Vehicle lower structure

Abstract

In this vehicle lower structure: a floor bulging portion (2) that bulges downward is formed in a floor panel (1) so as to straddle a central portion in the vehicle width direction; attachment brackets (5) for attaching suspension members are attached to the floor panel (1) at left and right positions of the floor bulging portion (2) in the vehicle width direction, so as to sandwich the floor bulging portion (2); the floor bulging portion (2) has a front wall portion (4) that extends in the vehicle width direction on the vehicle front side thereof; and a line segment that connects the positions, in the left and right attachment brackets (5) in the vehicle width direction, where the suspension members attach to the attachment brackets (5) overlaps at least a part of the front wall portion (4) when viewed from below the vehicle.

Description

Vehicle undercarriage

[0001] The present invention relates to a vehicle underbody structure, and more particularly to a vehicle underbody structure in which a suspension member is attached to the lower part of a vehicle body.

[0002] In the patent document 1, the rear end of the rear suspension member is attached to the rear side frame at the position of the rear cross member, i.e., the rear end of the rear suspension member is attached to the underside of the rear cross member.

[0003] Patent No. 6489035

[0004] For example, a floor bulge may be formed by bulging the rear floor panel downward to increase or secure the volume of a trunk or luggage compartment located in the rear of a vehicle. Because such a trunk or luggage compartment is located rearward of the rear wheels, in light of the example of Patent Document 1, the front portion of the floor bulge is located at or near the rear cross member. Therefore, the front wall of the floor bulge on the front side of the vehicle is restricted to be further rearward than the rear mounting position of the rear cross member, i.e., the rear suspension member, thereby restricting the volume of the floor bulge. In other words, a vehicle undercarriage structure is desired that can increase or secure the volume of the floor bulge by moving the front wall of the floor bulge closer to the mounting position of the suspension member. An object of the present invention is to provide a vehicle undercarriage structure that can increase or secure the volume of the floor bulge by moving the front wall of the floor bulge closer to the mounting position of the suspension member.

[0005] One aspect of the present invention is that a floor bulge that bulges downward is formed on a floor panel so as to straddle the center of the vehicle width direction, mounting brackets for attaching suspension members are attached to the floor panel at left and right positions in the vehicle width direction of the floor bulge so as to sandwich the floor bulge, the floor bulge has a front wall portion that extends in the vehicle width direction on the front side of the vehicle, and a line segment connecting the attachment positions of the suspension members to each mounting bracket on the left and right sides in the vehicle width direction overlaps with at least a portion of the front wall portion when viewed from below the vehicle.

[0006] According to one aspect of the present invention, the front wall of the floor bulge can be made closer to or coincide with the mounting position of the suspension member, thereby increasing or ensuring the volume of the floor bulge. The objects and advantages of the present invention are realized and attained by using the elements and combinations thereof set forth in the appended claims. It should be understood that both the foregoing general description and the following detailed description are merely exemplary and explanatory and are not intended to limit the invention as defined by the claims.

[0007] Fig. 2 is a perspective view showing a vehicle underbody structure of an embodiment. Fig. 3 is a bottom view of the vehicle underbody structure of Fig. 1. Fig. 4 is a schematic side cross-sectional view of the vehicle underbody structure of Fig. 1. Fig. 5 is a bottom view showing an example of a cross member.

[0008] The vehicle undercarriage structure of the embodiment shown in FIG. 1 is a perspective view of the underside of a floor panel at the rear of the vehicle, viewed diagonally from the front left to the rear right of the vehicle. The view shows the rear suspension member and the structure below it, i.e., the rear suspension and rear wheels, removed. Because the following description focuses on the rear of the vehicle, the term "rear" (rear or rear) may be omitted. In this embodiment, a rear floor panel 1 bulges downward to form a floor bulge 2 in the trunk or luggage compartment at the rear of the vehicle, specifically between rear side frames 3 rearward of the rear wheels. This floor bulge 2, for example, is provided to increase or secure the volume of the trunk or luggage compartment. It extends across the center of the floor panel 1 in the vehicle width direction to near both outer ends in the vehicle width direction, and as shown in FIG. 3 , it also extends to the rear end of the vehicle (vehicle body). This floor bulge 2 is formed by compressing the floor panel 1, which is made of a generally flat metal plate member, using press molding or the like. At its front end, a front wall 4 extending in the vehicle width direction is formed. As will be described later, the floor bulge 2 of this embodiment has a correspondingly increased rigidity in order to improve the quietness of the vehicle (interior).

