JP2019093803A - Lower vehicle body structure - Google Patents

Abstract

To provide a lower vehicle body structure allowing for improvement of energy absorption thereof upon side impact.SOLUTION: A lower vehicle body structure comprises: a lower vehicle body constituting member 2 extending in a longitudinal vehicle direction; a rocker 3 arranged on the outside in a vehicle width direction, of the lower vehicle body constituting member 2; and a cross member 4 extending in the vehicle width direction and connecting the lower vehicle body constituting member 2 and the rocker 3 to each other. The cross member 4 comprises an outside member 10 and an inside member 20, and both members are welded and connected. The outside member 10 comprises a widening part 11 and a connection part 12. The inside member 20 comprises an extension part 21 contacting with an inclined plane of the widening part 11 and a body part 22 provided with an overlap space 23 overlapping with the connection part 12. A welding place of the outside member 10 and the inside member 20 comprises a first welding part 31 for welding the widening part 11 and the extension part 21 and a second welding part 32 for welding the connection part 12 and the overlap space 23.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an underbody structure of a vehicle body.

  Conventionally, a floor frame (front side member) extending along the longitudinal direction of the vehicle and a longitudinal side outside the floor frame in the longitudinal direction of the vehicle are provided as vehicle body lower portions of an automobile as disclosed in Patent Document 1 There is known a configuration in which rockers are connected by a connecting member (also referred to as "outrigger") extending in the vehicle width direction.

JP, 2016-52866, A

  In the conventional vehicle body lower structure, the side member and the rocker are connected by the connecting member (cross member) to transmit the collision load inputted to the vehicle body from the side member to the rocker via the cross member at the time of a frontal collision. It can be dispersed. On the other hand, at the time of a side collision, the strength of the vehicle body is secured by transmitting and dispersing the collision load from the rocker to the side member through the cross member. In addition, when a large load is input during a side collision or a load is locally input during a pole side collision, the cross member plastically deforms (collapses) in the vehicle width direction while a load is applied to the cross member. Energy absorption (EA) at the time of a collision.

  However, in the case of the conventional cross member, the cross member may be broken in the vehicle width direction and not buckled due to the cross member being bent halfway or the like at the time of side collision (including pole side collision, the same applies hereinafter). In this case, it is difficult for the cross member to effectively absorb the load at the time of a side collision, and it is difficult to control the EA at the time of a side collision with the conventional vehicle body lower structure. Therefore, from the viewpoint of improving the EA at the time of a side collision, the cross member is stably buckled in the vehicle width direction by the load at the side collision so that the load at the side collision can be effectively absorbed by the cross member. Is desired.

  One of the objects of the present invention is to provide an underbody structure capable of improving energy absorption at the time of a side collision.

  The present inventors have found that energy absorption at the time of a side collision can be improved by devising the configuration of the cross member that connects the vehicle body lower component (for example, side member etc.) extending in the vehicle longitudinal direction and the rocker. Specifically, the cross member is configured to include an outer member located at an outer end in the vehicle width direction and an inner member extending inward in the vehicle width direction from the outer member, and welding the both at a specific point By connecting them, the buckling of the cross member at the time of a side collision is controlled. Thus, the cross member can be stably buckled in the vehicle width direction by the load at the side collision, and the load at the side collision can be effectively absorbed by the cross member. The present invention has been made based on the above findings.

The lower vehicle body structure according to one aspect of the present invention is
A lower vehicle body component extending in the longitudinal direction of the vehicle;
A rocker disposed on the outer side in the vehicle width direction of the vehicle body lower component;
A vehicle body lower structure comprising a cross member extending in a vehicle width direction and connecting the vehicle body lower component and the rocker,
The cross member includes an outer member located at an outer end in the vehicle width direction, and an inner member welded and connected to the outer member and extending inward in the vehicle width direction from the outer member.
The outer member is widened in the vehicle front-rear direction toward the outer side in the vehicle width direction, and has a widened portion joined to the rocker, and a connecting portion projecting from the widened portion toward the inner member.
The inner member includes an overhang portion contacting the inclined surface of the widening portion, and a main body portion formed along the vehicle width direction from the overhang portion and provided with an overlapping margin overlapping the connection portion.
The welding portion between the outer member and the inner member has a first welded portion for welding the widened portion and the overhang portion, and a second welded portion for welding the connecting portion and the overlapping margin.

