JP5239792B2 - Lower body structure - Google Patents

Description

  The present invention relates to a vehicle body lower structure provided with a cross member extending in a vehicle width direction.

  2. Description of the Related Art Conventionally, there is known a vehicle body lower structure in which a bottom wall of a cross member provided between a floor side member and a tunnel under reinforcement is formed in an arch shape so as to protrude upward on the lower surface of a front floor panel.

In this vehicle body lower structure, when a collision load is input to the cross member from the side of the vehicle body, the cross member is deformed so as to protrude upward from the vehicle body, thereby protecting the parts housed in the lower portion of the cross member. It is carried out.
JP 2007-125974 A

  However, in the conventional lower body structure described above, the upper surface of the cross member may be a flat surface, and when the input load from the side of the vehicle body acts above the upper surface of the cross member, it is the above flat surface. There is a risk that the upper surface of the cross member will buckle and deform greatly.

  Therefore, an object of the present invention is to suppress the deformation of the cross member with respect to the load input from the side of the vehicle body.

In the present invention, the upper surface and the lower surface of the cross member extending in the vehicle width direction are curved so as to protrude upward of the vehicle body, and the vehicle width direction end portion of the lower surface of the cross member is connected to the side member of the vehicle body , The upper surface of the cross member and the side member of the vehicle body are separated from each other, and the upper surface of the cross member and the side member of the vehicle body are connected by a connecting member having a strength lower than that of the cross member .
Further, according to the present invention, the upper surface and the lower surface of the cross member extending in the vehicle width direction are curved so as to protrude upward from the vehicle body, and the vehicle width direction end portion of the lower surface of the cross member is connected to the side member of the vehicle body. In addition, a load receiving member that protrudes outward from the side member than the side member is provided on the side of the vehicle body above the upper surface of the cross member.

According to the present invention, when a load is input from the side of the vehicle body above the upper surface of the cross member, the upper surface of the cross member that protrudes upward from the vehicle body receives a force that further protrudes above the vehicle body. On the other hand, the lower surface of the cross member is pulled by the side member of the vehicle body and receives a downward force so as to be in a horizontal state from a state of being convex upward of the vehicle body. The upward force received by the upper surface of the cross member cancels out, and deformation of the cross member can be suppressed.
Further, according to the present invention, the upper surface of the cross member and the side member of the vehicle body are connected by the connecting member having lower strength than the cross member. For this reason, it is possible to ensure the rigidity of the vehicle body against vibration input when the vehicle is running, while allowing deformation of the side member of the vehicle body toward the passenger compartment by breaking the connecting member.
Further, according to the present invention, even if the collision object is long in the vertical direction of the vehicle body and the lower part is in a position corresponding to the cross member, the collision object is in the vertical direction of the vehicle body and in the position corresponding to the load receiving member. The impact load due to is received by the load receiving member before the cross member and is transmitted to the cross member via the load receiving member, so that the effect of suppressing deformation of the cross member can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of a vehicle body lower part structure showing an embodiment of the present invention, and FIG. 2 is a plan view of the same, and both show a vehicle body half in a vehicle width direction indicated by an arrow A in the drawing. In this lower body structure, a cross member 3 extending in the vehicle width direction is provided on a floor panel 1. The cross member 3 includes a side wall 5a as a side member of the vehicle body in a side sill extending in the vehicle longitudinal direction indicated by an arrow B in the figure, and a floor tunnel extending in the vehicle longitudinal direction at the center in the vehicle width direction. It arrange | positions between the parts 7.

  The cross member 3 described above has a substantially hat-shaped cross section having an upper surface 3a, front and rear surfaces 3b and 3c, and flanges 3d and 3e continuous to lower ends of the front and rear surfaces 3b and 3c, respectively. By joining these flanges 3 d and 3 e on the floor panel 1, the cross member 3 forms a closed cross section with the floor panel 1. That is, the lower surface of the cross member 3 includes a part 1a (see FIG. 4) of the floor panel 1.

  As shown in FIG. 3 which is a view taken in the direction of arrow C in FIG. 2, the cross member 3 is curved so as to be convex upward in the vehicle body. That is, the cross member 3 is formed such that the upper surface 3a is curved so as to be convex upward of the vehicle body, and the flanges 3d and 3e that form part of the lower surface and the floor panel 1 that forms the other part of the lower surface. Also, a part 1a is curved between the sill inner 5 and the floor tunnel portion 7 so as to protrude upward from the vehicle body.

  Note that this curved shape protrudes upward so that the substantially central portion in the vehicle width direction between the sill inner 5 and the floor tunnel portion 7 is the most upper position of the vehicle body. Further, the bottom wall part 5b of the sill inner 5 corresponding to the cross member 3 is also connected to the curved shape of the part 1a of the floor panel 1, and the bottom wall at a position displaced from the cross member 3 in the vehicle longitudinal direction. It protrudes upward with respect to 5c. Therefore, the flanges 5d and 5e of the cross member 3 are also joined to the part 5b of the bottom wall at a position protruding upward.

