The lower body structure of the vehicle

Abstract

The present invention provides a lower body structure of a vehicle that can suppress side beam deformation during small overlap collisions without increasing the weight and manufacturing cost of the side beam. The side beam (2) constituting the body has an outer side beam (11) and an inner side beam (12). The upper side side portion (32A) (upper surface portion) and the lower side side portion (32B) (lower surface portion) of the inner side beam (12) are bent toward the inside of the side beam (2) to form a second bending portion (34) (bending portion). The inner side beam (12) has an upper inclined surface portion (36) and a lower inclined surface portion (39) (inclined surface portion) that are inclined toward the inner side beam (12) in the vertical direction as it approaches the outer side beam (11). The second upper surface portion (37) and the second lower surface portion (40) (vehicle width direction portion) extend from the second bending portion (34) toward the inside of the vehicle in the vehicle width direction.

Description

Technical Field

[0001] This invention relates to a lower body structure of a vehicle. Background Technology

[0002] In a small overlap collision (i.e., a frontal collision where the impact load is applied to a portion of the vehicle's frontal side extending less than one-quarter of its width), the front wheel, located in front of the side beam, applies the impact load to either of the paired side beams that form the lower side frame of the vehicle body. This impact load is then applied rearward and inward to the side beam, potentially causing the front end of the side beam to bend and deform inward, reducing the interior space. Various vehicle body structures have been proposed to prevent this bending deformation of the side beams during small overlap collisions.

[0003] The vehicle body structure described in Patent Document 1 includes a side beam (rocker arm) with a closed cross-section extending in the longitudinal direction of the vehicle. To reinforce the side beam, a plurality of reinforcing members are provided inside the front end of the outer beam, which constitutes the outer side portion of the vehicle. The reinforcing members are engaged with the front side portion (the surface facing the front of the vehicle), the side portion (the surface facing the inside of the vehicle), and the lower surface portion of the inner surface of the outer beam, thereby reinforcing the front end of the outer beam from the inside and preventing bending deformation of the side beam during small overlap collisions.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-58749. Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] In the aforementioned vehicle body structure, as a measure to address small overlap collisions, a reinforcing member is provided at the front end of the outer beam. However, this presents the following problem: when the collision load during a small overlap collision increases due to factors such as the large size of the vehicle, the weight and cost of the reinforcing member will increase in order to suppress deformation under the large collision load.

[0009] In view of the above, the present invention aims to provide a vehicle lower body structure that can suppress side beam deformation during small overlap collisions without increasing the weight and manufacturing cost of the side beams.

[0010] Technical means to solve technical problems

[0011] To solve the above-mentioned technical problems, the lower body structure of the vehicle of the present invention includes: a side beam in which an outer side beam and an inner side beam extending in the longitudinal direction of the vehicle cooperate to form a closed cross section; a cross beam that joins the inner side beam at a position relative to the front end of the side beam on the rear side of the vehicle and extends inward from the side beam in the vehicle width direction; the inner side beam has an upper surface portion and a lower surface portion that separates downward from the upper surface portion, and with respect to the upper surface portion and the lower surface portion, at least in the region between the front end of the side beam and the cross beam in the longitudinal direction of the vehicle, the upper surface portion and the lower surface portion bend inward towards the side beam, and have: an inclined surface portion extending from the bent portion towards the outer side beam and inclined in a direction that widens in the vertical direction towards the inner side beam as it approaches the outer side beam, and a vehicle width direction surface portion extending from the bent portion towards the vehicle width direction.

[0012] According to the relevant structure, the upper and lower surfaces of the inner side beam are bent inward toward the side beam, at least in the area between the front end of the side beam and the crossbeam in the vehicle's longitudinal direction. The inner side beam has an inclined portion extending from the bent portion toward the outer beam and widening in the vertical direction toward the inner side beam as it approaches the outer beam, and a width-direction portion extending from the bent portion toward the vehicle's interior in the vehicle's width direction. In this structure, during a small overlap collision, when a collision load is input to the front end of the side beam toward the rear of the vehicle and in the width-direction, a bending load is input to the side beam with the joint between the crossbeam and the inner side beam as a fulcrum. As the bent portions of the upper and lower surfaces of the inner side beam displace inward toward the cross section, the inclined portion extending from the bent portion toward the outer beam becomes more inclined toward the width-direction of the inner side beam. On the other hand, the width-direction portion extending from the bent portion toward the vehicle's interior maintains a state approximately parallel to the direction of the collision load. Therefore, the inner beam itself can generate a high reaction force, which can suppress the bending deformation of the side beam. Therefore, in the above structure, it is not necessary to install reinforcing members inside the side beam as in the past, thus suppressing the deformation of the side beam during small overlapping collisions without increasing the weight and manufacturing cost of the side beam.

[0013] Preferably, in the lower body structure of the vehicle described above, the upper surface of the crossbeam and the width-direction portion of the upper surface of the inner side beam are at the same height.

[0014] According to the relevant structure, for a side beam subjected to bending load during a small overlap collision, the torsion of the side beam can be suppressed and it can be supported by a crossbeam.

[0015] Preferably, in the lower body structure of the vehicle described above, the crossbeam has a first flange portion that engages with at least one of the upper surface portion and the lower surface portion of the inner side beam in the vehicle width direction.

[0016] According to the relevant structure, in at least one of the upper and lower surfaces of the inner side beam, the vehicle width direction facet on the inner side engages with the first flange of the crossbeam relative to the bent portion. Therefore, during the deformation of the side beam in a small overlap collision, the deformation of the vehicle width direction facet of the inner side beam can be suppressed, and the vehicle width direction facet is reliably maintained in a state that is approximately parallel to the direction of the collision load.

[0017] Preferably, in the lower body structure of the vehicle described above, the inner side beam has a longitudinal wall portion extending upward and downward from the end on the inner side in the vehicle width direction and connecting the upper surface portion and the lower surface portion, and the crossbeam has a second flange portion that engages with the longitudinal wall portion of the inner side beam.

[0018] In the relevant structure, the longitudinal wall portion at the end of the inner side beam in the vehicle width direction is joined to the second flange portion of the crossbeam, thus enabling the crossbeam to reliably support the side beam that bears bending loads during small overlap collisions.

[0019] Preferably, in the lower body structure of the vehicle described above, the inner beam has a longitudinal wall portion extending upward and downward from its inner end in the vehicle width direction and connecting the upper surface portion and the lower surface portion, and the longitudinal wall portion has a reinforcing rib extending in the vehicle front-rear direction.

[0020] According to the relevant structure, the overall rigidity of the side beams, including the inner side beams, can be improved in response to bending deformation.

[0021] Preferably, in the lower body structure of the vehicle described above, the reinforcing rib extends from the front end of the side beam to at least the rear end of the crossbeam.

[0022] According to the relevant structure, the rigidity of the part of the side beam from the front end to the rear end of the crossbeam is improved by the reinforcing ribs. Therefore, when there is a collision load input to the front end of the side beam during a small overlap collision, the bending deformation of the side beam can be effectively prevented.

[0023] Preferably, in the lower body structure of the vehicle described above, the inner side beam further includes upper and lower paired flange portions located at the ends of the outer side beams of the upper surface portion and the lower surface portion, and the side beam further includes a connecting plate portion connecting the upper and lower paired flange portions of the inner side beam.

[0024] According to the relevant structure, when there is a collision load input to the front end of the side beam during a small overlap collision, the upper and lower surfaces of the inner beam will be subjected to forces in the direction of upward and downward separation. However, the upper and lower paired flanges at the ends of the upper and lower surfaces are connected by the connecting plate. Therefore, the cross-section of the upper and lower surfaces of the inner beam can be suppressed by the tension of the connecting plate.

[0025] Preferably, in the lower body structure of the vehicle described above, the connecting plate portion is disposed in the side beam in the longitudinal direction of the vehicle to form the door opening portion of the body.

[0026] The door opening of the vehicle body is an area without pillars extending in the vertical direction, which is an area where the support rigidity of the side beam is weak. However, as mentioned above, the connecting plate is arranged in the side beam to form the part of the door opening. Therefore, even in the area without pillars, the cross-sectional crushing of the upper and lower surfaces of the inner side beam can be effectively suppressed by the tension of the connecting plate.

