigidity of the upper wall 91. The load can be efficiently transmitted from the upper wall 83 of the vertical frame reinforcement section 80 to the upper wall 91 of the bulkhead 90.

[0035] Similarly, the longitudinal wall 92 of the bulkhead 90 has at least one bead 96 (longitudinal wall bead 96) that is long in the longitudinal direction of the vehicle body. The longitudinal wall bead 96 increases the surface rigidity of the longitudinal wall 92 and improves the longitudinal load transmission of the longitudinal frame 21 to the bulkhead 90.

[0036] As shown in Figure 7, when the vertical frame 20 (reinforcement member 70) is viewed from the front-rear direction of the vehicle body, the reinforcement member 70 straddles the C-shaped opening 53 in the vehicle width direction, forming a parallelogram-shaped closed cross section. More specifically, when the reinforcement member 70 is viewed from the front-rear direction of the vehicle body, the overall shape, which combines the contour of the vertical frame reinforcement part 80 and the contour of the bulkhead 90, forms a parallelogram-shaped (including a generally parallelogram-shaped) closed cross section.

[0037] More specifically, the parallelogram-shaped closed section is formed by the outer vertical wall 22B and bottom wall 21 of the vertical frame 20 (the side edges of the front wall 81 and the rear wall 82 of the vertical frame reinforcement section 80), the bottom wall 31 of the horizontal frame 30 (the lower edge of the front wall 81 and the lower edge of the rear wall 82), the top wall 83 of the vertical frame reinforcement section 80, and the partition wall 90. The outer vertical wall 22B of the vertical frame 20 and the vertical wall 92 of the partition wall 90 are inclined in the same direction. The bottom wall 21 of the vertical frame 20, the bottom wall 31 of the horizontal frame 30, and the top wall 83 of the vertical frame reinforcement section 80 are parallel.

[0038] Therefore, although the vertical wall 22A (the inner vertical wall 22A) where the horizontal frames 30 of the vertical frame 20 intersect has a C-shaped opening 53 at the intersection 51, its strength and rigidity can be supplemented by the reinforcing member 70, which has a parallelogram-shaped closed cross-section structure.

[0039] As shown in Figure 2, the corner portion of the joint 52 having a C-shaped opening 53 within the vertical wall 22A on the inside of the vertical frame 20 is curved. This curved portion is called the "virtual vertical wall". As shown in Figure 7, this virtual vertical wall is represented by multiple vertical lines (shaded lines) at narrow intervals. The vertical wall 92 of the partition wall 90 extends downward and inclined from the upper wall 91 of the partition wall 90 to the bottom wall 31 of the horizontal frame 30. The downward-sloping vertical wall 92 of the partition wall 90 and the virtual vertical wall generally form an inverted V shape.

[0040] In other words, as shown in Figure 7, when viewing the vertical frame 20 from the front-rear direction of the vehicle body, the inner vertical wall 22A (see Figure 2) where the horizontal frame 30 intersects the vertical frame 20 and the bulkhead 90 form an inverted V shape. Therefore, load can be efficiently transmitted from the vertical frame 20 to the horizontal frame 30 via the bulkhead 90.

[0041] Next, the function of the vehicle body understructure 10 will be explained with reference to Figure 8. As described above, the vertical frame reinforcement section 80 is connected to the vertical frame 20. The partition wall 90 is connected to the horizontal frame 30. The vertical frame reinforcement section 80 and the partition wall 90 are continuous. Here, "continuous" includes both the case where the vertical frame reinforcement section 80 and the partition wall 90 are made from a single metal plate by press forming, and the case where the vertical frame reinforcement section 80 and the partition wall 90 are press-formed separately and then joined together.

