JP2019034691A - Lower part vehicle body structure of motor vehicle - Google Patents

Abstract

To secure rigidity of a frame member against a load applied from a rear wheel.SOLUTION: In a lower part vehicle body structure of a motor vehicle, at a vehicle fore and aft position which corresponds to a front side end part of a trailing arm 21 in a frame member (a support frame 100), a gusset 60 is provided having: a gusset front side wall part 61 joined to an outer side wall part (a support frame outer side wall part 103) as seen in a vehicle width direction and a lower wall part (a support frame lower wall part 102) of the frame member; a gusset rear side wall part 62 which is provided spaced apart from the gusset front side wall part 61 to the vehicle rear side and joined to the outer side wall part as seen in the vehicle width direction and the lower wall part of the frame member; and a gusset side wall part 63 connecting an inner end part of the gusset front side wall part 61 as seen in the vehicle width direction and an inner end part of the gusset rear side wall part 62 as seen in the vehicle width direction.SELECTED DRAWING: Figure 3

Description

  The present invention belongs to a technical field related to a lower body structure of an automobile.

  2. Description of the Related Art Conventionally, there has been known an automobile lower body structure (for example, Patent Document 1) in which a front end of a trailing arm of a rear wheel suspension is supported by a frame member having a rectangular closed cross section.

  In Patent Document 1, an opening is provided in a lower wall portion of a rear side frame (frame member), and a front end of a trailing arm extends into the rear side frame through the opening, An automobile lower body structure that is attached to and supported by an attachment bracket provided on the vehicle is disclosed.

  Patent Document 2 discloses a lower body structure of an automobile in which a node member that divides the rear side frame forward and backward is provided in the rear side frame (frame member) in order to increase the rigidity of the rear side frame. Yes.

JP 2010-1332026 A JP 2009-202620 A

  By the way, some rear wheel suspensions are supported by the vehicle body mainly at the front end portion of the trailing arm, such as a torsion beam suspension. Thus, in the rear wheel suspension of the type mainly supported by the vehicle body at the front end portion of the trailing arm, the front end portion of the trailing arm is formed relatively large. For this reason, if the front end of the trailing arm of the rear wheel suspension as described above is to be inserted into the frame member as in the lower body structure of an automobile disclosed in Patent Document 1, it is necessary to increase the width of the frame member. There is.

  However, if the width of the frame member is widened, the weight of the automobile increases and the passenger compartment becomes narrow. Therefore, in the rear wheel suspension as described above, the trailing is provided below the lower wall portion of the frame member. A configuration in which a front end portion of an arm is supported by a frame member is common.

  At this time, there is a demand for the front end of the trailing arm to be positioned as high as possible in order to smooth the vertical movement of the rear wheel supported by the trailing arm and improve running stability. . For this purpose, it is necessary to position the frame member as high as possible at the position where the front end of the trailing arm is located.

  On the other hand, there is also a demand for lowering the position of the floor panel as much as possible in order to make the vehicle interior space as wide as possible. Usually, the floor panel is joined to the upper end of a frame member such as a rear side frame. Therefore, in order to lower the position of the floor panel to the lower side, it is necessary to provide the frame member as low as possible.

  In order to satisfy these two requirements, it is conceivable to reduce the vertical width of the frame member. On the other hand, the portion corresponding to the position of the front end portion of the trailing arm in the frame member receives the load from the rear wheel via the trailing arm, so it is necessary to ensure rigidity against the load. The portion of the member needs to have as large a cross-sectional area as possible. Therefore, a trailing arm in the side wall portion on the inner side in the vehicle width direction among the side wall portions on both sides in the vehicle width direction of the frame member as a configuration in which the cross-sectional area of the portion in the frame member is made as large as possible while satisfying the above two requirements. It is conceivable to reduce the width in the vertical direction of only the portion corresponding to the position of the front end portion. Thereby, the cross-sectional area of the said part in a frame member can be enlarged as much as possible, satisfy | filling the said 2 requirements.

  On the other hand, in order to ensure the rigidity against the load from the rear wheel, it is necessary not only to increase the cross-sectional area but also to make it difficult to deform the cross-sectional shape. When the vertical width of the side wall portion inside the vehicle width direction of the frame member is reduced, the deformation amount itself is relatively small for the side wall portion inside the vehicle width direction, but the width in the vertical direction is relatively large. The side wall portion on the outer side in the vehicle width direction of the frame member remains easily deformed by the load.

  Although it is conceivable to provide a node member at a portion corresponding to the position of the front side end portion of the trailing arm in the frame member as in Patent Document 2, the portion in the frame member is connected to the side wall portion on the inner side in the vehicle width direction. Since the width in the vertical direction is greatly different from the side wall portion on the outer side in the vehicle width direction, it is difficult to provide the node member. For this reason, there is room for improvement in order to improve the running stability and form a wide vehicle interior space and to ensure the rigidity of the frame member against the load from the rear wheel.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a lower part of an automobile including a rear wheel suspension supported by the frame member below the lower wall portion of the frame member. In the vehicle body structure, the rigidity of the frame member with respect to the load from the rear wheel is ensured.

  In order to solve the above problems, the present invention is directed to a lower body structure of an automobile, and includes a pair of left and right frame members extending in the vehicle front-rear direction and having a rectangular closed cross section, and a vehicle body front-rear direction extending left and right rearward. A rear wheel suspension having a pair of left and right trailing arms that respectively support the wheels, and the front end of each trailing arm of the rear wheel suspension is below the frame member on each of the left and right sides of the vehicle. A gusset that is supported by the frame member at a position below the wall portion, and is provided in each of the frame members at a vehicle front-rear position corresponding to the front end portion of the trailing arm, The gusset front side wall portion joined to the side wall portion and the lower wall portion on the outer side in the vehicle width direction of the frame member, and the gusset front side wall portion A gusset rear side wall provided separately from the rear side of the vehicle and joined to the side wall and the lower wall of the frame member in the vehicle width direction; an end of the gusset front side wall in the vehicle width direction; The gusset further includes a gusset having a gusset side wall connecting the end of the gusset rear side wall in the vehicle width direction.

  According to this configuration, since the front end of the trailing arm includes the rear wheel suspension supported by the frame member below the lower wall portion of the frame member, the running stability is improved and the vehicle interior is wide. In order to form the space, the width in the vertical direction of the portion corresponding to the position of the front end of the trailing arm in the side wall portion on the inner side in the vehicle width direction of the frame member is It is made smaller with respect to the vertical width. For this reason, in order to ensure the rigidity of the frame member against the load from the rear wheel, the position of the front end of the trailing arm on the side wall portion on the outer side in the vehicle width direction of the frame member that is relatively large in the vertical direction. It is necessary to suppress the deformation of the part corresponding to.

