Lower vehicle-body structure of vehicle

Abstract

To provide a lower vehicle-body structure of a vehicle that can obtain excellent steering stability and preferable riding comfort by inhibiting inward falling deformation of a suspension housing formed by a sheet metal even when a load acting toward the vehicle-width-direction inner side is transmitted from the suspension housing during normal traveling.SOLUTION: A suspension housing 4 formed by a sheet metal, provided on a frame 3 forming a closed cross-section portion 3s extending in a front-back direction, and supporting a suspension, includes: a damper mounting surface portion 41; and a peripheral wall 42 extending downward from a peripheral edge of the damper mounting surface portion 41. A vehicle-width-direction inner side of the frame 3 has an inner flange portion 35b to which a floor panel 2 is fixed. At the inner side in the vehicle width direction relative to the peripheral wall 42, a connecting surface portion 61 is provided that connects a vehicle-width-direction inner part of the peripheral wall 42 with the inner flange portion 35b such that the connecting surface portion extends downward toward the vehicle-width-direction inner side.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle lower body structure including a frame that defines a closed cross-section portion extending in the front-rear direction on the vehicle width direction outer side of a floor panel, and a suspension housing provided on the frame. [Background technology]

[0002] In order to achieve excellent handling stability and a comfortable ride during normal driving, it is important for the lower body structure of a vehicle to ensure rigidity against the load input from the suspension via the suspension housing (hereinafter also referred to as "sus housing") that supports the suspension.

[0003] The lower body structure of such a vehicle has traditionally been configured to have a frame that forms a closed cross-section extending in the fore-and-aft direction on the outer side of the floor panel in the vehicle width direction, with a suspension housing located on the outer side of the frame in the vehicle width direction.However, recently, structures in which the suspension housing is located on the frame, such as that disclosed in Patent Document 1, have also become known.

[0004] The suspension housing in Patent Document 1 is made of die-cast aluminum, which is said to have a high degree of freedom in shape, and therefore can easily ensure the desired rigidity by providing ribs to the housing itself, thereby reinforcing the frame. On the other hand, it is also possible to make the suspension housing mounted on the frame out of sheet metal, which has the advantage of being easier to manufacture using conventional manufacturing processes than die-cast aluminum, but sheet metal tends to have less freedom in shape than die-cast aluminum and to be heavier in order to ensure rigidity.

[0005] In this case, for example, when an input load from the suspension to the inside of the vehicle width direction due to up and down displacement of the suspension during normal driving is transmitted from the suspension to the frame via the suspension housing, the frame may not be able to prevent the suspension housing, which is made of sheet metal and has low freedom of shape and tends to be heavy to ensure rigidity, from collapsing inward toward the frame, which may result in a negative impact on handling stability and ride comfort. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2023-035561 Summary of the Invention [Problem to be solved by the invention]

[0007] This invention has been made in consideration of these problems, and aims to provide a lower body structure for a vehicle in which the suspension housing mounted on the frame is made of sheet metal, and which is capable of suppressing inward deformation of the suspension housing even when a load is transmitted from the suspension housing to the inside in the vehicle width direction during normal driving, thereby achieving excellent handling stability and a good ride comfort. [Means for solving the problem]

[0008] The lower body structure of a vehicle of this invention comprises a frame that forms a closed cross-section extending in the fore-and-aft direction on the vehicle width outer side of the floor panel, and a suspension housing made of sheet metal that is attached to the frame and supports a suspension, the suspension housing having a damper mounting surface portion that follows the upper surface of the frame and a peripheral wall portion that extends downward from the periphery of the damper mounting surface portion, an inner flange portion to which the floor panel is fixed on the vehicle width inner side of the frame, and a connecting surface portion that is further inward in the vehicle width direction than the peripheral wall portion and connects the vehicle width inner portion of the peripheral wall portion and the inner flange portion downward as it moves inward in the vehicle width direction.

[0009] According to the above configuration, even if a load is transmitted from the suspension housing toward the inside in the vehicle width direction during normal driving, the connecting surface portion acts to brace between the inner flange portion and the peripheral wall portion, thereby suppressing inward deformation of the suspension housing. Therefore, excellent handling and stable driving are possible.

[0010] As an aspect of the present invention, the connecting surface portion may overlap in a front-to-rear position with an opening formed to penetrate the damper mounting surface portion in the up-down direction. With this configuration, the load from the suspension is input inward in the vehicle width direction through the opening in the damper mounting surface, which is the center of the damper mounting position, so the suspension housing can be efficiently supported by the connecting surface at a position as close as possible to the load input source.In other words, the connecting surface can exert a bracing effect against the load transmitted inward in the vehicle width direction from the suspension housing, effectively suppressing inward collapse of the suspension housing.

[0011] In another aspect of the present invention, the connecting surface portion may be fixed above a middle position in the height direction of the peripheral wall portion. For example, when the peripheral wall portion is configured to extend in the vertical direction so as to connect the lower wall portion of the frame and the damper mounting surface portion, the height of the peripheral wall portion is defined as the height of the portion excluding the R-shaped portion at the connecting portion between the lower wall portion and the damper mounting surface portion.

[0012] According to the above configuration, when the axial force of the connecting surface portion is used to support the peripheral wall portion that is about to undergo inward deformation, the connecting surface portion can be braced at a location where a large moment can be applied to the peripheral wall portion, thereby effectively suppressing the inward deformation of the peripheral wall portion.

[0013] In another aspect of the present invention, the connecting surface portion has an outer fixing portion relative to the peripheral wall portion and an inner fixing portion relative to the frame, and the outer fixing portion and the inner fixing portion may be arranged in positions where at least a portion of them overlap each other in the front-to-rear direction.

[0014] According to the above configuration, even if a load is input from the suspension to the suspension housing in the vehicle width direction during normal driving, the load can be transmitted smoothly and linearly along the vehicle width direction from the peripheral wall portion to the inner flange portion via the connecting surface portion, i.e., to the vehicle width direction inward of the vehicle body.

[0015] As another aspect of the present invention, the connecting surface portion may be formed linearly along the vehicle width direction. According to the above configuration, even if a load is input from the suspension to the suspension housing in the vehicle width direction during normal driving, the load can be smoothly transmitted from the peripheral wall portion to the inner flange portion, i.e., to the vehicle width direction inward of the vehicle body, via the connecting surface portion.

[0016] In another aspect of the present invention, the closed cross-sectional portion of the frame, which is located more inward in the vehicle width direction than the peripheral wall portion, may be provided with a U-shaped joint member whose cross-section along the fore-and-aft direction opens downward, and the connecting surface portion may be formed by the upper wall portion of the joint member. According to the above configuration, by forming the connecting surface portion as a part of the joint member having a U-shaped cross section, it is possible to increase rigidity compared to when the connecting surface portion is provided alone.