[0042] When a rear impact load fb acts on the rear bumper beam 44, the rear bumper beam 44 deforms from a curved shape to a flattened shape towards the front Fr, as shown by the dashed lines. As a result, a bending force is applied to the left and right longitudinal frames 20, 20 outward in the vehicle width direction. This bending force is transmitted from the longitudinal frames 20, 20 to the transverse frame 30 via the longitudinal frame reinforcement parts 80, 80 and the bulkheads 90, 90. The longitudinal frame reinforcement parts 80, 80, the bulkheads 90, 90 and the transverse frame 30 are integrated. The transverse frame 30 adequately supports the longitudinal frames 20, 20 under the bending force. Therefore, the longitudinal frames 20, 20 do not bend outward in the vehicle width direction, but instead buckle efficiently in the longitudinal direction of the vehicle body, absorbing the external force.

[0043] Next, Examples 2 to 5 will be described. The basic configuration of Examples 2 to 5 is the same as that of the vehicle body understructure 10 in Example 1. For parts that are common with the vehicle body understructure 10 in Example 1, the same reference numerals will be used, and detailed explanations will be omitted.

[0044] <Example 2> The vehicle body understructure 200 of Embodiment 2 will be described with reference to Figures 9 to 12. Figure 9 corresponds to Figure 5. Figures 11A to 11C correspond to Figures 3A to 10B. The vehicle body understructure 200 of Embodiment 2 is characterized in that the vertical frame 20, horizontal frame 30, and reinforcing member 70 of Embodiment 1 are replaced with the vertical frame 220, horizontal frame 230, and reinforcing member 270 shown in Figures 9 and 10.

[0045] As shown in Figures 9 and 10, the reinforcing member 270 is composed of a vertical frame reinforcing section 280 and a bulkhead 290. The vertical frame reinforcing section 280 corresponds to the vertical frame reinforcing section 80 (see Figure 4) in Embodiment 1, and the bulkhead 290 corresponds to the bulkhead 90 (see Figure 4) in Embodiment 1. The reinforcing member 270 is positioned to block the horizontal frame mounting area Ar2 (see Figure 10). In other words, the vertical frame reinforcing section 280 and the bulkhead 290 are longer in the longitudinal direction of the vehicle body than the horizontal frame mounting area Ar2.

[0046] The vertical frame 220 and the horizontal frame 230 are press-formed products of metal sheets such as steel plates or lightweight metal sheets. More specifically, a composite frame, which integrates the vertical frame 220 and the horizontal frame 230, can be obtained by press-forming (hot stamping, etc.) a single tailored blank material (TWB), which is made by butting the edges of multiple blank materials with different plate thicknesses and materials together and welding them, into a predetermined frame shape.

[0047] As an example of press forming, an overview of a typical tailored blank forming method is shown. First, as shown in Figure 11A, a tailored blank material 265 is obtained by butting one end face of a first blank material 261, which represents a vertical frame 220, with one end face of a second blank material 262, which represents a horizontal frame 230, and welding them together (tailored blank manufacturing process). In other words, there is no overlapping of the blank materials 261 and 262.

[0048] Next, the tailored blank material 265 is press-formed into the shape of the target part, that is, the shape of a composite frame 268 in which the vertical frame 220 and the horizontal frame 230 are integrated, using a press device (not shown) as shown in Figures 11B and 11C (forming process). In this way, the composite frame 268 can be obtained.

[0049] When press-formed, the intersection 251 of the vertical frame 220 and the horizontal frame 230 forms a C-shaped opening 53 throughout. As shown in Figure 10, in the horizontal frame 230, the pair of vertical walls 232, 232 rising from the bottom wall 231 are formed in a curved shape with a large radius of curvature Rc as they move from the center of the vehicle width toward the intersection 251, in order to prevent molding wrinkles and cracks. Therefore, the horizontal frame mounting area Ar2 (range Ar2 of the C-shaped opening 253) is larger than the horizontal frame mounting area Ar1 in the above embodiment 1 (see Figure 2).