  Therefore, at the position corresponding to the front end of the trailing arm in the frame member, the gusset front side wall portion joined to the side wall portion and the lower wall portion on the outer side in the vehicle width direction of the frame member, and the gusset front side wall portion A gusset rear side wall portion that is spaced apart from the rear side of the vehicle and is joined to the outer side wall portion and the lower wall portion of the frame member, and the inner side in the vehicle width direction of the gusset front side wall portion and the gusset rear side wall portion A gusset having a gusset side wall connecting the ends of the gusset is provided. By providing such a gusset, a closed cross section is constituted by the side wall portion and the lower wall portion on the outer side in the vehicle width direction of the frame member, and the gusset. Thereby, even if the load from the rear wheel is transmitted to the frame member via the trailing arm, the gusset can suppress the deformation of the frame member. As a result, it is possible to improve the running stability and form a wide vehicle interior space, and to ensure the rigidity of the frame member against the load from the rear wheel.

  In one embodiment of the lower body structure of the automobile, the rear wheel suspension is a torsion beam suspension further including a torsion beam extending in the vehicle width direction and connecting the pair of left and right trailing arms.

  That is, since the support of the torsion beam suspension to the vehicle body is mainly secured at the front end portion of the trailing arm, the front end portion of the trailing arm is formed relatively large in the torsion beam suspension. Therefore, the front end portion of the trailing arm in the torsion beam suspension is below the lower wall portion of the frame member, and the front end portion of the trailing arm is supported by the frame member. Therefore, when the rear wheel suspension is a torsion beam suspension, by providing a gusset at the front and rear positions of the vehicle corresponding to the front end of the trailing arm in each frame member, the running stability can be made as high as possible. The effect of forming a wide vehicle interior space and ensuring the rigidity of the frame member with respect to the load from the rear wheel is more appropriately exhibited.

  In the lower vehicle body structure of the automobile, corners between the gusset front side wall and the gusset side wall and corners between the gusset rear side wall and the gusset side wall face inward in the vehicle width direction. It is preferable that the protrusion part which protrudes is formed, respectively.

  With this configuration, the protruding portion plays a role like a bead, and the gusset itself is hardly deformed. Thereby, since the rigidity of gusset itself improves, the rigidity of the frame member with respect to the load from a rear wheel can be improved.

  In the lower body structure of the automobile, the gusset front side wall portion and the gusset rear side wall portion have a substantially right triangle shape when viewed from the vehicle front-rear direction, and the gusset front side wall portion and the gusset rear side wall portion are substantially right triangle shapes. Of the three sides are joined to the side wall portion and the lower wall portion on the outer side in the vehicle width direction of the frame member, respectively, and the remaining oblique sides of the three sides are connected by the gusset side wall portion. The upper end portion of the gusset side wall portion is joined to the outer side wall portion of the frame member, and the lower end portion of the gusset side wall portion is joined to the lower wall portion of the frame member. It is preferable.

  According to this configuration, the gusset side wall is also joined to the outer side wall and the lower wall of the frame member in the same manner as the front gusset side wall and the rear gusset side wall, so that the deformation of the gusset itself is more effective. Can be suppressed. Thereby, the deformation of the side wall portion on the outer side in the vehicle width direction of the frame member is effectively suppressed, and the deformation of the frame member is effectively suppressed. As a result, the rigidity of the frame member with respect to the load from the rear wheel can be further improved.

  In the lower body structure of the automobile, the frame member extends along the side wall portion and the lower wall portion on the inner side in the vehicle width direction, and is joined to the side wall portion and the lower wall portion on the inner side in the vehicle width direction, respectively. It is preferable to further include a reinforcing member.

  According to this configuration, since the deformation of the side wall portion on the inner side in the vehicle width direction of the frame member is suppressed by the reinforcing member when the load from the rear wheel is applied, the deformation of the frame member is more effectively suppressed. . As a result, the rigidity of the frame member with respect to the load from the rear wheel can be further improved.

  In the lower body structure of the automobile, a support bracket for supporting the front end of the trailing arm is joined to the lower surface of the lower wall portion of each frame member. Three joint portions of the support bracket with the lower wall portion of the frame member, the lower wall portion of the frame member, and the joint portion of the gusset with the lower wall portion of the frame member are joined. Is preferred.

  According to this configuration, since the deformation of the frame member is further effectively suppressed, the rigidity of the frame member with respect to the load from the rear wheel can be further improved.

In the lower vehicle body structure of the automobile provided with the reinforcing member, a lower surface of the lower wall portion of each frame member is supported to support the front end portion of the trailing arm with respect to the frame member. A bracket is joined, and a joined portion of the support bracket with the lower wall portion of the frame member, a lower wall portion of the frame member, and a joined portion of the gusset with the lower wall portion of the frame member, Three pieces are joined, and a joining portion of the support bracket to the lower wall portion of the frame member, a lower wall portion of the frame member, and a joining portion of the reinforcing member to the lower wall portion of the frame member are It is preferable that three sheets are joined.
According to this configuration, since there are two portions to be joined to each other, the deformation of the frame member is further effectively suppressed, so that the rigidity of the frame member against the load from the rear wheel can be further improved. it can.

  As described above, according to the lower body structure of an automobile according to the present invention, the gussets are respectively provided at the vehicle front and rear positions corresponding to the front end of the trailing arm in the frame member, A gusset front side wall portion joined to the outer side wall portion and the lower wall portion, and a side wall portion and a lower wall portion which are provided on the vehicle rear side of the frame member so as to be spaced apart from the front side wall portion of the gusset. A gusset rear side wall portion joined to the gusset, and a gusset side wall portion for connecting the inner side ends of the gusset front side wall portion and the gusset rear side wall portion in the vehicle width direction. In the lower body structure of an automobile, which includes a rear wheel suspension supported by the frame member on the lower side, improves running stability and forms a wide interior space Therefore, the vertical width of the portion corresponding to the position of the front end of the trailing arm in the side wall portion on the inner side in the vehicle width direction of the frame member is equal to the vertical direction of the side wall portion on the outer side in the vehicle width direction of the frame member. Even if the width is reduced, the deformation of the side wall of the frame member on the outer side in the vehicle width direction when a load is applied from the rear wheel can be suppressed, and the rigidity of the frame member against the load from the rear wheel is ensured. can do.