  In the vehicle body lower structure, the cross member includes the outer member and the inner member, the outer member and the inner member are welded and connected, and the wide portion of the outer member and the overhang of the inner member are welded (1) A welding portion and a second welding portion for welding the connecting portion of the outer member and the overlapping margin of the main body portion of the inner member. According to the vehicle body lower structure, when the load applied to the cross member at the time of the side collision becomes more than a certain degree, the second welded portion breaks and the connecting portion of the outer member and the overlapping margin of the inner member separate. The part is difficult to break, and the wide part of the outer member and the overhang of the inner member do not peel off. Therefore, in the process of applying a load to the cross member, the connecting portion of the outer member and the overlapping margin of the inner member separate, and the inner member (main portion) is easily crushed and buckled by the outer member in the vehicle width direction. At that time, the wide portion of the outer member and the projecting portion of the inner member are displaced synchronously without peeling, and the outer member presses the inner member along the vehicle width direction, thereby stabilizing the inner member. It is possible to make it buckle. Therefore, the vehicle body lower structure enables the cross member to be stably buckled in the vehicle width direction by the load at the side collision, and the load at the side collision can be effectively absorbed by the cross member. Energy absorption can be improved. Thereby, the deformation of the passenger compartment can be suppressed, and the impact on the occupant can be significantly suppressed.

  Furthermore, when the outer member has the widened portion, the load is likely to be received by the cross member when a load is locally input, such as at a pole side collision. Further, since the connection between the vehicle body lower structural member and the rocker by the cross member can be strengthened, and the twisting of the vehicle body generated at the time of turning of the vehicle can be effectively suppressed, the steering stability and the riding comfort can be improved.

FIG. 2 is a schematic view of the main part of the lower vehicle body structure according to Embodiment 1 as viewed obliquely from below the vehicle. FIG. 7 shows the main part of the lower vehicle body structure according to the first embodiment, wherein (A) is a schematic longitudinal sectional view cut along a plane orthogonal to the longitudinal direction of the vehicle, and (B) is taken along line B-B of (A) It is a schematic plan sectional view cut along. FIG. 2 is a schematic perspective view of a cross member provided in the lower vehicle body structure according to the first embodiment. FIG. 2 is a schematic exploded perspective view of a cross member provided in the lower vehicle body structure according to the first embodiment. FIG. 2 is a schematic view of a cross member provided in the vehicle body lower structure according to Embodiment 1 as viewed from the upper side. FIG. 2 is a schematic view of a cross member provided in the vehicle body lower structure according to Embodiment 1 as viewed from the front side.

  A vehicle body lower structure according to an embodiment of the present invention will be described with reference to the drawings. The same reference numerals in the drawings indicate the same names. In the following description, “front”, “rear”, “upper”, “lower”, “left”, and “right” mean that the front of the vehicle is “front” and a direction based on this is a reference. Do. In the figure, arrow FR indicates the front side in the longitudinal direction of the vehicle, arrow RR indicates the rear side, arrow UP indicates the upper side in the vertical direction of the vehicle, arrow LWR indicates the lower side, arrow IN indicates the inner side (center side) in the vehicle width direction, and arrow OUT indicates the outer side. Indicates

Embodiment 1
A lower vehicle body structure 1 according to a first embodiment will be described with reference to FIGS. 1 to 6. As shown in FIGS. 1 and 2, the vehicle body lower structure 1 extends in the longitudinal direction of the vehicle, the vehicle body lower component 2, the rocker 3 disposed outside the vehicle body lower component 2 in the vehicle width direction, and A cross member 4 is provided which extends and connects the vehicle body lower structural member 2 and the rocker 3. The cross member 4 shown in FIG. 1 is provided at an intermediate position in the front-rear direction of the vehicle body, and specifically attached near the lower part of the B-pillar (not shown). One of the features of the lower vehicle body structure 1 of the first embodiment resides in the configuration of the cross member 4, and the cross member 4 includes an outer member 10 and an inner member 20 having predetermined shapes, and the outer member 10 and the inner member 20 It is in the point where it is welded and connected at a predetermined place. The lower vehicle body structure 1 basically has a left-right symmetric structure. In FIGS. 1 and 2, only the right side portion of the lower vehicle body structure 1 is shown, and the left side portion is not shown. In FIGS. 1 and 2, the arrow OUT side corresponds to the right side of the vehicle.