[0050] As shown in Figures 9, 10, and 12, the lateral frame mounting area Ar2 is large, so the reinforcing member 270 is long in the longitudinal direction of the vehicle body. The vertical wall 292 of the bulkhead 290 does not extend into the space (interior) enclosed by the bottom wall 231 of the lateral frame 230 and the pair of vertical walls 232, 232. In other words, the vertical wall 292 overlaps the inner surface of the vertical wall 222 (inner vertical wall 222A) of the vertical frame 220 on the vehicle width center CL side, and is fixed by fixing means such as adhesive spot welding.

[0051] As shown in Figures 9 and 12, when the vertical frame 220 (reinforcement member 270) is viewed from the front-rear direction of the vehicle body, the reinforcement member 270, including the bulkhead 290, forms an inverted trapezoidal closed cross section. More specifically, when the reinforcement member 270 is viewed from the front-rear direction of the vehicle body, the overall shape, formed by combining the contour of the vertical frame reinforcement portion 280 and the contour of the bulkhead 290, forms an inverted trapezoidal (or generally inverted trapezoidal) closed cross section.

[0052] More specifically, the inverted trapezoidal closed section is formed by the side edges of the front wall 81 and the rear wall 82 of the vertical frame reinforcement section 80, the lower edge of the front wall 81 and the lower edge of the rear wall 82, the upper wall 83, and the partition wall 90. Therefore, although the inner vertical wall 222A (see Figure 9) of the vertical frame 220 where the horizontal frame 230 intersects has a large C-shaped opening 253 at the intersection 251, its strength and rigidity can be supplemented by the reinforcement member 270, which has an inverted trapezoidal closed section structure. The vertical wall 292 of the partition wall 290 overlaps the inner surface of the vertical wall 222A (inner vertical wall 222A) on the vehicle width center CL side of the vertical frame 220 and is fixed by fixing means such as adhesive or spot welding, so that it can adequately transmit the longitudinal load of the vertical frame 220.

[0053] The vehicle body understructure 200 of Example 2 exhibits the same functions and effects as the vehicle body understructure 10 of Example 1.

[0054] <Example 3> The vehicle body understructure 300 of Embodiment 3 will be described with reference to Figure 13. Figure 13 corresponds to Figure 7. The vehicle body understructure 300 of Embodiment 3 is characterized by not having the stepped portion 54 of Embodiment 1 (see Figure 7). In other words, the bottom wall 21 of the vertical frame 20 and the bottom wall 31 of the horizontal frame 30 are at the same height.

[0055] <Example 4> The vehicle body understructure 400 of Embodiment 4 will be described with reference to Figures 14 to 16. Figure 14 corresponds to Figure 4. Figure 15 corresponds to Figure 5. The vehicle body understructure 400 of Embodiment 4 is characterized in that the intersection portion 451 of the vertical frame 20 and the horizontal frame 30 is cross-shaped in plan view. In contrast, the intersection portion 51 of the vehicle body understructure 10 of Embodiment 1 shown in Figure 4 was T-shaped in plan view.

[0056] More specifically, the left and right horizontal frames 30, 30 are connected to the vertical frame 20 by connecting parts 52, 52, respectively. A reinforcing member 470 is provided at the intersection 451 of the vertical frame 20. This reinforcing member 470 consists of a vertical frame reinforcing part 80 that reinforces the vertical frame 20, and two bulkheads 90, 90 that reinforce the left and right horizontal frames 30, 30, respectively. Furthermore, the vehicle body lower structure 400 of Embodiment 4 does not have the stepped portion 54 (see Figure 7) of Embodiment 1. However, it is also possible to have a configuration with the stepped portion 54 of Embodiment 1.