[0027] Preferably, in the lower body structure of the vehicle described above, the connecting plate portion has a structure in which the bending strength of the connecting plate portion is less than the bending strength of the outer beam and the inner beam.

[0028] Based on the relevant structure, the quality and cost of the connecting plate can be controlled and the cross-sectional deformation of the inner beam can be suppressed.

[0029] Effects of the Invention

[0030] As described above, the lower body structure of the vehicle according to the present invention can suppress side beam deformation during small overlap collisions without increasing the weight and manufacturing cost of the side beams. Attached Figure Description

[0031] Figure 1 It is a perspective view of the overall structure of a vehicle body having the lower body structure of the vehicle according to the embodiments of the present invention;

[0032] Figure 2 yes Figure 1 An enlarged top view showing the configuration of the side beams, cross beams, and hinge pillars;

[0033] Figure 3 yes Figure 1 An enlarged oblique view showing the configuration of the side beams, cross beams, and hinge columns;

[0034] Figure 4 yes Figure 2 Sectional view of line IV-IV;

[0035] Figure 5 yes Figure 4 Cross-sectional view of the side beam;

[0036] Figure 6 This is a cross-sectional diagram illustrating the deformation of the side beam during a small overlap collision;

[0037] Figure 7 This is a graph showing the time variation of the bending load of the side beam during small overlap collisions in this embodiment and comparative examples;

[0038] Figure 8 This is a cross-sectional view of a typical side beam and cross beam, which serves as a comparative example of the present invention.

[0039] Figure 9 This is an explanatory diagram showing the stress distribution during small overlap collisions in the side beams of this embodiment;

[0040] Figure 10 This is a diagram showing the stress distribution during a small overlap collision in the side beams of the comparative example;

[0041] Figure 11 This is a graph showing the time variation of the bending load of the side beam in an example where the stiffener terminates at the front end of the crossbeam, which is a variation of the present invention, and in a comparative example.

[0042] Figure 12 This indicates that during a side collision of the vehicle... Figure 1 Oblique view illustration of the side beam generating bending load;

[0043] Figure 13 (a) to (d) are cross-sectional diagrams illustrating the deformation process of the side beam during a lateral collision of a vehicle.

[0044] Figure 14 This is a graph showing the time variation of the bending moment of the side beam in this embodiment and the comparative example;

[0045] Figure 15 This is a graph showing the time variation of the torque of the side beam in this embodiment and the comparative example;

[0046] Figure 16 This is a diagram of a test plate used to examine the location of bends;

[0047] Figure 17 It is a graph showing the change in the compressive bending performance ratio when the ratio of the distance from the top of the longitudinal plate to the bend to the total height of the longitudinal plate is changed. Detailed Implementation

[0048] Hereinafter, the lower body structure of a vehicle according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0049] like Figures 1-4As shown, in the vehicle body 1 of the vehicle body structure according to the embodiment of the present invention, the frame members constituting the frame of the vehicle body 1 include: a pair of side beams 2 extending in the vehicle longitudinal direction X at positions separated on both sides in the vehicle width direction Y, and a crossbeam 3 extending in the vehicle width direction Y and connecting the pair of side beams 2. Additionally, on both sides in the vehicle width direction Y, as other frame members, as pillars extending upward Z1 from the side beams 2, hinge pillars 4, central pillars 5, and rear pillars 6 are erected sequentially at intervals from each other in the vehicle longitudinal direction X. In this embodiment, the side beams 2 extend in the vehicle longitudinal direction X from the hinge pillars 4 to the rear pillars 6. A front pillar 7 is also provided, extending upward Z1 and backward X2 from the upper end of the hinge pillars 4 to the upper end of the central pillar 5. The side beams 2, hinge pillars 4, central pillars 5, and front pillars 7 form the door opening 8 on the front side of the vehicle. A door (not shown) is installed at the door opening 8 (specifically, the portion of the hinge pillar 4 that forms the door opening 8), and the door opens and closes freely. Additionally, a floor 9 forming the body floor is provided between the paired side beams 2 of the body 1.

[0050] like Figures 4-5 As shown, the side beam 2 is a generally cylindrical member that extends on both sides of the vehicle body 1 in the longitudinal direction X and has a closed cross section C. It has a pair of flange portions 23 and a pair of flange portions 33, which will be described later, protruding upward Z1 and downward Z1, respectively.

[0051] The side beam 2, which serves as the skeletal component of the vehicle body 1, includes an outer beam 11, an inner beam 12 located inside the vehicle width direction Y2 relative to the outer beam 11, and a connecting plate portion 14 sandwiched between the outer beam 11 and the inner beam 12.

[0052] The outer beam 11 is composed of two plates of steel or other plate-like materials (main plate 20 and patch 13), while the inner beam 12 and the connecting plate 14 are composed of one plate of steel or other plate-like material.

[0053] The outer side beam 11 is a component having a pair of upper and lower flange portions 23 and forming the outer Y1 portion of the side beam 2 in the vehicle width direction. The inner side beam 12 is a component having a pair of upper and lower flange portions 33 and forming the inner Y2 portion of the side beam 2 in the vehicle width direction.

[0054] The flange portion 23 of the outer beam 11 and the flange portion 33 of the inner beam 12 are joined together to form the side beam 2. That is, the closed section C of the side beam 2 is formed by the cooperation (specifically, the joining) of the outer beam 11 and the inner beam 12, which extend in the same direction (in this embodiment, the vehicle front-rear direction X).

[0055] The structure of the outer beam 11 is described in further detail below. Figures 4-5As shown, in this embodiment, the outer beam 11 is processed into a cap cross-section shape (i.e., a shape with paired flange portions 23) by joining two plate-shaped materials made of steel or the like, namely the main plate-shaped material 20 and the patch 13, and stamping them together.

[0056] Specifically, the outer beam 11 includes: a longitudinal wall portion 21 extending in the vertical direction Z; an upper side surface portion 22A and a lower side surface portion 22B, which are a pair of side surface portions 22 extending inward in the vehicle width direction Y2 from both ends of the longitudinal wall portion 21 toward the inner beam 12 in a vertical direction Z-expanding manner; and a pair of flange portions 23 extending upward Z1 and downward Z2 respectively from the ends of the pair of side surface portions 22 in the vehicle width direction Y2. The lower side surface portion 22B is located below and separated from the upper side surface portion 22A.

[0057] The paired side portions 22 (i.e., the upper side portion 22A and the lower side portion 22B) each have: a first bent portion 24 formed by bending the side portion 22 toward the inside of the side beam 2; a first part 25 located on the side of the longitudinal wall portion 21 relative to the first bent portion 24, with the first bent portion 24 as the starting point; and a second part 26 located on the side away from the longitudinal wall portion 21 relative to the first bent portion 24, with the first bent portion 24 as the starting point.

[0058] The first bending portion 24 is formed by bending the side portion 22 (specifically, the portion of the main board material 20 corresponding to the side portion 22) inward toward the side beam 2.

[0059] In cases of side collisions (such as when an obstacle or other object collides with the vehicle from the outside towards the side), there is a bending load B2 on the side beam 2 that bends inward towards the vehicle (refer to...). Figure 12 When the side beam 2 is input, compressive stress will be generated in the longitudinal wall portion 21. In addition, compressive stress will be generated in the first portion 25 and tensile stress will be generated in the second portion 26 of the paired side portions 22.

[0060] In this embodiment, the first part 25 (the first part) of the outer beam 11 has higher rigidity than the second part 26 (the second part) in response to the bending load B2 that compresses the longitudinal wall portion 21. In this embodiment, the first part 25 is constructed by joining two plate-like materials (the main plate-like material 20 and the patch 13). Figure 5 The patch 13 is bonded to the inner side of the main board-shaped material 20. The patch 13 has a main body portion 13a and paired side portions 13b formed by bending the two sides of the main body portion 13a. The main body portion 13a is bonded to the longitudinal wall portion 21, and the side portions 13b are bonded to the first portion 25. The front ends of the side portions 13b are positioned at the same position as the first bent portion 24. As a result, the longitudinal wall portion 21 in the outer beam 11 and the first portion 25 of the paired side portions 22 have high rigidity, while the second portion 26 without the patch 13 has low rigidity.