[0017] In another aspect of the present invention, a cross member connecting the pair of left and right frames may be provided along the vehicle width direction, and the cross member may be positioned in a front-to-rear position overlapping with the damper mounting surface portion.

[0018] It is preferable that the cross member is positioned so as to completely overlap the damper mounting surface, but it is sufficient that the cross member is positioned so as to overlap at least partially.

[0019] According to the above configuration, even if a load is input from the suspension to the suspension housing in the vehicle width direction during normal driving, the load can be smoothly transmitted to the cross member via the connecting surface portion.

[0020] In another aspect of the present invention, the frame may be composed of a front frame portion and a rear frame portion, and the connecting surface portion may be fixed to the joining portion where the front frame portion and the rear frame portion are overlapped.

[0021] According to the above configuration, the joint portion between the frame front portion and the frame rear portion can be reinforced by the connecting surface portion fixed to the joint portion. Furthermore, the joint portion between the frame front portion and the frame rear portion has high rigidity because the frame front portion and the frame rear portion are overlapped, and by fixing the connecting surface portion to such a joint portion with high rigidity, it is possible to enhance the effect of the connecting surface portion in bracing and supporting the peripheral wall portion, which tends to collapse inward. [Effects of the Invention]

[0022] According to this invention, in a configuration in which the suspension housing mounted on the frame is made of sheet metal, it is possible to provide a lower body structure for a vehicle that can suppress inward collapse deformation of the suspension housing even when a load is transmitted from the suspension housing to the inside in the vehicle width direction during normal driving, thereby achieving excellent handling stability and a good ride comfort. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a perspective cross-sectional view of the lower vehicle body structure of the present embodiment as viewed from the luggage compartment side. [Figure 2] An enlarged cross-sectional view showing the main part along the line AA in Figure 1. [Figure 3] 3 is a perspective cross-sectional view taken from above along the arrow BB in FIG. 2. [Figure 4] An enlarged view of the suspension housing and its surrounding area, with part of the rear frame omitted from Figure 1. [Figure 5] Enlarged cross-sectional view of line CC in Figure 4 [Figure 6] Enlarged cross-sectional view of line DD in Figure 4 [Figure 7] An end view showing the main part along the line DD in Figure 4. [Figure 8] An enlarged cross-sectional view showing the main part along the line EE in Figure 4. [Figure 9] Enlarged cross-sectional view of the main part along line GG in Figure 4. [Figure 10] (a) is a view taken along the arrow Da in Figure 4, and (b) is an enlarged cross-sectional view taken along the line HH in Figure 10(a). DETAILED DESCRIPTION OF THE INVENTION

[0024] An embodiment of the present invention will be described in detail below with reference to the drawings. The drawings show a lower body structure V1 of an automobile according to this embodiment. FIG. 1 is a perspective cross-sectional view of a rear body V including the lower body structure V1, cut along the longitudinal direction at a midpoint in the vehicle width direction and viewed from the luggage compartment side. FIG. 2 is an enlarged cross-sectional view of a main part taken along line AA in FIG. 1, omitting upper rear member 132R (see FIG. 1) of rear frame 3 and rear floor panel 2 (see FIG. 1). FIG. 3 is a perspective cross-sectional view taken from above along line BB in FIG. 2. FIG. 4 is a perspective cross-sectional view of the upper rear part 132R in FIG. 1. 4. FIG. 6 is an enlarged cross-sectional view taken along line DD in FIG. 4. FIG. 7 is an end view showing the main parts along line DD in FIG. 4. FIG. 8 is an enlarged cross-sectional view taken along line EE in FIG. 4. FIG. 9 is an enlarged cross-sectional view showing the main parts along line GG in FIG. 4. FIG. 10(a) is a view taken along arrow Da in FIG. 4. FIG. 10(b) is an enlarged cross-sectional view taken along line HH in FIG. 10(a).

[0025] In the drawings, arrow Rr indicates the rear of the vehicle body, arrow U indicates the upper side of the vehicle body, arrow RH indicates the right side of the vehicle body, and arrow OUT indicates the outer side in the vehicle width direction. In the following description, unless otherwise specified, the front, rear, left, right, up, and down directions respectively indicate the front, rear, left, right, up, and down directions of the vehicle body, and the above directions of the vehicle body are based on the passenger seated in the driver's seat.

[0026] Furthermore, since the automobile lower body structure V1 of this embodiment has a substantially bilaterally symmetrical shape, the following description will be based on the configuration of the right side of the vehicle body unless otherwise specified. Note that in the drawings, "x" marks indicate major spot weld locations, and "o" marks surrounding "x" marks indicate welding areas. In the following description, reinforcement will be abbreviated to "rein."

[0027] The lower body structure V1 of an automobile according to this embodiment is applied to the rear body V. Prior to describing the lower body structure V1, the upper peripheral structure of the lower body structure V1 in the rear body V will be described.

[0028] As shown in FIG. 1, the upper periphery of the lower vehicle body structure V1 of this embodiment mainly includes a side panel 100, a roof side rail 101, a roof rain 102, a rear header rain 103, an intermediate pillar 104, a rear pillar 105, and brace members 107, 108 on the front and rear sides.

[0029] The side panel 100 is located above a wheel house inner 1a (described later) and cooperates with the wheel house inner 1a to form a side wall of the luggage compartment in the rear part of the vehicle body V. The lower edge of the side panel 100 is joined to the upper edge of the wheel house inner 1a.

[0030] The roof side rail 101 comprises a roof side rail inner 101a and a roof side rail outer (not shown), and forms a closed cross-sectional portion 101s extending in the fore-and-aft direction of the vehicle at both ends in the vehicle width direction of the roof portion that forms the ceiling surface of the passenger compartment in the vehicle body.

[0031] The roof rain 102 is stretched between the left and right roof side rails 101 and joined to the underside of a plate-shaped roof panel provided on the roof portion and extending in the vehicle width direction and the front-to-rear direction so as to be able to support the roof panel. The rear header rain 103 cooperates with the rear end of the roof panel at the rear edge of the roof portion to form a closed cross-sectional portion 103s extending in the vehicle width direction. The rear header rain 103 also forms the upper edge of a rear luggage compartment opening 110 that opens from the luggage compartment side toward the rear of the vehicle body.

[0032] The intermediate pillar 104 (so-called C-pillar) has a closed cross-sectional portion 104s extending in the vertical direction of the vehicle body, and connects the rear of the roof side rail 101 with the rear of the side sill 111. The side sill 111 is a vehicle body strength member that forms the closed cross-sectional portion 111s extending in the longitudinal direction at both left and right ends of a front floor panel (not shown) that forms the floor of the vehicle interior. The upper part of the intermediate pillar 104 forms the front edge of an opening 112 for a quarter window. Furthermore, the vertical middle part of the intermediate pillar 104 is located at the front edge of the side panel 100, and the lower part of the intermediate pillar 104 is located at the front edge of the rear wheel house 1.

