Rear structure of electric vehicle

Abstract

In an electric vehicle in which a drive unit 1, which serves as the power source, is located at the rear of the vehicle, the layout flexibility and support rigidity of the drive unit 1 are ensured. [Solution] The rear structure of the electric vehicle includes a drive unit 1 located below the floor portion at the rear of the vehicle, a cradle frame 50 supporting the drive unit 1, a battery pack 2 located in front of the cradle frame 50, rear side members 10 located on both sides of the drive unit 1, and a first cross member 30 located in front of the cradle frame 50. The first cross member 30 is provided with a battery mounting portion 34b to which the battery pack 2 is attached. The cradle frame 50 has a frame shape including a front side member 51 located at the front, and a part of the front of the cradle frame 50 is joined to the lower part of the first cross member 30.

Description

Technical Field

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

Background Art

[0002] For example, as disclosed in Patent Document 1, there is known a vehicle in which a drive device for driving wheels is arranged at the rear of the vehicle. The vehicle in this example is a so-called hybrid vehicle, and an electric motor for mainly or subsidiarily driving the rear wheels is arranged at the rear of the vehicle.

[0003] The electric motor in this example is supported by a subframe fixed to the chassis frame. The chassis frame is a member arranged on the outer side in the vehicle width direction at the rear of the vehicle and extending in the vehicle longitudinal direction, and is a highly rigid member constituting the vehicle body frame. Further, the subframe is a member constituting a so-called cross-shaped structure and is attached to the chassis frame. That is, by attaching the subframe to the highly rigid chassis frame, the electric motor is stably supported.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the structure of the above example, a subframe is attached to the chassis frame arranged on the outer side in the vehicle width direction of the vehicle, and the subframe supports the electric motor. However, in the structure of the above example, when the cross-shaped subframe is attached to the chassis frame, since the subframe is attached to the lower part of the chassis frame, the region where the subframe can be arranged may be limited in the vehicle vertical direction.

[0006] Restricting the vertical position of the subframe on the vehicle also restricts the placement of the electric motors, reducing the flexibility of their layout. Furthermore, meeting the minimum ground clearance requirements may further reduce the flexibility of the subframe and electric motor layouts.

[0007] Battery packs used in electric vehicles are required to have a large capacity in order to extend the vehicle's driving range. As a result, battery packs tend to become larger. With larger battery packs, the proportion of space they occupy in the lower part of the floor increases. Therefore, depending on the position of the rear end of the battery pack, the space available for installing subframes and other components may be limited.

[0008] Furthermore, when attaching a subframe to the chassis frame in the example above, it may be necessary to reinforce the chassis frame where the subframe mounting points are located. This increases the vehicle's weight. Therefore, the structure in the example above had room for improvement in terms of ensuring both layout flexibility and rigidity of the area where the subframe is attached.

[0009] The present invention was made to solve the above problems, and its objective is to provide a rear structure for an electric vehicle in which a drive unit serving as a power source is located at the rear of the vehicle, and which can ensure the layout flexibility and support rigidity of the drive unit. [Means for solving the problem]

[0010] The rear structure of an electric vehicle according to the present invention for achieving the above objective includes a drive unit located below the floor portion at the rear of the vehicle, a cradle frame supporting the drive unit, and a battery pack located on the front side of the cradle frame. The rear structure of the electric vehicle further includes a pair of side members arranged on both sides of the drive unit in the vehicle width direction and extending in the vehicle longitudinal direction, and a cross member extending in the vehicle width direction so as to connect the side members and located on the front side of the cradle frame, wherein the cross member is provided with a battery mounting portion to which the battery pack is attached, and the cradle frame has a frame shape including a front side portion located at the front and extending in the vehicle width direction, and a part of the front portion of the cradle frame is joined to the lower part of the cross member. [Effects of the Invention]

[0011] According to the present invention, in an electric vehicle in which a drive unit serving as a power source is located at the rear of the vehicle, it is possible to ensure the layout flexibility and support rigidity of the drive unit. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic bottom view showing one embodiment of the rear structure of an electric vehicle according to the present invention. [Figure 2] This is a bottom view showing an enlarged view of the right side of the straight section in Figure 1. [Figure 3] This is a bottom view showing the cradle frame in Figure 2 with the frame removed. [Figure 4] Figure 2 is a perspective view of the right side and surrounding area of ​​the first cross member, seen from the rear and below the vehicle. [Figure 5] Figure 4 is a perspective view with the rear side member transparent. [Figure 6] This is an end view taken along the line AA in Figure 4. [Modes for carrying out the invention]

[0013] Hereinafter, one embodiment of the rear structure of an electric vehicle according to the present invention will be described with reference to the drawings (Figures 1 to 6). In the figures, the direction of arrow Fr indicates the front in the longitudinal direction of the vehicle. In the description of the embodiment, "front (front end) and rear (rear end)" correspond to the front and rear of the vehicle in the longitudinal direction. Arrows R and L indicate the right and left sides as seen from the perspective of an occupant looking forward of the vehicle. Arrow U indicates the upward direction in the vertical direction of the vehicle.