[0061] Furthermore, in the side portion 22 of this embodiment, the first part 25 is formed by joining the main board-shaped material 20 and the patch 13, while the second part 26 is formed solely by the main board-shaped material 20. Consequently, the rigidity of the side portion 22 changes discontinuously from the rigidity of the first part 25 to the rigidity of the second part 26, with the first bend 24 as the boundary. In other words, the first part 25 and the second part 26 of this embodiment have the same rigidity within their respective regions, but at the first bend 24, the rigidity of the first part 25 and the rigidity of the second part 26 change abruptly.

[0062] The patch 13 can be attached to one of the outer Y1 or inner Y2 surfaces of the main board material 20 in the vehicle width direction. However, it is preferred to attach it to the outer Y1 surface of the main board material 20 in the vehicle width direction because the first part 25 is difficult to crush (deform) during a vehicle collision.

[0063] In this embodiment, as described above, the side portion 22 has a structure where, with the first bending portion 24 as the boundary, the highly rigid first portion 25 and the low-rigidity second portion 26 change discontinuously, thus resulting in a bending load B2 during a vehicle side collision (see reference). Figure 12 When inputting side beam 2, it is prone to buckling at the first bend 24. Therefore, as Figure 5 As shown, even if the angle θ between the extension line of the first part 25 and the second part 16 in the first bending part 24 is set to less than 30 degrees, the side beam 2 can reliably buckle.

[0064] Next, the structure of the inner beam 12 will be described in detail. For example... Figures 4-5 As shown, the inner beam 12 is processed into a cap cross-section shape (i.e., a shape with paired flange portions 23) by stamping a sheet of steel or other plate material.

[0065] Specifically, the inner beam 12 includes: a longitudinal wall portion 31 extending upward and downward in the Z direction from the inner end in the vehicle width direction Y2; a pair of side portions 32 (i.e., upper side portion 32A (upper surface portion) and lower side portion 32B (lower surface portion)) extending outward in the vehicle width direction Y1 from both ends of the longitudinal wall portion 31 toward the outer beam 11 in an upward and downward Z direction; and a pair of flange portions 33 extending upward Z1 and downward Z2 respectively from the outer ends of the upper side portion 32A and lower side portion 32B in the vehicle width direction Y1 (i.e., the outer beam 11 side). The lower side portion 32B (lower surface portion) is separated from the upper side portion 32A (upper surface portion) by Z2 below it. Under bending load B2 (refer to...) Figure 1 When the input side beam 2 is applied, tensile stress is generated in the longitudinal wall 31.

[0066] like Figure 3 and Figure 5 As shown, near the middle of the longitudinal wall portion 31 in the vertical direction Z, a reinforcing rib 31a for strengthening the inner side beam 12 extends in the extension direction of the inner side beam 12 (i.e., the vehicle longitudinal direction X). The reinforcing rib 31a is formed by recessing the middle of the longitudinal wall portion 31 inward towards the side beam 2 (outward Y1 in the vehicle width direction). Figure 3 As shown, in this embodiment, the reinforcing rib 31a extends from the front end 2b (the part connected to the hinge column 4) of the side beam 2 on the vehicle front side X1 to the position E of the end of the crossbeam 3 on the vehicle rear side X2.

[0067] The upper side surface portion 32A (upper surface portion) and the lower side surface portion 32B (lower surface portion) respectively include: a second bent portion 34 (bent portion) formed by bending inward towards the side beam 2, and two surfaces extending in the vehicle width direction Y (see reference). Figure 5 (As shown in numbers 35, 37, 38, and 40). That is, the upper side surface 32A and the lower side surface 32B have a generally stepped cross-section with two levels.

[0068] Specifically, the upper side surface portion 32A includes: a first upper surface portion 35 extending in the vehicle width direction Y; an upper inclined portion 36 (inclined portion) extending from the inner Y2 end 35a of the first upper surface portion 35 in the vehicle width direction to the inner Y2 and lower Z2 in the vehicle width direction; and a second upper surface portion 37 (vehicle width direction portion) forming the second bending portion 34 (bending portion) from the inner Y2 end of the upper inclined portion 36 in the vehicle width direction and extending to the inner Y2 in the vehicle width direction.

[0069] Furthermore, the lower side surface portion 32B includes: a first lower surface portion 38 extending downward from the first upper surface portion 35 in the vehicle width direction Y; a lower inclined portion 39 (inclined portion) extending from the inner Y2 end 38a of the first lower surface portion 38 in the vehicle width direction inward Y2 and upward Z1; and a second lower surface portion 40 (vehicle width direction portion) forming the second bend 34 (bend) from the inner Y2 end of the lower inclined portion 39 in the vehicle width direction and extending inward Y2 in the vehicle width direction. The lower side surface portion 32B has a shape that is symmetrical to the upper side surface portion 32A. Therefore, in the vehicle width direction Y, the first lower surface portion 38 has the same width as the first upper surface portion 35, the lower inclined portion 39 has the same width and inclination angle as the upper inclined portion 36, and the second lower surface portion 40 has the same width as the second upper surface portion 37.

[0070] That is, in the inner beam 12, as a bending portion formed by bending the upper side surface portion 32A (upper surface portion) and the lower side surface portion 32B (lower surface portion) toward the inner side of the side beam 2, there are two pairs of second bending portions 34 that bend toward the inner side of the cross section of the side beam 2 between the second upper surface portion 37 and the upper inclined portion 36, and between the second lower surface portion 40 and the lower inclined portion 39.

[0071] Furthermore, the upper inclined surface 36 and the lower inclined surface 39, which are inclined surfaces, extend from the second bend 34 toward the outer beam 11 and are inclined in the direction of widening in the vertical direction Z toward the inner beam 12 as they approach the outer beam 11. Also, the second upper surface portion 37 and the second lower surface portion 40, which are surfaces in the vehicle width direction, extend from the second bend 34 toward the inner side Y2 in the vehicle width direction Y.

[0072] In this embodiment, in order to suppress the bending deformation of the side beam 2 during a small overlap collision, the upper side surface portion 32A (upper surface portion) and the lower side surface portion 32B (lower surface portion) of the inner side beam 12 may be provided with the above-mentioned second bending portion 34 (bending portion), upper inclined portion 36 and lower inclined portion 39 (inclined portion), second upper surface portion 37 and second lower surface portion 40 (vehicle width direction portion) in the region between the front end 2b of the side beam 2 and the cross beam 3 in the vehicle longitudinal direction X. However, the above-mentioned components may also be provided across the entire length of the side beam 2.

[0073] The longitudinal wall portion 31 extends in the vertical direction Z, connecting the inner Y2 ends of the second upper surface portion 37 and the second lower surface portion 40 in the vehicle width direction to each other, thereby achieving the connection between the upper side surface portion 32A (upper surface portion) and the lower side surface portion 32B (lower surface portion).

[0074] like Figures 3-4 As shown, the end of the crossbeam 3 extending in the vehicle width direction Y is joined to the inner side beam 12. In this embodiment, the crossbeam 3 is joined to the inner side beam 12 at a position X2 on the rear side of the vehicle relative to the front end 2b of the side beam 2, extending from the side beam 2 inward in the vehicle width direction Y2.

[0075] The crossbeam 3 has three flange portions at its ends that engage with the inner beam 12: a first flange portion 41, a second flange portion 42, and a third flange portion 43. The first flange portion 41 extends from the upper surface 3a of the crossbeam 3 outward in the vehicle width direction Y1 and engages with the second upper surface portion 37 of the inner beam 12. The second flange portion 42 extends from the end edge of the side surface 3b of the crossbeam 3 (facing the vehicle's longitudinal direction X) outward in the vehicle width direction Y1 and engages with the longitudinal wall portion 31 of the inner beam 12. The third flange portion 43 extends upward Z1 (i.e., inward of the crossbeam 3) from the end edge of the bottom wall portion of the crossbeam 3 outward in the vehicle width direction Y1 and engages with the longitudinal wall portion 31.

