JP2013103635A - Vehicle body lower structure of automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately protect a battery case against rear collision, when the battery case is provided to be extended at the rear side of a vehicle, without adding large quantity of components.SOLUTION: A vehicle body lower structure includes: a first cross member with both ends connected to right and left rear frames 14; a second cross member 26 located at the rear side of the first cross member, with both ends connected to right and left rear frames 14; right and left leg members 76 suspended from both ends of the first cross member respectively; and a third cross member 46 both ends of which are fixed to lower ends of the right and left leg members 76 and which supports the battery case 90 arranged at the lower face side of the rear floor panel. The second cross member 26 and the third cross member 46 are connected to each other by right and left rods 82.

Description

  The present invention relates to an underbody structure of an automobile, and more particularly, to an underbody structure of an automobile in which a battery case is mounted below a floor panel, such as an electric vehicle and a hybrid vehicle.

  An automobile equipped with a large battery case (battery pack) such as an electric vehicle has a floor structure with left and right side sills extending in the longitudinal direction of the vehicle body, a front floor panel disposed between the left and right side sills, The left and right floor frames that extend in the vehicle body longitudinal direction from the side sill respectively in the vehicle body width direction and the upper side (vehicle interior side) of the front floor panel extend in the vehicle body width direction and both ends are joined to the left and right floor frames. The battery case is disposed between the left and right floor frames below the front floor panel, that is, on the inner side in the vehicle width direction from the floor frame.

  In a vehicle with such a battery case arrangement, as a protective measure against damage to the battery case at the time of a side collision, an outrigger is arranged between the side sill and the floor frame, and the energy of the side collision is absorbed by the crushing deformation of the outrigger (for example, Further, there is a technique in which a reinforcing member (brace) is joined to a floor frame to prevent the floor frame from falling down at the time of a side collision (for example, Patent Document 2).

  In addition, by connecting a metal skeleton member embedded in a resin battery case to a metal body member via a metal connection member, the rigidity of the electric vehicle can be reduced and the rigidity can be improved. There are some which improve the collision resistance performance of a battery mounted on an electric vehicle (for example, Patent Document 3).

Japanese Patent No. 2891072 Japanese Patent No. 3132261 JP 2008-183947 A

  In an electric vehicle, there is a demand for further increasing the capacity of the battery. In response to this, it is conceivable to extend the battery case to the vicinity of the rear wheel arrangement part or the spare tire pan of the rear part of the vehicle body. When the battery case is extended to the rear side of the vehicle body in this way, it is necessary to protect the battery case against a rear collision (rear collision). However, the conventional one does not take measures for protecting the battery case against a rear collision (rear collision).

  The problem to be solved by the present invention is to appropriately protect the battery case against a rear collision when the battery case is extended to the rear side of the vehicle body without significant addition of parts.

  The lower body structure of an automobile according to the present invention includes a left and right rear frame (14) extending in the longitudinal direction of the vehicle body, and left and right rear frames (14) with left and right edges joined to the left and right rear frames (14). ) A rear floor panel (20) extending between, a first cross member (24) having both ends joined to the left and right rear frames (14), and a position behind the first cross member (24). An automobile having a second cross member (26) having lower arm attachment portions (26B) that are joined to the left and right rear frames (14) at both ends and support the left and right lower arms (110) of the rear wheel suspension. Left and right leg members (76) suspended from both ends of the first cross member (24), and both ends fixed to the lower ends of the left and right leg members (76). The third cross member (46) that supports the battery case (90) disposed on the lower surface side of the floor panel and the rear end between the left and right lower arm attachment portions (26B) of the second cross member (26) A pair of left and right rods (82) which are coupled to the vehicle width direction center portion of the third cross member (46) and which are coupled to the vehicle width direction end portion of the third cross member (46) to form a square shape in plan view.

