Vehicle body rear part structure

Abstract

A vehicle body rear part structure (1) integrally comprises, through die-cast molding, a pair of left and right rear wheelhouse parts (10) and a rear floor panel part (20) connecting the pair of left and right rear wheelhouse parts (10). The rear floor panel part (20) comprises rear frame connection parts (26) which are provided at the rear part of the rear floor panel part (20) and to which rear frames (40) are connected, and load transmission ribs (32a, 32c) extending from the front of the rear frame connection parts 26 so as to face inward in the vehicle width direction as the ribs go forward.

Description

Rear body structure

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

[0002] In recent years, research and development has been conducted into weight reduction that contributes to energy efficiency in order to ensure that more people have access to affordable, reliable, sustainable, and advanced energy. Meanwhile, Patent Document 1 discloses a die-cast rear floor body structure that integrates a pair of left and right rear wheel covers, a pair of left and right vertical beams provided along the lower ends of the rear wheel covers, a connecting beam that connects the pair of left and right vertical beams, and a pair of front and rear horizontal beams.

[0003] Chinese Patent Application Publication No. 117360634

[0004] In such a structure, the rear-end collision load is transmitted to the longitudinal and transverse beams that form the framework. Therefore, the framework and the joints between the frameworks, where the load is concentrated, require a lot of reinforcement (reinforcing ribs, reinforcing members, reinforcing longitudinal beams, etc.), and there is room for improvement in terms of weight reduction.

[0005] The present invention has been made in consideration of the above points, and its object is to provide a vehicle frame structure that can achieve weight reduction and ultimately contribute to energy efficiency.

[0006] In order to solve the above-mentioned problems, the rear body structure is a rear body structure that is integrally formed by die-casting a pair of left and right rear wheel house sections and a rear floor panel section that connects the pair of left and right rear wheel house sections, and is characterized in that the rear floor panel section is provided at the rear of the rear floor panel section and has a rear frame connecting section to which a rear frame is connected, and a load transmission rib that extends from in front of the rear frame connecting section inward in the vehicle width direction as it moves forward.

[0007] According to the present invention, it is possible to reduce the weight of the rear vehicle body structure, which in turn contributes to improving energy efficiency.

[0008] 5 is a schematic view of a rear vehicle body structure according to an embodiment of the present invention, as viewed from diagonally above the front. FIG. 6 is a schematic view of a rear vehicle body structure according to an embodiment of the present invention, as viewed from diagonally above the rear. FIG. 7 is a schematic side view of a rear vehicle body structure according to an embodiment of the present invention. FIG. 8 is a schematic plan view of a rear vehicle body structure according to an embodiment of the present invention. FIG. 9 is a schematic bottom view of a rear vehicle body structure according to an embodiment of the present invention. FIG. 10 is an enlarged view of part VII of FIG. 5. FIG. 11 is a cross-sectional view taken along line VIII-VIII of FIG. 4. FIG. 12 is a cross-sectional view taken along line IX-IX of FIG. 4. FIG. 13 is a schematic bottom view of a rear vehicle body structure according to an embodiment of the present invention, as viewed from diagonally above the rear.

[0009] Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, "front and rear" refers to the front-rear direction in the direction of travel of the vehicle (the front-rear direction of the vehicle body), and "left and right" refers to the left and right direction (the vehicle width direction) as seen from the driver's seat.

[0010] 1 and 2, a vehicle rear structure 1 according to an embodiment of the present invention is at least partially formed by a die-cast product formed by a die-cast method using aluminum as a material (aluminum die-cast method). The vehicle rear structure 1 includes a die-cast portion 2, which is a die-cast product, that is integrally formed with a pair of left and right rear wheel housing portions 10 and a rear floor panel portion 20 that connects the pair of left and right rear wheel housing portions 10. The vehicle rear structure 1 also includes a pair of left and right rear frames 40 (see FIG. 3) that are separate members from the die-cast portion 2.