[0076] In order to suppress the torsion of the side beam 2 in the event of a small overlap collision, it is preferable that the upper surface 3a of the cross beam 3 and the second upper surface portion 37 (vehicle width direction portion) of the inner side beam 12 are at the same height.

[0077] The first flange portion 41 extends from the upper surface 3a of the crossbeam 3 outward in the vehicle width direction Y1 and engages with the second upper surface portion 37 of the inner beam 12. Furthermore, as an additional first flange portion 41, it may extend from the lower surface of the crossbeam 3 outward in the vehicle width direction Y1 and engage with the second lower surface portion 40 of the inner beam 12.

[0078] like Figure 5 As shown, in the side beam 2 of this embodiment, the width L2 of the first portion 25 located on the outer side Y1 of the vehicle width direction (vehicle width direction Y) of the outer side beam 11 and the inner side beam 12 is set to less than 1 / 4 of the total width L1 of the side beam 2 in the specified direction (vehicle width direction Y). Therefore, during a side collision of the vehicle, a bending load B2 (refer to...) is generated. Figure 12 When inputting, it can make the side beam 2 buckle effectively at the first bend 24.

[0079] In addition, such as Figure 5 As shown, the width L3 of the second upper surface portion 37 and the second lower surface portion 40 in the specified direction (vehicle width direction Y) where the outer side beam 11 and the inner side beam 12 are arranged is set to less than 1 / 4 of the total width L1 of the side beam 2 in the specified direction (vehicle width direction Y). Therefore, when a bending load B2 is input during a vehicle side collision, buckling at the locations of the second upper surface portion 37 and the second lower surface portion 40 can be suppressed, allowing the side beam 2 to buckle reliably at the location of the second bending portion 34.

[0080] In addition, such as Figure 5 As shown, the flange portions 23 and 33 of the outer beam 11 and the inner beam 12 (especially the flange portions 23 and 33 protruding upwards Z1) are... Figure 1 The reference for the position of the door opening 8 (position in the vehicle width direction Y) is positioned on the outer side Y1 in the vehicle width direction relative to the cross-sectional center O of the side beam 2, thus ensuring interior space.

[0081] like Figures 4-5 As shown, the connecting plate portion 14 connects the upper and lower paired flange portions 23 and the upper and lower paired flange portions 33 when it is sandwiched between the upper and lower paired flange portions 23 of the outer beam 11 and the upper and lower paired flange portions 33 of the inner beam 12.

[0082] The connecting plate 14, as long as it is inside the side beam 2, can be positioned at any location in the vehicle's longitudinal direction X, such as... Figure 1As shown, in order to obtain a portion 2a of the door opening 8 that forms part 8 of the vehicle body 1 in the X-direction reinforcing side beam 2 of the vehicle, and to promote the buckling effect at this portion 2a, a connecting plate portion 14 is preferably provided.

[0083] The connecting plate portion 14 is structured such that its bending strength is less than that of the outer beam 11 and the inner beam 12. Specifically, it is made of a plate material that is thinner than the main plate material 20 and patch 13 constituting the outer beam 11 and the plate material constituting the inner beam 12.

[0084] The first bends 24 of the paired side portions 22 are arranged at equal distances from the longitudinal wall portion 21. That is, in this structure, the first bends 24 of the outer beam 11 are in symmetrical positions.

[0085] (Features of this embodiment) (1)

[0087] In the lower body structure of the vehicle according to this embodiment, such as Figure 5 As shown, the upper side surface portion 32A (upper surface portion) and the lower side surface portion 32B (lower surface portion) of the inner side beam 12 are bent inward toward the side beam 2 at least in the area between the front end 2b of the side beam 2 and the cross beam 3 in the vehicle longitudinal direction X, forming a second bending portion 34. The second bending portion 34 includes an upper inclined portion 36 and a lower inclined portion 39 (inclined portion) extending from the second bending portion 34 toward the outer beam 11 and inclining toward the inner side beam 12 in the vertical direction Z as it approaches the outer beam 11; and a second upper surface portion 37 and a second lower surface portion 40 (vehicle width direction portion) extending from the second bending portion 34 toward the vehicle interior Y2 in the vehicle width direction Y.

[0088] In this structure, such as Figures 1-2 and Figure 6 As shown, during a vehicle collision, the collision load A is input to the front end 2b of the side beam 2 via the front wheel W of the vehicle toward the rear X2 and inward Y2 in the vehicle width direction. At this time, a bending load B1 is input to the side beam 2 at the joint of the crossbeam 3 and the inner side beam 12 (near the end of the crossbeam 3 with the first to third flange portions 41 to 43) as the fulcrum.

[0089] like Figure 6As shown, during the inward displacement of the second bending portions 34 of the upper side surface portion 32A and the lower side surface portion 32B of the inner beam 12 after the input bending load B1, the upper inclined portion 36 and the lower inclined portion 39 extending from the second bending portion 34 towards the outer beam 11 have an increased inclination towards the inner beam 12 in the vertical direction Z. On the other hand, the second upper surface portion 37 and the second lower surface portion 40 extending from the second bending portion 34 towards the vehicle interior Y2 can maintain a state that is approximately parallel to the direction of the collision load A (specifically, the horizontal direction and the same direction as the vehicle width direction Y component of the collision load A). Therefore, the inner beam 12 itself can generate a high reaction force, which can suppress the bending deformation of the side beam 2. Therefore, in the above structure, it is not necessary to provide reinforcing members inside the side beam 2 as in the past, thus suppressing the deformation of the side beam 2 during small overlap collisions without increasing the weight and manufacturing cost of the side beam 2. Figures 4-5 A connecting plate portion 14 is provided inside the side beam 2. However, the connecting plate portion 14 is not a necessary structure in this invention. It is self-evident that the above-mentioned effects can be achieved even without the connecting plate portion 14.

[0090] <Explanation of Effect Verification>

[0091] Here, in order to verify the above-mentioned effects, such as Figures 1-2 and Figure 6 As shown, in a small overlap collision, the collision load A is input to the front end 2b of the side beam 2 via the front wheel W of the vehicle in a direction X2 towards the rear of the vehicle and Y2 in the vehicle width direction. The reaction force of the side beam 2 to the bending load B1 at this time is studied, and the results are shown in... Figure 7 The curve I in the chart. Figure 7 The graph shows the change of the bending load F generated in the side beam as a reaction force over time. Figure 7 Curve I represents the change of bending load over time in the side beam 2 of this embodiment, and curve II represents the change of bending load over time in a comparative example. Figure 8 The bending load of the previous side beam 50 changes over time.

[0092] Figure 8 The conventional side beam 50 is composed of an outer beam 51 and an inner beam 52 of the same plate thickness, and has a structure formed by the joint of a pair of flange portions 51a of the outer beam 51 and a pair of flange portions 52a of the inner beam 52. The inner beam 52 is joined to the end of the crossbeam 3. The structure of this side beam 50 is different from that of this embodiment. It does not have the aforementioned second bending portion 34, inclined surface (upper inclined surface 36 and lower inclined surface 39), and vehicle width direction surface (second upper surface portion 37 and second lower surface portion 40) used to increase the reaction force in the inner beam 52.

[0093] from Figure 7The diagrams clearly show that, as shown by curve I, the side beam 2 in this embodiment acts as a reaction force against the bending load during small overlap collisions, and can maintain a high bending load for a long time. In contrast, as shown by curve II, it can be seen that... Figure 8 In the comparative example, the bending load of the side beam 50 as a reaction force during small overlap collisions was almost always lower than curve I mentioned above.

[0094] Furthermore, in this embodiment, the side beam 2 and Figure 8 When comparing the stress distribution acting on the side beam 50 in the comparative example under small overlap collision, it can be seen that... Figure 9 In the side beam 2 shown in this embodiment, near the joint between the side beam 2 and the cross beam 3, the portion with high stress ( Figure 9 The darker colored portions (spread widely) generated a high reaction force across the entire side beam 2. On the other hand, it can be seen that... Figure 10 As shown Figure 8 In the comparative example of the side beam 50, the portion with high stress is near the joint with the crossbeam 3. Figure 10 The darker parts are concentrated in a narrower area, and from the perspective of the side beam 50 as a whole, they only produce low reaction forces.