[0033] The rear pillar 105 (so-called D-pillar) forms a closed cross-section portion 105s that extends downward and rearward from the outer end of the rear header train 103 in the vehicle width direction so as to form the side edge of the rear luggage compartment opening 110. The upper portion of the rear pillar 105 is joined to the rear edge of the side panel 100.

[0034] The front and rear brace members 107, 108 are both joined to the side panel 100 from the luggage compartment side. Of the front and rear brace members 107, 108, the front brace member 107 forms a closed cross-sectional portion 107s that extends in the vertical direction to connect the lower part of the intermediate pillar 104 to the outer edge of the cross member upper 51 in the vehicle width direction, which will be described later. Of the front and rear brace members 107, 108, the rear brace member 108 forms a closed cross-sectional portion 108s that extends in the vertical direction to connect the upper end of the rear pillar 105 to the portion of the wheelhouse inner 1a directly above a suspension housing 4, which will be described later.

[0035] Next, the vehicle lower body structure V1 of the present embodiment will be described. As shown in Figures 1 to 10, particularly Figure 1, the automobile lower body structure V1 of this embodiment mainly includes a rear wheel house 1, a rear floor panel 2, a rear frame 3, a suspension housing 4, and a plurality of rear cross members 51, 53, 55, 57, etc.

[0036] The rear wheel house 1 is provided directly below the side panel 100 and is formed in an arch shape with the central portion in the front-to-rear direction protruding upward in a side view of the vehicle so that a rear wheel can be accommodated, and is equipped with an outer wheel house (not shown) that protrudes outward in the vehicle width direction and an inner wheel house 1a that protrudes inward in the vehicle width direction. The inner wheel house 1a and the outer wheel house are joined together at their peripheral edges except for the lower end.

[0037] The rear floor panel 2 has a rear seat pan 21 and a rear floor pan 22 disposed on the front and rear sides, respectively, and integrally or integrally connected to each other.

[0038] The rear seat pan 21 is a front rear floor for mounting a rear seat (rear seat) on its upper portion, and the above-mentioned rear floor pan 22 is a rear rear floor for forming the luggage compartment floor surface, and a luggage compartment recess 22a is recessed and formed in the rear portion of the rear floor pan 22.

[0039] As shown in FIGS. 1, 7, etc., the rear frames 3 are disposed on both the left and right sides of the rear floor panel 2 and extend in the front-rear direction. 1, the front end of the rear frame 3 is arranged to overlap the rear end of side sills 111 provided on both the left and right sides of a front floor panel (not shown). Meanwhile, rear bumper reinforcements (not shown) extending in the vehicle width direction are connected to the rear end of each of the left and right rear frames 3 so as to be able to absorb impact energy in the event of a rear collision.

[0040] As shown in Figure 5, etc., the rear frame 3 has an upper wall portion 31 that forms the upper surface of the rear frame 3 that extends along the vehicle width direction, a lower wall portion 32 that forms the lower surface of the rear frame 3 that extends along the vehicle width direction, an inner wall portion 33 that joins the inner ends of the upper wall portion 31 and the lower wall portion 32 in the vehicle width direction at the top and bottom, and an outer wall portion 34 that joins the outer ends of the upper wall portion 31 and the lower wall portion 32 in the vehicle width direction at the top and bottom.

[0041] The rear frame 3 includes a rear frame lower 131 whose cross section along the vehicle width direction opens upward, and a rear frame upper 132 that closes the opening of the rear frame lower 131 from above. The rear frame lower 131 is integrally formed by press-forming a steel plate, including an outer wall portion 34, a lower wall portion 32, an inner wall main body portion 33a excluding the upper portion of the inner wall portion 33, a lower inner edge flange portion 35a, and a lower outer edge flange portion 36a. The lower inner edge flange portion 35a protrudes substantially horizontally from the upper end of the inner wall main body portion 33a toward the inside in the vehicle width direction. The lower outer edge flange portion 36a protrudes upward from the upper end of the outer wall portion 34.

[0042] The rear frame upper 132 is integrally formed by press-forming a steel plate, including the upper wall portion 31, an inner wall upper portion 33b corresponding to the upper portion of the inner wall portion 33, an upper inner edge flange portion 35b, and an upper outer edge flange portion 36b. The upper inner edge flange portion 35b is formed to protrude substantially horizontally from the lower end of the inner wall upper portion 33b toward the inside in the vehicle width direction. The upper outer edge flange portion 36b is formed to protrude upward from the outer edge of the upper wall portion 31 in the vehicle width direction.

[0043] The rear frame lower 131 and the rear frame upper 132 are spot welded together with the lower inner edge flange portion 35a and the upper inner edge flange portion 35b overlapping in the vertical direction, and the upper outer edge flange portion 36b and the lower outer edge flange portion 36a overlapping in the vehicle width direction.

[0044] As a result, the rear frame 3, the rear frame lower 131 and the rear frame upper 132 cooperate to form a closed cross-sectional portion 3s extending in the front-rear direction, that is, an internal space with a closed cross-section.

[0045] 3 and 9, the upper inner edge flange portion 35b and the lower inner edge flange portion 35a of the rear frame lower 131 are overlapped so as to sandwich the outer end of the rear floor pan 22 in the vehicle width direction from above and below, and these three pieces are joined by spot welding. As shown in FIG. 3, a plurality of spot welds w35 where these three pieces are overlapped are formed in the front-to-rear direction. As a result, both ends of the rear floor pan 22 in the vehicle width direction are connected to the left and right rear frames 3.

[0046] 1 and 4, the rear frame 3 extends in the front-rear direction so that its midsection in the front-rear direction is adjacent to the inside of the vertical-wall-shaped wheelhouse inner 1a in the vehicle width direction. In this midsection, as shown in Fig. 5, the lower outer edge flange 36a, to which the upper outer edge flange 36b is joined from the inside in the vehicle width direction, is joined to the wheelhouse inner 1a from the inside in the vehicle width direction by spot welding or the like.

[0047] 1 and 4, the rear frame upper 132 provided on the rear frame 3 includes an upper front member 132F and an upper rear member 132R on the front and rear sides as its constituent members. The connection portion between the rear portion of the upper front member 132F and the front portion of the upper rear member 132R is formed as an overlapping connection portion 132C in which the upper front and rear members are joined together while overlapping each other in the front-to-rear direction.

[0048] Similarly, as shown in Figures 3, 4, 8, and 9, the rear frame lower 131 provided on the rear frame 3 includes a lower front member 131F and a lower rear member 131R on the front and rear sides as its constituent members. The connection between the rear portion of the lower front member 131F and the front portion of the lower rear member 131R is formed as an overlapping connection portion 131C in which the two members are joined together while overlapping each other in the front-to-rear direction. Note that the overlapping connection portion 132C is located forward of the overlapping connection portion 131C.