It is the perspective view seen from the vehicle right side and the upper side which shows the rear part of the motor vehicle which applied the lower vehicle body structure which concerns on embodiment of this invention. It is the top view which looked at the vehicle left side of the rear part of the said motor vehicle from the upper side. It is the left side view which looked at the vehicle left side of the rear part of the said motor vehicle from the left side. It is the bottom view which looked at the vehicle left side of the rear part of the above-mentioned car from the lower side. It is sectional drawing equivalent to the VV line in FIG. It is sectional drawing equivalent to the VI-VI line in FIG. It is sectional drawing equivalent to the VII-VII line in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the front, rear, left, right, top and bottom of the automobile 1 are simply referred to as front, back, left, right, top and bottom, respectively.

  FIG. 1 schematically shows a rear portion of an automobile 1 to which a lower vehicle body structure according to an embodiment is applied. The rear part of the automobile 1 is a pair of left and right rear side frames 10 extending in the front-rear direction, and a front part 10a of the rear side frame 10 (a part ahead of a rear end of a kick-up part 10c described later, see FIG. 3). A pair of left and right side sills 3 joined to a side wall portion on the outer side in the vehicle width direction (hereinafter referred to as a frame outer side wall portion 11) and extending in the front-rear direction, and a side wall portion on the inner side in the vehicle width direction of the rear side frame 10 (hereinafter referred to as a frame inner side wall portion). 12) and a floor panel 4 constituting the floor of the automobile 1 is provided. In FIG. 1, the front portion 10a of the rear side frame 10 does not overlap with a side panel 5 described later of the floor panel 4, and a rear portion 10b of a rear side frame 10 (a rear end of a kick-up portion 10c described later). Only the rear part) is visible.

  As shown in FIG. 3, the front portion 10 a of the rear side frame 10 forms a kick-up portion 10 c that extends straight from the front side toward the rear side and then inclines upward toward the rear side. With respect to the side sill 3, as shown in FIG. 3, the front wall portion is inclined upward toward the rear side at the front and rear positions corresponding to the kick-up portion 10c. In the front-rear position corresponding to, the width in the vertical direction increases toward the rear side.

  The front end portions of the left and right rear side frames 10 and the left and right side sills 3 are connected by a first cross member 6 extending in the vehicle width direction. A tunnel portion 6a through which an exhaust pipe (not shown) of the engine passes is formed at the center of the first cross member 6 in the vehicle width direction.

  The rear end portions of the kick-up portions 10c of the rear side frames 10 are connected to each other by the second cross member 7 in the vehicle width direction.

  The floor panel 4 includes a front floor panel 4a constituting a floor surface of the passenger compartment of the automobile 1, a rear floor panel 4b constituting a floor surface of the cargo compartment of the automobile 1, and both side ends of the front floor panel 4a on the outer side in the vehicle width direction. And side panels 5 respectively joined to the parts. The front floor panel 4a is a portion of the floor panel 4 in the front-rear range between the first cross member 6 and the second cross member 7, and the rear floor panel 4b is more than the second cross member 7 in the floor panel 4. It is the rear part. The front floor panel 4 a is joined to the front portion 10 a of the rear side frame 10. On the other hand, the rear front panel 4 b is joined to the rear portion 10 b of the rear side frame 10.

  Specifically, the center of the front floor panel 4a in the vehicle width direction is located at the position corresponding to the tunnel portion 6a of the first cross member 6 in the vehicle width direction, as shown in FIGS. It becomes the convex part 4c processed so that it may protrude toward. The lower side of the convex portion 4c of the front floor panel 4a communicates with the tunnel portion 6a of the first cross member 6, and constitutes a tunnel portion through which the exhaust pipe of the engine passes.

  The rear floor panel 4b is formed with a recess that is substantially circular when viewed from above and is recessed downward. This recess constitutes a spare tire pan 4d in which spare tires are stored.

  As shown in FIGS. 6 and 7, the side panel 5 is positioned above the rear side frame 10 in the front portion 10a of the rear side frame 10, and is located outside the upper end of the side sill 3 and the front floor panel 4a in the vehicle width direction. Are connected to each other in the vehicle width direction on the left side and on the right side. In the present embodiment, as shown in FIGS. 6 and 7, the end of the front floor panel 4 a on the outer side in the vehicle width direction is located below the upper end of the side sill 3. Inclined and extended upward in the direction outward.

  In this embodiment, as shown in FIGS. 6 and 7, the front side 10 a of the rear side frame 10, the side sill 3, and the side panel 5 have a rectangular closed cross section extending in the front-rear direction on the left side and the right side, respectively. A supporting frame 100 is formed. More specifically, as shown in FIGS. 6 and 7, the front portion 10 a of the rear side frame 10 has a U-shaped cross section that opens upward, and includes a frame outer side wall portion 11 and the frame outer side wall portion 11. Frame inner side wall portion 12 that is spaced apart and opposed to the vehicle width direction, and frame lower side wall portion 13 that connects the lower end portion of frame outer side wall portion 11 and the lower end portion of frame inner side wall portion 12. Yes.

  An extending portion 12a extends from the upper end portion of the frame inner side wall portion 12 toward the inner side in the vehicle width direction, and the extending portion 12a is joined to the front floor panel 4a by welding. The frame outer side wall 11 is joined to the middle of the side sill 3 in the vertical direction by welding. As shown in FIGS. 6 and 7, the side panel 5 and the front floor panel 4a are joined at a joint portion between the front floor panel 4a and the extended portion 12a, thereby allowing the front floor panel 4a to pass through. Thus, the side panel 5 and the rear side frame 10 are joined.

  As described above, the front frame 10a, the side sill 3, and the side panel 5 of the rear side frame 10 are joined to form the support frame 100 having a quadrangular cross section as shown in FIGS. As shown in FIGS. 6 and 7, the support frame 100 has an inner side wall portion (hereinafter, referred to as a support frame inner side wall portion 101) that is an inner side wall portion 12 of the rear side frame 10, and a lower side wall portion in the vehicle width direction. A wall portion (hereinafter referred to as a support frame lower wall portion 102) is constituted by a lower wall portion 13 of the rear side frame 10, and a side wall portion on the outer side in the vehicle width direction (hereinafter referred to as a support frame outer side wall portion 103) is defined as the rear side frame 10. Frame outer side wall portion 11 and side sill 3 on the inner side in the vehicle width direction (hereinafter referred to as side sill side wall portion 3a), and the upper wall portion (hereinafter referred to as support frame upper wall portion 104) Consists of a panel 5. Although described in detail later, the support frame 100 is a frame member that supports a rear wheel suspension 20 described later.

  As shown in FIGS. 2 and 3, in each support frame 100, two node members 8 that partition the support frame 100 in the front-rear direction are provided apart from each other in the front-rear direction, and the relatively rear-side node members 8 are provided. A gusset 60 is provided at a position on the rear side. A detailed configuration of the gusset 60 will be described later.