[0095] To further verify the effect of the side beam of the present invention, as a variation of the present invention, the above-mentioned reinforcing rib 31a in the side beam 2 of this embodiment (refer to...) Figures 2-5 In the example where the beam extends only to the front end instead of the rear end of beam 3, the reaction force of the side beam under bending load B1 during a small overlap collision was also studied under the same conditions as described above. The results are presented below. Figure 11 The curve I' in the chart. From Figure 11 The graph shows that in the modified example of the present invention (short-term stiffener 31a) (curve I'), the bending load as a reaction force during small overlap collisions is also higher than the above for a long time. Figure 8 The side beam 50 (curve II) of the comparative example.

[0096] Therefore, from the above Figure 11 The results of the chart show that even when the reinforcing rib 31a only extends to the front end of the crossbeam 3, as long as the side beam 2 of this embodiment has the structure of the second bending portion 34, the inclined surface (upper inclined surface 36 and lower inclined surface 39), and the vehicle width direction surface (second upper surface portion 37 and second lower surface portion 40) for increasing the reaction force, the bending load as the reaction force can be maintained at a high level.

[0097] Modification of the present invention (reinforcing rib 31a for short time) Figure 11 The curve I') compared to the side beam 2 (when the length of the reinforcing rib 31a) in this embodiment ( Figure 7Regarding curve I), the maximum value of the bending load as a reaction force is slightly lower and the time of high bending load is slightly shorter. Therefore, the structure in which the stiffener 31a extends to the rear end of the crossbeam 3, such as the side beam 2 in this embodiment, is preferred because it can obtain a high bending load for a long time as a reaction force. (2)

[0099] In the lower body structure of the vehicle according to this embodiment, preferably Figures 2-4 The upper surface 3a of the crossbeam 3 shown is at the same height as the second upper surface 37 of the upper side surface portion 32A (upper surface portion) of the inner side beam 12. At this time, for the side beam 2 that bears the bending load B1 during a small overlap collision, the torsion of the side beam 2 can be suppressed and it can be supported by the crossbeam 3. (3)

[0101] In the lower body structure of the vehicle according to this embodiment, it is preferable that the crossbeam 3 has at least one of the upper side surface portion 32A and the lower side surface portion 32B of the inner side beam 12. Figures 2-4 At least one of the second upper surface portion 37 and the second lower surface portion 40 in the upper side surface portion 32A (only the upper side surface portion 32A) Figures 2-4 The first flange 41 is joined only to the second upper surface portion 37.

[0102] According to the relevant structure, in at least one of the upper side surface portion 32A and the lower side surface portion 32B of the inner side beam 12, at least one of the second upper surface portion 37 and the second lower surface portion 40 of the inner side Y2 of the vehicle is engaged with the first flange portion 41 of the crossbeam 3, relative to the second bending portion 34. Therefore, during the deformation process of the side beam 2 in a small overlap collision, the deformation of at least one of the second upper surface portion 37 and the second lower surface portion 40 of the inner side beam 12 can be suppressed, and the second upper surface portion 37 and the second lower surface portion 40 can be reliably maintained in a state that is approximately parallel to the direction of the collision load A. (4)

[0104] In the lower body structure of the vehicle according to this embodiment, the inner side beam 12 is as follows: Figures 2-3 As shown, the crossbeam 3 has a longitudinal wall portion 31 extending upward and downward in the Z direction from the end on the inner side Y2 in the vehicle width direction, connecting the upper side surface portion 32A (upper surface portion) and the lower side surface portion 32B (lower surface portion). The crossbeam 3 has a second flange portion 42 that engages with the longitudinal wall portion 31 of the inner beam 12. In this structure, the longitudinal wall portion 31 located at the end on the inner side Y2 in the vehicle width direction of the inner beam 12 engages with the second flange portion 42 of the crossbeam 3, thus enabling the crossbeam 3 to reliably support the side beam 2, which bears the bending load B1 during a small overlap collision.

[0105] In addition, in this embodiment, the crossbeam 3, besides the aforementioned second flange portion 42, includes, for example... Figure 4The device also includes a third flange 43 that engages with the aforementioned longitudinal wall portion 31, thus enabling the side beams to be supported more reliably by the crossbeam 3. (5)

[0107] In the lower body structure of the vehicle according to this embodiment, such as Figures 2-5 As shown, the longitudinal wall portion 31 of the inner side beam 12 has a reinforcing rib 31a extending in the vehicle longitudinal direction X. According to the relevant structure, the overall rigidity of the side beam 2, including the inner side beam 12, against bending deformation can be improved. (6)

[0109] In the lower body structure of the vehicle according to this embodiment, the reinforcing rib 31a extends at least from the front end 2b of the side beam 2 to the rear end of the crossbeam 3. Figure 3 (The position of line E). According to this structure, the part of the side beam 2 from the front end 2b of the side beam 2 to the rear end of the crossbeam 3 has improved rigidity through the reinforcing rib 31a. Therefore, when a collision load A is input to the front end 2b of the side beam 2 during a small overlap collision, the bending deformation of the side beam 2 can be effectively prevented. (7)

[0111] In the lower body structure of the vehicle according to this embodiment, the inner side beam 12 is as follows: Figure 5 As shown, the side beam 2 has a pair of upper and lower flange portions 33 located at the ends of the outer side beam 11 in the upper side portion 32A and the lower side portion 32B. The side beam 2 has a connecting plate portion 14 that connects to the pair of upper and lower flange portions 33 of the inner side beam 12.

[0112] In this structure, when a collision load A is input to the front end 2b of the inner beam 12 during a small overlap collision, the upper side surface 32A and the lower side surface 32B of the inner beam 12 will be subjected to forces in the direction of upward and downward separation. However, the upper and lower paired flanges 33 at the ends of the upper side surface 32A and the lower side surface 32B are connected by the connecting plate 14. Therefore, the tension of the connecting plate 14 can suppress the cross-section crushing of the upper side surface 32A and the lower side surface 32B of the inner beam 12. (8)

[0114] In the lower body structure of the vehicle according to this embodiment, the connecting plate portion 14 is disposed in the side beam 2 in the vehicle longitudinal direction X to form the door opening portion 8 of the body 1 (see reference). Figure 1 ( ) part.

[0115] The door opening 8 of the vehicle body 1 is an area without a pillar extending in the vertical direction Z, and is an area where the support rigidity of the side beam 2 is weak. However, as described above, the connecting plate 14 is disposed in the part of the side beam 2 that constitutes the door opening 8. Therefore, even in the area without a pillar, the tension of the connecting plate 14 can effectively suppress the cross-sectional crushing of the upper side surface 32A and the lower side surface 32B of the inner side beam 12. (9)

[0117] In small overlap collisions and side collisions, the connecting plate portion 14 is stretched vertically by the paired flange portions 23, 23, 33, 33, experiencing only tensile loads. Therefore, the bending strength of the connecting plate portion 14 is not as high as that required for the outer beam 11 and the inner beam 12. From this perspective, by making the structure of the connecting plate portion 14 such that its bending strength is lower than that of the outer beam 11 and the inner beam 12, the quality and cost of the connecting plate portion 14 can be controlled, and the cross-sectional deformation of the inner beam 12 can be suppressed. Furthermore, it is possible to achieve effective buckling of the side beam 2 and make the connecting plate portion 14 thin, allowing it to be manufactured using inexpensive materials.

[0118] (Deformation process of side beam 2 during a side collision of the vehicle)

[0119] Next, refer to Figure 13 (a) to (d) represent the deformation process of the side beam 2 constructed as above when subjected to bending load B2 during a lateral collision of the vehicle.

