Vehicle rear structure

Abstract

Avoid contact between the floor panel and the battery unit. [Solution] The vehicle rear structure 100 includes a side sill 1, a rear side member 2 having an overlapping portion 2X joined to the rear of the inner portion 1b of the side sill 1 in the vehicle width direction and extending from the overlapping portion 2X rearward and upward beyond the rear end 1b of the side sill 1, a floor panel 3, a front cross member 4 connected to the front of the overlapping portion 2X and extending in the vehicle width direction, and a rear cross member 5. The rear end of the battery unit B is supported by a portion of the rear side member 2 located rearward from the front cross member 4. The rear side member 2 has a compression deformation promoting portion 2V that promotes compression deformation in the longitudinal direction of the vehicle. The compression deformation promoting portion 2V is provided in a range from a predetermined position rearward from the rear end B1 of the battery unit B and forward from the rear end of the overlapping portion 2X to a position corresponding to the front end of the rear cross member 5 of the rear side member 2.

Description

Technical Field

[0001] The present invention relates to a vehicle rear structure.

Background Art

[0002] Below the floor panel of an electric vehicle, a large battery unit is arranged. At the rear of the outer side portion of the floor panel in the vehicle width direction, side sills and rear side members extend in the front-rear direction. In an electric vehicle, the rear side member may extend rearward from the rear portion of the inner side portion of the side sill in the vehicle width direction and project rearward and upward from the rear end of the side sill. And, in the case of a rear-end collision, in order to efficiently absorb the collision energy (impact) input to the rear portion of the vehicle, a structure for promoting the deformation of the rear side member may be applied to the vehicle rear structure.

[0003] As an example of a vehicle rear structure in which the rear side member is used as an impact absorbing member, the structure disclosed in Patent Document 1 is known. In the structure disclosed in this Patent Document 1, the rear side member includes a member base portion connected to the inner side portion of the side sill in the vehicle width direction, a kick-up portion that rises obliquely from the member base portion, and a general member portion that extends substantially horizontally from the kick-up portion. The cross member extends in the vehicle width direction along the floor panel from the front portion of the member base portion. And, this rear side member has a first bending promotion portion set at an intermediate position in the vehicle front-rear direction of the general member portion and promoting an upward mountain-fold deformation with respect to the axial input during a rear collision of the vehicle, and a second bending promotion portion set at the continuous position of the member base portion and the kick-up portion and promoting a downward valley-fold deformation with respect to the axial input. As a result, during a rear-end collision, in the rear side member, a bending deformation substantially in a Z shape in a side view starting from the first and second bending promotion portions is promoted. Thus, the structure disclosed in Patent Document 1 attempts to absorb a part of the collision energy by promoting an up-and-down bending deformation in a side view in the rear side member during a rear-end collision.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2015-71327 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, in cases where the rear portion of a rear side member is positioned higher than the front portion of the rear side member, as disclosed in Patent Document 1, a rear-end collision may cause the front portion of the rear side member to sink downwards and the rear portion to spring upwards (i.e., vertical rotational deformation). Furthermore, in electric vehicles, the battery unit may be located below the floor panel, and the rear end of the battery unit may be supported by a portion of the rear side member that is located behind the front cross member. In this case, during a rear-end collision, the rear end of the battery unit may be lifted upwards along with the upward deformation of the rear portion of the rear side member, and the front portion of the rear side member may sink downwards, potentially causing the floor panel and the battery unit to come closer together and come into contact.

[0006] Therefore, the present invention aims to provide a vehicle rear structure having a structure for avoiding contact between the floor panel and the battery unit. [Means for solving the problem]

[0007] To achieve the above objective, according to one aspect of the present invention, a rear vehicle structure is provided which includes: a side sill provided on the outer side in the vehicle width direction at the lower part of the vehicle and extending in the vehicle longitudinal direction; a rear side member having an overlapping portion that overlaps and is joined to the rear part of the inner side portion in the vehicle width direction of the side sill, and which extends from the overlapping portion rearward and upward beyond the rear end of the side sill; a floor panel to which the side sill and the rear side member are joined; and a front cross member having an end connected to the front part of the overlapping portion and extending along the floor panel in the vehicle width direction, wherein the battery unit is located below the floor panel, and the rear vehicle structure extends rearward beyond the rear end of the side sill The battery unit includes a rear cross member having an end connected to a floor member and extending in the vehicle width direction along the floor panel, wherein the rear end of the battery unit is located behind the rear end of the front cross member, and the rear end of the battery unit is supported by a portion of the rear side member located behind the front cross member, and the rear side member has a compression deformation promoting portion that promotes compression deformation of the rear side member in the vehicle longitudinal direction, and the compression deformation promoting portion is provided in the vehicle longitudinal direction from a predetermined position behind the rear end of the battery unit and in front of the rear end of the overlap portion to a position of the rear side member corresponding to the front end of the rear cross member. [Effects of the Invention]

[0008] According to one aspect of the present invention, a vehicle rear structure having a structure for avoiding contact between the floor panel and the battery unit can be provided. [Brief explanation of the drawing]