  As shown in FIG. 3, a rear wheel suspension 20 is supported on the kick-up portion 10 c of the rear side frame 10.

  The rear wheel suspension 20 is a so-called torsion beam suspension, which extends in the front-rear direction and supports a pair of left and right trailing arms 21 that respectively support left and right rear wheels (not shown), and extends in the vehicle width direction and includes both the trailing rings. A torsion beam 22 connecting the arm 21. A suspension bush 30 is provided at the tip of each trailing arm 21 (only the left suspension bush 23 is shown in FIG. 3), and each trailing arm 21 is supported via the suspension bush 30. The frame 100 is supported so as to be swingable.

  As shown in FIG. 3, the front portion 21a of each trailing arm 21 has a curved shape that protrudes inward in the vehicle width direction so as to avoid the rear wheel. Specifically, the front portion 21a of the trailing arm 21 has a middle portion in the front-rear direction positioned on the inner side in the vehicle width direction, and approaches the front end of the front portion 21a and the rear end of the front portion 21a from there. It is curved so as to be located on the outer side in the vehicle width direction. As shown in FIG. 2, the rear portion 21 b of the trailing arm 21 has a shape that is inclined outward in the vehicle width direction from the rear end of the front portion 21 a of the trailing arm 21 toward the rear side.

  The torsion beam 22 has a circular cross-section that is the original shape of the hollow pipe at the ends on both sides in the longitudinal direction, and the odd-shaped cross-section at the middle portion in the longitudinal direction has a U-shape with the opening located on the lower side. I am doing. The irregular cross-sectional shape is such that the U-shaped opening becomes larger from the ends on both sides in the longitudinal direction toward the center in the longitudinal direction.

  As shown in FIG. 3, the end portions on both sides in the longitudinal direction of the torsion beam 22 are respectively welded to a portion of the front portion 21 a of the trailing arm 21 slightly behind the center in the front-rear direction.

  As shown in FIGS. 3 and 4, spring seats 24 are provided at the corners between the ends of the torsion beam 22 and the pair of left and right trailing arms 21 on the rear side of the torsion beam 22 and between the ends of the longitudinal direction of the torsion beam 22. Each is provided (in FIG. 3, only the left spring seat 24 is shown). Coil springs (not shown) for suspension are attached to the spring seats 24, respectively.

  As shown in FIG. 4, the spring seat 24 has a substantially rectangular shape. The front end portion of the spring seat 24 is joined to the rear surface of the torsion beam 22, and the outer end portion of the spring seat 24 in the vehicle width direction is on the lower wall portion of the trailing arm 21 and the side wall portion on the inner side in the vehicle width direction. Each is joined.

  As shown in FIGS. 1 to 4, an axle unit 25 for supporting the rear wheel protrudes outward in the vehicle width direction through an axle bracket 26 at the rear portion 21 b of each trailing arm 21. Are provided respectively.

  As shown in FIG. 4, the axle bracket 26 is formed by bending a metal plate so as to be substantially U-shaped in plan view, and the rear portion of the trailing arm 21 so that the U-shaped opening faces inward in the vehicle width direction. 21b is joined to the outer portion in the vehicle width direction.

  The axle unit 25 is attached to a surface portion of the axle bracket 26 on the outer side in the vehicle width direction by a plurality of (four in this embodiment) bolts. The axle unit 25 includes a wheel hub 25a and a housing 25b that accommodates a part of the wheel hub 25a. The wheel hub 25a is formed with a hub flange that extends outward in the radial direction of the wheel hub 25a. The rear wheel is fastened to the hub flange of the wheel hub 25a by a hub bolt 51.

  A damper bracket 27 for supporting a rear damper (not shown) is joined to a portion of the trailing arm 21 on the rear side of the axle unit 25.

  As shown in FIGS. 5 to 7, the suspension bush 30 is arranged on the outer cylinder 31 fixed to the front end portion of the trailing arm 21, and is arranged coaxially with the outer cylinder 31 inside the outer cylinder 31. It has the inner cylinder 32 and the elastic member 33 arrange | positioned between the outer cylinder 31 and the inner cylinder 32. FIG.

  As shown in FIG. 3, the front end of the side wall portion on the inner side in the vehicle width direction and the front end portion of the side wall portion on the outer side in the vehicle width direction of the trailing arm 21 correspond to the shape of the outer cylinder 31. A notch portion that is notched in a U-shape that is open toward the front (in FIG. 3, the notch portion of the side wall portion on the inner side in the vehicle width direction does not overlap the suspension bush 30). The suspension bush 30 is fixed to the front end portion of the trailing arm 21 by fitting the outer cylinder 31 into the portion 21c and joining them by welding. As shown in FIG. 4, the suspension bush 30 is disposed such that the cylinder shaft (the cylinder axis of the outer cylinder 31 and the inner cylinder 32) is slightly inclined in the front-rear direction with respect to the vehicle width direction. Specifically, the suspension bush 30 is disposed such that the cylinder shaft is inclined slightly rearward from the inner side in the vehicle width direction toward the outer side in the vehicle width direction.

  As shown in FIGS. 4 and 6, the suspension bush 30 is positioned below the support frame lower wall portion 102 of the support frame 100 via the support bracket 40, more specifically, in the support frame lower wall portion 102. The trailing arm 21 is supported by the support frame 100 at a position below the front and rear position where the front end is located.

  Hereinafter, the support structure of the suspension bush 30 will be specifically described. Since the lower body structure according to the present embodiment is configured symmetrically, in the following description, only the support structure of the left suspension bush 30 will be described, and the support structure of the suspension bush 30 will be described in detail. Omitted.

  As shown in FIGS. 4, 6, and 7, the support bracket 40 includes a first panel 41 that is L-shaped when viewed from the up-down direction and a second panel 42 that is L-shaped when viewed from the front-rear direction. It is configured.

  As shown in FIG. 4, the first panel 41 extends in the vehicle width direction and has an end portion on the outer side in the vehicle width direction joined to a portion of the side sill 3 below the support frame lower wall portion 102 by welding. 1 panel front side wall part 41a and the 1st panel inner side wall part 41b extended toward the back side from the edge part of the vehicle width direction inner side of this 1st front side wall part 41a.

  As shown in FIG. 4, an upper welding allowance 41c extends from the upper end of the first panel front side wall 41a toward the front, and the upper welding allowance 41c is joined to the support frame lower wall 102 by welding. Has been. Further, as shown in FIGS. 6 and 7, the first panel inner side wall portion 41 b has an upper end portion extending to the upper side of the support frame lower wall portion 102, and the support frame inner side wall portion 101 (that is, the rear side frame 10). A portion overlapping with the frame inner side wall portion 12) in the vehicle width direction is joined to the support frame inner side wall portion 101 by welding.