[0009] The rear suspension member (not shown) of this embodiment is, for example, similar to that described in Patent Document 1, and has a structure in which suspension member side portions extending approximately in the longitudinal direction on the left and right sides of the vehicle width direction and suspension member cross portions extending approximately in the transverse direction of the vehicle at positions on the front and rear sides of the vehicle are combined in a lattice shape. In this rear suspension member, the suspension member side portions disposed on the left and right sides of the vehicle width direction are curved so that the longitudinal ends of the suspension member side portions protrude outward in the transverse direction of the vehicle, and the longitudinal ends of the suspension member side portions are attached to the vehicle body at the positions of side frames 3. In the example shown in FIG. 1 , the front end of the suspension member side portion of the rear suspension member is attached to a front attachment position 21 of the side frame 3. Meanwhile, a mounting bracket 5 is attached to the underside of a floor panel 1 at a position where the rear end of the suspension member side portion of the rear suspension member is attached.

[0010] The mounting brackets 5 are attached to the left and right sides (i.e., both sides) of the floor bulge 2 in the vehicle width direction at the vehicle front end of the floor bulge 2. The mounting brackets 5 are formed by pressing a metal plate member using a press or other method. The mounting brackets 5 are formed with a channel cross-section that is open at the upper end of the vehicle and extends substantially in the vehicle width direction. The outer end of the mounting bracket 5 in the vehicle width direction is formed into a cylindrical shape with a closed lower surface (bottom). The cylindrical portion at the outer end of the mounting bracket 5 in the vehicle width direction serves as the mounting portion 6 for the vehicle rear end of the rear suspension member. The mounting portion 6 is located below the side frame 3, and the vehicle rear end of the rear suspension member is attached by threading a fastener such as a bolt into a mounting hole 7 formed in the center of the lower surface of the mounting bracket 5. That is, the mounting hole 7 in the center of the mounting portion 6 is the mounting position (for the vehicle rear end) of the rear suspension member. As described above, the upper end of the mounting bracket 5 is connected to the floor panel 1 or the underside of the side frame 3 by welding or other methods. In addition, the inner end of the mounting bracket 5 in the vehicle width direction is formed as a flange portion 5a that extends outward from the channel cross-sectional shape, and this flange portion 5a is joined by welding or the like to the left and right sides of the floor bulge portion 2 in the vehicle width direction, i.e., both outer surfaces in the vehicle width direction.

[0011] FIG. 2 is a bottom view (underside view) of the floor bulge 2 and the mounting bracket 5. As mentioned above, the mounting hole 7 provided in the center of the mounting portion 6 of the mounting bracket 5 is the mounting position of the rear end of the rear suspension member. If a line (straight line) is drawn connecting the mounting positions of the left and right mounting brackets 5 in the vehicle width direction, the line at least partially overlaps with the front wall 4 of the floor bulge 2 in a vehicle bottom view. In this example, the line connecting the mounting positions of the rear suspension member almost coincides with the front wall 4 of the floor bulge 2. Forces acting between the wheels (rear wheels) and the road surface act on the mounting positions of the rear suspension member. Because the mounting positions of the rear suspension member on the left and right mounting brackets 5 in the vehicle width direction are the same in the vehicle front-rear direction, the component of the force acting on the mounting position that acts in the vehicle width direction (lateral direction) acts in the direction of the line connecting the mounting positions of the left and right rear suspension members in the vehicle width direction. In this case, since the line segment connecting the rear suspension member mounting positions of the mounting brackets 5 on the left and right sides of the vehicle width overlaps with the front wall portion 4 of the floor bulge portion 2 when viewed from the bottom of the vehicle, this front wall portion 4 functions as a rigid member against inputs in the vehicle width direction.