[0009] [Figure 1] This is a bottom view of the rear vehicle structure according to an embodiment of the present invention. [Figure 2] This is a bottom view of the rear structure of the vehicle with the battery unit and rear suspension removed. [Figure 3] Figure 1 is a cross-sectional view of the vehicle's rear structure along the AA line. [Figure 4] This is a top view of the main parts illustrating the internal structure of the rear side member of the vehicle's rear structure. [Figure 5] Figure 2 is a partial cross-sectional view of the rear structure along the BB line. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will now be described with reference to the accompanying drawings. Figure 1 is a bottom view of a vehicle rear structure 1 according to one embodiment of the present invention, and Figure 2 is a bottom view of the vehicle rear structure 1 with the battery unit B and rear suspension structure 6, etc., which will be described later, removed. Figure 3 is a cross-sectional view of the vehicle rear structure 1 along line AA shown in Figure 1. In the figures, the direction of arrow Fr indicates the front in the longitudinal direction of the vehicle, the direction of arrow U indicates the up in the vertical direction of the vehicle, the direction of arrow R indicates the right side in the vehicle width direction when the occupants inside the vehicle are facing forward, and the direction of arrow L indicates the left side in the vehicle width direction when the occupants inside the vehicle are facing forward. In the following description, "front" and "rear" correspond to the front and rear in the longitudinal direction of the vehicle, "up" and "down" correspond to the up and down in the vertical direction of the vehicle, and "left" and "right" correspond to the left and right in the vehicle width direction when the occupants inside the vehicle are facing forward.

[0011] Referring to Figures 1 to 3, the vehicle rear structure 100 includes a side sill 1, a rear side member 2, a floor panel 3, a front cross member 4, and a rear cross member 5.

[0012] The vehicle rear structure 100 is applied to the rear structure of an electric vehicle driven by a drive unit M including a traction motor. The drive unit M, a battery unit B that supplies power to the drive unit M via a power supply junction box J, and a torsion beam type rear suspension structure 6 are located below the floor panel 3. The side sills 1, rear side members 2, front cross members 4 and rear cross members 5 are each highly rigid members that constitute part of the vehicle body structure (vehicle frame) and are made of metal material.

[0013] The side sill 1 is located on the outer side in the vehicle width direction at the bottom of the vehicle and extends in the vehicle longitudinal direction. The side sill 1 is positioned on each of the outer sides in the vehicle width direction. The side sill 1 is a member having a roughly hat-shaped cross-section that is open to the outside in the vehicle width direction.

[0014] The rear side member 2 extends from the rear of the side sill 1 towards the rear of the vehicle at the rear of the underside of the vehicle. The rear side member 2 is positioned on each of the outer sides in the vehicle width direction. The cross-sectional shape and internal structure of the rear side member 2 will be described in detail later.

[0015] The rear side member 2 has an overlapping portion 2X that overlaps and is joined to the rear of the inner portion 1a in the vehicle width direction of the side sill 1, and extends from the overlapping portion 2X rearward and upward beyond the rear end 1b of the side sill 1. In other words, the rear side member 2 extends rearward along the rear of the inner portion 1a in the vehicle width direction of the side sill 1, and extends rearward and upward beyond the rear end of the side sill 1. The overlapping portion 2X constitutes the front part of the rear side member 2, which extends along the rear of the side sill 1. When the overlapping portion 2X of the rear side member 2 is joined to the side sill 1, a high-strength frame portion Z is formed in the portion corresponding to the overlapping portion 2X, consisting of the side sill 1 and the overlapping portion 2X.

[0016] The overlapping portion 2X of the rear side member 2 is joined to the rear part of the inner portion 1a in the vehicle width direction of the side sill 1 by spot welding or the like. In the illustrated example, the rear side member 2 is divided into a front rear side member 2a that extends in the longitudinal direction, a rear rear side member 2b that is located rearward and above the front rear side member 2a and extends in the longitudinal direction, and a rear side member inclined portion 2c that connects the rear end of the front rear side member 2a and the front end of the rear side member rear 2b. The entire front rear side member 2a and the front part of the rear side member inclined portion 2c constitute the overlapping portion 2X that overlaps and is joined to the side sill 1. The rear rear side member 2b extends horizontally in the longitudinal direction. The rear side member 2 is curved so that it approaches the center in the vehicle width direction as it moves rearward from the overlapping portion 2X.

[0017] Specifically, the rear of the side sill 1 overlaps with the overlapping portion 2X of the rear side member 2, and protrudes from the overlapping portion 2X both above and below. Around the rear end 1b of the side sill 1, the upper part of the outer portion in the vehicle width direction of the overlapping portion 2X (rear side member inclined portion 2c) of the rear side member 2 (more specifically, the outer vertical wall 21b of the rear side member body 21, which will be described later) is joined to the inner portion 1a of the side sill 1 in the vehicle width direction. However, the lower part of the outer portion of the overlapping portion 2X in the vehicle width direction is recessed inward so as to be separated inward in the vehicle width direction from the inner portion 1a of the side sill 1 in the vehicle width direction. Around the rear end 1b of the side sill 1, the rear of the inner portion 1a in the vehicle width direction of the side sill 1 and the inwardly recessed lower part of the overlapping portion 2X of the rear side member 2 form a bracket upper arrangement space S where the upper part of the arm support bracket 7, which will be described later, is arranged. This bracket upper placement space S is a region (space) with a roughly U-shaped cross-section that is open to the lower part of the vehicle and is also open to the rear of the vehicle.

[0018] The floor panel 3 is a panel member to which the side sill 1 and the rear side member 2 are joined, and constitutes the floor portion of the lower part of the vehicle body. The floor panel 3 extends from the lower part of the front of the passenger compartment to the rear of the vehicle, and is a member made of a thin metal plate. The dimension of the floor panel 3 in the vehicle width direction substantially corresponds to the dimension of the vehicle body in the vehicle width direction. The side sill 1 and the rear side member 2 extend in the vehicle longitudinal direction along the outer edge portions of the floor panel 3 in the vehicle width direction. The floor panel 3 is provided above the side sill 1 and the rear side panel 2, and is joined to the upper surface 1c of the side sill 1 and the flange of the rear side member 2 (specifically, the outer flange 21d and the inner flange 21e of the rear side member main body 21 described later) by spot welding or the like.