[0057] As shown in Figure 16, when the vertical frame 20 (reinforcement member 470) is viewed from the front-rear direction of the vehicle body, the reinforcement member 470, including the bulkheads 90, 90, forms a trapezoidal closed cross-section. More specifically, when the reinforcement member 470 is viewed from the front-rear direction of the vehicle body, the overall shape, formed by combining the contour of the vertical frame reinforcement portion 80 and the contours of the left and right bulkheads 90, 90, forms a trapezoidal (generally trapezoidal) closed cross-section. Therefore, although the vertical walls 22A, 22A (see Figure 14) where the left and right horizontal frames 30, 30 of the vertical frame 20 intersect have C-shaped openings 53, 53 at the intersection portion 451, the strength and rigidity can be supplemented by the trapezoidal closed cross-section structure of the reinforcement member 470.

[0058] The vehicle body understructure 400 of Example 4 exhibits the same functions and effects as the vehicle body understructure 10 of Example 1.

[0059] <Example 5> Referring to Figure 17, Embodiment 5 will be described in which at least a portion of the vehicle body 500 is composed of the above-mentioned vehicle body lower structures 10, 200 to 400.

[0060] The above-mentioned lower body structures 10,200~400 constitute at least one of the rear structure 40, front structure 510, and floor structure 520 of the vehicle body 500. The rear structure 40 includes left and right rear frames 41, 41 consisting of vertical frames 20, 220, and rear cross members 42, 42 consisting of horizontal frames 30, 230. The front structure 510 includes left and right front side frames 511, 511 consisting of vertical frames 20, 220, and a dash cross member 512 consisting of horizontal frames 30, 230. Front bumper beams 513 are attached to the front ends of the left and right front side frames 511, 511. The floor structure 520 includes left and right side sills 521, 5tatoeba 21 made of vertical frames 20, 220, floor frames 522, 522 made of vertical frames 20, 220, and floor cross members 523, 523 made of horizontal frames 30, 230. The rear ends of the left and right front side frames 511, 511 and the front ends of the left and right side sills 521, 521 are connected by left and right side outriggers 524, 524.

[0061] To summarize the above explanation of the structure, it is as follows:

[0062] Refer to Figure 4 (Figures 9, 13, and 14). Firstly, the lower body structure 10;200;300;400 is A longitudinal frame 20;220 extending in the longitudinal direction of the vehicle body, having a bottom wall 21 and longitudinal walls 22;222, and having a U-shaped or hat-shaped cross-section, Horizontal frames 30;230, which extend in the vehicle width direction and intersect the vertical walls 22;222 of the vertical frames 20;220, and which have a U-shaped or hat-shaped cross-section, It includes a connecting portion 52 that forms a C-shaped opening 53 over the entire intersection portion 51;251;451 of the vertical frames 20;220 and the horizontal frames 30;230. Reinforcement members 70, 270, and 470 are provided at the intersections 51, 251, and 451 of the vertical frames 20 and 220. These reinforcement members 70, 270, and 470 include partition walls 90 and 290 that close the C-shaped opening 53. These partition walls 90 and 290 are positioned to be continuous with the vertical walls 22 and 222 of the vertical frames 20 and 220.

[0063] The vehicle body understructures 10;200;300;400 each have a C-shaped opening 53 that extends across the entire intersection 51;251;451 of the vertical frame 20 and the horizontal frame 30, with a U-shaped or hat-shaped cross-section. In other words, the formation of the C-shaped opening 53 at the intersection 51;251;451 is permitted by press forming. Therefore, the vehicle body understructures 10;200;300;400 can be obtained simply by press forming a single tailored blank material 65;265, which is formed by joining multiple blanks 61,62;261,262 using spot tailored blanks (see Figure 3A) or butt-joining them (see Figure 11A), using a hot stamping press or similar method. Consequently, the vehicle body understructures 10;200;300;400 can be made lighter and productivity improved.

[0064] Furthermore, since the intersection portion 51 of the vertical walls 22;222 of the vertical frames 20;220 is open, partition walls 90;290 are provided to close the C-shaped opening 53 and to be continuous with the vertical walls 22;222 in order to compensate for the lack of strength and rigidity in that portion. These partition walls 90;290 can compensate for the strength and rigidity of the vertical walls 22;222 of the vertical frames 20;220.