[0014] The rear structure of the electric vehicle in this embodiment includes a drive unit 1 located below the floor portion (rear floor portion 6 in this example) at the rear of the vehicle, a cradle frame 50 supporting the drive unit 1, and a battery pack 2 located on the front side of the cradle frame 50.

[0015] The drive unit 1 is, for example, a drive source for driving the rear or front wheels, and is electrically connected to the battery pack 2 via a harness (not shown), and is driven by power supplied from the battery pack 2. In this example, the schematic of the drive unit 1 is shown by a dashed line in Figure 1. The cradle frame 50 is a member that forms a roughly rectangular frame shape when viewed from below, and is attached to the vehicle body frame. Details of the cradle frame 50 will be described later.

[0016] The floor of the electric vehicle in this embodiment has a front floor section 5 located below a vehicle seat (not shown) and a rear floor section 6 located on the rear side of the front floor section 5. The front floor section 5 and the rear floor section 6 may be made of a single panel or multiple panels. The front floor section 5 is a panel that constitutes the floor of the vehicle compartment and is made of a metal material. The front floor section 5 is joined to the upper part of the front side member 21, which will be described later.

[0017] The rear floor portion 6 is a panel that constitutes the floor portion of the luggage compartment located on the vehicle rear side of the rear seat (not shown), and is formed of a metal material. The rear floor portion 6 has an inclined portion 6A and a flat portion 6B. The inclined portion 6A is inclined upward with respect to the vehicle from the rear portion of the front floor portion 5 toward the vehicle rear. The flat portion 6B is a portion that extends rearward of the vehicle from the rear end of the inclined portion 6A. The inclined portion 6A and the flat portion 6B are integrally formed. Further, the rear floor portion 6 is joined to the upper portion of a rear side member 10, which will be described later. The relationship between the rear floor portion 6 and the rear side member 10 will be described later.

[0018] As shown in FIG. 1, the battery pack 2 is disposed on the vehicle front side of the drive device 1 disposed at the vehicle rear and on the lower side of the floor portion of the vehicle. In this example, the battery pack 2 is a so-called heavy object, is disposed on the lower side of the front floor portion 5, and has a substantially rectangular parallelepiped shape extending in the vehicle longitudinal direction and the vehicle width direction. The rear end of the battery pack 2 is disposed on the vehicle front side of the rear end of the front floor portion 5.

[0019] The rear structure of the electric vehicle of the present embodiment further includes side members 10, 21, three cross members 30, 42, 45, three braces 47, 48, and a rear end panel 46. Hereinafter, details of each member will be described. The rear end panel 46 is disposed at the rear end of the vehicle and extends in the vehicle width direction. The rear end panel 46 is a panel having a front surface portion facing the vehicle front, and the rear portion of the flat portion 6B of the rear floor portion 6 and the rear portion of the rear side member 10, which will be described later, are joined to the front surface portion.

[0020] The side members 10, 21 are highly rigid members formed of a metal material and constitute a part of the vehicle body frame. The side members 10, 21 of the present embodiment include a front side member 21 disposed on the lower side of the front floor portion 5 and a rear side member 10 extending rearward of the vehicle from the rear portion of the front side member 21, as shown in FIG. 1.

[0021] The front side member 21 is disposed outside the battery pack 2 in the vehicle width direction and extends in the vehicle front-rear direction along the side portion of the battery pack 2. An outer support bracket (not shown) or the like for supporting the side portion of the battery pack 2 is joined to the front side member 21. Further, a side sill, for example, is joined to the outer portion of the front side member 21.

[0022] As shown in FIGS. 4 to 6, the front side member 21 has an outer wall portion 22 extending in the vehicle front-rear direction, an inner wall portion 23 disposed at an interval inside the outer wall portion 22 in the vehicle width direction and extending in the vehicle front-rear direction, and a lower surface portion 24 connecting the lower end of the outer wall portion 22 and the lower end of the inner wall portion 23 and extending in the vehicle front-rear direction.

[0023] The outer wall portion 22 has a wall surface facing the outside of the vehicle, extends downward from the lower surface of the front floor portion 5, and extends in the vehicle front-rear direction. The inner wall portion 23 has a wall surface facing the inside of the vehicle, extends downward from the lower surface of the front floor portion 5, and extends in the vehicle front-rear direction. As shown in FIGS. 4 and 5, a flange portion 23a protruding inward in the vehicle width direction is provided at the upper end of the inner wall portion 23, and the flange portion 23a is joined to the lower surface of the front floor portion 5. In this example, the inner wall portion 23 of the front side member 21 is disposed at an interval from the side portion of the battery pack 2. An outer support bracket for supporting the battery pack 2 may be joined to the lower surface portion 24 of the front side member 21, for example.