[0019] In the illustrated example, the floor panel 3 has a main floor panel 31 and a rear floor panel 32. The main floor panel 31 extends from the lower part of the front of the passenger compartment to the rear of the vehicle. The rear floor panel 32 extends rearward from the rear part of the main floor panel 31. In the illustrated example, the rear end portion of the main floor panel 31 and the front end portion of the rear floor panel 32 are overlapped with each other and joined by spot welding or the like.

[0020] On the rear floor panel 32, a front bulging portion 32a and a rear bulging portion 32b are formed. The front bulging portion 32a bulges upward in a region from the left rear side member 2 to the right rear side member 2 among the front portion of the rear floor panel 32. The rear bulging portion 32b bulges upward in a region shifted toward one rear side member 2 in the vehicle width direction (in the illustrated example, the left rear side member 2 side) of the rear portion of the rear floor panel 32.

[0021] The front bulging portion 32a has a front vertical wall 32a1, a rear vertical wall 32a2, a left side wall 32a3, a right side wall 32a4, and an upper wall 32a5. The lower end of the front vertical wall 32a1 is located below the lower end of the rear vertical wall 32a2. The lower edges of the left side wall 32a2 and the right side wall 32a3 are inclined in accordance with the inclined shape of the rear side member inclined portion 2c, and the upper edges of the left side wall 32a2 and the right side wall 32a3 extend substantially horizontally in the front-rear direction. The upper wall 32a5 extends substantially horizontally. The front vertical wall 32a1 has a height corresponding to the vertical height difference (step) caused by the rear side member inclined portion 2c in the rear side member 2 and constitutes a stepped portion.

[0022] The rear bulging portion 32b has a mountain-shaped cross-sectional shape with the top portion shifted to the rear side. The front end of the upper wall 32b1 of the rear bulging portion 32b is continuous with the horizontal portion between the front bulging portion 32a and the rear bulging portion 32b in the rear floor panel 32. The upper wall 32b1 is inclined upward to the rear.

[0023] The front cross member 4 has an end portion 4a connected to the front portion of the overlapping portion 2X of the rear side members 2 and extends in the vehicle width direction along the floor panel 3. The front cross member 4 extends in the vehicle width direction along the floor panel 3 so as to connect the front portions of the left rear side member 2 and the right rear side member 2. In the illustrated example, the front cross member 4 extends along the lower surface of the floor panel 3 (specifically, the front portion of the rear floor panel 32). And the front cross member 4 is joined to the front portion of the overlapping portion 2X of the rear side members 2 (that is, the front portion of the rear side members 2) and the floor panel 3 by spot welding or the like.

[0024] The rear cross member 5 has an end 5a that connects to the rear side member 2 behind the rear end 1b of the side sill 1, and extends in the vehicle width direction along the floor panel 3. The rear cross member 5 extends in the vehicle width direction along the floor panel 3 at a position separated from the front cross member 4 in the vehicle longitudinal direction, connecting the left rear side member 2 and the right rear side member 2. In the illustrated example, the rear cross member 5 extends along the lower surface of the floor panel 3 (specifically, the middle part of the rear floor panel 32). The rear cross member 5 is joined to the middle part of the rear side member 2 (specifically, the front end of the horizontally extending rear part 2b of the rear side member) and to the horizontal part of the floor panel 3 between the front bulge 32a and the rear bulge 32b by spot welding or the like.

[0025] Each cross member (4, 5) is a component with a roughly hat-shaped cross section that is open to the upper side of the vehicle. Each cross member (4, 5) has a front flange (4b, 5b) and a rear flange (4c, 5c), and each flange (4b, 4c, 5b, 5c) is joined to the lower surface of the floor panel 3 by spot welding or the like.

[0026] In the illustrated example, the rear suspension structure 6 is a torsion beam type rear suspension structure to which the rear tires T are attached. The rear suspension structure 6 comprises a torsion beam 6a and a pair of left and right trailing arms 6b, 6b.

[0027] The torsion beam 6a is a metal member that extends linearly in the vehicle width direction and applies torsional reaction forces to each of the left and right rear tires T. The left end of the torsion beam 6a is joined to the middle section of the left trailing arm 6b, and the right end of the torsion beam 6a is joined to the middle section of the right trailing arm 6b.

[0028] Each trailing arm 6b is provided with a metal vehicle-side connecting portion 6b1 at its front end, which extends roughly in the vehicle width direction and is formed in a cylindrical shape. A cylindrical rubber bushing is fitted into the vehicle-side connecting portion 6b1. A pin (not shown) supported by the vehicle body (specifically, the arm support bracket 7, which will be described later) is inserted into the bushing. As a result, the trailing arm 6b is connected to the vehicle body so that it can swing vertically with the pin as a pivot point. In addition, a spring support portion 6d is joined to the rear of the inner part of the trailing arm 6b in the vehicle width direction, which supports the lower end of a coil spring 6c (see Figure 3) having an upper end that is connected to the vehicle body. This spring support portion 6b is also joined to the rear of the outer part of the trailing arm 6b in the vehicle width direction.