  According to this configuration, the pair of left and right rods (82) cooperate with the second cross member (26) and the third cross member (46) to construct a truss structure. As a result, the strength of the second cross member (26) against the forward / backward tilt of the vehicle body is improved, and the movement of the second cross member (26) forward of the vehicle body at the time of a rear collision is suppressed. This prevents the second cross member (26) from hitting the rear part of the battery case (90) due to forward movement at the time of a rear collision, and the battery case (90) is protected against the rear collision by the two right and left rods ( 82) is added appropriately without significant addition of parts. Moreover, since the top part of the truss structure is located in the vicinity of the lower arm attachment part (26B), the lateral rigidity of the lower arm attachment part (26B) is improved.

  In the vehicle lower body structure according to the present invention, preferably, the rod (82) is bent or curved so as to bulge downward from the lower surface of the battery case (90).

  According to this configuration, in the back curb mode in which the curb (projection from the road surface) passes between the left and right rear tires when the vehicle moves backward, the rod (82) has the curb to the battery case (90). It also functions as a grounding guard that prevents contact (grounding).

  In the lower body structure of an automobile according to the present invention, preferably, the left and right rear frames (14) have attachment portions (14A) of left and right trailing arms (114) of a rear wheel suspension, and the third cross The member (46) is arranged behind the attachment portion (14A) of the trailing arm (114).

  According to this configuration, since the third cross member (46) that acts as a support member for the battery case (90) is disposed behind the attachment portion of the trailing arm (114), the battery case 90 is attached to the trailing arm. The mounting portion (14A) of (114) can be extended to the vicinity of the rear wheel axle arrangement. Thus, the capacity of the battery pack (92) accommodated in the battery case (90) can be increased under effective use under the floor panel.

  In the vehicle lower body structure according to the present invention, preferably, the ground guard member (88) projecting downward from the second cross member (26) at the center in the vehicle width direction of the second cross member (26). ) Is attached.

  According to this configuration, the ground guard member (88) also serves as a jack-up plate and functions as a ground guard that prevents the curb from contacting (grounding) the battery case (90) in the back curb mode. To do.

  In the vehicle lower body structure according to the present invention, preferably, the third cross member (46) is fixed to the leg member (76), and the rod (82) is fixed to the third cross member (46). Is detachable by a fastener such as a bolt.

  According to this configuration, the battery case (90) can be easily removed by removing the third cross member (46) and the rod (82).

  The lower body structure of the automobile according to the present invention preferably further includes left and right side sills (16) extending in the longitudinal direction of the vehicle body and having rear ends joined to the left and right rear frames (14), and the left and right side sills. (14) left and right floor frames (12) extending inward in the vehicle body width direction from the vehicle longitudinal direction and having rear ends joined to the left and right rear frames (14), and the left and right floor frames (12), Left and right connecting members (64) respectively joined to the left and right side sills (16), and a fourth cross member that is fixed to the left and right connecting members (64) at both ends and supports the battery case (90). (44).

  According to this configuration, the battery case (90) is supported also by the fourth cross member (44), and the connecting member (64) connects the floor frame (12) and the side sill (16). Therefore, the rigidity of the rear part of the vehicle body is improved and the road noise performance is improved.

  According to the lower body structure of the automobile according to the present invention, the left and right two rods cooperate with the second cross member) and the third cross member to construct the truss structure. The strength against the falling of the direction is improved, and the movement of the second cross member toward the front of the vehicle body at the time of rear collision is suppressed. Thereby, it is avoided that the second cross member hits the rear part of the battery case by the forward movement at the time of the rear collision, and the protection of the battery case against the rear collision is accompanied by a significant addition of parts only by adding two right and left rods. Done properly without.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overhead perspective view showing the whole of one embodiment in which a lower body structure according to the present invention is applied to an electric vehicle. The schematic bottom view which shows the whole vehicle body lower structure by a present Example. The expanded bottom view in the rear floor removal state which shows the rear part of the vehicle body lower structure by a present Example. The enlarged plan view in the rear floor removal state which shows the rear part of the vehicle body lower part structure by a present Example. The expanded rear view which looked at the vehicle body lower part structure by a present Example from back. FIG. 3 is an enlarged overhead perspective view of the rear part of the vehicle body lower structure according to the embodiment in a state where the rear floor is removed. The expansion perspective view in the rear floor removal state of the rear part of the vehicle body lower part structure by a present Example. FIG. 4 is an enlarged cross-sectional view taken along line IIX-IIX in FIG. 3. FIG. 4 is an enlarged sectional view taken along line IX-IV in FIG. 3.