[0120] exist Figure 13 In (a), during a lateral collision, the obstacle S collides with the side beam 2 from the outer side (Y1) to the inner side (Y2) in the vehicle width direction, thus inputting a collision load to the side beam 2 from the side. Therefore, as... Figure 12 As shown, the bending load B2 of the side beam 2, which is bent towards the inside of the vehicle, is input through the hinge column 4 and the central column 5 and other body components, and is fixed at both ends of the side beam 2 in the front-rear direction X of the vehicle.

[0121] like Figure 13 As shown in (b), in the initial state of a vehicle side collision, when compressive stress acts on the longitudinal wall portion 21 of the outer side beam 11 of the side beam 2, the longitudinal wall portion 21 moves towards the inner side beam 12 (inner Y2 in the vehicle width direction). Furthermore, on the paired side portions 22 of the outer side beam 11, with the first bending portion 24 as the boundary, compressive stress acts on the first portion 25 and tensile stress acts on the second portion 26. The first portion 25 of the side portion 22, which has the patch 13, is more rigid than the second portion 26. Therefore, even if the first bending portion 24 is at a small angle (less than 30 degrees), the movement of the first bending portion 24 towards the inner side of the side beam 2 is promoted (induced).

[0122] As the first bending portion 24 moves inward toward the side beam 2, the second portion 26 undergoes tensile deformation toward the inward of the side beam 2, and the first bending portion 24 displaces inward toward the side beam 2, causing buckling of the side beam 2. During this process, midway through the displacement of the first bending portion 24 toward the inward of the side beam 2, the highly rigid first portions 25 of each pair of side portions 22 deform to a state approximately parallel to the direction of the impact load (i.e., the direction in which the longitudinal wall portion 21 moves toward the inner side beam 12, specifically the vehicle width direction Y). Therefore, the first portions 25 generate a high reaction force against the bending load B2. Furthermore, during compression, the upward and downward separation of the upper and lower flange portions 23, 33 of the side beam 2 is suppressed by the connecting plate portion 14, generating a high reaction force against the bending load B2.

[0123] Regarding the aforementioned reaction force, from Figure 14 The rise of the bending moment MB at time t1 in curve III of the graph can be clearly seen. Figure 14 The graph shows the time variation of the bending moment MB generated in the side beam as a reaction force. Figure 14 Curve III represents the time variation of the bending moment in the side beam 2 of this embodiment, and curve IV represents the bending moment in the comparative example described above. Figure 8 The temporal variation of bending moment in the previous side beam 50. Figure 8 The conventional side beam 50 does not have the structure of the first bend 24 and the second bend 34 that serve as buckling triggers as in this embodiment.

[0124] In this embodiment, side beam 2 becomes... Figure 13 In state (b), as described above Figure 14 In the graph, corresponding to time t1, curve III indicates that the reaction force of side beam 2 generates a high bending moment. On the other hand, curve IV at time t1 indicates that only the reaction force of the previous side beam 50 generates a low bending moment.

[0125] Then, as Figure 13As shown in (c), as the time of onset of the vehicle side collision progresses further, the deformation of the inner beam 12 also progresses along with the deformation of the outer beam 11. During the deformation of the inner beam 12, the ends (paired flange portions 33 and their surrounding portions) of the paired side portions 32 (upper side portion 32A and lower side portion 32B) of the inner beam 12 extend upward Z1 and downward Z2 respectively at the outer Y1 in the vehicle width direction. The first and second upper surface portions 35, 37 and the first and second lower surface portions 38, 40 of the inner beam 12 expand and deform outward from the cross-section of the side beam 2. However, at the same time, the second bending portion 34 of each of the paired side portions 32 of the inner beam 12 is displaced outward from the cross-section of the side beam 2. Therefore, the first and second upper surface portions 35, 37 and the first and second lower surface portions 38, 40 can maintain a state that is approximately parallel to the direction of the collision load (i.e., the direction in which the longitudinal wall portion 21 moves toward the inner beam 12, specifically the vehicle width direction Y). Therefore, the first and second upper surface portions 35, 37 and the first and second lower surface portions 38, 40 of the inner beam 12 support the outer beam 11 during deformation, which can generate a higher reaction force and suppress the bending deformation of the side beam 2.

[0126] The reaction force of the inner beam 12 can also be obtained from Figure 14 The height of the bending moment at time t2 on curve III of the graph is clearly visible. That is, the side beam 2 in this embodiment becomes Figure 13 In state (c), Figure 14 In the graph, corresponding to time t2, curve III indicates that the reaction force of side beam 2 maintains a high bending moment. From curve III, it can be seen that by making not only the outer beam 11 have a first bending portion 24 but also the inner beam 12 have a second bending portion 34, the buckling of side beam 2 inward Y2 in the vehicle width direction can be effectively suppressed, and the reaction force of side beam 2 can be sustained.

[0127] On the other hand, observing curve IV at time t2 shows that the bending moment of the reaction force of the side beam 50, which is the previous one, only reached a level lower than that of curve III.

[0128] And, as Figure 13 As shown in (d), as the time of the vehicle side collision progresses further, the second bend 34 of the inner beam 12 moves outward toward the side beam 2, and the inner beam 12 extends outward and deforms, generating a reaction force.

[0129] In this embodiment, side beam 2 becomes... Figure 13 In state (d), Figure 14 In the chart, this corresponds to time t3. From Figure 14It can be seen that at time t3, in curve III, the bending moment, as the reaction force of side beam 2, gradually decreases but also inhibits the decrease of the reaction force, and remains at a sufficiently high level compared to the reaction force of side beam 50 shown in curve IV.

[0130] (Regarding the torsion of side beam 2)

[0131] In the bending deformation of the side beam 2 described above, a reaction force as bending moment was observed when a bending load B2 was applied to the side beam 2 during a side collision of the vehicle. The side beam 2 of this embodiment has a first bending portion 24 and a second bending portion 34 as described above, thereby generating a high reaction force when a torque is applied around an axis extending in the forward and backward direction X of the vehicle.

[0132] exist Figure 15 In the graph, the time variation of torque MT, which is the reaction force in the side beam 2 of this embodiment, is represented by curve V. Figure 8 The time variation of torque MT in the previous side beam 50 is represented by curve VI. See this... Figure 15 The graphs also clearly show that: in the initial stage of torque input, the side beam 2 (curve V) of this embodiment and the conventional side beam 50 (curve VI) generate the same level of torque as a reaction force, but thereafter the side beam 2 of this embodiment maintains a higher torque than the conventional side beam 50 as a reaction force.

[0133] (Other features of this embodiment) (11)

[0135] In order to obtain high reaction force in the event of a side collision, even if a structure with a reduced cross-sectional width of the side beam 2 is adopted to ensure interior space, the lower body structure of the vehicle in this embodiment has the following structure: not only the first bend 24 of the outer beam 11, but also the second bend 34 of the inner beam 12, and four upper and lower surfaces (first upper surface 35, second upper surface 37, first lower surface 38, and second lower surface 40) extending in the vehicle width direction Y (i.e., four transverse walls).

[0136] In this structure, when a lateral collision load is input to the side beam 2 during a side collision, the first bending portion 24 in the upper side portion 22A and the lower side portion 22B of the outer side beam 11 displaces inward toward the cross-section of the side beam 2. Compared to the first bending portion 24 in the upper side portion 22A and the lower side portion 22B, the first part 25 on the outer side Y1 in the vehicle width direction becomes approximately parallel to the lateral input during deformation, thus generating a high reaction force and collapsing in the vehicle width direction Y.

[0137] During the deformation of the inner beam 12, the ends (paired flange portions 33 and their surrounding portions) of the outer Y1 of the upper side portion 32A and the lower side portion 32B of the inner beam 12 in the vehicle width direction extend upward Z1 and downward Z2 respectively. The first and second upper surface portions 35, 37 and the first and second lower surface portions 38, 40 of the inner beam 12 expand and deform outward from the cross section of the side beam 2. However, at the same time, the second bending portion 34 of each of the upper side portion 32A and the lower side portion 32B of the inner beam 12 displaces outward from the cross section of the side beam 2. Therefore, the first upper surface portion 35, the second upper surface portion 37, the first lower surface portion 38 and the second lower surface portion 40 can maintain a state that is approximately parallel to the direction of the collision load (i.e., the direction in which the longitudinal wall portion 21 moves towards the inner beam 12, specifically the vehicle width direction Y). Therefore, the first and second upper surfaces 35 and 37 and the first and second lower surfaces 38 and 40 of the inner beam 12 support the outer beam 11 during deformation, which can generate a higher reaction force and suppress the bending deformation of the side beam 2.