[0029] Specifically, the front end of the trailing arm 6b (vehicle body side connecting portion 6b1) is pivotably supported by an arm support bracket 7, which is joined to the rear of the overlapping portion 2X of the rear side member 2 by spot welding or the like. In this way, it is pivotably connected to the vehicle body via the arm support bracket 7. In other words, the arm support bracket 7, which supports the front end of the trailing arm 6b (vehicle body side connecting portion 6b1) of the rear suspension structure 6, is joined to the rear of the overlapping portion 2X.

[0030] More specifically, the lower part of the arm support bracket 7 protrudes below the lower surface of the rear side member 2. The arm support bracket 7 is joined to the overlapping portion 2X at multiple points at the rear of the overlapping portion 2X.

[0031] In the illustrated example, the arm support bracket 7 is joined to the rear side member 2 at the overlapping portion 2X of the rear side member 2, at a position closer to the side sill 2 in the vehicle width direction. In other words, most of the multiple joining points of the arm support bracket 7 to the rear side member 2 (overlapping portion 2X) are located at positions closer to the outer side in the vehicle width direction at the rear of the overlapping portion 2X of the rear side member 2.

[0032] The arm support bracket 7 is also joined to the portion of the rear of the inner portion 1a of the side sill 1 in the vehicle width direction that faces the overlapping portion 2X. Specifically, the inner portion of the arm support bracket 7 in the vehicle width direction is joined to the lower surface of the overlapping portion 2X of the rear side member 2 (more specifically, the bottom wall 21a of the rear side member body 21, described later). The upper part of the arm support bracket 7 is fitted into the bracket upper arrangement space S formed (partitioned) by the rear of the inner portion 1a of the side sill 1 in the vehicle width direction and the inwardly recessed lower part of the overlapping portion 2X of the rear side member 2, and is joined to the inner portion 1a of the side sill 1 in the vehicle width direction and the outer surface of the rear side member 2 in the vehicle width direction (the outer vertical wall 21b of the rear side member body 21, described later).

[0033] Next, the main parts of the vehicle rear structure 100 will be described with reference to Figures 1 to 5. Figure 4 is a top view of the main parts illustrating the internal structure of the rear side member 2, and Figure 5 is a partial cross-sectional view of the rear structure along the BB line shown in Figure 2.

[0034] Referring to Figures 1 and 3, the drive unit M, including the drive motor, the battery unit B, and the rear suspension structure 6 are located below the floor panel 3. In other words, the battery unit B, through which the high-voltage current supplied to the drive motor of the drive unit M flows, is located below the floor panel 3.

[0035] Specifically, the drive unit M is positioned below the rear bulge 32b of the rear floor panel 32. The rear corner of the drive unit M is positioned above the rear cross member 5 in the vehicle's vertical direction. In the vehicle's longitudinal direction, the drive unit M is positioned behind the torsion beam 6a and between the rear cross member 5 and the rear end of the floor panel 3 (rear floor panel 32). In the illustrated example, the drive unit M is supported by the vehicle body via a first bracket 8a, a second bracket 8b, and a third bracket 8c. The first bracket 8a is connected to the lower surface of the left rear side member 2, the second bracket 8b is connected to the lower surface of the rear cross member 5, and the third bracket 8c is connected to the lower surface of the center member 9 that extends from the rear cross member 5 along the lower surface of the rear floor panel 32 between the left and right rear cross members 2.

[0036] The power supply junction box J is located below the front bulge 32a of the rear floor panel 32. The power supply junction box J is positioned at a height corresponding to the front cross member 4 in the vehicle's vertical direction. The front cross member 4, the power supply junction box J, and the drive unit M are arranged to be aligned in the vehicle's longitudinal direction. The power supply junction box J is located between the front cross member 4 and the rear cross member 5 in the vehicle's longitudinal direction, specifically between the battery unit B and the torsion beam 6a. The position of the power supply junction box J in the vehicle's longitudinal direction is generally set to correspond to the position of the arm support bracket 7. Therefore, the arm support bracket 7 is located between the front cross member 4 and the rear cross member 5 in the vehicle's longitudinal direction, specifically between the battery unit B and the torsion beam 6a.

[0037] The battery unit B has a roughly rectangular shape when viewed from one side in the vertical direction of the vehicle. The rear end B1 of the battery unit B is located behind the rear end of the front cross member 4. The majority of the battery unit B, excluding the rear, is located in front of the front cross member 4 and is positioned below the main floor panel 31.

[0038] The rear end of the battery unit B is supported by the portion of the rear side member 2 located behind the front cross member 4. In the illustrated example, the vehicle width end of the rear end of the battery unit B is fixed to a battery support bracket 10, which is joined to the rear of the overlapping portion 2X of the rear side member 2 by spot welding or the like. In other words, the rear end of the battery unit B is supported by the overlapping portion 2X of the rear side member 2 via the battery support bracket 10. The battery support bracket 10 consists of multiple members, and in Figures 2, 4, and 5, some of the members constituting the battery support bracket 10 have been removed.

[0039] Specifically, the battery support bracket 10 is joined to the rear side member 2 at a position adjacent to the arm support bracket 7, on the inward side in the vehicle width direction. In other words, the rear end of the battery unit B is joined (fixed) to the rear side member 2 near the joint of the arm support bracket 7 on the rear side member 2. Furthermore, the battery support bracket 10 is also joined to the arm support bracket 7. Therefore, the rear end of the battery unit B is also supported (fixed) to the arm support bracket 7.