[0011] <Rear Wheel House> The rear wheel house 10 integrally includes a bulging portion 11, a flange portion 12, and a plurality of ribs 13.

[0012] The bulging portion 11 is a rear wheel house main body that bulges inward in the vehicle width direction. The bulging portion 11 accommodates the upper portion of the rear wheel 3 (see FIG. 3 ) of the vehicle on the outer side in the vehicle width direction.

[0013] The flange portion 12 extends outward from the outer end of the bulging portion 11 in the vehicle width direction.

[0014] The rib 13 extends outward in the vehicle width direction from the bulging portion 11 .

[0015] <Rear Floor Panel> The rear floor panel 20 is a plate-shaped portion provided to connect the bulging portions 11 of the pair of left and right rear wheel housing portions 10. The rear floor panel 20 includes an upper wall portion 21, a front wall portion 22, a first lower wall portion 23, a rear wall portion 24, and a second lower wall portion 25 as a rear floor panel main body portion.

[0016] <Upper Wall Portion> The upper wall portion 21 extends in the front-rear direction and the vehicle width direction.

[0017] <<Front Wall>> The front wall 22 extends downward from the front end of the upper wall 21 .

[0018] <First outer wall portion> The first lower wall portion 23 extends forward from the lower end portion of the front wall portion 22. A vehicle width direction intermediate portion of the first lower wall portion 23 forms a flange portion relative to the front wall portion 22. A vehicle width direction end portion of the first lower wall portion 23 extends forward of the rear wheel house portion 10.

[0019] <Rear Wall> The rear wall 24 extends downward from the rear end of the upper wall 21 .

[0020] <<Second Lower Wall Portion>> The second lower wall portion 25 extends rearward from the lower end of the rear wall portion 24. The vehicle width direction end of the second lower wall portion 25 extends rearward of the rear wheel housing portion 10. The rear end of the vehicle width direction middle portion of the second lower wall portion 25 is located forward of the rear end of the rear wheel housing portion 10 (bulge portion 11) and forms a notch 25a. The notch 25a is intended to ensure component placement space. In addition, the surface precision of the second lower wall portion 25 is improved by performing a cutting process after casting.

[0021] <Rear Frame Joint Portions> As shown in FIGS. 4 and 6, the rear floor panel portion 20 includes a pair of left and right rear frame joint portions 26 as portions to which the rear frame 40 is joined.

[0022] The rear frame connecting portion 26 is a recess that is recessed forward and is formed across the rear wall portion 24 and the second lower wall portion 25. The rear frame connecting portion 26 includes an opposing wall portion 26a, an outer wall portion 26b, an inner wall portion 26c, and a lower wall portion 26d.

[0023] The opposing wall portion 26a is a part of the rear wall portion 24 of the rear floor panel main body, and extends in the vehicle width direction and the up-down direction.

[0024] The outer wall portion 26b is a part of the rear wall portion 24 of the rear floor panel main body, and extends rearward from the outer end of the opposing wall portion 26a in the vehicle width direction. The rear frame 40 is connected to the outer wall portion 26b by bolting or the like.

[0025] In this embodiment, the outer wall portion 26b is formed with a protrusion (base portion) 26b1 that protrudes inward in the vehicle width direction. The tip end of the rear frame 40 is fixed to the protrusion 26b1 by a bolt that is inserted into a hole formed in the tip surface of the protrusion 26b1 on the inner side in the vehicle width direction. The head of the bolt is accommodated in a space on the outer side in the vehicle width direction of the protrusion 26b1.

[0026] The inner wall portion 26c is a part of the rear wall portion 24 of the rear floor panel main body, and extends rearward from the inner end of the opposing wall portion 26a in the vehicle width direction. The inner wall portion 26c is inclined inward in the vehicle width direction as it extends rearward. The rear frame 40 is connected to the inner wall portion 26c by bolting or the like.