  Hereinafter, an embodiment in which the vehicle body lower structure according to the present invention is applied to an electric vehicle will be described with reference to FIGS. In the following description, “joining” is joining by welding such as spot welding unless otherwise specified. Each member may be made of a general steel plate, and some members may be made of a high-tensile steel plate as necessary. The “hat-shaped cross-sectional shape” is a cross-sectional shape of a shape including a groove-shaped cross-sectional shape portion and having flange pieces (welding allowance) extending outward on both side pieces of the groove-shaped cross-sectional shape portion.

  As shown in FIGS. 1 and 2, the electric vehicle of the present embodiment includes, as a lower skeleton structure, left and right front side frames 10 that extend in the longitudinal direction of the vehicle body, and a front end that extends in the longitudinal direction of the vehicle body. Left and right floor frames 12 joined to the left and right front side frames 10 respectively, and left and right rear frames 14 extending in the longitudinal direction of the vehicle body and joined to the left and right floor frames 12 respectively. Left and right side sills 16 that extend in the vehicle longitudinal direction from the floor frame 12 in the vehicle longitudinal direction, have front ends joined to the left and right front side frames 10 and rear ends joined to the rear ends of the left and right rear frames 14, respectively. Have

  The upper portions of the floor frame 12 and the side sill 16 are at substantially the same height as shown in FIGS. 8 and 9, but the height dimension of the rear frame 14 is smaller than the height dimension of the side sill 16. Thus, the lower part of the rear frame 14 is located higher than the lower part of the side sill 16.

  In the present embodiment, the left and right side members are individually constituted by the floor frame 12, the rear frame 14, and the side sill 16.

  Between the left and right side sills 16, a front floor panel 18 extending between the left and right side sills 16 having left and right edge portions joined to the side sill 16 is provided. The left and right rear frames 14 are provided with rear floor panels 20 having left and right edges joined to the left and right rear frames 14 and extending between the left and right rear frames 14. The rear floor panel 20 is joined at the front edge to the rear edge of the front floor panel 18 and is continuous with the front floor panel 18 in the longitudinal direction of the vehicle body. A rear tire body 22 of the rear floor panel 20 forms a spare tire pan 22 having a large recess 22A formed at the center in the vehicle width direction.

  The rear frame 14 has a hat-shaped cross-sectional shape with an upper opening, and has a closed cross-sectional shape by being joined to the lower surface of the rear floor panel 20 (see FIG. 9). The side sill 16 is constituted by a joined body (see FIG. 5) of an inner member 16A and an outer member 16B having a hat-shaped cross-sectional shape with side openings, and has a closed cross-sectional shape.

  On the lower surface side of the front floor panel 18 and the rear floor panel 20, a substantially plate-shaped battery case 90 having a horizontal width between the left and right floor frames 12 and between the left and right rear frames 14 that is substantially full in the vehicle width direction is horizontally disposed. Yes. The battery case 90 continuously extends in the vehicle longitudinal direction from the vicinity of the rear end of the front side frame 10 to the vicinity of the rear wheel axle (not shown) in the vehicle longitudinal direction.

  The battery case 90 is made of metal and includes therein a battery pack 92 (see FIG. 8) made of a Li ion secondary battery, a battery control unit, a DC-DC converter, an inverter, etc., not shown. It is an outer shell of (Intelligent Power Unit).

  As shown in FIG. 4, the left and right rear frames 14 have both ends of a first rear floor cross member (first cross member) 24 and a second rear floor cross member (second cross member) 26. Are joined.