[0040] Furthermore, the rear end position of the arm support bracket 7 and the rear end position of the overlapping portion 2X are approximately the same in the longitudinal direction of the vehicle. The battery support bracket 10 is positioned adjacent to the arm support bracket 7 on the inward side in the vehicle width direction and offset to the rear of the vehicle relative to the arm support bracket 7. The battery support bracket 10 is joined to the overlapping portion 2X at multiple points in front of the rear end of the overlapping portion 2X. As described above, most of the multiple joining points of the arm support bracket 7 to the overlapping portion 2X are located on the outward side in the vehicle width direction. Therefore, the arm support bracket 7 and the battery support bracket 10 are joined to the overlapping portion 2X around the rear end of the overlapping portion 2X in such a way that they avoid the inward portion of the overlapping portion 2X in the vehicle width direction. As a result, the increase in strength of the overlapping portion 2X due to the bracket joining is suppressed in the inward portion of the area around the rear end of the overlapping portion 2X in the vehicle width direction.

[0041] Here, the vehicle rear structure 100 has a compression deformation promoting section 2V, which is described in detail below, in order to avoid contact between the battery unit B and the floor panel 3 in the event of a rear collision.

[0042] The rear side member 2 of the vehicle rear structure 100 has a compression deformation promoting portion 2V that promotes compression deformation of the rear side member 2 in the vehicle longitudinal direction, located behind the rear end B1 of the battery unit B. In other words, the compression deformation promoting portion 2V has a compression strength in the vehicle longitudinal direction that is lower than the compression strength in the vehicle longitudinal direction of the portion of the rear side member 2 outside the range of the compression deformation promoting portion 2V.

[0043] The compression deformation promoting section 2V is provided in the vehicle's longitudinal direction from a predetermined position behind the rear end B1 of the battery unit B and in front of the rear end of the overlapping section 2X to a position corresponding to the front end of the rear cross member 5 of the rear side member 2. Therefore, the compression deformation promoting section 2V is located behind the rear end B1 of the battery unit B and is provided in the rear side member 2 in a range that crosses the rear end position of the overlapping section 2X in the longitudinal direction. More specifically, the front end of the range of the compression deformation promoting section 2V is located between the rear end B1 of the battery unit B and the rear end of the overlapping section 2X (the rear end of the side sill 1) in the vehicle's longitudinal direction. Therefore, the front part of the compression deformation promoting section 2V extends to the range of the overlapping section 2X of the high-strength frame section Z, which consists of the side sill 1 and the overlapping section 2X, and mitigates the increase in strength of the rear part of the high-strength frame section Z.

[0044] Specifically, referring to Figure 5, the front end of the compression deformation promotion section 2V is aligned with the rear end of one of the multiple connection points of the battery support bracket 10 to the rear side member 2 (in other words, the rear end of the battery support bracket connection point on the rear side member 2).

[0045] Furthermore, the front end of the compression deformation promotion section 2V is positioned behind the rear end of the rear seat (not shown) in the vehicle's longitudinal direction, in relation to the rear seat located inside the passenger compartment.

[0046] In this embodiment, the rear side member 2 includes a rear side member body 21 extending in the longitudinal direction of the vehicle, and a reinforcing portion 22 extending along the rear side member body 21 and joined to the rear side member body 21 by spot welding or the like.

[0047] The rear side member body 21 extends over the entire length of the rear side member 2 and constitutes the main body (outer shell) of the rear side member 2. The rear side member body 21 has a groove-shaped (approximately U-shaped) cross-section that is open upwards. In the illustrated example, the rear side member body 21 has a bottom wall 21a, an outer vertical wall 21b, an inner vertical wall 21c, an outer flange 21d, and an inner flange 21e. The lower surface of the bottom wall 21a constitutes the lower surface of the rear side member 2. The outer vertical wall 21b extends upward from the outer end of the bottom wall 21a in the vehicle width direction, and the inner vertical wall 21c extends upward from the inner end of the bottom wall 21a in the vehicle width direction. The outer flange 21d extends upward in a continuous manner with the outer vertical wall 21b and extends above the upper end of the inner vertical wall 21c. The inner flange 21e extends inward in the vehicle width direction from the upper end of the inner vertical wall 21c.

[0048] The reinforcing section 22 consists of a front reinforcing member 22a and a rear reinforcing member 22b provided behind the front reinforcing member 22a. The front reinforcing member 22a and the rear reinforcing member 22b are arranged inside the rear side member body 21.

[0049] Both the front reinforcing member 22a and the rear reinforcing member 22b have a groove-shaped (approximately U-shaped) cross-section that is open upwards. The front reinforcing member 22a and the rear reinforcing member 22b are positioned inside the rear side member body 21 and extend along the rear side member body 21. The front reinforcing member 22a and the rear reinforcing member 22b are spaced apart from each other in the longitudinal direction of the vehicle within the range of the compression deformation promotion section 2V.