[0065] Furthermore, these bulkheads 90;290 are included in the reinforcing members 70;270;470 provided at the intersections 51;251;451 of the longitudinal frames 20;220. These reinforcing members 70;270;470 (including the bulkheads 90;290) ensure sufficient strength and rigidity at the intersections 51;251;451. Therefore, when an external force such as a rear impact load fb (see Figure 8) acts on the underbody structure 10;200;300;400, the load can be sufficiently transmitted and absorbed between the longitudinal frames 20;220 and the transverse frames 30;230. For example, if the underbody structure 10;200;300;400 is configured as a rear structure 40 with a rear frame 41 and a rear cross member 42 as shown in Figure 1, the rear impact load fb can be effectively transmitted from the rear frame 41 to the rear cross member 42 via the bulkheads 90.

[0066] In this way, the joint portion 52 that forms a C-shaped opening 53 over the entire intersection portion 51, 251, 451 of the vertical frames 20, 220 and the horizontal frames 30, 230 is formed by press-forming a tailored blank 65, 265 which is made by joining multiple blanks 61, 62, 261, 262, thereby integrating each frame 20, 30, 220, 230, and thus increasing the productivity of the vehicle body understructure 10, 200, 300, 400. Furthermore, the reduction in strength and rigidity of the C-shaped opening 53 can be compensated for by providing reinforcing members 70, 270, 470 at the intersection portion 51, 251, 451 of the vertical frames 20, 220. In particular, the reinforcing members 70;270;470 include partition walls 90;290 that close the C-shaped opening 53, and these partition walls 90;290 are positioned to be continuous with the vertical walls 22;222, thereby increasing the axial load acting in the longitudinal direction of the vertical frames 20;220. As is clear from the above explanation, we can provide technology for a vehicle underbody structure 10;200;300;400 that is highly resistant to collisions and can increase productivity.

[0067] Refer to Figure 7 (Figures 12, 13, and 16). Secondly, assuming the first underbody structure 10;200;300;400, when viewed from the front-rear direction of the vehicle body, the reinforcing members 70;270;470, including the bulkheads 90;290, form a closed section with a parallelogram or inverted trapezoid shape.

[0068] Since the reinforcing members 70;270;470 (including the partition walls 90;290) form a closed cross-section in the shape of a parallelogram or an inverted trapezoid, they compensate for the strength and rigidity caused by the openings at the intersections 51;251;451 of the vertical walls 22;222 of the vertical frames 20;220, thereby achieving further improvements in strength and rigidity.

[0069] Refer to Figure 7 (Figures 12, 13, and 16). Thirdly, assuming the second vehicle body understructure 10;200;300;400, the reinforcing members 70;270;470 are composed of vertical frame reinforcing parts 80;280 that reinforce the vertical frames 20;220 and bulkheads 90;290. When viewing the vertical frames 20;220 from the front-rear direction of the vehicle body, the vertical walls 22A;222A where the horizontal frames 30;230 of the vertical frames 20;220 intersect and the bulkheads 90;290 form an inverted V shape.

[0070] Therefore, when an external force such as a rear impact load fb (see Figure 8) acts on the underbody structure 10;200;300;400, the load can be transmitted more effectively between the longitudinal frames 20;220 and the transverse frames 30;230.

[0071] Refer to Figure 4 (Figures 10, 13, and 14). Fourthly, assuming the second underbody structure 10;200;300;400, the reinforcing members 70;270;470 are composed of vertical frame reinforcing sections 80;280 that reinforce the vertical frames 20;220 and bulkheads 90;290. When viewed from the vehicle width direction, the vertical frame reinforcement section 80;280 is in an inverted U shape and is composed of a front wall 81 and a rear wall 82 extending upward from the bottom wall 21 of the vertical frame 20;220, an upper wall 83 connecting the front wall 81 and the rear wall 82, and an upper wall 83 that is connected and parallel to the bottom wall 21 of the vertical frame 20;220. The partition wall 90;290 is continuous with the upper wall 83 of the vertical frame reinforcement section 80;280.