[0049] In this embodiment, as shown in FIG. 3 and other figures, the front portion of the lower rear member 131R is disposed so as to overlap the rear portion of the lower front member 131F from below at the overlapping connection portion 131C.

[0050] 1 and 4, a suspension housing 4 (abbreviated as "sus housing 4") is provided on the rear frame 3. As shown in Fig. 6, the suspension housing 4 is a damper support part that supports the upper end of a rear suspension damper 120 equipped with a damper spring, and is made of sheet metal and has a damper mounting surface part 41 and a peripheral wall part 42.

[0051] The suspension housing 4 is provided on the rear frame 3 adjacent to the wheelhouse inner 1a on the inner side in the vehicle width direction, and the upper part of the suspension housing 4 is raised in a stepped manner from the upper surface of the rear frame 3 around the suspension housing 4 to form part of the upper surface of the rear frame 3. The configuration of the suspension housing 4 and its surrounding areas will be explained later.

[0052] Furthermore, as shown in Figure 1, the above-mentioned multiple rear cross members 51, 53, 55, 57 include front rear cross members 51, 53 arranged forward of the suspension housing 4, an intermediate rear cross member 55 located in the same fore-and-aft position as the suspension housing 4, and a rear rear cross member 57 arranged rearward of the suspension housing 4, and are arranged spaced apart from each other in the fore-and-aft direction.

[0053] The front rear cross members 51, 53 are composed of an upper cross member 51 (so-called No. 4 upper cross member) and a lower cross member 53 (so-called No. 4 lower cross member).

[0054] The upper cross member 51 has a hat-shaped cross section along the front-rear direction that opens downward, and the lower cross member 53 has a hat-shaped cross section along the front-rear direction that opens upward. The upper cross member 51 and the lower cross member are joined to the boundary between the rear seat pan 21 and the rear floor pan 22 so as to sandwich the boundary from above and below. The upper cross member 51 and the lower cross member each define closed cross-sectional portions 52, 54 extending in the vehicle width direction between the boundary and are connected at both widthwise ends to the corresponding left and right rear frames 3.

[0055] 1, the intermediate rear cross member 55 and the rear rear cross member 57 both have a cross section along the fore-and-aft direction that is hat-shaped and open at the top, and are joined to the rear floor pan 22 from below, forming closed cross-sectional portions 56, 58 that extend in the vehicle width direction between them and the rear floor pan 22. Furthermore, the intermediate rear cross member 55 and the rear rear cross member 57 both extend along the width direction below the rear floor pan 22, and both ends in the width direction are connected to the corresponding left and right rear frames 3, respectively.

[0056] As shown in Figures 3, 6, 7, and 9, the intermediate rear cross member 55 is located at the same fore-and-aft position as the overlapping connection portion 131C, which connects the rear end of the lower front member 131F and the front end of the lower rear member 131R of the rear frame 3 by overlapping them in the fore-and-aft direction.

[0057] The configuration of the intermediate rear cross member 55 will now be described in further detail. As shown in Figures 3 and 9, the intermediate rear cross member 55 comprises a lower wall portion 55a, a front wall portion 55b and a rear wall portion 55c extending upward from both the front and rear ends of the lower wall portion 55a, a leading edge flange portion 55d extending forward from the upper end of the front wall portion 55b, and a rear edge flange portion 55e extending rearward from the upper end of the rear wall portion 55c, and its cross section along the fore-and-aft direction is configured in a hat shape with an upward opening.

[0058] 1, intermediate rear cross member 55 has leading edge flange portion 55d and trailing edge flange portion 55e joined from below to rear floor pan 22, except for both ends in the vehicle width direction. As a result, intermediate rear cross member 55 forms a closed cross-sectional portion 56 that extends linearly in the vehicle width direction between it and rear floor pan 22.

[0059] 3 and 9, intermediate rear cross member 55 has ridge lines extending linearly along the vehicle width direction at corners between front wall portion 55b and leading edge flange portion 55d, between front wall portion 55b and lower wall portion 55a, between rear wall portion 55c and trailing edge flange portion 55e, and between rear wall portion 55c and lower wall portion 55a. These ridge lines are referred to as front upper ridge line 551, front lower ridge line 552, rear upper ridge line 553, and rear lower ridge line 554, in the order of the corners.

[0060] 6, 7 and 9, intermediate rear cross member 55 is provided at both ends in the vehicle width direction with a front outer edge flange portion 55f, a rear outer edge flange portion 55g and a lower outer edge flange portion 55h.

[0061] As shown in Figure 9, the front outer edge flange portion 55f is formed at both ends of the intermediate rear cross member 55 in the vehicle width direction so as to protrude forward relative to the front wall portion 55b and downward relative to the front edge flange portion 55d, and is spot welded to the inner wall portion 33 of the rear frame 3.

[0062] The rear outer edge flange portion 55g is formed at both ends of the intermediate rear cross member 55 in the vehicle width direction so as to protrude rearward relative to the rear wall portion 55c and downward relative to the rear edge flange portion 55e, and is spot welded to the inner wall portion 33 of the rear frame 3.

[0063] 6 and 7, the lower outer edge flange portions 55h are formed at both widthwise ends of the intermediate rear cross member 55 so as to protrude outward in the vehicle width direction relative to the lower wall portions 55a, and are spot welded to the lower wall portions 32 of the overlapping connection portions 131C of the rear frames 3. As a result, both widthwise ends of the intermediate rear cross member 55 are connected to the corresponding left and right rear frames 3, as described above.

[0064] 9, the "x" marks on the intermediate rear cross member 55 indicate spot welds to the rear frame 3. Of these spot welds, the spot weld on the front outer edge flange portion 55f of the intermediate rear cross member 55 is designated as the front outer fixed portion w5a, and the spot weld on the rear outer edge flange portion 55g of the intermediate rear cross member 55 is designated as the rear outer fixed portion w5b. Furthermore, as shown in FIG. 6, the spot weld on the lower outer edge flange portion 55h of the intermediate rear cross member 55 is designated as the lower outer fixed portion w5c.

[0065] Next, the configuration of the suspension housing 4 and its surrounding areas will be described in detail. As described above, the suspension housing 4 includes the damper mounting surface portion 41 and the peripheral wall portion 42 (see FIGS. 2 to 5, 6, 8, and 9). The damper mounting surface 41 corresponds to the upper surface of the suspension housing 4, and is formed in the shape of a flat plate that fits along the upper surface of the rear frame 3. An opening 46 is formed in the center of the damper mounting surface 41 in a plan view, penetrating the damper mounting surface 41 in the vertical direction. The rear suspension damper 120 (see FIG. 6) is attached from below to the periphery of the opening 46 of the damper mounting surface 41, with its top, i.e., the damper top, protruding upward from the opening 46.