  As shown in FIG. 7, a bolt 52 for supporting the suspension bush 30 is fastened to a portion of the first panel inner side wall 41b of the first panel 41 below the support frame lower wall 102. A weld nut 43 is joined. A hole 41d communicating with the bolt hole 43a is formed in a portion of the first panel inner side wall 41b corresponding to the bolt hole 43a of the weld nut 43.

  As shown in FIGS. 6 and 7, the second panel 42 includes a second panel upper side wall portion 42a extending in the vehicle width direction along the support frame lower wall portion 102, and a vehicle width of the second panel upper side wall portion 42a. It has the 2nd panel inner side wall part 42b extended toward the lower side from the edge part inside a direction. The second panel upper side wall portion 42a is joined to the lower surface of the support frame lower wall portion 102 by welding, and the second panel inner side wall portion 42b is welded to the outer surface in the vehicle width direction of the first panel inner side wall portion 42a. It is joined by. As shown in FIG. 7, a portion of the second panel inner side wall portion 42b corresponding to the bolt hole 43a of the weld nut 43 is a hole communicating with the bolt hole 43 and the hole portion 41d of the first panel inner side wall portion 41b. A portion 42c is formed.

  Further, at the same height position as the weld nut 43 in the side sill side wall 3a, a hole 3b is formed through which a bolt 52 for supporting the suspension bush 30 is inserted, as shown in FIG. .

  Then, the suspension bracket 30 and the side sill side wall portion 3a form a substantially U shape with a cross-section opening below the support frame lower wall portion 102, and the suspension bush 30 is accommodated therein. The part is composed.

  As shown in FIG. 6, the second panel inner side wall portion 42 b of the second panel 42 and the side sill 3 are connected by a mouth opening preventing member 44 at a position below the suspension bush 30. The mouth opening prevention member 44 is an elongated plate-like member, and is a member for preventing the U-shaped opening of the suspension support portion from spreading in the vehicle width direction (so as not to open the mouth). As shown in FIG. 6, the end portion of the mouth opening preventing member 44 on the outer side in the vehicle width direction is fixed to the lower wall portion of the side sill 3 with a bolt 53. Is bent so as to extend downward, and a portion extending downward is fixed to the second panel inner side wall portion 42b by a bolt 54.

  Actually, when the suspension bush 30 is supported by the support frame 100, first, the suspension bush 30 is positioned between the first panel inner side wall 41b, the second panel inner side wall 41b, and the side sill side wall 3b. Next, the position of the suspension bush 30 is adjusted so that the cylinder hole 32 a of the inner cylinder 32 of the suspension bush 30, the hole 3 b of the side sill 3, and the bolt hole 43 a of the weld nut 43 communicate with each other. Next, the bolt 52 is inserted from the outer side in the vehicle width direction toward the weld nut 43 through the hole 3b of the side sill 3 and the cylindrical hole 32a of the inner cylinder 32 of the suspension bush 30, and the tip of the bolt 52 is welded. Fasten to nut 43. As described above, the suspension bush 30 is supported by the support frame 100 via the support bracket 40 and the bolts 52 at a position below the support frame lower wall portion 102. Accordingly, the front end portion of the trailing arm 21 is supported by the support frame 100 at a position below the support frame lower wall portion 102.

  In the present embodiment, the support structure of the left suspension bush 30 is configured as described above. The support structure of the right suspension bush 30 is configured to be bilaterally symmetric with the support structure of the left suspension bush 30 described above.

  Here, in order to improve the running stability by smoothing the vertical movement of the rear wheel supported by the trailing arm 21, the front end of the trailing arm 21 should be positioned as high as possible. Therefore, there is a demand for the front end portion of the trailing arm 21, that is, the suspension bush 30 to be positioned as high as possible. For this purpose, it is necessary to position the support frame 100 as high as possible at the position where the suspension bush 30 is supported.

  On the other hand, there is also a demand for lowering the position of the front floor panel 4a as much as possible in order to make the interior space of the automobile 1 as wide as possible. In this embodiment, since the front floor panel 4a is joined to the support frame inner side wall portion 101 of the support frame 100, the support frame 100 is as low as possible in order to lower the position of the front floor panel 4a. Need to be positioned.

  Furthermore, since the trailing arm 21 of the rear wheel suspension 20 is mainly supported by the support frame 100 at the front end via the suspension bush 30, the front end of the trailing arm 21 in the support frame 100 is used. The load from the rear wheel is input to the portion corresponding to the position of the portion, that is, the portion supporting the suspension bush 30 via the trailing arm 21. For this reason, a portion of the support frame 100 that supports the suspension bush 30 needs to secure rigidity against a load from the rear wheel, and the portion of the support frame 100 needs to have a cross-sectional area as large as possible.

  In order to satisfy all of these requirements, in this embodiment, as shown in FIGS. 6 and 7, trailing is performed on the support frame inner side wall portion 101 among the side wall portions 101 and 103 on both sides in the vehicle width direction of the support frame 100. The front end of the arm 21, that is, the width in the vertical direction of the portion corresponding to the position of the suspension bush 30 is reduced. In this way, the cross-sectional area of the portion corresponding to the position of the suspension bush 30 in the support frame 100 can be ensured while improving traveling stability and forming a wide vehicle interior space.

  On the other hand, in order to ensure rigidity against the load from the rear wheel, it is necessary not only to increase the cross-sectional area but also to make it difficult to deform the cross-sectional shape. When the vertical width of the support frame inner side wall portion 101 is reduced as in the present embodiment, the deformation amount of the support frame inner side wall portion 101 is relatively small, but the vertical width is relatively small. The large support frame outer side wall portion 103 remains easily deformed by the load. In particular, in this embodiment, the side sill side wall portion 3a constituting the support frame outer side wall portion 103 supports the suspension bush 30 via the bolt 52, and the load from the rear wheel is directly input. For this reason, it is easily deformed by a load from the rear wheel.

  Although it is conceivable to provide a node member at a position corresponding to the front end of the trailing arm 21 in the support frame 100, in order to improve traveling stability and to form a wide vehicle interior space, FIG. 7, the support frame 100 has a substantially different vertical width between the support frame inner side wall portion 101 and the support frame outer side wall portion 103 and has a substantially trapezoidal cross section. The installation itself is difficult.

  Therefore, in the present embodiment, the gusset 60 and the reinforcing panel 70 are provided in the left and right support frames 100 at positions corresponding to the front end portions of the trailing arm 21, that is, the position of the suspension bush 30, respectively.