[0012] Figure 4 is a bottom view (underside view) showing an example of a cross member 51 disposed at a position where the rear end of a rear suspension member is attached. For example, in the case of this cross member 51, the vertical end in the figure is the mounting portion 56 to which the rear end of the rear suspension member is attached, and as in Figure 2, a mounting hole 577 provided in the center of this mounting portion 56 is the mounting position for the rear end of the rear suspension member. If the cross member 51 in Figure 4 is attached to the bottom view in Figure 2 so that the mounting position of the rear suspension member on this cross member 51 is superimposed on the mounting position of the rear suspension member in Figure 2, the cross member 51 will naturally interfere with the front portion of the floor bulge 2. 3 is a side cross-sectional view that shows a schematic view of the floor panel 1 and floor bulge 2. However, if the cross member 51 shown in FIG. 4 is placed in the mounting position of the rear suspension member, the front portion of the floor bulge 2, i.e., the front wall 4, must be retracted toward the rear of the vehicle, as shown by the two-dot chain line in the figure, to avoid interference with the cross member 51. Therefore, when the cross member 51 is used, the volume of the floor bulge 2 is reduced.

[0013] In the example shown in Figure 2, as indicated by the solid line in Figure 3, the front wall 4 of the floor bulge 2 can be maintained toward the front of the vehicle, thereby increasing or securing the volume of the floor bulge 2. Needless to say, the cross member is an important rigid component forming the vehicle body frame. As described above, in this vehicle, the rigidity of each vehicle body component, including the floor bulge 2, has been improved to achieve a quieter interior. The high rigidity of the floor bulge 2 allows the front wall 4 of the floor bulge 2 to be used as part of the vehicle's lateral rigidity component, instead of the cross member, to withstand lateral force acting from the rear suspension member mounting position. As a result, mounting brackets 5 can be individually positioned on the left and right sides of the floor bulge 2 in the vehicle width direction, thereby eliminating the need for a cross member and maintaining the front wall 4 of the floor bulge 2 toward the front of the vehicle, thereby increasing or securing the volume of the floor bulge 2.

[0014] Although the vehicle underbody structure according to the embodiment has been described above, the present invention is not limited to the configuration described in the above embodiment, and various modifications are possible within the scope of the present invention. For example, in the above embodiment, the floor panel 1 is bulged downward to form the floor bulge 2 in order to increase or ensure the volume of the trunk or luggage compartment provided in the rear of the vehicle. However, the vehicle underbody structure according to the present invention can, in principle, be applied to any vehicle configuration in which the floor bulge 2 is provided rearward of the suspension member mounting position.

[0015] As described above, in this embodiment, the floor bulge 2 that bulges downward is formed on the floor panel 1 so as to straddle the center of the vehicle in the vehicle width direction, mounting brackets 5 for attaching suspension members are attached to the floor panel 1 at left and right positions in the vehicle width direction of the floor bulge 2 so as to sandwich the floor bulge 2, the floor bulge 2 has a front wall 4 that extends in the vehicle width direction at the front of the vehicle, and a line segment connecting the attachment positions of the suspension members to the attachment brackets 5 on the left and right sides in the vehicle width direction overlaps at least a part of the front wall 4 when viewed from below the vehicle. This allows the front wall 4 of the floor bulge 2 to function as a rigid member against forces acting in the vehicle width direction, ensuring lateral rigidity of the suspension member and allowing the attachment position of the suspension member to be closer to or coincident with the attachment position, thereby increasing or ensuring the volume of the floor bulge 2.

[0016] Furthermore, by connecting the inner ends of the mounting brackets 5 on the left and right sides of the vehicle width to the floor bulge 2, the force acting in the vehicle width direction on the mounting position of the suspension member can be transmitted directly to the front wall 4 of the floor bulge 2, thereby further ensuring the lateral rigidity of the suspension member.

[0017] 1... floor panel, 2... floor bulge portion, 3... side frame, 4... front wall portion, 5... mounting bracket, 6... mounting portion, 7... mounting hole (mounting position)

Claims

A floor bulge portion that bulges downward is formed on the floor panel so as to straddle the center portion in the vehicle width direction, Mounting brackets for mounting suspension members are attached to the floor panel at left and right positions in the vehicle width direction of the floor bulge portion so as to sandwich the floor bulge portion, the floor bulge portion has a front wall portion extending in the vehicle width direction on the vehicle front side, A vehicle undercarriage structure characterized in that a line segment connecting the attachment positions of the suspension members to the left and right mounting brackets in the vehicle width direction overlaps with at least a portion of the front wall portion when viewed from below the vehicle.

2. The vehicle underbody structure according to claim 1, wherein inner ends of the left and right mounting brackets in the vehicle width direction are connected to the floor bulge portion.

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