[0072] Therefore, the reinforcing members 70;270;470 can be easily manufactured by press molding. Furthermore, since the partition walls 90;290 are continuous with the upper wall 83, the load can be smoothly transmitted from the upper wall 83 to the partition walls 90;290 of the reinforcing members 70;270;470. In addition, if a mounting member 100 (see Figure 6) for supporting an on-board component 111 (see Figure 6) is provided inside the inverted U-shaped reinforcing members 70;270;470, the support rigidity of the mounting member 100 supported by the reinforcing members 70;270;470 can be improved.

[0073] Refer to Figure 4 (Figures 10, 13, and 14). Fifth, assuming the fourth underbody structure 10;200;300;400, the longitudinal frame reinforcement sections 80;280 are connected to the longitudinal frames 20;220. The bulkheads 90;290 are connected to the transverse frames 30;230. The longitudinal frame reinforcement sections 80;280 and the bulkheads 90;290 are continuous.

[0074] When an external force such as a rearward impact load fb (see Figure 8) acts on the vehicle body understructure 10;200;300;400, and a bending force in the vehicle width direction acts on the longitudinal frames 20;220, this bending force is transmitted from the longitudinal frames 20;220 to the transverse frames 30;230 via the longitudinal frame reinforcements 80;280 and the bulkheads 90;290. However, since the longitudinal frame reinforcements 80;280, the bulkheads 90;290, and the transverse frames 30;230 are integrated, the transverse frames 30;230 can adequately withstand the bending force. Therefore, the longitudinal frames 20;220 can efficiently buckle in the longitudinal direction of the vehicle body without bending and deforming in the vehicle width direction, thereby absorbing the external force.

[0075] Refer to Figure 4 (Figures 10, 13, and 14). Sixth, assuming the fourth underbody structure 10;200;300;400, the strength of the bulkhead 90;290 is greater than or equal to the strength of the longitudinal frame reinforcement 80;280. The portion of the inner vertical wall 22A;222A of the vertical frame 20;220 that has the C-shaped opening 53 has reduced strength and rigidity compared to other portions, resulting in reduced support strength against rear impact loads. However, the strength and rigidity of the portion of the inner vertical wall 22A;222A that has the C-shaped opening 53 can be compensated for by the bulkhead wall 90;290. As a result, the rear impact load acting on the vertical frame 20;220 can be sufficiently transmitted in the longitudinal direction of the vehicle body. Furthermore, since the vertical frames 20;220 are complemented by the bulkheads 90;290, the plate thickness of the vertical frames 20;220 can be reduced, and as a result, the weight of the underbody structure 10;200;300;400 can be reduced.

[0076] Refer to Figure 5 (Figures 9, 13, and 14). Seventh, assuming the fourth underbody structure 10;200;300;400, the longitudinal frame reinforcement parts 80;280 and the bulkheads 90;290 are press-formed products of separate sheet metal. Therefore, even if the longitudinal frame reinforcement parts 80;280 and the bulkheads 90;290 are made of sheet metal of different thicknesses, the reinforcing members 70;270;470 can be easily manufactured by press-forming them individually and spot-welding them to each other. Moreover, flanges 84-86 and 93-94 that attach to the longitudinal frames 20;220 and transverse frames 30;230 can also be easily formed from the longitudinal frame reinforcement parts 80;280 and the bulkheads 90;290. In addition, beads 88, 95, and 96 can be easily formed individually to increase the strength and rigidity of the plate material that forms the vertical frame reinforcement parts 80;280 and the partition walls 90;290.