[0024] As shown in Figure 1, the rear side members 10 are arranged in pairs on both sides of the drive unit 1 in the vehicle width direction and extend as a whole in the vehicle longitudinal direction. In this example, as shown in Figure 4, the rear side members 10 have a member inclined portion 10A and a member straight portion 10B. The member inclined portion 10A is the part located at the front of the rear side member 10 and is the part that slopes upward from the front end of the rear side member 10 towards the rear of the vehicle. The rear of the member inclined portion 10A corresponds to the joint to which the second cross member 42, which will be described later, is joined. The member straight portion 10B is the part that extends almost in a straight line from the rear of the member inclined portion 10A to the rear end panel 46 (Figure 1). The upper part of the member inclined portion 10A is spaced apart from the inclined portion 6A and the flat portion 6B of the rear floor portion 6. A reinforcement 15 is placed in this space.

[0025] The rear side member 10, like the front side member 21, has an outer wall portion 11, an inner wall portion 12, and a lower surface portion 13 (Figure 6). In this embodiment, a reinforcement 15 is located inside the rear side member 10.

[0026] The outer wall portion 11 of the rear side member 10 is a wall portion located on the outer side of the rear side member 10 in the vehicle width direction. Although not shown in the diagram, the upper part of the outer wall portion 11 located on the member inclined portion 10A of the rear side member 10 is spaced apart from the inclined portion 6A and the flat portion 6B of the rear floor portion 6, as described above. The outer wall portion 11 located on the member straight portion 10B is joined to the flat portion 6B of the rear floor portion 6.

[0027] The inner wall portion 12 of the rear side member 10 is a wall portion that is positioned at a distance from the outer wall portion 11 of the rear side member 10 in the vehicle width direction. As shown in Figure 4, the upper part of the inner wall portion 12 located on the member inclined portion 10A is positioned at a distance from the inclined portion 6A and the flat portion 6B of the rear floor portion 6 in the vehicle vertical direction. The inner wall portion 12 located on the member straight portion 10B is joined to the flat portion 6B of the rear floor portion 6. In this example, a flange portion 12a that protrudes inward in the vehicle width direction is provided at the upper end of the inner wall portion 12, and this flange portion 12a is joined to the flat portion 6B of the rear floor portion 6.

[0028] The lower surface portion 13 of the rear side member 10 connects the outer wall portion 11 and the inner wall portion 12. That is, the rear side member 10 has a U-shaped cross-section due to the outer wall portion 11, the inner wall portion 12, and the lower surface portion 13. The lower surface portion 13 located at the connection point between the member inclined portion 10A and the member straight portion 10B is provided with a spring receiving portion 13a of the rear suspension structure, etc.

[0029] The reinforcement 15 is a member for reinforcing the rear side member 10, particularly the member inclined portion 10A. As shown in Figure 6, the reinforcement 15, like the rear side member 10, has an outer wall portion 16, an inner wall portion 17, and a lower surface portion 18, and has a U-shaped cross-section.

[0030] The lower surface portion 18 of the reinforcement 15 connects the outer wall portion 16 and the inner wall portion 17, and is positioned above the lower surface portion 13 of the member inclined portion 10A of the rear side member 10. As shown in Figure 5, the lower surface portion 18 of the reinforcement 15 is inclined upward as it approaches the rear of the vehicle. In the longitudinal direction of the vehicle, the front end of the lower surface portion 18 of the reinforcement 15 is located outside the first cross member 30, and the rear end of the lower surface portion 18 is positioned between the second cross member 42 and the third cross member 45.

[0031] The outer wall portion 16 of the reinforcement 15 is joined to the outer wall portion 11 of the rear side member 10 from the inside in the vehicle width direction, reinforcing the outer wall portion 11 of the rear side member 10. Furthermore, the upper part of the outer wall portion 16 of the reinforcement 15 is positioned above the upper part of the outer wall portion 11 located on the member inclined portion 10A of the rear side member 10, and is joined to the inclined portion 6A and the flat portion 6B of the rear floor portion 6.

[0032] The inner wall portion 17 of the reinforcement 15 is joined to the inner wall portion 12 of the rear side member 10 from the outside in the vehicle width direction, reinforcing the inner wall portion 12 of the rear side member 10. Also, as shown in Figure 5, the upper part of the inner wall portion 17 of the reinforcement 15 is positioned above the upper part of the inner wall portion 12 located on the member inclined portion 10A of the rear side member 10, and is joined to the inclined portion 6A and the flat portion 6B of the rear floor portion 6. An inclined flange portion 17a is provided at the front end of the inner wall portion 17, which is joined to the inclined portion 6A of the rear floor portion 6, and an upper flange portion 17b is provided at the upper end of the inner wall portion 17, which is joined to the flat portion 6B of the rear floor portion 6.

[0033] Next, the first cross member 30 will be described. The first cross member 30 is a member that extends in the vehicle width direction so as to connect the left and right rear side members 10, and is made of a metal material. The first cross member 30 is a highly rigid member that constitutes the vehicle body frame, similar to the side members 10 and 21. The first cross member 30 is positioned across the front of the inclined portion 6A of the rear floor portion 6 and the rear of the front floor portion 5.

[0034] The first cross member 30 has a central member 31 and an extension member 36. The central member 31 is a portion that extends linearly in the vehicle width direction. The extension member 36 extends outward in the vehicle width direction from each of the outer portions of the central member 31 in the vehicle width direction and is joined to the inner wall portion 12 of the rear side member 10.