[0138] Therefore, the side beam 2 can generate high reaction forces on both the outer side beam 11 and the inner side beam 12 in response to collision loads from the side, thereby increasing the bending resistance of the side beam 2 without increasing its weight and manufacturing cost.

[0139] In other words, in the side beam 2 of this embodiment, the first and second upper surface portions 35 and 37 and the first and second lower surface portions 38 and 40 can support the outer beam 11 during deformation and generate a high reaction force. If the inner beam 12 is only provided with the shape of the second bending portion 34 on the upper side surface portion 32A (upper surface portion) and the lower side surface portion 32B (lower surface portion), that is, if the upper side surface portion 32A and the lower side surface portion 32B are only U-shaped in cross section, during lateral input, the upper side surface portion 32A and the lower side surface portion 32B of the inner beam 12 become less parallel to the input direction during the movement of the second bending portion 34 towards the outside of the side beam 2 (for example, only the second upper surface portion 37 and the second lower surface portion 40 of the inner beam 12 located inside Y2 in the vehicle width direction), and therefore cannot obtain a high reaction force. (12)

[0141] In the lower body structure of the vehicle in this embodiment, the width L2 of the first part 25 located outside the first bending part 24 in the specified direction (vehicle width direction Y) of the outer side beam 11 and the inner side beam 12 is set to 1 / 4 or less relative to the total width L1 of the side beam 2 in the specified direction (vehicle width direction Y).

[0142] According to the relevant structure, in the event of a side collision, the buckling of the side beam 2 within the first part 25 of the upper side surface portion 22A and the lower side surface portion 22B of the outer side beam 11 can be suppressed, and the first bending portion 24 at the boundary between the first part 25 and the second part 26 of the upper side surface portion 22A and the lower side surface portion 22B can be reliably bent, thereby generating a high reaction force through the upper side surface portion 22A and the lower side surface portion 22B.

[0143] Here, refer to Figures 16-17 Verify the optimal location of the bend in the total width of the side beam to promote buckling. First, as... Figure 16 As shown, in the vehicle width direction of the side beam, a portion of the total width is replaced by a model of a longitudinal plate 61. The upper and lower ends of the longitudinal plate 61 are connected to and constrained by end plates 62 and 63.

[0144] To approximate the total plastic moment of the original longitudinal plate 61, which represents the ideal buckling performance index, a bending portion 64 can be provided on the longitudinal plate 61 as a point of shape change (i.e., the point where the longitudinal plate 61 buckles). Here, as... Figure 16 As shown, when a bending load in the vertical direction is applied to the longitudinal plate 61, the model of the longitudinal plate 61 buckling and bending at the bending portion 64 is used. The compressive bending resistance ratio R, a measure of the magnitude of the reaction force of the longitudinal plate 61, is calculated by simulation when the bending portion 64 is located at a distance b' from the upper end within the total height b of the longitudinal plate 61. As a result, if... Figure 17 The graph shows the relationship between the ratio of the distance b' to the total height b of the longitudinal plate 61 (b' / b) and the compressive bending performance ratio R (the ratio relative to the ideal compressive bending performance). It can be seen that if the bending part 64 is set at 1 / 4 of the total height b of the longitudinal plate 61, the compressive bending performance is the highest.

[0145] The results show that the bending resistance is highest when the position of the first bend 24 of the side beam 2 is 1 / 4 × L1 from the longitudinal wall portion 21 relative to the total width L1 of the side beam 2. Based on this verification result, the following result can be derived: if the width L2 of the first part 25 is set to less than 1 / 4 of the total width L1 of the upper side beam 2 in the specified direction (vehicle width direction Y), the buckling of the side beam 2 in the first part 25 can be suppressed, and the first bend 24 at the boundary between the first part 25 and the second part 26 in the upper side surface portion 22A and the lower side surface portion 22B can be effectively bent, generating a high reaction force in the upper side surface portion 22A and the lower side surface portion 22B. (13)

[0147] In the lower body structure of the vehicle according to this embodiment, the width L3 of the second upper surface portion 37 and the second lower surface portion 40 in the predetermined direction (vehicle width direction Y) where the outer side beam 11 and the inner side beam 12 are arranged is set to less than 1 / 4 of the total width L1 of the upper side beam 2 in the predetermined direction (vehicle width direction Y). By setting the width L3 of the second upper surface portion 37 and the second lower surface portion 40 in this way, buckling at the second upper surface portion 37 and the second lower surface portion 40 can be suppressed when bending loads are input during a side collision of the vehicle, so that the side beam 2 can reliably buckle at the second bending portion 34.

[0148] Regarding the matter of setting the width L3 of the second upper surface portion 37 and the second lower surface portion 40 to less than 1 / 4 of the total width L1 of the upper side beam 2 in the specified direction (vehicle width direction Y), the same logic applies as when setting the width L2 of the first portion 25 to less than 1 / 4 of the total width L1 of the side beam 2. Figures 16-17 The descriptions provided can also be exported.

[0149] In addition, during a small overlap collision of the vehicle, the front end 2b of the side beam 2 cantilever deforms, thereby compressing the inner side beam 12. By setting the width L3 of the second upper surface portion 37 and the second lower surface portion 40 as described above, a high reaction force can also be obtained in the inner side beam 12, thus preventing large cross-sectional deformation of the side beam 2. (14)

[0151] In the lower body structure of the vehicle according to this embodiment, the paired side portions 22 (upper side portion 22A and lower side portion 22B) of the outer beam 11 each have a first portion 25 located on the outer side Y1 of the vehicle width direction relative to the first bend 24, and a second portion 26 located on the inner side Y2 of the vehicle width direction relative to the first bend 24. The first portion 25 has higher rigidity than the second portion 26. Therefore, even if the angle θ between the extension line of the first portion 25 in the first bend 24 and the second portion 26 is set to a small angle of 30 degrees or less, since the second portion 26 of the upper side portion 22A and the lower side portion 22B of the outer beam 11 has lower rigidity than the first portion 25, in the event of a side collision, the second portion 26 can be stretched and deformed inward toward the side beam 2, and the first bend 24 can be displaced inward toward the side beam 2, thus effectively causing the side beam 2 to buckle.

[0152] That is, according to the side beam 2 of this embodiment, in a structure where the width of the upper and lower paired side portions 22 (upper side portion 22A and lower side portion 22B) of the outer side beam 11 cannot be ensured, even if the angle θ of the first bending portion 24 of the outer side beam 11 cannot be sufficiently ensured, the first bending portion 24 of the paired side portions 22 can be displaced inward in the cross section and the side beam 2 can be reliably buckled during a side collision of the vehicle. (15)

[0154] Furthermore, in the structure of the outer beam 11, each side portion 22 (upper side portion 22A and lower side portion 22B) has: a first portion 25 located on the side of the longitudinal wall portion 21 relative to the first bend portion 24, originating from the first bend portion 24; and a second portion 26 located on the side away from the longitudinal wall portion 21 relative to the first bend portion 24, originating from the first bend portion 24. The first portion 25 has higher rigidity than the second portion 26 in response to the bending load B2 that compresses the longitudinal wall portion 21. In other words, the rigidity of the side portion 22 changes discontinuously from the rigidity of the first portion 25 to the rigidity of the second portion 26, with the first bend portion 24 as the boundary. Therefore, in a side collision of the vehicle, if... Figure 13 As shown in (b), as the first bending portion 24 moves inward toward the side beam 2, the second portion 26 undergoes tensile deformation toward the inward of the side beam 2, and the first bending portion 24 displaces inward toward the side beam 2, causing the side beam 2 to buckle. During this process, midway through the displacement of the first bending portion 24 toward the inward of the side beam 2, the highly rigid first portions 25 of each pair of side portions 22 deform to a state approximately parallel to the direction of movement of the longitudinal wall portion 21 toward the inner side beam 12. Therefore, the first portions 25 generate a high reaction force against the bending load B2, thus suppressing the bending deformation of the side beam 2. Consequently, when a bending load B2 is input to the side beam 2 during a vehicle side collision, the side beam 2 can suppress bending deformation and reliably buckle and absorb the impact. (16)