[0050] In the illustrated example, the front reinforcing member 22a has a first bottom wall 22a1, a first outer vertical wall 22a2, and a first inner vertical wall 22a3. Similarly, the rear reinforcing member 22b has a second bottom wall 22b1, a second outer vertical wall 22b2, and a second inner vertical wall 22b3. The first bottom wall 22a1 and the second bottom wall 22b1 extend along the upper surface of the bottom wall 21a of the rear side member body 21 and are joined to the bottom wall 21a. The first outer vertical wall 22a2 protrudes upward from the outer end in the vehicle width direction of the first bottom wall 22a1, extends along the inner surface of the outer vertical wall 21b of the rear side member body 21, and is joined to the outer vertical wall 21b. The first inner vertical wall 22a3 protrudes upward from the inner end in the vehicle width direction of the first bottom wall 22a1, extends along the inner surface of the inner vertical wall 21c of the rear side member body 21, and is joined to the inner vertical wall 21c. The second outer vertical wall 22b2 protrudes upward from the outer end in the vehicle width direction of the second bottom wall 22b1, extends along the inner surface of the outer vertical wall 21b of the rear side member body 21, and is joined to the outer vertical wall 21b. The second inner vertical wall 22b3 protrudes upward from the inner end in the vehicle width direction of the second bottom wall 22b1, extends along the inner surface of the inner vertical wall 21c of the rear side member body 21, and is joined to the inner vertical wall 21c.

[0051] The compression deformation promoting section 2V has an unreinforced section 2V1 in the separation range between the front reinforcement member 22a and the rear reinforcement member 22b, where the inner surface of the rear side member body 21 (in the illustrated example, the upper surface of the bottom wall 21a, the inner surface of the outer vertical wall 21b, and the inner surface of the inner vertical wall 21c) is not covered by the front reinforcement member 22a and the rear reinforcement member 22b. In other words, the rear side member body 21 is not covered by the reinforcement member 22 and is not reinforced by the reinforcement section 22 in the unreinforced section 2V1.

[0052] In this embodiment, the rear end position of the non-reinforced portion 2V1 of the compression deformation promotion portion 2V is set to a position that aligns with the rear end of the overlapping portion 2X (rear end 1b of the side sill 1) in the vehicle longitudinal direction.

[0053] Referring to Figures 4 and 5, the front reinforcing member 22a extends along the rear side member body 21 in the longitudinal direction of the vehicle, from a position corresponding to the rear flange 4c of the front cross member 4 to the rear end of the connection point of the battery support bracket 10 to the overlapping portion 2X. In the illustrated example, the range of the unreinforced portion 2V1 in the longitudinal direction of the vehicle is roughly aligned with the inner portion in the vehicle width direction of the periphery of the rear end of the overlapping portion 2X, where the increase in strength of the overlapping portion 2X due to the aforementioned bracket connection is suppressed.

[0054] The rear reinforcing member 22b extends from the rear end of the overlapping portion 2X (the rear end 1b of the side sill 1) to the rear end of the rear side member body 21. The rear reinforcing member 22b intersects with the rear cross member 5 and extends both forward and backward of the rear cross member 5.

[0055] In this embodiment, the first height h1, which is the height of the vertical walls of the rear reinforcing member 22b within the range of the compression deformation promotion section 2V (i.e., the second outer vertical wall 22b2 and the second inner vertical wall 22b3), is set to a predetermined height that is less than half of the second height h2, which is the height of the vertical walls of the rear reinforcing member 22b outside the range of the compression deformation promotion section 2V (the second outer vertical wall 22b2 and the second inner vertical wall 22b3). Therefore, the lower vertical walls of the rear reinforcing member 22b (the second outer vertical wall 22b2 and the second inner vertical wall 22b3) extend from the front end of the rear reinforcing member 22b to a position corresponding to the front end of the rear cross member 5 in the longitudinal direction of the vehicle. Furthermore, the second height h2 is set to approximately the same height as the height of the vertical walls of the rear cross member 5. Furthermore, the height of the vertical walls of the front reinforcing member 22a (i.e., the first outer vertical wall 22a2 and the first inner vertical wall 22a3) is set to the same height as the second height h2 of the vertical walls of the rear reinforcing member 22b (the second outer vertical wall 22b2 and the second inner vertical wall 22b3) located outside the range of the compression deformation promotion section 2V.

[0056] In this embodiment, the second bottom wall 22b1, which is the bottom wall of the rear reinforcing member 22b within the range of the compression deformation promotion section 2V, is provided with a deformation induction section 23 having a shape that induces compression deformation. In the illustrated example, the deformation induction section 23 is a bead with a U-shaped cross-section that protrudes upward from the vehicle and extends in the vehicle width direction.

[0057] In the vehicle body understructure 100 configured as described above, the rear side member 2 has a compression deformation promoting section 2V located behind the rear end B1 of the battery unit B, which promotes compression deformation of the rear side member 2 in the longitudinal direction of the vehicle. As a result, when an impact load is applied from the rear of the vehicle during a rear collision, the compression deformation of the rear side member 2 is promoted (induced) at the compression deformation promoting section 2V located behind the rear end B1 of the battery unit B, and the compression deformation promoting section 2V of the rear side member 2 is crushed and compressed in the longitudinal direction.

[0058] Here, the rear end of the high-strength frame section Z, which consists of the side sill 1 and the overlapping section 2X, is continuous with the portion of the rear side member 2 that is further rear than the overlapping section 2X. Therefore, if the front end of the range of the compression deformation promotion section 2V were set at the rear end of the overlapping section 2X, the compressive strength would change excessively at the rear end of the overlapping section 2X, which is undesirable from the viewpoint of stress concentration, etc. In contrast, in the vehicle rear structure 100 according to this embodiment, the front end of the range of the compression deformation promotion section 2V is located between the rear end B1 of the battery unit B and the rear end of the overlapping section 2X in the longitudinal direction of the vehicle. Therefore, the increase in strength at the rear of the high-strength frame section Z is mitigated by the front part of the compression deformation promotion section 2V. As a result, the change in strength at the rear end of the overlapping section 2X is mitigated, the intended compressive deformation is reliably induced, and the impact energy is efficiently absorbed by the compressive deformation in the compression deformation promotion section 2V. And, since the impact energy is preferentially absorbed by the compressive deformation, the occurrence of vertical rotational deformation, which was a concern in the prior art, is prevented in the rear side member 2. In this manner, the rear vehicle structure 100 prevents vertical rotational deformation of the rear side member 2 and the floor panel 3 by generating longitudinal compression deformation in the compression deformation promoting section 2V of the rear side member 2 during a rear-end collision, thereby avoiding contact between the floor panel 3 and the battery unit B.