[0035] As shown in Figures 1 to 3, the central member 31 has a front wall portion 32, a rear wall portion 33, and a lower surface portion 34. The front wall portion 32 of the central member 31 has a wall surface facing the front of the vehicle and extends in the vehicle width direction. The middle portion of the front wall portion 32 of the central member 31 in the vehicle width direction protrudes forward relative to the outer portion and extends in the vehicle width direction. The lower surface portion 34 is connected to the lower end of the front wall portion 32 of the central member 31. The outer portion of the front wall portion 32 of the central member 31 in the vehicle width direction is joined to an extension member 36, with the front wall portion 37 attached. Furthermore, a front flange portion 32a that protrudes forward is provided at the upper end of the front wall portion 32 of the central member 31 and is joined to the lower surface of the front floor portion 5, for example, by spot welding.

[0036] The rear wall portion 33 of the central member 31 has a wall surface facing the rear of the vehicle and extends in the vehicle width direction. The upper part of the rear wall portion 33 is joined to the inclined portion 6A of the rear floor portion 6. In addition, the outer part of the rear wall portion 33 of the central member 31 in the vehicle width direction is joined to the rear wall portion 38 of the extension member 36.

[0037] Furthermore, the lower surface portion 34 of the central member 31 extends forward from the lower end of the rear wall portion 33 and is connected to the upper end of the front wall portion 32. The lower surface portion 34 has a substantially horizontal central lower surface portion 34a located in the middle of the vehicle width direction, an outer inclined portion 34c located outside the central lower surface portion 34a, and an outer lower surface portion 34d located further outside the outer inclined portion 34c.

[0038] The outer inclined portion 34c is the part that slopes upward from the outer end in the vehicle width direction of the central lower surface portion 34a as it extends outward in the vehicle width direction. The outer lower surface portion 34d is the part that extends outward in the vehicle width direction from the outer end of the outer inclined portion 34c and is substantially horizontal. The outer inclined portion 34c and the outer lower surface portion 34d are preferably arranged substantially symmetrically on both the left and right sides of the central lower surface portion 34a.

[0039] In this embodiment, as shown in Figures 4 and 5, a convex portion 34A is provided in the middle of the lower part of the first cross member 30 in the vehicle width direction, projecting downwards from the vehicle and extending in the vehicle width direction. In this example, the convex portion 34A is composed of a central lower surface portion 34a, left and right outer inclined portions 34c, and a front wall portion 32 and a rear wall portion 33 connected thereto. A battery mounting portion 34b is provided on the outer part of the central lower surface portion 34a that constitutes the convex portion 34A, and a battery bracket 3 for supporting the battery pack 2 is joined to the battery mounting portion 34b. The battery bracket 3 will be described later.

[0040] Next, the extension member 36 will be described. The extension member 36 is a member positioned on the outer side of the central member 31 in the vehicle width direction, and has a front wall portion 37, a rear wall portion 38, and a lower surface portion 39. The front wall portion 37 of the extension member 36 has a wall surface facing the front of the vehicle, similar to the front wall portion 32 of the central member 31, and extends in the vehicle width direction. The upper end of the front wall portion 37 of the extension member 36 is provided with a front flange portion 37b, similar to the front wall portion 32 of the central member 31, and is joined to the front floor portion 5 located in front of the inclined portion 6A, for example, by spot welding. In this embodiment, the outer portion of the front flange portion 32a of the front wall portion 32 of the central member 31, the inner portion of the front flange portion 37b of the front wall portion 37 of the extension member 36, and the front floor portion 5 are joined in a three-layer stack by spot welding.

[0041] Furthermore, the inner portion of the front wall portion 37 of the extension member 36 in the vehicle width direction is joined to the outer portion of the front wall portion 32 of the central member 31. In this example, a front weld portion 37a is provided on the interior of the front wall portion 37 of the extension member 36 in the vehicle width direction, and on the outer portion of the front wall portion 32 of the central member 31 in the vehicle width direction. In this embodiment, the front weld portion 37a is spot-welded with the interior of the front wall portion 37 of the extension member 36 in the vehicle width direction overlapping the outer portion of the front wall portion 32 of the central member 31 in the vehicle width direction. The front weld portion 37a has a plurality of welding points 37a1 (spot weld points shown by dashed lines in Figure 3). In this example, a plurality of welding points are arranged at intervals in the vertical direction of the vehicle to form one row of welding points, and two rows of welding points are arranged at intervals in the vehicle width direction.

[0042] Furthermore, the front outer flange portion 37c is provided on the outer side in the vehicle width direction of the front wall portion 37 of the extension member 36, projecting forward of the vehicle and extending in the vertical direction of the vehicle. The front outer flange portion 37c is joined to the inner wall portion 12 of the rear side member 10. In addition, the front outer flange portion 37c, the inner wall portion 12 of the rear side member 10, and the inner wall portion 17 of the reinforcement 15 are spot-welded together in a triple-layer configuration.