  The first rear floor cross member 24 is a vehicle-side seat belt fixing cross member to which a seat belt fixing tool (not shown) is attached. The first rear floor cross member 24 has a hat-shaped cross-section with a downward opening and extends along the upper surface of the rear floor panel 20. Thus, it extends in the vehicle body width direction and is joined to the upper surface of the rear floor panel 20 to form a closed cross-sectional shape (see FIG. 9). The first rear floor cross member 24 is disposed at a position in the front-rear direction of the vehicle body corresponding to the vicinity of the front end of the rear frame 14, and is located on the front side of the vehicle body from the rear end of the battery case 90. In other words, the battery case 90 extends from the vehicle longitudinal direction position corresponding to the arrangement position of the first rear floor cross member 24 to the rear of the vehicle body.

  As shown in FIGS. 3 to 7, the second rear floor cross member 26 is located at a rear position from the first rear floor cross member 24 and at a rear position from the rear end of the battery case 90, and has a top opening. It has a cross-sectional shape, extends in the vehicle body width direction along the lower surface of the spare tire pan 22, and is joined to the lower surface of the spare tire pan 22 to form a closed cross-sectional shape (see FIG. 5). As shown in FIG. 6, the inside of the groove shape of the second rear floor cross member 26 extends forward and backward in the groove shape at each of two left and right sides as shown in FIG. Thus, the bulkhead members 28 and 30 for separating the inside of the groove shape are joined.

  The second rear floor cross member 26 has two left and right bulging portions 26 </ b> A that bulge downward at a portion located below the concave portion 22 </ b> A of the spare tire pan 22. The left and right bulging portions 26A are formed with lower arm attachment portions 26B that support the left and right lower arms 110 of the rear wheel suspension. Each of the lower arm attachment portions 26B has a bracket structure that supports both of the support shafts 112. One end portion (inner end) of the lower arm 110 extending in the vehicle width direction is horizontally supported in the vehicle longitudinal direction by the support shaft 112. The center axis is supported so as to be rotatable. In this way, the second rear floor cross member 26 forms a suspension mounting cross member that is essential for the rear wheel suspension.

  Trailing arm attachment portions (trailing arm attachment points) 14A that support the left and right trailing arms 114 of the rear wheel suspension are formed at the lower bottoms near the front ends of the left and right rear frames 14. The trailing arm mounting portion 14A is in front of the vehicle body in the vehicle longitudinal direction position corresponding to the arrangement position of the first rear floor cross member 24 (see FIG. 4). The trailing arm mounting portion 14A has a concave shape when the rear frame 14 is viewed from the lower surface side, and is fixed to the lower bottom portion of the rear frame 14 so as to rotatably support the front end (base end) of the trailing arm 114. The upper half of the bracket 116 is received.

  Each of the left and right trailing arms 114 has a rear end (front end) connected to the other end (outer end) of the left and right lower arms 110 so as to be pivotable. In the vicinity of the rear ends of the left and right trailing arms 114, mounting portions 114A for left and right rear wheel knuckle members (not shown) are formed. The trailing arm mounting portion 14A of the rear frame 14 is located in front of the vehicle body from the vehicle longitudinal direction position corresponding to the position of the first rear floor cross member 24 (see FIG. 4).

  Next, a support structure for the battery case 90 will be described with reference to FIGS. 1 to 3 and FIGS. 7 to 9. The battery case 90 is supported by a first lower cross member 40, a second lower cross member 42, a third lower cross member 44, and a fourth lower cross member 46 provided at four locations in the longitudinal direction of the vehicle body. Yes. The first lower cross member 40 is located at the foremost side of the vehicle body, whereby the second to fourth lower cross members 42, 44, and 46 are sequentially arranged behind the vehicle body at a predetermined longitudinal interval. The first to fourth lower cross members 40, 42, 44, and 46 are each formed by joining two press-formed steel plates and have a flat closed cross-sectional shape.

  As shown in FIGS. 1 and 2, the first lower cross member 40 extends horizontally so as to cross the lower surface side of the battery case 90 in the vehicle body width direction, and both ends thereof are respectively left and right from the floor frames 12. It is detachably fixed to the lower end of the suspended box-shaped leg member 48 with a bolt 50 or the like. The first lower cross member 40 is fixed to the lower surface of the battery case 90 by a plurality of bolts 52 between the left and right floor frames 12, and supports the battery case 90 from below.