[0059] Furthermore, the strength of the high-strength frame section Z, which consists of the side sill 1 and the overlapping section 2X, is higher than the strength of other surrounding parts. Therefore, the shape and orientation of the high-strength frame section Z are generally maintained during a rear-end collision. When the compression deformation accelerating section 2V of the rear side member 2 is compressed and crushed in the longitudinal direction due to a rear-end collision, the portion of the rear side member 2 behind the compression deformation accelerating section 2V (i.e., the rear part 2b of the rear side member) and the portion of the rear floor panel 32 located behind the front end of the rear cross member 5 generally maintain a horizontal orientation and shape while moving horizontally forward. In other words, during a rear-end collision, the main floor panel 31 and the portion of the rear floor panel 32 behind the front end of the rear cross member 5 each maintain a generally parallel orientation. Therefore, contact between the floor panel 3 and the battery unit B is more effectively avoided. Furthermore, even if the drive unit M is positioned below the rear floor panel 32 in the space between the front end of the rear cross member 5 and the rear end of the rear floor panel 32 in the longitudinal direction, the shape of the vehicle body structure above the drive unit M (rear floor panel 32, rear side member 2, center member 10) is generally maintained during a rear-end collision. This ensures that a space is secured to protect the drive unit M, thus protecting the drive unit M from the impact of a rear-end collision.

[0060] As described above, the rear vehicle structure 100 according to this embodiment has a structure for avoiding contact between the floor panel 3 and the battery unit B.

[0061] In this embodiment, the compression deformation promoting section 2V has an unreinforced section 2V1 on the inner surface of the rear side member body 21 that is not covered by the front reinforcing member 22a and the rear reinforcing member 22b, located in the separation range between the front reinforcing member 22a and the rear reinforcing member 22b. As a result, compression deformation of the compression deformation promoting section 2V is induced starting from the intended region on the rear side member 2 where the unreinforced section 2V1 is provided, and the intended compression deformation occurs more reliably.

[0062] In this embodiment, the rear end position of the non-reinforced portion 2V1 is set to align with the rear end of the overlapping portion 2X of the rear side member 2 in the vehicle's longitudinal direction. Therefore, the weakest point in the compression deformation promoting portion 2V is located around the rear end of the overlapping portion 2X in the high-strength frame portion Z, which consists of the side sill 1 and the overlapping portion 2X. As a result, compression deformation in the longitudinal direction of the compression deformation promoting portion 2V occurs more reliably.

[0063] In this embodiment, the first height h1 of the vertical walls (second outer vertical wall 22b2, second inner vertical wall 22b3) of the rear reinforcing member 22b within the range of the compression deformation promotion section 2V is less than half the second height h2 of the vertical walls (second outer vertical wall 22b2, second inner vertical wall 22b3) of the rear reinforcing member 22b outside the range of the compression deformation promotion section 2V. As a result, adequate rigidity necessary for normal driving is ensured at the rear of the compression deformation promotion section 2V, and sufficient impact energy absorption due to compression deformation in the event of a rear collision is ensured.

[0064] In this embodiment, the second bottom wall 22b1 of the rear reinforcing member 22b within the range of the compression deformation promotion section 2V is provided with a deformation induction section 23 having a shape that induces compression deformation. As a result, compression deformation occurs more reliably in the tip portion of the rear reinforcing member 22b.

[0065] Furthermore, the arm support bracket 7 and the battery support bracket 10 are joined to the overlapping portion 2X around the rear end of the overlapping portion 2X, avoiding the inner portion of the overlapping portion 2X in the vehicle width direction. This suppresses the increase in strength of the overlapping portion 2X due to the bracket joining in the inner portion of the rear end of the overlapping portion 2X in the vehicle width direction. As a result, the compression deformation in the front part of the compression deformation promotion portion 2V is not hindered by the bracket joining.

[0066] Specifically, in the portion of the compression deformation promotion section 2V behind the rear end of the overlapping section 2X (the rear end 1b of the side sill 1), compression deformation occurs in the longitudinal direction, crushing evenly on both sides during a rear-end collision. In the portion of the compression deformation promotion section 2V in front of the rear end of the overlapping section 2X, compression deformation occurs in the longitudinal direction, crushing the inner wall of the overlapping section 2X (i.e., the inner vertical wall 21b of the rear side member body 1) during a rear-end collision. Therefore, in this embodiment, the compression deformation of the compression deformation promotion section 2V generally occurs behind the rear end 1b of the side sill 1, the arm support bracket 7, and the battery support bracket 10. As a result, the front part of the trailing arm 6b supported by the arm support bracket 7 and the trailing arm 6b maintain approximately the same distance from the battery unit B as before the collision, even after the collision, and surround the rear of the battery unit B from behind. Therefore, the front part of the trailing arm 6b and the trailing arm 6b also function as a barrier to protect the battery unit B during a rear-end collision.