[0077] Refer to Figure 7 (Figures 12, 13, and 14). Eighth, assuming the seventh vehicle body lower structure 10;200;300;400, the upper wall 83 of the longitudinal frame reinforcement 80;280 has a bead 88 formed in the longitudinal direction of the vehicle body. This increases the surface rigidity of the upper wall 83, and as a result, the support rigidity supporting the mounting member 100 can be further increased.

[0078] Refer to Figure 7 (Figures 13 and 16). Ninthly, assuming the first underbody structure 10;300;400, the bulkheads 90;290 have beads 96 formed in the longitudinal direction of the vehicle body. This increases the surface rigidity of the bulkheads 90;290. When an external force acts on the longitudinal frames 20;220 from one side in the longitudinal direction of the vehicle body, this external force can be efficiently transmitted from one side of the longitudinal frame 20;220 to the other side in the longitudinal direction of the vehicle body via the joint 52 and the bulkheads 90;290.

[0079] Refer to Figure 7 (Figure 12). Tenth, assuming the first vehicle body lower structure 10;200, an outer reinforcing member 120 is further provided on the opposite side from the reinforcing members 70;270 to the bottom wall 21 of the vertical frame 20;220. The bottom walls 31;231 of the horizontal frame 30;230 are configured to be one step higher than the bottom wall 21 of the vertical frame 20;220, so that a stepped portion 54 is provided between the bottom wall 21 of the vertical frame 20;220 and the bottom wall 31;231 of the horizontal frame 30;230. The outer reinforcing member 120 reinforces each bottom wall 21, 31;231 and the stepped portion 54 by surrounding them.

[0080] By forming the vertical frames 20;220 that transmit the main load deeper than the horizontal frames 30;230, even if a step 54 occurs in the joint 52, the strength and rigidity of the joint 52 can be ensured by surrounding the bottom walls 21,31;231 and the step 54 with the reinforcing members 70;270 and the outer reinforcing member 120.

[0081] Refer to Figure 1 (Figures 10, 13, 14, and 17). Eleventh, assuming the first vehicle body understructure 10;200;300;400, Front structure 510 (see Figure 17) having front side frames 511, 511 and dash cross member 512, A floor structure 520 (see Figure 17) has side sills 521, 521, floor frames 522, 522, and floor cross members 523, 523. It constitutes at least one of the rear structure 40 (see Figures 1 and 17), which has a rear frame 41 and rear cross members 42, 42.

[0082] Therefore, by integrally molding the components of at least one of the front structure 510, floor structure 520, and rear structure 40 using a press such as hot stamping, the manufacturing of individual parts becomes unnecessary, and productivity can be improved.

[0083] Furthermore, the present invention is not limited to the examples provided, provided that it achieves the function and effects of the present invention. For example, it is optional to combine any two or more of the examples. Furthermore, the shape of the C-shaped opening 53 is not limited to a C-shape, but includes, for example, a U-shape or a U-shape. Furthermore, although the reinforcing members 70;270;470 consist of separate pressed parts for the vertical frame reinforcing sections 80;280 and the partition walls 90;290, they may also be made as a single pressed product from a single steel plate, or as a single piece of aluminum alloy, or a single piece of rigid resin foam, or a single piece in which steel plate brackets are inserted into one of these (aluminum alloy or rigid resin foam). Furthermore, the reinforcing members 70;270;470 may consist of only the bulkheads 90;290. [Industrial applicability]

[0084] The vehicle body understructure 10,200~400 and vehicle body 500 of the present invention are suitable for use in automobiles. [Explanation of symbols]