  Similarly, as shown in FIGS. 1 and 2, the second lower cross member 42 extends horizontally so as to cross the lower surface side of the battery case 90 in the vehicle body width direction, and has both ends of the left and right floor frames. 12 are respectively detachably fixed to the lower ends of box-shaped leg members 54 depending from each other by bolts 56 or the like. The second lower cross member 42 is fixed to the lower surface of the battery case 90 by a plurality of bolts 58 between the left and right floor frames 12, and supports the battery case 90 from below.

  The upper ends of the leg members 48 and 54 are fixed to the floor frame 12 by welding.

  Outriggers 60 and 62 are provided between the left and right floor frames 12 and the side sill 16 at the position in the vehicle longitudinal direction corresponding to the positions of the first lower cross member 40 and the second lower cross member 42. Yes. The outriggers 60 and 62 are joined to the floor frame 12 and the side sill 16 to form a box shape.

  The outriggers 60 and 62 have lower strength and lower rigidity than the floor frame 12 and the side sill 16 and are weaker than the floor frame 12 and the side sill 16. For example, the outriggers 60 and 62 are made of plain steel plates having a small thickness. Acts as an impact-absorbing member that is crushed (plastically deformed) by side impact energy greater than the value.

  As shown in FIGS. 1 to 3, 7, and 8, a connecting member 64 is provided between the vicinity of the rear ends of the left and right floor frames 12 and the vicinity of the rear ends of the left and right side sills 16. ing. The connecting member 64 has a groove-like cross-sectional shape and is joined to each lower surface of the floor frame 12, the side sill 16, and the front floor panel 18 by a flange piece 64A provided at each edge portion to form a box shape.

  Since the connecting member 64 connects the floor frame 12 and the side sill 16, the rigidity of the rear part of the vehicle body is improved and the road noise performance is improved. Further, similar to the outriggers 60 and 62, the floor frame 12 and the side sill 16 may be lower in strength and rigidity, and more fragile than the floor frame 12 and the side sill 16. In this case, the connecting member 64 also functions as an impact absorbing member that is crushed (plastically deformed) by side collision energy of a predetermined value or more.

  The third lower cross member (fourth cross member) 44 extends horizontally so as to cross the lower surface side of the battery case 90 in the vehicle body width direction, and both ends thereof are fixed to the left and right connecting members 64. The third lower cross member 44 is fixed to the connecting member 64 by a bolt 70 and a nut 72 that pass through the mounting member 66 having a U-shaped cross section and the collar member 68 disposed inside the mounting member 66. It has been broken. The third lower cross member 44 is fixed to the bottom surface of the battery case 90 between the left and right floor frames 12 by welding, and supports the battery case 90 from below.

  As shown in FIG. 9, the upper ends of the left and right leg members 76 are detachably fixed to the left and right sides of the lower surface of the first rear floor cross member 24 by bolts 74 with the rear floor panel 20 interposed therebetween. The left and right leg members 76 are high-rigidity members having ribs 76 </ b> A, are located on the inner side in the vehicle body width direction from the left and right rear frames 14, and are suspended from the first rear floor cross member 24.

  The fourth lower cross member (third cross member) 46 extends horizontally so as to cross the lower surface side of the battery case 90 in the vehicle body width direction, and both ends are connected to the lower ends of the left and right leg members 76 via the collar 80. The bolt 78 and the nut 79 are detachably fixed. The fourth lower cross member 46 is fixed to the bottom surface of the battery case 90 between the left and right floor frames 12 by welding, and supports the battery case 90 from below.

  In this way, the fourth lower cross member 46 is disposed behind the trailing arm attachment portion 14A, which is the attachment portion of the trailing arm 114 to the rear frame 14, and the battery case 90 is located behind the trailing arm attachment portion 14A. The rear end side is supported.

  Since the fourth lower cross member 46 is fixed to the first rear floor cross member 24 via the leg member 76 not on the rear frame 14 but on the inner side in the vehicle width direction from the rear frame 14, it interferes with the trailing arm 114. The rear end side of the battery case 90 can be supported behind the trailing arm attachment portion 14A. Thus, the battery case 90 can be extended to the vicinity of the rear wheel axle arrangement behind the trailing arm mounting portion 14A, and the battery stored in the battery case 90 can be used under the floor panel effectively. The capacity of the pack 92 is increased.