[0027] In the present embodiment, the inner wall portion 26c is formed with a protrusion (seat portion) 26c1 that protrudes rearward. The tip end of the rear frame 40 (more specifically, a flange portion (not shown) attached to the tip end of the rear frame 40) is fixed to the protrusion 26c1 with a bolt that is inserted into a hole formed in the rear tip surface of the protrusion 26c1.

[0028] The lower wall portion 26d is a part of the second lower wall portion 25 of the rear floor panel main body, and extends rearward from the lower end of the opposing wall portion 26a. The lower wall portion 26d connects the lower ends of the outer wall portion 26b and the inner wall portion 26c.

[0029] The rear frame connecting portion 26 is located at the rear of the rear floor panel main body, forward of the notch 25a which serves as the rear end of the rear floor panel main body. The rear frame connecting portion 26 is also provided inward in the vehicle width direction from the inner end of the bulge 11, and at least a portion of the rear frame connecting portion 26 is disposed forward of the rear end of the bulge 11. Therefore, the vehicle rear structure 1 can shorten the rear overhang of the vehicle, thereby achieving weight reduction and improving the freedom of vehicle design.

[0030] The rear frame connecting portion 26 and the front end portion 41 of the rear frame 40 are located forward of the rear end portion of the drive unit 4. The rear portion of the drive unit 4 is disposed between the pair of left and right rear frames 40.

[0031] <Rib Structure> As shown in FIGS. 4 and 5, a plurality of ribs are formed on the rear floor panel main body of the rear floor panel portion 20 to improve the rigidity of the rear floor panel main body, transmit loads, and absorb collision energy.

[0032] <Upper Surface Rib Structure> As shown in Figure 4, the rear floor panel portion 20 has ribs erected on its upper surface (inside the vehicle compartment), including multiple left and right ribs 31, multiple front and rear ribs 32, multiple annular ribs 33, and a pair of left and right opposing ribs 34. These ribs transmit loads in the direction along the ribs and can absorb collision energy. In the following description, the front and rear ribs 32a, 32c, 37a, 37b, 37c (see Figure 5), which are inclined inward in the vehicle width direction as they extend forward, are referred to as load transmission ribs.

[0033] The left and right ribs 31 are erected upward from the upper wall portion 21 of the rear floor panel main body and extend in the vehicle width direction. In this embodiment, both ends of the left and right ribs 31 in the vehicle width direction are connected to the bulge portion 11 of the rear wheel house portion 10, respectively.

[0034] <<Front and Rear Ribs>> The front and rear ribs 32 are erected upward from the upper wall portion 21, the front wall portion 22, and the first lower wall portion 23 of the rear floor panel main body (they are erected forward from the front wall portion 22) and extend in the front-rear direction. Of the multiple front and rear ribs 32, the front and rear ribs 32 located on the outer sides in the vehicle width direction are inclined so as to extend outward in the vehicle width direction as they extend forward.

[0035] <Load Transmission Ribs / Upper Ribs> Of the multiple front and rear ribs 32, a pair of left and right front and rear ribs 32a on the inner side in the vehicle width direction are load transmission ribs (upper ribs) that incline toward the inside in the vehicle width direction as they extend forward. The rear ends of the front and rear ribs 32a are located forward of the rear frame connecting portion 26. In this embodiment, the rear ends of the front and rear ribs 32a are connected to the opposing wall portion 26a of the rear frame connecting portion 26. The front portions of the front and rear ribs 32a extend in the front-to-rear direction.

[0036] The pair of left and right front and rear ribs 32c, which are located outside the pair of left and right front and rear ribs 32a in the vehicle width direction, are load transfer ribs (upper ribs) that slope inward in the vehicle width direction as they extend forward. The rear ends of the front and rear ribs 32c are located forward of the rear frame connector 26. In this embodiment, the rear ends of the front and rear ribs 32c are connected to the opposing wall portion 26a of the rear frame connector 26. The rear portions of the front and rear ribs 32a extend in the front-to-rear direction.