[0156] In the lower body structure of the vehicle according to this embodiment, such as Figure 5 As shown, the flange portions 23 and 33 of the outer side beam 11 and inner side beam 12 constituting the side beam 2 are positioned on the outer side Y1 in the vehicle width direction relative to the cross-sectional center O of the side beam 2. Therefore, it is easy to position the door opening portion 8 of the body 1 defined by the aforementioned flange portions 23 and 33 on the outer side Y1 in the vehicle width direction, which easily ensures the space inside the passenger compartment. Thus, it is possible to suppress the bending deformation of the side beam 2 and maintain its impact absorption performance, while ensuring the space inside the passenger compartment. (17)

[0158] In the lower body structure of the vehicle according to this embodiment, the side beam 2 includes a connecting plate portion 14. The connecting plate portion 14 connects the upper and lower paired flange portions 23 and 33 between the outer side beam 11 and the inner side beam 12, respectively. Therefore, during the bending deformation of the side beam 2 in a side collision, even if the upper and lower paired flange portions 23 and 33 are to be displaced in the direction of upward and downward separation, the connecting plate portion 14 can suppress the upper and lower paired flange portions 23 and 33 from displacing in the upward and downward direction Z (i.e., the paired flange portions 23 and 33 separate from each other in the upward and downward direction Z). Therefore, the side beam 2 can reliably bend at the first bending portion 24 and the second bending portion 34. (18)

[0160] In the lower body structure of the vehicle in this embodiment, the connecting plate portion 14 is disposed in the side beam 2 in the vehicle longitudinal direction X, forming part 2a of the door opening portion 8 of the body 1 (see reference). Figure 1 The door opening 8 of the vehicle body 1 is an area without a pillar extending in the vertical direction Z, and is an area where the support rigidity of the side beam 2 is weak. However, as described above, the connecting plate portion 14 is disposed in the portion 2a of the side beam 2 that constitutes the door opening 8, so even in the area without a pillar, the side beam 2 can reliably bend at the location of the first bend portion 24. (19)

[0162] In the lower body structure of the vehicle according to this embodiment, the first portion 25 of the outer beam 11 is formed by joining two sheet materials, namely the main sheet material 20 and the patch 13. According to the related structure, the first portion 25 of the side portion 22 of the outer beam 11 is formed by joining two sheet materials, so a flexible side beam 2 can be easily manufactured by joining the two sheet materials in the outer beam 11. (20)

[0164] In the lower body structure of the vehicle according to this embodiment, the first bends 24 of the paired side portions 22 of the outer beam 11 are arranged at equal distances from the longitudinal wall portion 21. In this structure, when a bending load B2 is input to the side beam 2 during a side collision of the vehicle, the first bends 24 of the paired side portions 22 can simultaneously displace inward, enabling the side beam 2 to reliably buckle at the location of the first bend 24 of each of the paired side portions 22.

[0165] (Modified example)

[0166] (A)

[0167] In this embodiment, the outer beam 11 is manufactured by joining and stamping two sheet-like materials made of steel or the like, namely, a main sheet 20 and a patch 13. However, the present invention is not limited to this, and the patch 13 may be omitted. The patch 13 allows for reliable bending at the first bend 24 of the outer beam 11.

[0168] (B)

[0169] In the outer beam 11 of the above embodiment, the first part 25 is formed by joining two sheet-like materials, namely the main sheet-like material 20 and the patch 13, but the present invention is not limited thereto. When the outer beam 11 is formed of a single sheet-like material, the thickness of the first part 25 may be greater than the thickness of the second part 26. In this structure, the bendable side beam 2 can be easily manufactured by integrally forming the outer beam 11.

[0170] (C)

[0171] As an example of the outer and inner beams working together to form a closed section C, the outer beam 11 and inner beam 12, as different components, are joined to form the side beam 2 of the above embodiment. However, the present invention is not limited to this; the side beam can also be a structure integrally formed with the outer and inner beams corresponding to the outer and inner beams, respectively. In this case, it can also achieve the same effect as the side beam 2 of the above embodiment.

[0172] 1. Body

[0173] 2 Side beams

[0174] 3. Crossbeam

[0175] 8. Door opening

[0176] 11. Outer beam

[0177] 12 Inner Beams

[0178] 13 Patch

[0179] 14 Connecting plate section

[0180] 20 Mainboard-shaped material

[0181] 21. Longitudinal wall section

[0182] 22 Side profile

[0183] 22A Upper side face

[0184] 22B Lower side face

[0185] 23 Flange section

[0186] 24 First bend

[0187] 25 Part 1

[0188] 26 Part 2

[0189] 31. Longitudinal wall section

[0190] 31a Reinforcing rib

[0191] 32 Side profile

[0192] 32A Upper side surface (upper surface)

[0193] 32B Lower side surface (lower surface)

[0194] 33 Flange section

[0195] 34 Second bend

[0196] 35 1st upper surface part

[0197] 36. Upper lateral tilt of the face (tilted face)

[0198] 37. Second upper surface (width direction)

[0199] 38 Lower Surface Part 1

[0200] 39. Lower tilted face (tilted face)

[0201] 40 Second lower surface (vehicle width direction)

Claims

1. A lower body structure for a vehicle, comprising: The outer and inner beams, extending in the front and rear directions of the vehicle respectively, work together to form a side beam with a closed cross section. A crossbeam that joins the inner side beam at a position relative to the front end of the side beam on the rear side of the vehicle, and extends inward from the side beam in the vehicle width direction; wherein, The inner beam has an upper surface portion and a lower surface portion that separates downward from the upper surface portion. Regarding the upper surface portion and the lower surface portion, at least in the region between the front end of the side beam and the cross beam in the vehicle longitudinal direction, the upper surface portion and the lower surface portion bend inward toward the side beam, and have: an inclined surface portion extending from the bent portion toward the outer beam and widening in the vertical direction toward the inner beam as it approaches the outer beam; and a vehicle width direction surface portion extending from the bent portion toward the vehicle interior in the vehicle width direction.

2. The lower body structure of the vehicle according to claim 1, characterized in that: The upper surface of the crossbeam is at the same height as the width-direction portion of the upper surface of the inner beam.

3. The lower body structure of the vehicle according to claim 1 or 2, characterized in that: The crossbeam has a first flange portion that engages with at least one of the upper surface portion and the lower surface portion of the inner beam in the vehicle width direction.

4. The lower body structure of the vehicle according to claim 1 or 2, characterized in that: The inner beam has a longitudinal wall portion that extends in the vertical direction from the inner end in the vehicle width direction and connects the upper surface portion and the lower surface portion. The crossbeam has a second flange portion that engages with the longitudinal wall portion of the inner beam.

5. The lower body structure of the vehicle according to claim 1 or 2, characterized in that: The inner beam has a longitudinal wall portion that extends in the vertical direction from the inner end in the vehicle width direction and connects the upper surface portion and the lower surface portion. The longitudinal wall portion has reinforcing ribs extending in the longitudinal direction of the vehicle.

6. The lower body structure of the vehicle according to claim 5, characterized in that: The reinforcing rib extends from the front end of the side beam to at least the rear end of the cross beam.

7. The lower body structure of the vehicle according to claim 1 or 2, characterized in that: The inner beam also includes a pair of upper and lower flanges located at the ends of the outer beam side of the upper and lower surface portions. The side beam also includes a connecting plate portion that connects the upper and lower paired flange portions of the inner side beam.

8. The lower body structure of the vehicle according to claim 7, characterized in that: The connecting plate portion is disposed in the side beam in the longitudinal direction of the vehicle to form the door opening portion of the vehicle body.

9. The lower body structure of the vehicle according to claim 8, characterized in that: The connecting plate portion has a structure in which the bending strength of the connecting plate portion is less than the bending strength of the outer beam and the inner beam.

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