[0066] 6, the damper mounting surface 41 is formed as an inclined surface that slopes downward in a substantially linear manner toward the inner side in the vehicle width direction. Accordingly, the rear suspension damper 120 is mounted to the damper mounting surface 41 in a position that slopes downward slightly toward the outer side in the vehicle width direction. Therefore, during normal driving, the suspension displaces up and down, and as a result, a load is input from the rear suspension to the vehicle body not only in the vertical direction but also inward in the vehicle width direction.

[0067] 3, 5, and 6, the peripheral wall portion 42 is formed in the shape of a plate, i.e., a vertical wall, extending downward from the peripheral edge excluding the outer edge in the vehicle width direction of the upper damper mounting surface portion 41. As shown in Figure 3 etc., the peripheral wall portion 42 includes a peripheral wall inner portion 43 located on the inner side in the vehicle width direction, a front first partition wall portion 44 located in front of the peripheral wall inner portion 43, and a rear first partition wall portion 45 located on the rear side of the same.

[0068] The front first partition wall portion 44 and the rear first partition wall portion 45 are respectively arranged as a front-to-rear pair separated by the peripheral wall inner portion 43. The front first partition wall portion 44 has a curved shape that curves outward in the vehicle width direction as it moves forward from the peripheral wall inner portion 43 so as to form the front surface of the peripheral wall portion 42, and the rear first partition wall portion 45 has a curved shape that curves outward in the vehicle width direction as it moves rearward from the peripheral wall inner portion 43 so as to form the rear surface of the peripheral wall portion 42.

[0069] 5 and 6, the peripheral wall portion 42 is formed in a curved surface shape that protrudes in a generally semicircular arc shape in plan view toward the closed cross-sectional portion 3s (internal space) of the rear frame 3 relative to the outer wall portions 34 of the adjacent portions in the front and rear of the suspension housing 4 of the rear frame 3. The peripheral wall portion 42 thus formed protruding toward the closed cross-sectional portion 3s also serves as at least a part of the outer wall portion 34 of the portion of the rear frame 3 that corresponds to the suspension housing 4 in the front-to-rear direction.

[0070] In contrast, as shown in Figures 5 and 8, the outer wall portion 34 of the rear frame 3 at the portion adjacent to the front and rear of the suspension housing 4 has a lower outer wall portion 341 extending approximately vertically upward from the lower wall portion 55a of the rear frame 3, and an upper outer wall portion 342 that slopes outward in the vehicle width direction from the upper end of the first portion upward.

[0071] 6, the portion of the outer wall portion 34 of the rear frame 3 corresponding to the suspension housing 4 has a peripheral wall portion 42 that is locally recessed inward in the vehicle width direction relative to the outer wall portions of the adjacent portions at the front and rear. Therefore, the portion of the rear frame 3 adjacent to the suspension housing 4 at the inner side in the vehicle width direction forms a narrow portion 37 in which the width dimension of the closed cross-sectional portion 3s of the rear frame 3 is reduced compared to the portions adjacent to the suspension housing 4 at the front and rear.

[0072] As shown in Figure 6, the lower edge 42a of the peripheral wall portion 42 of the suspension housing 4 is joined and fixed by spot welding from the inside in the vehicle width direction to the lower part of the outer wall portion 34 that rises upward in a flange shape from the outer end in the vehicle width direction of the lower wall portion 32 of the rear frame lower 131.

[0073] As shown in Fig. 6, outer edge flanges 41a are formed on the vehicle width outer ends of the damper mounting surface 41 of the suspension housing 4 and the peripheral wall 42. As shown in Fig. 4, the outer edge flanges 41a of the damper mounting surface 41 and the peripheral wall 42 are spot welded to the vertical wall-shaped wheelhouse inner 1a from the vehicle width inner side. As a result, the suspension housing 4 is located adjacent to the vehicle width inner side of the wheelhouse inner 1a so as to form part of the rear frame 3.

[0074] 5, 6, 8, and 9, at the front-rear position corresponding to the suspension housing 4 of the rear frame 3, the outer edge flange portion 36b located on the outer side in the vehicle width direction of the rear frame upper 132 is joined by spot welding or the like along the upper portion of the peripheral wall portion 42 and is formed as part of the peripheral wall portion 42.

[0075] Furthermore, as shown in Figures 2 to 6 and 8, the lower body structure V1 of the automobile of this embodiment further includes a joint member 60 as a load transmission part that connects the suspension housing 4 and the intermediate rear cross member 55 in the closed cross-sectional portion 3s of the narrow width portion 37 of the rear frame 3.

[0076] As shown in Figure 8, etc., the joint member 60 comprises a connecting surface portion 61 as an upper wall portion (upper surface portion), a front second partition wall portion 62 as a front wall portion extending downward from the front end of the connecting surface portion 61, a rear second partition wall portion 63 as a rear wall portion extending downward from the rear end of the connecting surface portion 61, a front edge flange portion 64 extending forward from the lower end of the front second partition wall portion 62, and a rear edge flange portion 65 extending rearward from the lower end of the rear second partition wall portion 63, and is configured such that its cross section along the fore-and-aft direction is hat-shaped with a downward opening.

[0077] The joint member 60 has a leading edge flange portion 64 and a trailing edge flange portion 65 joined from above to the lower wall portion 32 of the rear frame 3 so that the lower opening is blocked by the lower wall portion 32 of the rear frame 3, and a closed cross-sectional portion 6s extending linearly in the vehicle width direction is formed between the lower wall portion 32 of the rear frame 3 and the joint member 60.

[0078] Furthermore, in the joint member 60, ridge lines extending linearly along the vehicle width direction are formed at the corner portion between the front second partition wall portion 62 and the leading edge flange portion 64, the corner portion between the front second partition wall portion 62 and the connecting surface portion 61, the corner portion between the rear second partition wall portion 63 and the trailing edge flange portion 65, and the corner portion between the rear second partition wall portion 63 and the connecting surface portion 61. These multiple ridge lines are referred to as a front lower ridge line 601, a front upper ridge line 602, a rear lower ridge line 603, and a rear upper ridge line 604 in the order of the corners described above.

[0079] 2, the front lower ridgeline 552 and the rear lower ridgeline 554 of the intermediate rear cross member 55 described above both overlap in the fore-and-aft positions with the joint member 60. Furthermore, in this example, as shown by the imaginary line La in FIG. 2, the front lower ridgeline 552 of the intermediate rear cross member 55 overlaps in the fore-and-aft positions with the front upper ridgeline 602 of the joint member 60, and the rear lower ridgeline 554 of the intermediate rear cross member 55 overlaps in the fore-and-aft positions with the rear upper ridgeline 604 of the joint member 60.