(Vehicle lower component)
As shown in FIG. 1, the vehicle body lower component 2 is a member disposed so as to extend in the longitudinal direction of the vehicle, and in this example, is a side member. The lower vehicle body constituent members (side members) 2 are disposed symmetrically to the left and right, and are welded and joined to the lower surface of the floor panel 5 constituting the vehicle floor (see also the upper view in FIG. 2).

(Rocca)
As shown in FIG. 1, the rocker 3 is a member that extends in the longitudinal direction of the vehicle and is disposed outside the vehicle body lower component (side member) 2 in the vehicle width direction. The rockers 3 are provided on the left and right sides of the floor panel 5 (see also the upper drawing in FIG. 2). The Rocca 3 is typically composed of a Rockainna located on the inner side in the vehicle width direction and a Rocca outta located on the outer side in the vehicle width direction, and the Rockaina and the Rocca outta are welded and joined. In FIG. 1, 2, only the inner part (rocka) of the rocker 3 is shown in figure.

(Cross member)
As shown in FIG. 1, the cross member 4 is disposed to extend in the vehicle width direction, and is a member that connects the vehicle body lower component (side member) 2 and the rocker 3 and is also called an “outrigger”. The cross members 4 are respectively disposed between the left and right side members 2 and the left and right rockers 3 and are attached symmetrically. The end of the cross member 4 on the outer side in the vehicle width direction is welded and joined to the inner surface of the rocker 3, and the inner end of the cross member 4 on the vehicle width direction is welded to the outer side of the vehicle body lower component 2 It is joined (see also FIG. 2). The cross member 4 is substantially U-shaped in cross section perpendicular to the vehicle width direction, and the cross member 4 is disposed along the vehicle width direction such that the opening thereof is directed upward. The upper portion of the cross member 4 is welded and joined to the lower surface of the floor panel 5.

  As shown in FIGS. 1 and 2, the cross member 4 is welded to and coupled to the outer member 10 and the outer member 10 located at the outer end of the cross member 4 in the vehicle width direction. And an inner member 20 extending inward. Hereinafter, the outer member 10 and the inner member 20 which constitute the cross member 4 will be described in detail, mainly with reference to FIGS. 3 to 6.

(Outer member)
As shown in FIGS. 3 and 4, the outer member 10 includes a widening portion 11 which is widened in the vehicle longitudinal direction toward the outer side in the vehicle width direction, and a connecting portion 12 which protrudes from the widening portion 11 toward the inner member 20. Have. The widening section 11 is joined to the rocker 3 (see FIG. 1). In this example, as shown in FIG. 4, the outer side member 10 is formed in a substantially U-shaped cross section opening upward, and a pair of side walls 10 s positioned so as to face each other in the vehicle longitudinal direction, and both side walls A bottom wall 10b is provided to connect the lower ends of the 10s. The side walls 10s in the widening portion 11 are formed in an inclined surface that is inclined with respect to the vehicle width direction so that the distance between the side walls becomes wider toward the outer side in the vehicle width direction. In the connecting portion 12, the side wall 10s is formed along the vehicle width direction. The flange 15 joined to the rocker 3 is formed in the outer edge of 10 s of side walls.

(Inner member)
As shown in FIGS. 3 and 4, the inner member 20 is formed along the vehicle width direction from the overhanging portion 21 contacting the inclined surface (side wall 10s) of the widening portion 11 of the outer side member 10 and the overhanging portion 21 And a main body portion 22 provided with an overlapping margin 23 overlapping the connecting portion 12 of the outer member 10. In this example, as shown in FIG. 4, the inner member 20 is formed in a substantially U-shaped cross section in which the main body portion 22 opens upward, and a pair of side walls 20 s located in front and back so as to face each other in the vehicle longitudinal direction. And a bottom wall 20b connecting lower ends of both side walls 20s. The overhanging portion 21 is provided so as to project from the outer edge of the both side walls 20s of the main body portion 22 in the vehicle width longitudinal direction, and is inclined along the side wall 10s of the widening portion 11. The overlapping margin 23 is a portion provided on the bottom wall 20 b of the main body portion 22 and overlapping the bottom wall 10 b of the connecting portion 12. In addition, the end on the inner side in the vehicle width direction of the main body 22 is joined to the vehicle body lower component (side member) 2 (see FIG. 1), and the upper end of the main body 22 is on the floor panel 5 (see FIG. 1) It is joined. The flange 25 joined to the vehicle body lower component 2 and the floor panel 5 is formed in the inner edge and upper edge of the side wall 20s.