  Further, the end surface 3f on the outer side in the vehicle width direction of the cross member 3 is spaced apart from the side wall 5a of the sill inner 5 by forming a gap 9 as shown in FIG. It is joined inside the corner. That is, the vehicle width direction end of the lower surface (flanges 3d, 3e) of the cross member 3 is connected to the sill inner 5 which is a side member of the vehicle body.

  Here, the gap 9 between the end surface 3f on the outer side in the vehicle width direction of the cross member 3 and the side wall 5a of the sill inner 5 is widest on the upper surface 3a side of the cross member 3 and on the lower end corner 3g side as shown in FIG. The end flange 3 h formed at the end of the upper surface 3 a of the cross member 3 and the side wall 5 a of the sill inner 5 are connected to each other by a bracket 11. The bracket 11 is a connecting member that is lower in strength than the cross member 3 and that can ensure vehicle body rigidity against vibration input during traveling of the vehicle.

  On the other hand, the end surface 3 i on the inner side in the vehicle width direction of the cross member 3 is connected to the side wall 7 a of the floor tunnel portion 7.

  Further, a bulkhead 13 as a load receiving member located near the upper side of the vehicle body than the bracket 11 is attached to the outside of the vehicle body on the side wall 5a of the sill inner 5. The bulkhead 13 includes an outer surface 13a, upper and lower surfaces 13b and 13c, and flanges 13d and 13e continuous to the upper and lower surfaces 13b and 13c, respectively, and these flanges 13d and 13e are joined to the side wall 5a of the sill inner 5. In the state, it extends in the longitudinal direction of the vehicle body.

  In addition, what is shown with the code | symbol 15 in a figure is the seat bracket fixed on the floor panel 1. FIG.

  Next, the operation will be described. First, as shown in FIG. 5, it is assumed that a collision object 17 from the side of the vehicle collides with a center pillar 19 above the vehicle body with respect to the upper surface 3 a of the cross member 3. In this case, when the collision object 17 collides with the center pillar 19 from the state of FIG. 5A and the load F is input as shown in FIG. 5B, the center pillar 19 is pushed into the vehicle compartment 21. To deform.

  At this time, since the lower end of the center pillar 19 is connected to the upper end of the side wall 5a of the sill inner 5 and the bracket 11 is a weak member, the side wall 5a of the sill inner 5 pushes the bracket 11 against the cross member 3. While being crushed and broken, it is pulled by the center pillar 19 and bent toward the passenger compartment 21 side. When the sill inner 5 is bent and deformed, the sill inner 5 is deformed so as to rotate about the lower end corner 3g of the end surface 3f which is a connecting portion to the sill inner 5 on the lower surface of the cross member 3.

  As a result of this bending deformation, the side wall 5a of the sill inner 5 transmits a load to the cross member 3 so as to press the end face 3f of the cross member 3. Here, since the upper surface 3a of the cross member 3 is curved so as to protrude upward, the axial force F1 in the vehicle width direction exerted on the cross member 3 when the collision load F is input as described above. Thus, a force is applied in the direction of deformation so that the convex shape of the upper surface 3a becomes further convex.

  On the other hand, when the side wall 5a of the sill inner 5 transmits a load to the cross member 3 as described above, the cross 1 is applied to the part 1a of the floor panel 1 and the flanges 3d and 3e constituting the lower surface of the cross member 3. A moment is generated that rotates the outer end of the member 3 in the vehicle width direction as indicated by an arrow F2. As a result, the lower surface of the cross member 3 that is curved so as to be convex toward the upper side of the vehicle body receives a downward force that extends the curved state.

  As a result, the force received in the direction in which the upper surface 3a of the cross member 3 protrudes upward in the vehicle body and the force received in the downward direction of the vehicle body in the direction in which the lower surface of the cross member 3 extends are within the cross member 3. Will cancel each other out. That is, the axial force F1 and moment F2 applied to the cross member 3 work in opposite directions in the cross member 3 and balance each other. As a result, deformation of the cross member 3 can be suppressed, and the vehicle The deformation suppressing effect of the chamber 21 can be obtained.

  Here, in the present embodiment, since the end surface 3f of the cross member 3 and the side wall 5a of the sill inner 5 are spaced apart from each other by forming a gap 9, the deformation movement of the sill inner 5 toward the passenger compartment 21 is prevented. It becomes easy, the force for extending the lower surface of the cross member 3 can be further increased, and the deformation of the cross member 3 can be more reliably suppressed.

  At this time, in the present embodiment, the end (end surface 3f) of the upper surface 3a of the cross member 3 on the outer side in the vehicle width direction and the side wall 5a of the sill inner 5 are lower in strength than the cross member 3 and can secure vehicle body rigidity. The brackets 11 are connected. For this reason, the deformation of the sill inner 5 toward the passenger compartment 21 is allowed by the destruction of the bracket 11, and the rigidity of the vehicle body against vibration input during traveling of the vehicle can be ensured.