[0043] The rear wall portion 38 of the extension member 36, like the rear wall portion 32 of the central member 31, has a wall surface facing the rear of the vehicle and extends in the vehicle width direction. The upper part of the rear wall portion 38 of the extension member 36 is joined to the lower part of the inclined portion 6A by spot welding, similar to the rear wall portion 32 of the central member 31. In this embodiment, the upper part of the rear wall portion 32 of the central member 31, the upper part of the rear wall portion 37 of the extension member 36, and the inclined portion 6A may be joined in a triple-layered configuration by spot welding.

[0044] Furthermore, the inner portion of the rear wall portion 38 of the extension member 36 in the vehicle width direction is joined to the outer portion of the rear wall portion 32 of the central member 31. In this example, a rear weld portion 38a is provided on the interior of the rear wall portion 37 of the extension member 36 in the vehicle width direction, and on the outer portion of the rear wall portion 32 of the central member 31 in the vehicle width direction. In this embodiment, the rear weld portion 38a is spot-welded with the interior of the rear wall portion 38 of the extension member 36 in the vehicle width direction overlapping the outer portion of the rear wall portion 32 of the central member 31 in the vehicle width direction. Similar to the front weld portion 37a, the rear weld portion 38a has multiple welding points 38a1 (spot weld points shown by dashed lines in Figures 4 and 5). In this example, multiple welding points are arranged at intervals in the vertical direction of the vehicle to form one row of welding points, and two rows of welding points are arranged at intervals in the vehicle width direction.

[0045] Furthermore, a rear outer flange portion 38c is provided on the outer side in the vehicle width direction of the rear wall portion 37 of the extension member 36, which protrudes to the rear of the vehicle and extends in the vertical direction of the vehicle, and the rear outer flange portion 38c is joined to the inner wall portion 12 of the rear side member 10.

[0046] The lower surface portion 39 of the extension member 36 is the part that connects the front wall portion 37 and the rear wall portion 38, and faces downwards towards the vehicle. The inner portion of the lower surface portion 39 of the extension member 36 in the vehicle width direction is joined to the outer portion of the outer lower surface portion 34d of the central member 31 in the vehicle width direction. The outer end of the lower surface portion 37 of the extension member 36 is provided with a flange (not shown) that protrudes upward, and the flange is joined to the inner wall portion 12 of the rear side member 10.

[0047] A fastening portion 60 is provided at the joint between the extension member 36 and the central member 31 of the first cross member 30, to which the cradle frame 50 is fastened. The relationship between the cradle frame 50 and the first cross member 30 will be explained later.

[0048] Next, the second cross member 42 will be described. As shown in Figure 1, the second cross member 42 is positioned at a distance from the first cross member 30 at the rear of the vehicle. Like the first cross member 30, the second cross member 42 is made of metal and is a highly rigid member that constitutes part of the vehicle body frame. The front wall portion and rear wall portion 42a of the second cross member 42 are each provided with a front flange portion 43a and a rear flange portion 43b at their upper ends, and the front flange portion 43 and the rear flange portion are joined to the lower surface of the rear floor portion 6 by spot welding. In addition, the outer portions in the vehicle width direction of the front wall portion and rear wall portion 42a of the second cross member 42 are each provided with a front outer flange portion and a rear outer flange portion 43c, and the front outer flange portion and the rear outer flange portion 43c are joined to the inner wall portion 12 of the rear side member 10 (Figures 4 and 5).

[0049] A support member 44 extending in the vehicle's vertical direction is provided on the outer side in the vehicle width direction of the lower surface portion 42c of the second cross member 42. The support member 44 is spot-welded to the inner wall portion 12 of the rear side member 10, the rear wall portion 42a and rear outer flange portion 43c of the second cross member 42, etc. The lower end of the support member 44 is preferably positioned to correspond to the lower surface portion 13 of the rear side member 10. A spring receiving portion 13a constituting the rear suspension structure is provided at the lower end of the support member 44.

[0050] Next, the third cross member 45 will be described. The third cross member 45 is positioned at a distance from the second cross member 42 at the rear of the vehicle. The third cross member 45 is also positioned at a distance from the rear end panel 46 on the front side of the vehicle. Like the first cross member 30, the third cross member 45 is made of metal and is a highly rigid member that constitutes part of the vehicle body frame. The front wall portion and the rear wall portion of the third cross member 45 are each provided with a front flange portion and a rear flange portion at the top, and the front flange portion and the rear flange portion are joined to the underside of the rear floor portion 6 by spot welding. Further detailed explanations using illustrations are omitted, but the outer portion of the third cross member 45 in the vehicle width direction is joined to the rear side member 10.

[0051] Furthermore, an intermediate brace 47 extending in the longitudinal direction of the vehicle and two outer braces 48 are positioned between the second cross member 42 and the third cross member 45. The intermediate brace 47 is positioned between the two outer braces 48. The intermediate brace 47 and the two outer braces 48 are made of metal and are highly rigid members that constitute part of the vehicle body frame.