  Each of the outer member 10 and the inner member 20 is made of a metal plate material (specific example, steel plate), and is formed by pressing the plate material. The plate thicknesses of the respective plate members constituting the outer member 10 and the inner member 20 may be appropriately set so as to ensure the strength and the rigidity of the cross member 4 and are not particularly limited. In this example, the thickness of the outer member 10 is set to be thicker than the thickness of the inner member 20. For example, the plate thickness of the plate member constituting the outer member 10 is 2.0 mm or more and 3.0 mm or less, and the plate thickness of the plate member constituting the inner member 20 is 0.8 mm or more and 1.8 mm or less.

  In this example, as shown in FIGS. 3 and 4, the side wall 10 s of the wide portion 11 of the outer member 10 is in contact with the projecting portion 21 of the inner member 20, and the bottom wall 10 b of the connecting portion 12 is a stack of the main body 22. The outer member 10 is fitted from the lower side of the inner member 20 so as to overlap the lugs 23. That is, the connecting portion 12 of the outer member 10 is disposed outside the main body portion 22 of the inner member 20.

(Welding point)
The welding location of the outer member 10 and the inner member 20 in the cross member 4 is indicated by a mark X in FIG. 2, FIG. 5 and FIG. The welded portion between the outer member 10 and the inner member 20 is a first welded portion 31 (see FIGS. 5 and 6) for welding the widened portion 11 of the outer member 10 and the overhang portion 21 of the inner member 20; A second welding portion 32 (see FIG. 5) for welding the connecting portion 12 and the overlapping margin 23 of the main body portion 22 of the inner member 20 is provided. As shown in FIGS. 5 and 6, the first welding portion 31 is provided on the contact surface between the side wall 10s of the widening portion 11 and the overhanging portion 21. It is formed at intervals. As shown in FIG. 5, the second welding portion 32 is provided on the contact surface between the bottom wall 10 b of the connecting portion 12 and the overlap margin 23, and is formed at two points with respect to the contact surface. In this example, welds are welded by spot welding.

EA mechanism
The energy absorption (EA) mechanism at the time of a side collision by the lower vehicle body structure 1 will be described mainly with reference to FIG. The dashed-two dotted line in FIG. 2 has shown the state after a collision. At the time of a side collision, a load is input from the outside in the vehicle width direction, and a load directed inward in the vehicle width direction is applied to the cross member 4. At the beginning of the collision, the entire cross member 4 (the outer member 10 and the inner member 20) receives a load. After the middle stage of the collision, the load in the vehicle width direction applied to the cross member 4 causes the second welded portion 32 to break and the connecting portion 12 of the outer member 10 and the overlapping margin 23 of the inner member 20 to separate. The portion 31 is not broken, and the wide portion 11 of the outer member 10 and the overhang portion 21 of the inner member 20 do not peel off. This is because, when a load in the vehicle width direction is applied to the cross member 4, a load in the shear direction acts on the second welded portion 32, which causes spot welding spotting. On the other hand, the first welded portion 31 is provided on the contact surface between the wide portion 11 and the overhang portion 21 and the contact surface is an inclined surface inclined with respect to the vehicle width direction. The load in the shear direction acting on the first welded portion 31 becomes smaller, and is less likely to break compared to the second welded portion 32. That is, the first welded portion has higher welding strength to the load at the side collision than the second welded portion 32, and the first welded portion 31 is maintained without peeling after the middle stage of the collision.

  From the middle stage of the collision to the latter stage of the collision, the widening portion 11 of the outer member 10 and the overhanging portion 21 of the inner member 20 are displaced synchronously without peeling. At this time, the connecting portion 12 of the outer member 10 is guided by the main body portion 22 of the inner member 20, and the outer member 10 is displaced along the vehicle width direction, thereby pressing the inner member 20. As a result, while the inner member 20 (main body 22) is crushed and buckled by the outer member 10 in the vehicle width direction, EA is performed by absorbing the load at the time of the side collision.