[0080] Furthermore, as shown in FIGS. 3 and 8, the outer edge of the joint member 60 in the vehicle width direction is provided with a front outer edge flange portion 66a, a rear outer edge flange portion 66b, and an upper outer edge flange portion 66c. The front outer edge flange portion 66a is formed at the outer end portion of the section member 60 in the vehicle width direction so as to protrude forward relative to the front second partition wall portion 62, and is joined and fixed by spot welding to a vehicle width directional inner portion of the front first partition wall portion 44 of the peripheral wall portion 42 in a state overlapping with the vehicle width directional inner side. The rear outer edge flange portion 66b is formed at the outer end portion of the section member 60 in the vehicle width direction so as to protrude rearward relative to the rear second partition wall portion 63, and is joined and fixed by spot welding to a vehicle width directional inner portion of the rear first partition wall portion 45 of the peripheral wall portion 42 in a state overlapping with the vehicle width directional inner side.

[0081] The upper outer edge flange portion 66c is formed to protrude upward from the outer end portion in the vehicle width direction of the connecting surface portion 61 of the section member 60, and is joined and fixed by spot welding in a state in which it is overlapped with the inner peripheral wall portion 43 of the peripheral wall portion 42 from the inside in the vehicle width direction.

[0082] Furthermore, as shown in FIG. 2, the inner edge of the joint member 60 in the vehicle width direction is provided with a front inner edge flange portion 67a, a rear inner edge flange portion 67b, and an upper inner edge flange portion 67c. 2 and 5, the front inner edge flange portion 67a is formed at the inner end portion in the vehicle width direction of the node member 60 so as to protrude forward relative to the front second partition wall portion 62, and is joined and fixed by spot welding in a state where it overlaps with the inner wall portion 33 of the rear frame 3 from the outer side in the vehicle width direction. As shown in FIG. 2, the rear inner edge flange portion 67b is formed at the inner end portion in the vehicle width direction of the node member 60 so as to protrude rearward relative to the rear second partition wall portion 63, and is joined and fixed by spot welding in a state where it overlaps with the inner wall portion 33 of the rear frame 3 from the outer side in the vehicle width direction.

[0083] As shown in Figures 2 and 3, a pair of upper inner edge flange portions 67c are formed at the front and rear that protrude inward in the vehicle width direction from the vehicle width direction inner end of the connecting surface portion 61 of the section member 60, and each of these front and rear upper inner edge flange portions 67c is joined and fixed by spot welding in a state where it is overlapped from above with the lower inner edge flange portion 35a of the rear frame lower 131.

[0084] The joining of the lower inner edge flange portion 35a of the rear frame lower 131 and the upper inner edge flange portions 67c on the front and rear sides of the joint member 60 will be described in further detail. When the upper inner edge flange portions 67c on each front and rear side are joined to the lower inner edge flange portions 35a of the rear frame lower 131, as shown in Figures 3 and 9, at the overlapping connection portion 131C between the rear portion of the lower front member 131F of the rear frame 3 and the front portion of the lower rear member 131R, the upper inner edge flange portions 67c on each front and rear side of the section member 60 and the rear portion of the lower front member 131F of the rear frame 3 overlap so as to sandwich the front portion of the lower rear member 131R of the rear frame 3 from both the top and bottom, and these three pieces are joined together by spot welding.

[0085] As a result, as shown in Figures 3 and 6, the connecting surface portion 61 of the joint member 60, which is formed in a planar shape along the vehicle width direction and the fore-and-aft direction, overlaps in the fore-and-aft position with the overlapping connecting portion 131C of the rear frame 3, and is joined and fixed to the overlapping connecting portion 131C via the upper inner edge flange portion 67c.

[0086] Furthermore, as described above, the joint member 60 connects the peripheral wall portion 42 and the vehicle widthwise inner portion of the rear frame 3 (the ridge extending in the fore-and-aft direction between the inner wall portion 33 and the lower inner edge flange portion 35a) in the vehicle width direction at a fore-and-aft position corresponding to the suspension housing 4 of the rear frame 3, so that the closed cross-sectional portion 3s of the rear frame 3 can be divided into front and rear portions by either the front second partition wall portion 62 or the rear second partition wall portion 63.

[0087] That is, as shown in Figures 2 to 6 and 8, the front second partition wall portion 62 cooperates with the front first partition wall portion 44 to divide the closed cross-sectional portion 3s of the rear frame 3 into front and rear portions, and the rear second partition wall portion 63 cooperates with the rear first partition wall portion 45 to divide the closed cross-sectional portion 3s of the rear frame 3 into front and rear portions.

[0088] 6, the connecting surface portion 61 of the joint member 60 is joined to the peripheral wall portion 42 via an upper outer edge flange portion 66c, and is joined to the inner edge flange of the rear frame lower 131 via an upper inner edge flange portion 67c. The upper outer edge flange portion 66c of the joint member 60, which is joined to the peripheral wall inner portion 43 of the peripheral wall portion 42, is joined and fixed to a position above the central position hc of the peripheral wall portion 42 in the up-down direction.

[0089] As a result, the joint member 60 has a joining position of the upper outer edge flange portion 66c to the peripheral wall portion 42 located above the joining position of the upper inner edge flange portion 67c to the lower inner edge flange portion 35a of the rear frame lower 131.

[0090] Therefore, the connecting surface portion 61 of the joint member 60 connects the inner peripheral wall portion 43 of the peripheral wall portion 42 and the lower inner edge flange portion 35a of the rear frame 3 in a position that slopes linearly downward toward the inside in the vehicle width direction in the closed cross-sectional portion 3s of the narrow width portion 37.

[0091] 2 to 4 and 6 to 8, at least the connecting surface portion 61 of the joint member 60 in the front-to-rear direction overlaps in the front-to-rear position with the opening 46 formed through the damper mounting surface portion 41. In this embodiment, of the joint member 60, the connecting surface portion 61, the front second partition wall portion 62, the rear second partition wall portion 63, the upper inner edge flange portion 67c, and the upper outer edge flange portion 66c overlap in the front-to-rear position with the opening 46 of the damper mounting surface portion 41.

[0092] 3 and 8, of the multiple spot welds on the peripheral wall portion 42 of the node member 60, the two front and rear spot welds on the upper outer edge flange portion 66c of the node member 60 are referred to as upper outer fixed portions w6a, the two top and bottom spot welds on the front outer edge flange portion 66a are referred to as front outer fixed portions w6b, and the two top and bottom spot welds on the rear outer edge flange portion 66b are referred to as rear outer fixed portions w6c.

[0093] Also, as shown in FIG. 2, of the multiple spot welds of the joint member 60 to the rear frame 3, the two front and rear spot welds on the upper inner edge flange portion 67c of the joint member 60 are designated as upper inner fixing portions w6e, the spot weld on the front inner edge flange portion 67a is designated as front inner fixing portion w6f, and the spot weld on the rear inner edge flange portion 67b is designated as rear inner fixing portion w6g.