[0052] The front of the intermediate brace 47 is joined to the second cross member 42, and the rear of the intermediate brace 47 is joined to the third cross member 45. A rear brace 49 is provided on the rear side of the intermediate brace 47. The rear brace 49 extends in the longitudinal direction of the vehicle, with the front of the rear brace 49 joined to the third cross member 45, and the rear of the rear brace 49 joined to the rear end panel 46. The rear brace 49 is also joined to the lower surface of the flat portion 6B of the rear floor portion 6. The intermediate brace 47 and the rear brace 49 are arranged linearly in the longitudinal direction of the vehicle via the third cross member 45.

[0053] Furthermore, the front portions of the two outer braces 48 are joined to the second cross member 42, and the rear portions of the two outer braces 48 are joined to the third cross member 45. This creates a high-rigidity region between the second cross member 42 and the third cross member 45. The outer braces 48 are provided with fastening points to which the cradle frame 50 is fastened. The relationship between the cradle frame 50 and the outer braces 48 will be explained later.

[0054] Next, the cradle frame 50 will be described. The cradle frame 50 in this embodiment has a frame shape that includes a front side portion located at the front and extending in the vehicle width direction, and a part of the front side portion is joined to the lower part of the first cross member 30.

[0055] The cradle frame 50 in this example has a front member 51, a rear member 52, a left outer member 53, and a right outer member 54. The front member 51 is the part located at the front of the cradle frame 50 and has a straight section 51a extending in the vehicle width direction, and rear protruding sections 51b that project outward from both outer sides in the vehicle width direction at the rear of the straight section 51a. As shown in Figure 1, a left mount 57 and a right mount 58 supporting the drive unit 1 are attached to the lower part of the left and right rear protruding sections 51b, respectively.

[0056] The left outer member 53 is joined to the left outer portion of the front member 51 in the vehicle width direction and extends toward the rear of the vehicle. In this example, as shown in Figure 1, the front portion of the left outer member 53 extends linearly in the vehicle longitudinal direction, and the rear portion of the left outer member 53 inclines in the vehicle width direction as it approaches the rear of the vehicle. As shown in Figure 2, the front portion of the left outer member 53 is fastened to the extension member 36 located to the left of the first cross member 30 by fastening members such as bolts. In this example, the rear projection 51b of the front member 51 is fastened to the lower surface of the left outer member 53.

[0057] The right outer member 54 is joined to the right outer portion of the front member 51 in the vehicle width direction and extends toward the rear of the vehicle. For example, the right outer member 54 may be configured to be approximately symmetrical with the left outer member 53. The front portion of the right outer member 54 is fastened to an extension member 36 located to the right of the first cross member 30 by fastening members such as bolts.

[0058] The rear member 52 is a portion that extends in the vehicle width direction, connecting the rear of the left outer member 53 and the rear of the right outer member 54. The left side of the rear member 52 in the vehicle width direction is joined to the middle of the left outer brace 48 in the vehicle longitudinal direction. The right side of the rear member 52 is joined to the middle of the right outer brace 48 in the vehicle longitudinal direction. In addition, the left outer member 53 is joined to the lower surface of the left side of the rear member 52 in the vehicle width direction, and the right outer member 54 is joined to the lower surface of the right side of the rear member 52. In this example, the rear of the left outer member 53 and the rear of the right outer member 54 are fastened to the left and right sides of the rear member 52, respectively, by fastening members such as bolts.

[0059] Furthermore, as shown in Figure 1, a rear mount 59 is attached to the middle portion of the rear member 52 in the vehicle width direction. The portion to which the rear mount 59 is attached is positioned to overlap with the intermediate brace 47 when viewed from below the vehicle. For example, the rear mount 59 may be attached to the portion where the rear portion and the intermediate brace 47 are joined.

[0060] The drive unit 1 of this embodiment is supported by three mounts. The rear structure of this embodiment has a left mount 57, a right mount 58, and a rear mount 59. The left mount 57 and the right mount 58 are attached to the left and right sides of the front member 51 of the cradle frame 50 in the vehicle width direction, respectively. The rear mount 59 is attached to the rear member 52 of the cradle frame 50, as described above.

[0061] The left mount 57, the right mount 58, and the rear mount 59 are each attached to the cradle frame 50 and have a base portion extending in the vertical direction of the vehicle, and a support portion provided at the lower part of the base portion. The support portion is connected, for example, to a protruding portion that extends from the main body of the drive unit 1 via a bushing. As a result, the drive unit 1 is elastically supported by the left mount 57, the right mount 58, and the rear mount 59.

[0062] Here, we will describe the battery bracket 3 that supports the rear of the battery pack 2. The battery bracket 3 is joined to the central member 31 of the first cross member 30. In this example, the upper part of the battery bracket 3 is fastened to the outer parts on both sides in the vehicle width direction of the central lower surface of the convex-shaped portion 34A of the central member 31 by fastening members such as bolts. The lower part of the battery bracket 3 is connected to the rear end of a projection that protrudes rearward from the rear of the battery pack 2, thereby supporting the rear of the battery pack 2 by the battery bracket 3.