  In the embodiment described above, the first lower cross member 40 and the second lower cross member 42 are fixed to the battery case 90 by bolt fastening, and the third lower cross member 44 and the fourth lower cross member 46 are fixed to the battery case 90. Although it is welded, all of this may be done by bolting or welding.

  Since the first to fourth lower cross members 40, 42, 44, 46 are fixed to the floor frame 12, the connecting member 64, and the leg member 76 by detachable bolts 50, 56, 70, 78, the battery Attachment and removal of the case 90 can be easily performed from below the floor panel.

  As shown in FIGS. 1, 2, 5, and 7, two right and left rods 82 are bridged between the second rear floor cross member 26 and the fourth lower cross member 46. . Each of the left and right rods 82 has a rear end coupled to the center of the second rear floor cross member 26 in the vehicle width direction by a bolt 84 and a front end coupled to the end of the fourth lower cross member 46 in the vehicle width direction by a bolt 86. Thus, it is arranged in a “C” shape in plan view.

  The positions at which the rear ends of the left and right rods 82 are connected to the second rear floor cross member 26 are positions adjacent to the inner side in the vehicle width direction of the left and right lower arm attachment portions 26B, respectively, on the valley-side inclined surfaces between the two bulging portions 26A. It is in.

  Each of the left and right rods 82 has a bent portion 82A bent downward at the front end vicinity portion and the rear end vicinity portion, and the space between the front and rear bent portions 82A is as shown in FIG. The bulging portion 82B bulges downward from the lower surface of the battery case 90. The bulging portion 82B prevents a curb collision between the attachment point of the rod 82 to the second rear floor cross member 26 and the attachment point of the lower arm 110 to the second rear floor cross member 26 when retreating.

  Further, the left and right rods 82 form a truss structure in cooperation with the second rear floor cross member 26 and the fourth lower cross member 46.

  As a result, the strength of the second rear floor cross member 26 against the vehicle body tilting in the longitudinal direction is improved, and the movement of the second rear floor cross member 26 toward the front of the vehicle body at the time of a rear collision is suppressed. Thus, it is avoided that the second rear floor cross member 26 for supporting the lower arm of the rear wheel suspension hits the rear part of the battery case 90 by the forward movement at the time of the rear collision, and the battery case 90 is protected from the rear collision by two right and left. Only the addition of the rod 82 can be appropriately performed without significant addition of parts.

  Further, the two left and right rods 82 form a truss structure with the second rear floor cross member 26 and the fourth lower cross member 46, whereby the lateral rigidity of the lower arm mounting portion 26B is improved. As a result, the lateral rigidity of the lower arm 110 is improved and the stability of the geometry of the rear wheel suspension is improved. Thereby, steering stability performance improves. The effect of improving the maneuverability is that the position of the rear end of the left and right rods 82 connected to the second rear floor cross member 26 is located adjacent to the inner side in the vehicle width direction of the lower arm mounting portion 26B. It will be located in the vicinity of the lower arm attachment portion 26B, and the lateral rigidity of the lower arm attachment portion 26B will be effectively improved and will be remarkable.

  When the collision energy exceeding the allowable value is applied to the second rear floor cross member 26 due to the rear collision, the rod 82 is bent. As a result, the collision energy of the rear collision is absorbed by the bending of the rod 82, and a large collision load is avoided from acting on the battery case 90. Since the bending of the rod 82 due to the collision energy is likely to be generated by the bent portion 82A, the bending performance of the rod 82 due to the collision energy can be set by the bent shape of the bent portion 82A.

  Further, the bulging portion 82B of the rod 82 located below the battery case 90 is a curb in the back curb mode in which the curb (projection from the road surface) passes between the left and right rear tires when the vehicle moves backward. Functions as a grounding guard that prevents the battery case 90 from contacting (grounding).