[0037] The angle θ of the inclined portions of the front and rear ribs 32a, 32c relative to the front and rear direction is 30 degrees or less (for example, 30 degrees).

[0038] <Annular Rib> The annular rib 33 has a cylindrical shape in a plan view and is provided in front of the rear frame connecting portion 26. In the present embodiment, the annular rib 33 connects the front-rear rib 32a serving as a load transmission rib, the front-rear rib 32 adjacent to the front-rear rib 32a, and the left-right rib 31. In other words, the front-rear rib 32a, the front-rear rib 32 adjacent to the front-rear rib 32a, and the left-right rib 31 are formed to extend radially from the annular rib 33. In other words, the front-rear rib 32a, the front-rear rib 32 adjacent to the front-rear rib 32a, and the left-right rib 31 are divided into front-rear or left-right by the annular rib 33.

[0039] <<Opposing Rib>> The opposing rib 34 extends rearward from the opposing wall portion 26a of the rear frame connecting portion 26. In the present embodiment, the opposing rib 34 has a lattice shape (e.g., a honeycomb shape) in rear view. The rear end portion of the opposing rib 34 faces the front end portion of the rear frame 40 at a distance.

[0040] <Rib structure on the underside> As shown in Figure 5, the rear floor panel portion 20 has ribs erected on the underside (outside the vehicle compartment) including multiple left and right ribs 36, multiple front and rear ribs 37, multiple annular ribs 38, and reinforcing ribs 39.

[0041] <Left and Right Ribs> The left and right ribs 36 are erected downward from the upper wall portion 21 of the rear floor panel main body at positions corresponding to the upper left and right ribs 31 and extend in the vehicle width direction.

[0042] <<Front and Rear Ribs>> The front and rear ribs 37 are erected downward from the upper wall 21, front wall 22, and first lower wall 23 of the rear floor panel main body at positions corresponding to the upper front and rear ribs 32 and at other positions (they are erected rearward from the front wall 22) and extend in the front-to-rear direction. Of the multiple front and rear ribs 37, the front and rear ribs 37 located on the outer sides in the vehicle width direction are inclined outward in the vehicle width direction as they extend forward.

[0043] <Load Transmission Ribs / Lower Ribs> Of the multiple front and rear ribs 37, a pair of left and right front and rear ribs 37a on the inner side in the vehicle width direction are load transmission ribs (lower ribs) that are inclined toward the inside in the vehicle width direction as they extend forward at positions corresponding to the upper front and rear ribs 32a. The rear ends of the front and rear ribs 37a are located forward of the rear frame connector 26. In this embodiment, the rear ends of the front and rear ribs 37a are connected to the opposing wall portion 26a of the rear frame connector 26. The front ends of the front and rear ribs 32a extend in the front-to-rear direction.

[0044] The front-rear rib 37b adjacent to the front-rear rib 37a is a load-transmitting rib (lower rib) that slopes inward in the vehicle width direction as it extends forward. The rear ends of the front-rear ribs 37b are located forward of the rear frame connecting portion 26. In this embodiment, the rear ends of the front-rear ribs 37b are connected to the annular rib 38.

[0045] The pair of left and right front and rear ribs 37b located outside the pair of left and right front and rear ribs 37b in the vehicle width direction are load transfer ribs (lower ribs) that slope inward in the vehicle width direction as they extend forward. The rear ends of the front and rear ribs 37c are located forward of the rear frame connector 26. In this embodiment, the rear ends of the front and rear ribs 37c are connected to the opposing wall portion 26a of the rear frame connector 26. The rear portions of the front and rear ribs 37b extend in the front-to-rear direction.

[0046] The angle θ of the inclined portions of the front and rear ribs 37a, 37b relative to the front and rear direction is 30 degrees or less (for example, 30 degrees for the front and rear ribs 37a, 37c, and 15 degrees for the front and rear rib 37b).