[0067] The arm support bracket 7 and the battery support bracket 10 are joined to the rear of the overlapping portion 2X, respectively, and the strength of the portion of the overlapping portion 2 other than the area around the rear end is more effectively increased. As a result, the shape and posture of the high-strength frame portion Z are maintained more effectively, and contact between the floor panel 3 and the battery unit B is more reliably avoided.

[0068] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and further modifications and changes are possible based on the technical concept of the present invention.

[0069] For example, the drive unit M may be located at the front of the vehicle rather than below the rear floor panel 32. Also, the rear suspension structure 6 is not limited to a torsion beam type, and any appropriate type of structure may be applied. Furthermore, although the rear side member 2 is curved so as it extends from the overlapping portion 2X towards the rear, it is not limited to this and may extend to the rear without curving. [Explanation of Symbols]

[0070] 1. Side sill 1a Inner part in the vehicle width direction 1b rear end 1c top surface 2 Rear side member 2a Front of rear side member 2b Rear side member 2c Rear side member inclined section 2V Compression Deformation Acceleration Unit 2V1 Non-reinforced part 2X overlapping area 21 Rear side member body 21a Bottom wall 21b Outer vertical wall 21c Inner vertical wall 21d Outer flange 21e Inner flange 22 Reinforcement section 22a Front reinforcing member 22a1 1st bottom wall 22a2 1st outer vertical wall 22a3 1st inner vertical wall 22b Rear reinforcing member 22b1 Second bottom wall (bottom wall) 22b2 Second outer vertical wall (vertical wall) 22b3 Second Inner Vertical Wall (Vertical Wall) 23 Deformation Inducing Section 3 Floor Panels 31 Main floor panel 32 Rear floor panel 32a Anterior bulge 32a1 Front vertical wall 32a2 Rear vertical wall 32a3 Left side wall 32a4 Right side wall 32a5 upper wall 32b Posterior bulge 32b1 Upper wall 4 Front crossmember 4a end 4b Front flange 4c rear flange 5. Rear cross member 5a end 5b Front flange 5c rear flange 6. Rear suspension structure 6a Torsion beam 6b Trailing Arm 6b1 Body-side coupling section (front end) 6c coil spring 6d Spring support section 7. Arm support bracket 8a First bracket 8b Second bracket 8c Third bracket 9 Center Members 10 Battery support bracket 100 Rear structure of the vehicle B Battery Unit B1 rear end h1 First height h2 Second height J Power supply junction box M Drive Unit S bracket upper placement space T Rear tire Z High-strength frame section

Claims

1. A side sill is provided on the outer side in the vehicle width direction at the lower part of the vehicle and extends in the vehicle longitudinal direction, A rear side member having an overlapping portion that overlaps and is joined to the rear of the inner portion of the side sill in the vehicle width direction, and extending from the overlapping portion further rearward and upward than the rear end of the side sill, The floor panel to which the side sill and the rear side member are joined, A front cross member having an end connected to the front of the overlapping portion and extending in the vehicle width direction along the floor panel, A rear vehicle structure including a battery unit located below the floor panel, A rear cross member having an end connected to the rear side member behind the rear end of the side sill, extending in the vehicle width direction along the floor panel, Includes, The rear end of the battery unit is located further back than the rear end of the front cross member. The rear end of the battery unit is supported by a portion of the rear side member located further back than the front cross member. The rear side member has a compression deformation promoting portion that promotes compression deformation of the rear side member in the vehicle longitudinal direction, The rear vehicle structure is characterized in that the compression deformation promoting portion is provided in a range from a predetermined position in the longitudinal direction of the vehicle that is behind the rear end of the battery unit and in front of the rear end of the overlapping portion, to a position corresponding to the front end of the rear cross member of the rear side member.

2. The rear side member comprises a rear side member body extending in the longitudinal direction of the vehicle, and a reinforcing portion extending along the rear side member body and joined to the rear side member body. The reinforcing portion consists of a front reinforcing member and a rear reinforcing member provided behind the front reinforcing member. Each of the rear side member body, the front reinforcing member, and the rear reinforcing member has a groove-shaped cross-section that is open upwards. The aforementioned front reinforcing member and the aforementioned rear reinforcing member are arranged inside the rear side member body and are spaced apart from each other in the vehicle's longitudinal direction within the range of the compression deformation promoting section. The rear vehicle structure according to claim 1, characterized in that the compression deformation promoting portion has an unreinforced portion on the inner surface of the rear side member body that is not covered by the front reinforcing member and the rear reinforcing member, within the separation range between the front reinforcing member and the rear reinforcing member.

3. The vehicle rear structure according to claim 2, characterized in that the rear end position of the unreinforced portion is set to a position that aligns with the rear end of the overlapping portion in the longitudinal direction of the vehicle.

4. The vehicle rear structure according to claim 2, characterized in that the first height, which is the height of the vertical wall of the rear reinforcing member within the range of the compression deformation promotion section, is set to a predetermined height that is less than half of the second height, which is the height of the vertical wall of the rear reinforcing member outside the range of the compression deformation promotion section.

5. The vehicle rear structure according to any one of 2 to 4, characterized in that the bottom wall of the rear reinforcing member within the range of the compression deformation promoting portion is provided with a deformation inducing portion having a shape that induces compression deformation.

6. The rear end of the battery unit is supported at the rear of the overlapping portion via a battery support bracket, as described in claim 1.

7. The rear vehicle structure according to claim 1, wherein an arm support bracket that supports the front end of the trailing arm of the rear suspension structure is joined to the rear of the overlapping portion.

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