  In the present embodiment, since the thickness of the outer member 10 is thicker than the thickness of the inner member 20, the outer member 10 is less susceptible to plastic deformation than the inner member 20, and the outer member 10 squeezes the inner member 20 to cause buckling. It is easy to do.

<Function effect>
The lower vehicle body structure 1 of the first embodiment described above has the following effects.
When the load applied to the cross member 4 at the time of the side collision becomes equal to or more than a certain degree, the second welded portion 32 breaks and the connecting portion 12 of the outer member 10 and the overlapping margin 23 of the inner member 20 separate. No breakage occurs, and the wide portion 11 of the outer member 10 and the overhang portion 21 of the inner member 20 do not peel off. Therefore, in the process of applying a load to the cross member 4, the connecting portion 12 of the outer member 10 and the overlapping margin 23 of the inner member 20 peel off, and the outer member 10 in the vehicle width direction It can be crushed and buckled. At that time, the widened portion 11 of the outer member 10 and the projecting portion 21 of the inner member 20 are displaced synchronously without peeling, and the outer member 10 presses the inner member 20 along the vehicle width direction. It is possible to stabilize the inner member 20 in a stable manner. Therefore, the vehicle body lower portion structure 1 can effectively absorb the load at the time of the side collision by the cross member 4, so that the EA at the time of the side collision can be improved. Therefore, the deformation of the passenger compartment can be suppressed, and the impact on the occupant can be greatly suppressed.

  Furthermore, when the outer member 10 has the widening portion 11, the load is easily received by the cross member 4 when a load is locally input, such as at a pole side collision. Further, by having the widening portion 11, the connection between the vehicle body lower structural member 2 and the rocker 3 by the cross member 4 can be strengthened, and the twisting of the vehicle body generated at the time of turning of the vehicle can be effectively suppressed. The comfort can be improved. In particular, in the present embodiment, the plate thickness of the outer member 10 is thicker than the plate thickness of the inner member 20, and the connecting portion 12 of the outer member 10 is disposed outside the main body portion 22 of the inner member 20. As a result, it is possible to more effectively suppress the deflection of the vehicle body at the time of turning of the vehicle.

  The present invention is not limited to these exemplifications, is shown by the claims, and is intended to include all modifications within the scope and meaning equivalent to the claims.

  For example, in the first embodiment described above, the connection portion 12 of the outer member 10 is disposed outside the main body portion 22 of the inner member 20. However, the connection portion 12 of the outer member 10 is the main body portion of the inner member 20 It is good also as composition arranged inside 22. In the first embodiment, the vehicle body lower structural member 2 is the side member, and the cross member 4 is used to connect the side member and the rocker 3. However, the present invention is not limited to this. The lower vehicle body component 2 may be, for example, a tunnel (not shown) provided at the center of the floor panel 5 in the vehicle width direction, and the cross member 4 is used to connect the floor tunnel and the rocker 3. It is also good.

1 Body lower structure 2 Body lower component (side member)
3 Rocker 4 Cross member 5 Floor panel 10 Outer member 10s Side wall 10b Bottom wall 11 Widening portion 12 Connecting portion 15 Flange 20 Inner member 20s Side wall 20b Bottom wall 21 Overhang 22 Main portion 23 Overlap margin 25 Flange 31 1st weld portion 32 Second weld

Claims (1)

A lower vehicle body component extending in the longitudinal direction of the vehicle;
A rocker disposed on the outer side in the vehicle width direction of the vehicle body lower component;
A vehicle body lower structure comprising a cross member extending in a vehicle width direction and connecting the vehicle body lower component and the rocker,
The cross member includes an outer member located at an outer end in the vehicle width direction, and an inner member welded and connected to the outer member and extending inward in the vehicle width direction from the outer member.
The outer member is widened in the vehicle front-rear direction toward the outer side in the vehicle width direction, and has a widened portion joined to the rocker, and a connecting portion projecting from the widened portion toward the inner member.
The inner member includes an overhang portion contacting the inclined surface of the widening portion, and a main body portion formed along the vehicle width direction from the overhang portion and provided with an overlapping margin overlapping the connection portion.
A vehicle body having a first welding portion for welding the widening portion and the projecting portion, and a second welding portion for welding the connecting portion and the overlapping margin, at a welding portion between the outer member and the inner member. Substructure.

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