[0047] 7 , the annular rib 38 has a cylindrical shape in a plan view and is provided in front of the rear frame connecting portion 26. In the present embodiment, the annular rib 38 connects the front and rear ribs 37a, 37b serving as load transmission ribs, the front and rear rib 37 adjacent to the front and rear rib 37b, and the left and right ribs 36. In other words, the front and rear ribs 37a, 37b, the front and rear ribs 37 adjacent to the front and rear ribs 37b, and the left and right ribs 36 are formed to extend radially from the annular rib 38. In other words, the front and rear ribs 37a, 37b, and the left and right ribs 36 adjacent to the front and rear ribs 37a, 37b are divided into front and rear or left and right by the annular rib 38.

[0048] <Reinforcing Rib> As shown in Figure 5, the reinforcing rib 39 improves the rigidity of the rear floor panel portion 20 and extends downward from the upper wall portion 21 in an area surrounded by the pair of front and rear left and right ribs 36 and the pair of left and right front and rear ribs 37a. The reinforcing rib 39 has a lattice shape (e.g., a honeycomb shape) when viewed from the bottom. In this embodiment, the reinforcing rib 39 is connected to the pair of front and rear left and right ribs 36 and the pair of left and right front and rear ribs 37a. Note that the reinforcing rib 39 is not limited to a lattice shape and may be ribs arranged only in the front-rear direction, ribs arranged only in the left-right direction, or a mixture of these ribs arranged irregularly.

[0049] <Upper and Lower Load Transmission Ribs> As shown in FIGS. 4 and 5, the load transmission ribs extending inward in the vehicle width direction toward the front are the lower front and rear ribs 37a, 37b, 37c, which are more numerous than the upper front and rear ribs 32a, 32c.

[0050] 8, in the front and rear ribs 32a, 37a serving as load transmission ribs extending inward in the vehicle width direction as they extend forward, the erect height H2 of the lower front and rear rib 37a is greater than the erect height H1 of the upper front and rear rib 32a. Note that this height relationship can also be applied to the other front and rear ribs 32, 37, the left and right ribs 31, 36, and the annular ribs 33, 38.

[0051] The vehicle body rear structure 1 can suppress accumulation of electrocoating paint and prevent deterioration of painting quality by making the upper front and rear ribs 32a lower than the lower front and rear ribs 37a and making the upper front and rear ribs 32a smaller than the lower front and rear ribs 37a, 37b.

[0052] As described above, it is sufficient that the front and rear ribs 32a, 32c, 37a, 37b, 37c serving as load transmission ribs are able to transmit forward the rear collision load input to the rear frame connecting portion 26. In other words, the rear ends of the front and rear ribs 32a, 32c, 37a, 37b, 37c may be connected to (the opposing wall portion 26a of) the rear frame connecting portion 26, or may be located in front of (the opposing wall portion 26a of) the rear frame connecting portion 26 and spaced apart from (the opposing wall portion 26a of) the rear frame connecting portion 26.

[0053] <Rear Frame> As shown in Figures 3 and 4, the rear frame 40 is a metallic tubular member extending in the front-rear direction. The rear frame 40 has a closed cross-sectional shape (an octagonal shape in this embodiment) in a front view. The rear frame 40 extends rearward from the rear floor panel portion 20. The front portion of the rear frame 40 overlaps the rear floor panel portion 20 in a plan view, and the rear portion of the rear frame 40 protrudes rearward from the rear floor panel portion 20 in a plan view. A front end portion 41 of the rear frame 40 is connected to the rear frame connecting portion 26. A bumper beam (not shown) is installed between the rear ends of the pair of left and right rear frames 40.

[0054] As shown in Figure 9, the vehicle width direction distance W2 between the rear frame 40 and rear frame connecting portion 26 on one side in the vehicle width direction (e.g., the left side) and the vehicle body end on the other side in the vehicle width direction (e.g., the right side) is located at a position that is within 70% (and greater than 50%) of the overall vehicle body width W1.