[0094] As shown by the imaginary line Lb in Figure 3, the front upper outer fixing portion w6a and the front upper inner fixing portion w6e are arranged in front-to-back positions where they overlap each other, and the rear upper outer fixing portion w6a and the rear upper inner fixing portion w6e are arranged in front-to-back positions where they overlap each other.

[0095] As shown in Figures 3 and 9, the spot welded location w35, where the lower inner edge flange portion 35a of the rear frame lower 131 and the upper inner edge flange portion 35b of the rear frame upper 132 are joined together in an overlapping state so as to sandwich the vehicle width direction outer edge of the rear floor panel 2 in the vertical direction, is located between the upper inner fixed portions w6e on both the front and rear sides in the overlapping connection portion 131C of the rear frame 3. The rear floor pan 22 extends substantially horizontally and linearly along the vehicle width direction at the height position of the upper inner fixing portions w6e on both the front and rear sides.

[0096] Furthermore, symbols 6 and 7 in Figure 9 denote through holes formed through each of these members 131R, 55 to prevent a welding gun placed from below against the front portion of the lower rear member 131R of the rear frame 3 from interfering with the front portion of the lower rear member 131R and the lower wall portion 55a of the intermediate rear cross member 55 when forming a spot weld w35 where three sheets are overlapped between the front and rear positions of the upper inner fixed portions w6e on each side.

[0097] 2, 9, and 10(a) and 10(b), the front outer edge flange portion 55f of the intermediate rear cross member 55 overlaps in the fore-and-aft position with the front inner edge flange portion 67a of the joint member 60. More specifically, the front outer fixing portion w5a of the intermediate rear cross member 55 overlaps in the fore-and-aft position with the front inner fixing portion w6f of the joint member 60.

[0098] 2 and 9, the rear outer edge flange portion 55g of the intermediate rear cross member 55 overlaps in the fore-and-aft position with the rear inner edge flange portion 67b of the joint member 60. More specifically, as shown in FIGS. 2 and 9, the rear outer fixing portion w5b of the intermediate rear cross member 55 overlaps in the fore-and-aft position with the rear inner fixing portion w6g of the joint member 60.

[0099] Furthermore, as shown in FIG. 6, the lower outer edge flange portion 55h of the intermediate rear cross member 55, more specifically the lower outer fixing portion w5c, overlaps with the joint member 60, more specifically the connecting surface portion 61, in the front-rear position.

[0100] Furthermore, as shown in Figures 2, 3, 6, 7, and 9, the intermediate rear cross member 55 is provided at a front-to-rear position overlapping with the suspension housing 4 as described above, but in this example, the intermediate rear cross member 55 is positioned at a front-to-rear position overlapping with the damper top, i.e., the opening 46 of the damper mounting surface portion 41.

[0101] As shown in FIGS. 1 and 4, the automobile lower body structure V1 of the present embodiment includes a rear frame 3 that forms a closed cross-sectional portion 3s extending in the front-rear direction on the vehicle width direction outer side of the rear floor panel 2 (floor panel), and a sheet metal suspension housing 4 that is provided on the rear frame 3 and supports a rear suspension damper 120 (see FIG. 6) (suspension). As shown in FIGS. 2 to 9, the suspension housing 4 has a damper mounting surface portion 41 that fits along the upper surface of the rear frame 3, and a damper mounting surface 3, 5 to 7, and 9, the rear frame 3 has, on the vehicle width inner side, an upper inner edge flange portion 35b and a lower inner edge flange portion 35a (inner flange portion) to which the rear floor panel 2 is fixed, and, as shown in FIG. 6, a connecting surface portion 61 is provided on the vehicle width inner side of the peripheral wall portion 42, which connects the peripheral wall inner portion 43 (inner portion in the vehicle width direction) of the peripheral wall portion 42 and the inner edge flange portions 35a, 35b downward as it moves inward in the vehicle width direction.

[0102] According to the above configuration, even if a load is transmitted from the suspension housing 4 toward the inside in the vehicle width direction during normal driving, the connecting surface portion 61 acts to brace between the inner edge flange portions 35a, 35b and the peripheral wall portion 42, thereby suppressing inward collapse deformation of the suspension housing 4.

[0103] In an embodiment of this invention, as shown in Figures 2, 3, 6, and 8, the connecting surface portion 61 overlaps in the front-to-rear position with the opening 46 formed through the damper mounting surface portion 41 in the vertical direction.

[0104] With this configuration, during normal driving, the load from the rear suspension damper 120 (see FIG. 6) is input inward in the vehicle width direction through the opening 46 of the damper mounting surface 41, which is the center of the damper mounting position, so the suspension housing 4 can be supported by the connecting surface 61 at a position as close as possible to the load input source. In other words, the connecting surface 61 can exert a bracing effect against the load transmitted inward in the vehicle width direction from the suspension housing 4, so inward collapse deformation of the suspension housing 4 can be effectively suppressed.

[0105] In one embodiment of the present invention, as shown in FIG. 6, the connecting surface portion 61 is fixed above the intermediate position hc in the height direction of the peripheral wall portion 42 via an upper outer edge flange portion 66c. According to the above configuration, when the axial force of the connecting surface portion 61 receives the peripheral wall portion 42 that is about to undergo inward deformation, the connecting surface portion 61 can brace itself at a location where a large moment can be applied to the peripheral wall portion 42, thereby effectively suppressing the inward deformation of the peripheral wall portion 42.

[0106] In one aspect of the present invention, as shown by the imaginary straight line Lb in Figure 3, the connecting surface portion 61 has an upper outer fixing portion w6a (outer fixing portion) relative to the peripheral wall portion 42 and an upper inner fixing portion w6e (inner fixing portion) relative to the rear frame 3, and the upper outer fixing portion w6a and the upper inner fixing portion w6e are arranged in positions that overlap each other in the fore-and-aft direction.

[0107] According to the above-described configuration, even if a load is input from the rear suspension damper 120 to the suspension housing 4 toward the inside in the vehicle width direction during normal driving, the load can be transmitted smoothly and linearly via the connecting surface portion 61 from the peripheral wall portion 42 to the inner edge flange portions 35a, 35b of the rear frame 3, i.e., toward the inside in the vehicle width direction of the vehicle body.

[0108] In one embodiment of the present invention, as shown in FIG. 6, the connecting surface portion 61 is formed linearly along the vehicle width direction. According to the above-described configuration, the load input from the rear suspension damper 120 to the suspension housing 4 toward the inside in the vehicle width direction during normal driving can be firmly received by utilizing the axial force of the connecting surface portion 61, and therefore can be smoothly transmitted via the connecting surface portion 61 to the inner edge flange portions 35a, 35b of the rear frame 3, i.e., toward the inside in the vehicle width direction of the vehicle body.

[0109] Furthermore, in this embodiment, the connecting surface portion 61 is arranged in an attitude that slopes linearly downward toward the inside of the vehicle width direction in the closed cross-sectional portion 3s of the narrow width portion 37, thereby enhancing the effect of providing tension support against the above-mentioned load from the suspension housing 4.