  Hereinafter, the configuration of the gusset 60 and the reinforcing panel 70 will be described in detail. In the following description, only the configuration of the left gusset 60 and the reinforcing panel 70 will be described as in the description of the support structure of the suspension bush 30, and the configuration of the right gusset 60 and the reinforcing panel 70 will be described in detail. Description is omitted.

  The gusset 60 includes a gusset front side wall portion 61 joined to the support frame outer side wall portion 103 and the support frame lower wall portion 102, and is provided on the rear side with respect to the gusset front side wall portion 61. 103 and the gusset rear side wall 62 joined to the support frame lower wall 102, the gusset side wall connecting the end in the vehicle width direction of the gusset front side wall 61 and the end in the vehicle width direction of the rear side wall 62. Part 63.

  As shown in FIGS. 3 and 5, the gusset front side wall portion 61 and the gusset rear side wall portion 62 of the gusset 60 extend so as to be perpendicular to the support frame lower wall portion 102. Further, the gusset 60 is arranged so that the suspension bush 30 is positioned on an extension line extending downward from the gusset 60. More specifically, as shown in FIG. 5, in a cross section passing through the outer cylinder 31 of the suspension bush 30 and perpendicular to the axis of the outer cylinder 31 (coincident with the axis of the inner cylinder 32), A straight line A extending from the center in the width direction of the gusset 60 in a direction perpendicular to both the width direction and the vehicle width direction is defined as a direction in which the gusset 60 is separated from the rear side wall 62. The bush 30 is disposed so as to cross the tube hole 32 a of the inner tube 32.

  As shown in FIG. 2, the gusset front side and rear side wall portions 61 and 62 have a substantially right triangle shape when viewed from the front-rear direction. Of the three sides of the substantially right triangle shape of the gusset front side and the rear side wall portions 61, 62, two sides that intersect at right angles are arranged so as to be the lower end and the outer end in the vehicle width direction, respectively. More specifically, as shown in FIG. 2, the opposite side portions of the substantially right triangular shape of the gusset front side and the rear wall portions 61, 62 are located at the lower ends of the gusset front side and the rear wall portions 61, 62, and the gusset front side And the part of the adjacent side of the substantially right triangle shape of the rear wall parts 61 and 62 is located in the edge of the vehicle width direction outer side of the gusset front side and the rear wall parts 61 and 62. As shown in FIG. 2, a first front welding allowance 61 a extends from the lower end of the gusset front side wall 61 toward the front side, and from the lower end of the gusset rear side wall 62, One rear welding allowance 62a extends. The first front side and rear side welding allowances 61a and 62a are joined to the support frame lower wall portion 102 by welding. Further, as shown in FIG. 3, a second front welding allowance 61b extends from the end of the gusset front side wall 61 on the outer side in the vehicle width direction toward the front side. A second rear welding allowance 62b extends toward the rear side from the end portion. The second front side and rear side welding allowances 61b and 62b are joined to the support frame outer side wall portion 103 (that is, the side sill side wall portion 3a) by welding. Thereby, two sides which intersect at right angles among the three sides of the substantially right triangle shape of the gusset front side and the rear side wall portions 61 and 62 are joined to the support frame outer side wall portion 103 and the support frame lower wall portion 102, respectively.

  Further, the first front welding allowance 61a of the gusset front side wall 61 and the first rear welding allowance 62a of the gusset rear side wall 62 are the second of the support frame lower wall 102 and the support bracket 40 as shown in FIG. It is joined to the support frame lower wall portion 102 at the same position as the joining portion with the panel 42. As a result, the second panel 42 of the support bracket 40 (strictly, the second panel upper side wall part 42a), the support frame lower wall part 102, and the first front side welding allowance 61a of the gusset front side wall part 61 are three. While being joined, the second panel 42 of the support bracket 40 (strictly, the second panel upper side wall part 42a), the support frame lower wall part 102, and the first rear side welding allowance 62a of the gusset rear side wall part 62, Are joined.

  As shown in FIG. 5, the separation distance L <b> 1 between the gusset front side wall portion 61 and the gusset rear side wall portion 62 is set to a length larger than the outer diameter D of the outer cylinder 31 of the suspension bush 30.

  The gusset side wall portion 63 connects the oblique sides of the substantially right triangle shape of the gusset front side and the rear side wall portions 61 and 62. As shown in FIGS. 2 and 5, the corner between the gusset front side wall 61 and the gusset side wall 63 and the corner between the gusset rear side wall 62 and the gusset side wall 63 are respectively located on the upper side. And the protrusion part 64 which protrudes toward a vehicle width direction inner side is formed over the whole part of the oblique side of a gusset front side and the rear side wall parts 61 and 62. As shown in FIG.

  As shown in FIGS. 6 and 7, a lower welding allowance 63 a extends inward in the vehicle width direction along the support frame lower wall portion 102 from the lower end portion of the gusset side wall portion 63. The margin 63a is joined to the lower wall 102 of the support frame by welding. Further, as shown in FIGS. 6 and 7, an upper welding allowance 63b extends upward from the upper end portion of the gusset sidewall 63, and the upper welding allowance 63b is welded to the support frame outer sidewall 103. It is joined.

  Further, as shown in FIGS. 6 and 7, the lower welding allowance 63a of the gusset side wall portion 63 is located at the same position as the joint portion between the support frame lower wall portion 102 and the second panel 42 of the support bracket 40. It is joined to the lower wall portion 102. Thereby, three pieces of the second panel 42 (strictly speaking, the second panel upper side wall portion 42a), the support frame lower wall portion 102, and the lower welding allowance 63a of the gusset side wall portion 63 of the support bracket 40 are joined. The

  As shown in FIG. 2, the lower welding allowance 63a of the gusset side wall 63 is connected to the first front welding allowance 61a of the gusset front side wall 61 and the first rear welding allowance 62a of the gusset rear side wall 62. Yes. In other words, the first front welding allowance 61a and the first rear welding allowance 62a are connected back and forth by the lower side wall portion 63a.

  A hole 63c is provided at a substantially central portion in the vertical direction in the portion between the two protruding portions 64 of the gusset side wall portion 63. The hole 63c is a hole for inserting a welding device when the frame outer side wall 11 of the rear side frame 10 and the side sill side wall 3a of the side sill 3 are welded.

  Further, as shown in FIG. 7, the upper welding allowance of the gusset side wall portion 63 from the inner end in the vehicle width direction of the gusset side wall portion 63 in the vehicle width direction (that is, the inner end in the vehicle width direction of the lower welding allowance 63a). The distance L2 in the vehicle width direction up to 63b is set to be longer than the length of the outer cylinder 31 of the suspension bush 30 in the cylinder axis direction. More specifically, the distance L2 in the vehicle width direction from the vehicle width direction inner end of the gusset side wall 63 to the upper welding allowance 63b of the gusset side wall 63 is the vehicle width of the outer cylinder 31 when viewed from above. The end on the inner side in the direction is set to a length that does not protrude further inward in the vehicle width direction than the lower end of the gusset side wall 63.