[0063] According to this embodiment, the battery pack 2 and the cradle frame 50 are fixed to the first cross member 30. Specifically, the front part of the cradle frame 50, which supports the heavy drive unit 1, is joined to the first cross member 30, and the battery bracket 3, which supports the heavy battery pack 2, is also joined to the first cross member 30. This allows the support parts for heavy objects to be concentrated on a single member (the first cross member 30) that constitutes the vehicle frame.

[0064] As a result, reinforcing structures for supporting heavy objects can be concentrated on the first cross member 30, allowing for a more compact structure between the battery pack 2 and the drive unit 1 in the vehicle's longitudinal direction. This compact configuration also allows for larger battery packs, particularly increasing their dimensions in the vehicle's longitudinal direction. This improves the layout flexibility in structures where the drive unit 1 is located at the rear of the vehicle.

[0065] Furthermore, by joining the central member 31 and the extension member 36 of the first cross member 30, the rigidity of a part of the first cross member 30 can be further increased. In addition, by fastening the cradle frame 50 to the joint between the central member 31 and the extension member 36, the cradle frame 50 can be stably fixed. In particular, the rigidity in the vertical direction of the vehicle is improved by overlapping and joining the front wall portion 32 of the central member 31 and the front wall portion 37 of the extension member 36, and by overlapping and joining the rear wall portion 33 of the central member 31 and the rear wall portion 38 of the extension member 36. Since the cradle frame 50 is fastened to this joint, the mounting rigidity of the cradle frame 50 is improved.

[0066] Furthermore, by providing two rows of welding points arranged in the vehicle's vertical direction at the overlapping portions of the front wall 32 of the central member 31 and the front wall 37 of the extension member 36, and at the overlapping portions of the rear wall 33 of the central member 31 and the rear wall 38 of the extension member 36, the welding points are concentrated near the fastening portion 60 of the cradle frame 50, making it easier to withstand loads acting in the direction from the fastening portion 60 toward the welding points (vehicle's vertical direction). In other words, the rigidity in the vehicle's vertical direction in a part of the first cross member 30 is improved. In addition, by providing two rows of welding points, the force resisting loads (acting in the delamination direction) when rotational loads occur is improved. That is, in this embodiment, for example, the torque generated by the rotation of the electric motor of the drive unit 1 can be stably withheld at the fastening portion 60 between the cradle frame 50 and the first cross member 30 and its surroundings.

[0067] Furthermore, in this embodiment, since the reinforcement 15 is provided on the rear side member 10, the rigidity of the rear side member 10 is improved. In addition, since the outer portion in the vehicle width direction of the extension member 36 of the first cross member 30 is joined to the inner wall portion 17 of the reinforcement 15 via the inner wall portion 12 of the rear side member 10, the load input to the cradle frame 50 can be effectively received by the rear side member 10.

[0068] Furthermore, the first cross member 30 of this embodiment is provided with a convex portion 34A, and a battery mounting portion 34b is provided on the lower surface of the convex portion 34A. A battery bracket 3 is joined to the battery mounting portion 34b.

[0069] The battery pack 2 is positioned below the front floor section 5, and the drive unit 1 is positioned below the rear floor section 6. In addition, in order to ensure the capacity of the battery pack 2, it is necessary to ensure that the vertical dimension of the battery pack 2 is greater than a predetermined length. Therefore, when laying out the battery pack 2, the lower end of the battery pack 2 is likely to be positioned lower than the lower end of the drive unit 1. Consequently, when attaching the battery bracket 3 that supports the battery pack 2 to the first cross member 30 to which the front part of the cradle frame 50 that supports the drive unit 1 is joined, the vertical dimension of the battery bracket 3 may increase.

[0070] In contrast, the first cross member 30 of this embodiment is provided with a convex portion 34A that protrudes downward from the vehicle, thus suppressing an increase in the vertical length of the battery bracket 3. Furthermore, since the cradle frame 50 is fastened to the first cross member 30 which is located outward in the vehicle width direction from the convex portion 34A, the layout becomes easier when providing the battery mounting portion 34b on the first cross member 30 and the fastening portion 60 on the cradle frame 50.

[0071] When the front portion of the cradle frame 50 has a shape that extends in the vehicle width direction, if the outer portion of the front portion of the cradle frame 50 in the vehicle width direction is fastened to the first cross member 30, it may become difficult to secure space for the battery bracket 3 on the underside of the first cross member 30. In contrast, in this embodiment, the central lower surface portion 34a of the first cross member 30 is positioned further forward than the outer lower surface portion 34d of the vehicle, so that the fastening portion 60 to which the outer portion of the front member 51 of the cradle frame 50 in the vehicle width direction is fastened and the battery mounting portion 34b can be arranged in a substantially straight line along the vehicle width direction. As a result, the degree of freedom in the layout of the battery mounting portion 34b is improved.

[0072] Furthermore, since the battery mounting portion 34b and the fastening portion 60 of the cradle frame 50 can be positioned adjacent to each other along the vehicle width direction, it becomes easier to provide a reinforcing structure.