  As shown in FIG. 1, a plate-like under cover 89 that covers the entire lower surface of the battery case 90 is provided below the first to fourth lower cross members 40, 42, 44, 46. 12 and side sill 16 are detachably attached. The under cover 89 protects the battery case 90 against grounding, stepping stones, and the like.

  Further, a grounding guard member 88 having a V-shaped cross section projecting downward from the second rear floor cross member 26 is attached to the center of the second rear floor cross member 26 in the vehicle width direction. The ground guard member 88 also serves as a jack-up plate, and functions as a ground guard that prevents the curb from contacting (grounding) the battery case 90 in the back curb mode.

  Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to such embodiments so that those skilled in the art can easily understand, and departs from the spirit of the present invention. It is possible to change appropriately within the range not to be.

  For example, the rear frame 14 may be integrated with the side sill 16 or the floor frame 12. The floor frame 12 may not be joined to the rear frame 14, and the rear end of the floor frame 12 may be joined to the left and right side sills 16 or the floor cross member connecting the rear frame 14. Further, the floor frame 12, the rear frame 14, and the side sill 16 may each be formed by joining a plurality of constituent members. The rod 82 may bulge downward from the lower surface of the battery case by bending. The first to fourth lower cross members 40, 42, 44, 46 can be fixed to the side members by using other detachable fasteners such as clips, without using the bolts 50, 56, 70, 78. You may go.

  In addition, all the components shown in the above embodiment are not necessarily essential, and can be appropriately selected without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Front side frame 12 Floor frame 14 Rear frame 16 Side sill 18 Front floor panel 20 Rear floor panel 22 Spare tire pan 24 1st rear floor cross member (1st cross member)
26 Second rear floor cross member (second cross member)
26A bulging portion 40 first lower cross member 42 second lower cross member 44 third lower cross member (fourth cross member)
46 Fourth lower cross member (third cross member)
64 connecting member 76 leg member 82 rod 82A bent portion 82B bulging portion 88 ground guard member 90 battery case 110 lower arm 114 trailing arm

Claims (6)

Left and right rear frames extending in the longitudinal direction of the vehicle body, left and right edge portions joined to the left and right rear frames and a rear floor panel extending between the left and right rear frames, and both ends joined to the left and right rear frames A first cross member, and a lower arm attachment portion that is located rearward of the first cross member and has both ends joined to the left and right rear frames and supports the left and right lower arms of the rear wheel suspension. A vehicle body rear structure having two cross members, the left and right leg members respectively hanging from both ends of the first cross member, and both ends fixed to lower ends of the left and right leg members, A vehicle between the third cross member that supports the battery case disposed on the lower surface side of the floor panel and the left and right lower arm attachment portions (26B) of the second cross member at the rear end. A pair of left and right rods forming the Ha-shape in plan view are coupled with the front end being coupled to the widthwise central portion to the end portion of the vehicle body width direction of the third cross member,
An underbody structure of an automobile having   The vehicle body lower part structure according to claim 1, wherein the rod is bent or curved so as to bulge downward from a lower surface of the battery case.   The left and right rear frames have attachment portions for left and right trailing arms of a rear wheel suspension, and the third cross member is disposed rearward of the attachment portion for the trailing arms. The car body lower structure described.   The vehicle body lower part structure according to any one of claims 1 to 3, wherein a grounding guard member protruding downward from the second cross member is attached to a center part of the second cross member in the vehicle width direction. .   The automobile according to any one of claims 1 to 4, wherein the fixing of the third cross member to the leg member and the fixing of the rod to the third cross member are detachable by a fastener. Car body lower structure. Furthermore,
Left and right side sills that extend in the longitudinal direction of the vehicle body and have rear ends joined to the left and right rear frames;
Left and right floor frames that extend in the vehicle body longitudinal direction from the left and right side sills in the vehicle longitudinal direction, and the rear ends are joined to the left and right rear frames;
Left and right connecting members respectively joined to the left and right floor frames and the left and right side sills;
A fourth cross member having both ends fixed to the left and right connecting members and supporting the battery case;
The vehicle body lower part structure according to any one of claims 1 to 5, comprising:

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