  In the present embodiment, the end surface 3 i, which is the inner end in the vehicle width direction of the cross member 3, is connected to the side wall 7 a of the floor tunnel portion 7. For this reason, as described above, when the cross member 3 receives a load input from the side of the vehicle body, the floor tunnel portion 7 receives the input load so that the deformation of the cross member 3 is suppressed. You can definitely get it.

  In the present embodiment, the lower surface of the cross member 3 includes the part 1a of the floor panel 1 and shares the part 1a. Therefore, the weight of the vehicle body can be reduced and the part 1a of the floor panel 1 can be crossed compared to the case where the cross member 3 itself is provided with a lower surface in addition to the part 1a of the floor panel 1 to have a closed cross section. By forming the curve in accordance with the upper surface 3a of the member 3, the rigidity of the floor panel 1 can be increased.

  The seat bracket 15 provided on the floor panel 1 has a position that does not hinder the deformation movement of the sill inner 5 toward the passenger compartment 21, in other words, the force received by the upper surface 3a of the cross member 3, and the cross member 3 is set to a position that does not hinder the balance with the force received by the lower surface of 3.

  Next, as shown in FIG. 6, a case is assumed in which a long colliding object 23 collides in the vertical direction of the vehicle body from the side of the vehicle. In FIG. 6, the center pillar 19 shown in FIG. 5 is omitted. In this case, the collision object 23 first interferes with the bulkhead 13 as shown in FIG. 6B and the collision load F acts from the state of FIG. It is deformed so that it is pushed into. At this time, as in the case of FIG. 5, since the bracket 11 is a fragile member, the side wall 5 a of the sill inner 5 is destroyed by crushing the bracket 11 with the cross member 3, while Bends and deforms.

  Thereby, the side wall 5a of the sill inner 5 transmits the load to the cross member 3 so as to press the end face 3f of the cross member 3, so that the axial force F1 and the moment F2 with respect to the cross member 3 are the same as in the case of FIG. In the cross member 3, they work in opposite directions and balance each other, so that the deformation of the cross member 3 can be suppressed.

  As in the collision object 23 shown in FIG. 6 above, even if the vehicle body is long in the vertical direction and the lower portion is in a position corresponding to the cross member 3, the upper side is in the vertical direction of the vehicle body and in a position corresponding to the bulkhead 13. The collision load F caused by the collision object 23 is received by the bulkhead 13 prior to the cross member 3 and is transmitted to the cross member 3 via the bulkhead 13, so that an effect of suppressing deformation of the cross member 3 can be obtained.

1 is a perspective view of a lower body structure showing an embodiment of the present invention. It is a top view of the vehicle body lower part structure of FIG. It is C arrow line view of FIG. It is a perspective view of the state fractured | ruptured by the DD line | wire of FIG. FIG. 2 is an operation explanatory diagram illustrating a case where a collision object collides with a center pillar in the vehicle body lower structure in FIG. 1. FIG. 3 is an operation explanatory view showing a case where a collision object that is long in the vertical direction collides with a vehicle body side portion in the vehicle body lower structure in FIG.

Explanation of symbols

1 Floor panel 1a Part of the floor panel (underside of the cross member)
3 Cross member 3a Cross member upper surface 3d, 3e Cross member flange (lower surface of cross member)
5 Sill Inner (Car body side member)
7 Floor tunnel part 7a Side wall of floor tunnel part 11 Bracket (connection member) for connecting the cross member and the sill inner
13 Bulkhead (Load receiving member)

Claims (5)

The upper and lower surfaces of the cross member extending in the vehicle width direction while forming a closed cross-section are curved so as to protrude upward in the vehicle body, and the vehicle width direction end of the lower surface of the cross member is used as a side member of the vehicle body. Connecting , separating the upper surface of the cross member and the side member of the vehicle body, and connecting the upper surface of the cross member and the side member of the vehicle body with a connection member having lower strength than the cross member. The car body lower structure that is characteristic. The upper and lower surfaces of the cross member extending in the vehicle width direction while forming a closed cross-section are curved so as to protrude upward in the vehicle body, and the vehicle width direction end of the lower surface of the cross member is used as a side member of the vehicle body. linked, wherein a vehicle body side portion of the vehicle body upper position than the upper surface of the cross member, the car body substructure you characterized in that a load receiving member which protrudes outside the vehicle body than the side member. The vehicle body lower part structure according to claim 1 or 2 , wherein an end portion of the upper surface of the cross member in the vehicle width direction is made weaker than an end portion of the lower surface of the cross member in the vehicle width direction. According to any one of claims 1 to 3, characterized in that coupled to the side wall of the floor tunnel portion extending the end of the inboard in the vehicle longitudinal direction at the vehicle width center of the cross member Lower body structure. The vehicle body lower part structure according to any one of claims 1 to 4 , wherein the lower surface of the cross member includes a part of a floor panel.

Images