[0085] 10...Underbody structure (Example 1), 20...Longitudinal frame, 21...Bottom wall, 22...Longitudinal wall, 22A...Inner longitudinal wall, 30...Horizontal frame, 31...Bottom wall, 32...Longitudinal wall, 40...Rear structure, 41...Rear frame, 42...Rear cross member, 51...Intersection, 52...Joint, 53...C-shaped opening, 54...Stepped section, 70...Reinforcement member, 80...Longitudinal frame reinforcement, 81...Front wall, 82...Rear wall, 83...Top wall, 88...Bead, 90...Bulkhead, 91...Top wall, 92...Longitudinal wall, 95...Bead (Top wall bead), 96...Bead (Longitudinal wall bead), 100...Mounting member, 111...Onboard component, 120...Outer reinforcement member, 200…Underbody structure (Example 2), 220…Longitudinal frame, 222…Longitudinal wall, 222A…Inner vertical wall, 230…Horizontal frame, 231…Bottom wall, 232…Longitudinal wall, 251…Intersection, 270…Reinforcement member, 280…Longitudinal frame reinforcement, 290…Bulkhead, 292…Longitudinal wall, 300…Underbody structure (Example 3), 400…Underbody structure (Example 4), 451…Intersection, 470…Reinforcement member, 500…Vehicle body (Example 5), 510…Front structure, 511…Front side frame, 512…Dash cross member, 513…Front bumper beam, 520…Floor structure, 521…Side sill, 522…Floor frame, 523…Floor cross member, Ar1…Horizontal frame mounting area, Ar2... Side frame mounting area.

Claims

1. A longitudinal frame extending in the front-to-rear direction of the vehicle body, having a bottom wall and vertical walls, and having a U-shaped or hat-shaped cross-section, A horizontal frame with a U-shaped or hat-shaped cross-section extends in the vehicle width direction and intersects the vertical wall of the vertical frame, The joint includes a connecting portion that forms a U-shaped opening in cross-section that is open only at the top along the vertical wall of the vertical frame, extending over the entire intersection of the vertical frame and the horizontal frame, Reinforcement members are provided at the intersection portion of the aforementioned vertical frame. The reinforcing member includes a vertical frame reinforcing portion that reinforces the vertical frame and a partition wall that closes the opening. The partition wall is positioned to be continuous with the vertical wall, The corner portion of the joint having the opening among the vertical walls of the vertical frame is curved toward the vertical wall of the horizontal frame when viewed from above. A lower structure of the vehicle body in which, when the longitudinal frame is viewed from the front-rear direction of the vehicle body, the bulkhead extends from the reinforcing portion of the longitudinal frame, across the opening in the vehicle width direction, beyond the curved corner portion, and slopes downward and is joined to the bottom wall of the transverse frame.

2. When the vertical frame is viewed from the vehicle width direction, the vertical frame reinforcing portion is in the shape of an inverted U, and is composed of a front wall and a rear wall extending upward from the bottom wall of the vertical frame, and an upper wall connecting the front wall and the rear wall, The vehicle body lower structure according to claim 1, wherein the bulkhead is continuous with the upper wall.

3. The aforementioned vertical frame reinforcement is connected to the vertical frame, The partition wall is joined not only to the bottom wall of the horizontal frame, but also to the vertical wall of the horizontal frame. The vertical frame reinforcement section and the partition wall are continuous. The vehicle body understructure according to claim 2.

4. The vehicle body understructure according to claim 2, wherein the strength of the bulkhead is greater than or equal to the strength of the vertical frame reinforcement portion.

5. The vehicle body understructure according to claim 2, wherein the vertical frame reinforcement portion and the bulkhead are press-formed products of separate plate materials.

6. The lower body structure of a vehicle according to claim 5, wherein the upper wall of the vertical frame reinforcement portion has a bead formed in the longitudinal direction of the vehicle body.

7. The vehicle body understructure according to claim 5, wherein the bulkhead has a bead formed in the longitudinal direction of the vehicle body.

8. The aforementioned lower body structure of the vehicle body is Front structure having front side frames and dash cross members, A floor structure having side sills, a floor frame, and floor cross members. A rear structure having a rear frame and a rear cross member, The vehicle body understructure according to claim 1, comprising at least one of the above.

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