[0073] Furthermore, in this embodiment, an inclined portion 6A is provided in the floor section, and the upper part of the reinforcement 15 is inclined along the inclined portion 6A and joined to the outer side of the inclined portion 6A in the vehicle width direction. This allows the load to be effectively transmitted from the rear side member 10 to the floor section via the reinforcement 15. In other words, the load transmitted from the drive unit 1 via the cradle frame 50 is transmitted to the reinforcement 15 via the first cross member 30 and the rear side member 10, and then transmitted to the floor section. As a result, the support performance of the cradle frame 50 can be improved.

[0074] The description of this embodiment is illustrative for explaining the present invention and does not limit the invention as described in the claims. Furthermore, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications are possible within the technical scope described in the claims.

[0075] Furthermore, although the cradle frame 50 in this embodiment is composed of four members, it is not limited to this. For example, the front member 51 and the left and right outer members may be integrally formed. Also, the rear structure of the electric vehicle in this embodiment is applicable to hybrid vehicles that have an internal combustion engine in the front of the vehicle. [Explanation of Symbols]

[0076] 1. Drive unit 2 Battery Packs 3 Battery bracket 5 Front floor section 6. Rear floor section 6A Slope 6B Flat part 10 Rear side member 10A Member Inclined Section 10B Member straight section 11 Exterior wall 12 Inner wall section 12a Flange section 13 Bottom part 13a Spring receiving part 15 Reinforcement 16 Exterior wall 17. Interior wall section 17a Inclined flange section 17b Upper flange section 18 Bottom part 21 Front side member 22 Exterior wall 23 Inner wall section 23a Flange section 24 Bottom part 30 First Crossmember 31 Central Member 32 Front wall 32a Front flange section 33 Rear wall 34 Bottom part 34A Convex shape part 34a Center bottom part 34b Battery mounting section 34c outer slope 34d Lower outer surface 36 Extension member 37 Front wall 37a Front weld 37b Front flange section 37c Front outer flange section 38 Rear wall 38a Rear weld 38c Rear outer flange section 39 Bottom part 42. Second Crossmember 42a Rear wall 42c Bottom part 43a Front flange section 43b Rear flange section 43c Rear outer flange section 44 Support Member 45. Third Crossmember 46 Rear End Panel 47 Intermediate brace 48 Outer brace 49 Rear brace 50 Cradle Frame 51 Front member 51a Straight section 51b Posterior protrusion 52 Rear part 53 Left outer member 54 Right outer member 57 Left-side mount 58 Right-side mount 59 Rear mount

Claims

1. A rear structure for an electric vehicle comprising: a drive unit located below the floor portion at the rear of the vehicle; a cradle frame supporting the drive unit; and a battery pack located on the front side of the cradle frame. The drive unit is arranged in pairs on both sides in the vehicle width direction, and the side members extend in the vehicle longitudinal direction, A cross member extends in the vehicle width direction so as to connect the aforementioned side members and is positioned on the vehicle front side of the cradle frame, It has, The cross member is provided with a battery mounting portion to which the battery pack is attached. The rear structure of an electric vehicle is characterized in that the cradle frame has a frame shape including a front side portion located at the front and extending in the vehicle width direction, and a part of the front portion of the cradle frame is joined to the lower part of the cross member.

2. The cross member comprises a central member extending in the vehicle width direction, and an extension member joined to the outer portion of the central member in the vehicle width direction and extending outward from the outer portion in the vehicle width direction, wherein the outer portion of the extension member in the vehicle width direction is joined to the side member. The rear structure of an electric vehicle according to claim 1, characterized in that the cradle frame is joined to the joint between the extension member and the central member.

3. The side member has an inner wall portion facing inward in the vehicle width direction and an outer wall portion positioned at a distance from the inner wall portion in the vehicle width direction, and a reinforcement is positioned between the inner wall portion and the outer wall portion. The rear structure of an electric vehicle according to claim 2, characterized in that the inner portion of the reinforcement in the vehicle width direction is joined to the outer portion of the extension member in the vehicle width direction via the inner wall portion of the side member.

4. The cross member, where the joint to which the front portion of the cradle frame is joined is located, is provided with a welded portion where the rear wall portion of the central member and the rear wall portion of the extension member overlap and are welded together. The rear structure of an electric vehicle according to claim 1, characterized in that a plurality of welding points by spot welding are arranged at intervals in the vertical direction of the vehicle in the welded portion.

5. A convex-shaped portion is provided in the middle of the lower part of the cross member in the vehicle width direction, which protrudes downward from the vehicle and extends in the vehicle width direction. The rear structure of an electric vehicle according to claim 1, characterized in that the battery mounting portion is provided on the lower surface of the convex-shaped portion.

6. The floor portion, located rearward from the cross member, has an inclined portion on its lower surface that slopes upward toward the rear of the vehicle. The rear structure of an electric vehicle according to claim 1, characterized in that the upper part of the reinforcement is inclined along the inclined portion and joined to the outer portion of the inclined portion in the vehicle width direction.

7. The rear portion of the front portion of the cradle frame is joined to a vehicle body frame that is spaced apart on the rear side of the cross member, as described in claim 1, for the rear structure of an electric vehicle.

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