[0110] In one embodiment of the present invention, as shown in Figures 2 to 8, the closed cross-sectional portion 3s of the rear frame 3, which is located more inward in the vehicle width direction than the peripheral wall portion 42, is provided with a U-shaped joint member 60 whose cross section along the fore-and-aft direction opens downward, and the connecting surface portion 61 is formed by the upper wall portion of the joint member 60.

[0111] According to the above configuration, by forming the connecting surface portion 61 as the upper wall portion of the joint member 60 having a U-shaped cross section and having a front second partition wall portion 62 and a rear second partition wall portion 63 as vertical wall portions on each of the front and rear sides, it is possible to increase rigidity compared to when it is formed in a flat plate shape, and to improve the effect of suppressing inward collapse of the peripheral wall portion 42 during normal driving.

[0112] In one embodiment of the present invention, as shown in Figures 2, 3, 6, 7, and 9, an intermediate rear cross member 55 (cross member) that connects a pair of left and right rear frames 3 is provided along the vehicle width direction, and the intermediate rear cross member 55 is positioned in a front-to-rear position overlapping with the damper mounting surface portion 41.

[0113] According to the above configuration, even if a load is input from the rear suspension damper 120 to the suspension housing 4 in the vehicle width direction during normal driving, the load can be smoothly transmitted to the intermediate rear cross member 55 via the connecting surface portion 61.

[0114] In one embodiment of the present invention, as shown in Figures 2, 3, 6, 7, and 9, the rear frame lower 131 provided on the rear frame 3 is composed of a lower front member 131F (rear frame front portion) and a lower rear member 131R (rear frame rear portion), and as shown in Figures 3 and 9, the connecting surface portion 61 is fixed to an overlapping connecting portion 131C (joint portion) where the lower front member 131F and the lower rear member 131R are overlapped.

[0115] According to the above configuration, the overlapping connection portion 131C between the lower front member 131F and the lower rear member 131R can be reinforced by the connecting surface portion 61 fixed to the overlapping connection portion 131C via the upper inner edge flange portion 67c. Furthermore, the joint portion between the lower front member 131F and the lower rear member 131R has high rigidity because the lower front member 131F and the lower rear member 131R are overlapped. By fixing the connecting surface portion 61 to such a highly rigid overlapping connection portion 131C, it is possible to enhance the effect of the connecting surface portion 61 in bracing and supporting the peripheral wall portion 42, which tends to deform inwardly.

[0116] In the configuration of the present invention and the correspondence between the above-mentioned embodiments, the vehicle corresponds to an automobile, and similarly, The floor panel corresponds to the rear floor panel 2, The frame is compatible with rear frame 3, The inner flange portion corresponds to the lower inner edge flange portion 35a, The inner portion in the vehicle width direction corresponds to the inner peripheral wall portion 43, The cross member corresponds to the intermediate rear cross member 55, The front side of the rear frame corresponds to the lower front member 131F, The rear side of the rear frame corresponds to the lower rear member 131R, The joining portion where the rear frame front side portion and the rear frame rear side portion are overlapped corresponds to the overlapping joint portion 131C, The outer fixing portion corresponds to the upper outer fixing portion w6a, The inner fixing part corresponds to the upper inner fixing part w6e, The suspension corresponds to the rear suspension damper 120, but the present invention is not limited to the configuration of the above-described embodiment, and many other embodiments can be obtained.

[0117] For example, in this embodiment, the upper outer fixing portion w6a on each of the front and rear sides and the upper inner fixing portion w6e on each of the front and rear sides are provided in front and rear positions where they overlap each other, respectively, but the present invention may also be configured so that at least one of the front and rear sides is provided in a front and rear position where they overlap each other. [Explanation of symbols]

[0118] V1: Lower body structure 2...Rear floor panel (floor panel) 3...Rear frame (frame) 3s...Closed cross section of rear frame 4...Suspension housing 35a...Lower inner edge flange portion (inner flange portion) 35b...Upper inner edge flange portion (inner flange portion) 41...Damper mounting surface 42...Peripheral wall part 43...Inner portion of peripheral wall (inner portion in the vehicle width direction) 46...Opening of damper mounting surface 55...Intermediate rear cross member (cross member) 60...knob member 61…Connecting surface part 131F... Lower front member (rear frame front part) 131R...Lower rear member (rear frame rear part) 131C... Polymer connection part (the joint part where the front side of the rear frame and the rear side of the rear frame are overlapped) w6a...Upper outer fixing part (outer fixing part) w6e...Upper inner fixing part (inner fixing part) hc: Middle position in the height direction of the peripheral wall

Claims

1. a frame that defines a closed cross-section portion extending in the front-rear direction on the outer side of the floor panel in the vehicle width direction; a metal plate-made suspension housing that is attached to the frame and supports the suspension, The suspension housing has a damper mounting surface portion that is aligned with the upper surface of the frame; a peripheral wall portion extending downward from a peripheral edge of the damper mounting surface portion, an inner flange portion to which the floor panel is fixed on the inner side of the frame in the vehicle width direction; a connecting surface portion that connects the inner flange portion and the inner portion of the peripheral wall portion in the vehicle width direction downward toward the inner side in the vehicle width direction, the connecting surface portion being located on the inner side of the peripheral wall portion in the vehicle width direction; The vehicle's underbody structure.

2. The connecting surface portion overlaps in the front-rear position with an opening formed through the damper mounting surface portion in the up-down direction. The vehicle underbody structure according to claim 1 .

3. The connecting surface portion is fixed above the intermediate position in the height direction of the peripheral wall portion. The vehicle underbody structure according to claim 1 .

4. the connecting surface portion has an outer fixing portion that is fixed to the peripheral wall portion and an inner fixing portion that is fixed to the frame, The outer fixing portion and the inner fixing portion are provided at positions where at least a part of them overlap each other in the front-rear direction. The vehicle underbody structure according to claim 1 .

5. The connecting surface portion is formed linearly along the vehicle width direction. The vehicle underbody structure according to claim 1 .

6. The closed cross-sectional portion of the frame is provided on the inner side of the peripheral wall portion in the vehicle width direction and includes a U-shaped joint member whose cross section along the front-rear direction is open downward, The connecting surface portion is formed by the upper wall portion of the joint member. The vehicle underbody structure according to claim 1 .

7. A cross member is provided between the pair of left and right frames along the vehicle width direction, The cross member is disposed at a front-rear position overlapping with the damper mounting surface. The vehicle underbody structure according to claim 1 .

8. The frame is composed of a frame front side portion and a frame rear side portion, and the connecting surface portion is fixed to a joining portion where the frame front side portion and the frame rear side portion are overlapped. The vehicle underbody structure according to claim 1 .

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