  As shown in FIGS. 6 and 7, the reinforcing panel 70 has an L-shaped cross section and extends along the supporting frame inner side wall portion 101 (that is, the frame inner side wall portion 12 of the rear side frame 10). A side wall portion 71 and a reinforcing panel lower wall portion 72 extending along the support frame lower wall portion 102 are provided. As shown in FIGS. 2 and 3, the reinforcing panel 70 is provided over substantially the entire kick-up portion 10 c of the rear side frame 10. That is, a part of the reinforcing panel 70 is provided at a position corresponding to the position of the suspension bush 30 in the support frame 100.

  6 and 7, the reinforcing panel inner side wall portion 71 is joined to the support frame inner side wall portion 101 at the same position as the joint portion between the support frame inner side wall portion 101 and the first panel 41 of the support bracket 40. Has been. As a result, the first panel 41 (strictly speaking, the first panel inner side wall portion 41b), the support frame inner side wall portion 101, and the reinforcing panel inner side wall portion 71 of the support bracket 40 are joined. On the other hand, as shown in FIGS. 6 and 7, the reinforcing panel lower wall portion 72 is disposed at the same position as the joint portion between the supporting frame lower wall portion 102 and the second panel 42 of the supporting bracket 40. 102. As a result, the second panel 42 (strictly speaking, the second panel upper wall portion 42a), the support frame lower wall portion 102, and the reinforcing panel lower wall portion 72 of the support bracket 40 are joined.

  In the present embodiment, the left gusset 60 and the reinforcing panel 70 are configured as described above. The right gusset 60 and the reinforcing panel 70 are configured to be symmetrical with the left gusset 60 and the reinforcing panel 70 described above.

  In the present embodiment, as described above, by providing the gusset 60, the support frame outer side wall portion 103, the support frame lower wall portion 102, and the gusset 60 form a closed cross section. Thereby, even if the load from the rear wheel is transmitted to the support frame 100 via the trailing arm 21, the gusset 60 prevents the support frame 100, particularly the support frame outer wall 103, from being deformed. can do. As a result, by reducing the vertical width of the support frame inner side wall portion 101, the running stability is improved and a wide vehicle interior space is formed, and the gusset 60 is provided to support the load from the rear wheel. The rigidity of the frame 100 can be ensured.

  In the present embodiment, the gusset front side wall 61 and the gusset rear side wall in a cross section passing through the outer cylinder 31 of the suspension bush 30 and perpendicular to the axis of the outer cylinder 31 (coincident with the axis of the inner cylinder 32). A straight line A extending from the center in the width direction of the gusset 60 in the direction perpendicular to both the width direction and the vehicle width direction is defined as the inner direction of the suspension bush 30. Since it is arranged so as to cross the tube hole 32 a of the tube 32, the load from the rear wheel input to the support frame via the suspension bush 30 can be appropriately received by the gusset 60. Thereby, the rigidity of the support frame 100 with respect to the load from the rear wheel can be ensured. In the cross section, if the straight line A passes through the axis of the inner cylinder 32, the load from the rear wheel can be more appropriately received by the gusset 60.

  Furthermore, in this embodiment, since the separation distance L1 between the gusset front side wall portion 61 and the gusset rear side wall portion 62 is set to a length larger than the outer diameter D of the outer cylinder 31 of the suspension bush 30, The load from the rear wheel input to the support frame via the suspension bush 30 can be more appropriately received by the gusset 60.

  In this embodiment, the corner between the gusset front side wall 61 and the gusset side wall 63 and the corner between the gusset rear side wall 62 and the gusset side wall 63 are respectively inward in the vehicle width direction. Since the projecting portion 64 projecting toward the gusset is formed over the entire oblique side of the gusset front side and the rear side wall portions 61 and 62, these two projecting portions 64 serve as beads, and the gusset 60 itself Becomes difficult to deform. Thereby, since the rigidity of gusset 60 itself improves, the rigidity of the support frame 100 with respect to the load from the said rear wheel can be improved.

  Furthermore, in this embodiment, all of the gusset front side wall part 61, the gusset rear side wall part 62, and the gusset side wall part 63 are joined to the support frame outer side wall part 103, and the gusset front side wall part 61, gusset rear side wall part. Since 62 and the gusset side wall 63 are all joined to the support frame lower wall 102, deformation of the gusset 60 itself can be more effectively suppressed. The deformation of the support frame outer side wall portion 103 is effectively suppressed, and the deformation of the support frame 100 is effectively suppressed. As a result, the rigidity of the support frame 100 against the load from the rear wheel can be further improved.

  Further, in the present embodiment, the reinforcing panel 70 extending along the support frame inner side wall portion 101 and the support frame lower wall portion 102 is provided at a position corresponding to the position of the suspension bush 30 in the support frame 100. The frame inner side wall 101 is also restrained from being deformed when the load from the rear wheel is applied by the reinforcing panel 70, so that the deformation of the support frame 100 is more effectively suppressed. As a result, the rigidity of the support frame 100 with respect to the load from the rear wheel can be further improved.

  Further, in the present embodiment, the joint portion of the second panel upper wall portion 42a of the support bracket 40, the support frame lower wall portion 102, and the support frame lower wall portion 102 in the gusset 60 (the first front side welding allowance 61a, the first Since the 1 rear welding allowance 62a and the lower welding allowance 63a) are joined, the deformation of the support frame 100 is further effectively suppressed, and thereby the support frame against the load from the rear wheel. The rigidity of 100 can be further improved.

  Furthermore, in the present embodiment, since the second panel upper side wall portion 42a of the support bracket 40, the support frame lower wall portion 102, and the reinforcing panel lower wall portion 72 of the reinforcing panel 70 are joined together, Since there are two portions to be joined, the deformation of the support frame 100 is further effectively suppressed. As a result, the rigidity of the support frame 100 against the load from the rear wheel can be further improved.

  Therefore, in the present embodiment, the rear frame includes a pair of left and right support frames 100 extending in the front-rear direction and having a rectangular closed cross section, and a pair of left and right trailing arms 21 extending in the front-rear direction and supporting the left and right rear wheels. The rear suspension 20 is supported by the support frame 100 at the position below the support frame lower wall 102 at the front end of each trailing arm 21 on each of the left and right sides. The gussets 60 are provided at the front and rear positions corresponding to the front end of the trailing arm 21 in each support frame 100, and are joined to the support frame outer side wall 102 and the support frame lower wall 102, respectively. The gusset front side wall 61 and the rear side of the gusset front side wall 61 are provided apart from each other. Gusset rear side wall portion 62 joined to each of the support frame outer side wall portion 103 and the support frame lower wall portion 102, the vehicle width direction inner end portion of the gusset front side wall portion 61 and the gusset rear side wall portion 62 in the vehicle width direction inner side. Since the gusset 60 having the gusset side wall portion 63 that connects the end portion of the support frame 100 is further provided, the running stability is improved, a wide vehicle interior space is formed, and the rigidity of the support frame 100 against the load from the rear wheel is increased. Can be secured.

  The present invention is not limited to the embodiment described above, and can be substituted without departing from the spirit of the claims.

  For example, in the above-described embodiment, the gusset front side wall portion 61 and the gusset rear side wall portion 62 of the gusset 60 have a substantially right triangle shape when viewed from the front-rear direction. The gusset rear side wall 62 may have a rectangular shape. In this case, the gusset side wall 63 may not be joined to the support frame outer side wall 103.

  Further, in the above-described embodiment, the protrusion 64 has both the corner between the gusset front side wall 61 and the gusset side wall 63 and the corner between the gusset rear side wall 62 and the gusset side wall 63. However, the present invention is not limited to this, and the protrusion 64 may be provided only at one of the two corners.

  Further, in the above-described embodiment, the rear wheel suspension 20 is a torsion beam type suspension. However, the rear wheel suspension 20 is not limited to this, and the front end of each trailing arm 21 has a support frame lower wall portion 102. As long as it is supported by the vehicle body by being supported by the support frame 100 at a lower position than the torsion beam suspension, it is not necessary.

  The above-described embodiments are merely examples, and the scope of the present invention should not be interpreted in a limited manner. The scope of the present invention is defined by the scope of the claims, and all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  INDUSTRIAL APPLICABILITY The present invention is useful as a lower body structure of an automobile including a rear wheel suspension supported by the frame member at a position below the lower wall portion of the frame member.

DESCRIPTION OF SYMBOLS 1 Automobile 3 Side sill 5 Side panel 10 Rear side frame 20 Rear wheel suspension 21 Trailing arm 22 Torsion beam 40 Support bracket 42a 2nd panel upper side wall part (joining part with the lower wall part of the frame member in a support bracket)
60 Gusset 61 Gusset front side wall part 61a First front side welding allowance (joint part with lower wall part of frame member in gusset)
62 Gusset rear side wall part 62a First rear side welding allowance (joint part with lower wall part of frame member in gusset)
63 Gusset side wall 63a Lower welding allowance (joint part of frame member with lower wall of gusset)
64 Projection 70 Reinforcement panel (reinforcement member)
72 Reinforcing panel lower wall portion (joint portion of the reinforcing member with the lower wall portion of the frame member)
100 Support frame (frame member)
101 Inner side wall portion of support frame (outer side wall portion of frame member in vehicle width direction)
102 Lower wall portion of support frame (lower wall portion of frame member)
103 Support frame outer side wall (side wall in the vehicle width direction of the frame member)

Claims (7)

A lower body structure of an automobile,
A pair of left and right frame members extending in the longitudinal direction of the vehicle and having a quadrangular closed cross section;
A rear wheel suspension having a pair of left and right trailing arms extending in the longitudinal direction of the vehicle and supporting the left and right rear wheels, respectively.
Front end portions of the trailing arms of the rear wheel suspension are supported by the frame members at positions below the lower wall portions of the frame members on the left and right sides of the vehicle,
Gussets provided at the vehicle front and rear positions corresponding to the front end of the trailing arm in each frame member, respectively, and joined to the side wall portion and the lower wall portion on the outer side in the vehicle width direction of the frame member. A gusset front side wall portion, and a gusset rear side wall portion that is spaced apart from the gusset front side wall portion on the vehicle rear side and is joined to the outer side wall portion and the lower wall portion of the frame member, respectively. The lower part of the automobile further comprising a gusset having a gusset side wall connecting the vehicle width direction inner end of the gusset front side wall and the vehicle width direction inner end of the gusset rear side wall. Body structure. The lower body structure of an automobile according to claim 1,
2. The lower body structure of an automobile according to claim 1, wherein the rear wheel suspension is a torsion beam suspension that further includes a torsion beam extending in the vehicle width direction and connecting the pair of left and right trailing arms. The lower body structure of an automobile according to claim 1 or 2,
At the corner between the gusset front side wall and the gusset side wall, and at the corner between the gusset rear side wall and the gusset side wall, a protrusion that protrudes inward in the vehicle width direction is formed. A lower body structure of an automobile characterized by being made. In the lower vehicle body structure of an automobile according to any one of claims 1 to 3,
The gusset front side wall part and the gusset rear side wall part form a substantially right triangle when viewed from the vehicle front-rear direction,
Two sides intersecting at right angles among the three sides of the substantially right triangle shape of the gusset front side wall part and the gusset rear side wall part are joined to the side wall part and the lower wall part on the vehicle width direction outer side of the frame member, respectively. Of the three sides, the remaining hypotenuses are connected by the gusset side wall,
The upper end of the gusset side wall is joined to the outer side wall of the frame member,
A lower body structure of an automobile, wherein a lower end portion of the gusset side wall portion is joined to a lower wall portion of the frame member. In the lower body structure of an automobile according to any one of claims 1 to 4,
The frame member further includes a reinforcing member that extends along the side wall portion and the lower wall portion on the inner side in the vehicle width direction, and is joined to the side wall portion on the inner side in the vehicle width direction and the lower wall portion, respectively. The lower body structure of the car. In the lower body structure of an automobile according to any one of claims 1 to 5,
A support bracket for supporting the front end portion of the trailing arm is joined to the lower surface of the lower wall portion of each frame member.
Three joint portions of the support bracket with the lower wall portion of the frame member, the lower wall portion of the frame member, and the joint portion of the gusset with the lower wall portion of the frame member are joined. The lower body structure of an automobile characterized by The lower body structure of an automobile according to claim 5,
A support bracket for supporting the front end portion of the trailing arm is joined to the lower surface of the lower wall portion of each frame member.
Three joint portions of the support bracket with the lower wall portion of the frame member, the lower wall portion of the frame member, and the joint portion of the frame member with the lower wall portion of the gusset are joined, Three joint portions of the support bracket with the lower wall portion of the frame member, a lower wall portion of the frame member, and a joint portion of the reinforcing member with the lower wall portion of the frame member are joined. A lower body structure of an automobile characterized by that.

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