[0055] 4 and 6 , the front end 41 of the rear frame 40 is connected to the rear frame connecting portion 26 while facing and spaced apart from the opposing rib 34. That is, the outer wall portion of the front end 41 of the rear frame 40 is attached to the outer wall portion 26b of the rear frame connecting portion 26 by fastening bolts. Here, the convex portion 26b1 of the outer wall portion 26b is integrated with the lower portion of the bulge portion 11 and is accessible from outside the bulge portion 11 in the vehicle width direction. Therefore, bolt fastening can be performed using a jig X from outside the bulge portion 11 of the rear wheel house portion 10 in the vehicle width direction (see FIG. 9 ).

[0056] 3 , the rear frame connecting portion 26, i.e., the front end portion 41 of the rear frame 40 connected to the rear frame connecting portion 26, is positioned to overlap the rear wheel 3 in a side view. The front end portion 41 of the rear frame 40 may be positioned to overlap the wheel 3 a of the rear wheel 3 in a side view, or may be positioned to overlap the tire 3 b of the rear wheel 3. In the present embodiment, the portion of the outer wall portion 26 b to which the rear frame 40 is connected is positioned to overlap the tire 3 b of the rear wheel 3 in a side view, and is accessible from the vehicle exterior side of the bulge portion 11 of the rear wheel house portion 10.

[0057] 4 and 6, the inner wall portion of the front end portion 41 of the rear frame 40 is attached to the inner wall portion 26c of the rear frame connecting portion 26 by bolts via a flange member (not shown). The bolts can be fastened from behind the inner wall portion 26c.

[0058] 10 , the drive unit 4 includes a power source (e.g., a motor) 4a for rotating the pair of left and right rear wheels 3, and a pair of left and right transmission parts (e.g., shafts) 4b for transmitting the rotational force of the power source 4a to the rear wheels 3. The drive unit 4, more specifically, the power source 4a of the drive unit 4, is disposed below the upper wall 21 in an area surrounded by the upper wall 21, the front wall 22, and the rear wall 24, and is attached to a plurality of drive unit attachment parts 27 by bolting or the like. The plurality of drive unit attachment parts 27 are disposed so as to surround a reinforcing rib 39, which will be described later.

[0059] The drive unit mounting portions 27 are provided on the lower wall portions 26d of the pair of left and right rear frame connecting portions 26. The drive unit mounting portions 27 are provided on the rear frame connecting portions 26, which have improved strength due to the connection of the rear frame 40, and therefore can hold the drive unit 4 in an appropriate manner.

[0060] <Load Transmission During Rear-End Collision> During a rear-end collision of a vehicle, the rear-end collision load is transmitted from the pair of left and right rear frames 40 to the rear-frame connecting portion 26 of the vehicle body rear structure 1. The rear-end collision load transmitted to the rear-frame connecting portion 26 is transmitted forward while being dispersed in the vehicle width direction via the upper and lower front and rear ribs 32, 37. Therefore, the vehicle body rear structure 1 can suitably transmit the rear-end collision load and can suitably absorb the collision energy throughout the entire rear floor panel, including the vehicle width direction middle portion.

[0061] In the event of a rear-end collision of the vehicle, the rear frame 40 deforms such that the rear end of the rear frame is lifted. That is, the upper front and rear ribs 32 deform in a compressive direction, and the lower front and rear ribs 37 deform in a tensile direction. In the vehicle body rear structure 1, the lower front and rear ribs 37 that deform in a tensile direction are higher and more numerous than the upper front and rear ribs 32 that deform in a compressive direction, so that the rear-end collision load can be suitably transmitted via the lower front and rear ribs 37 that are less likely to deform.

[0062] In addition, the rear body structure 1 has an angle θ of the front and rear ribs 32a, 32c, 37a, 37b, and 37c, which act as load transmission ribs, set to 30 degrees or less relative to the fore-and-aft direction, thereby suppressing deformation of the ribs and enabling rear-end collision loads to be transmitted appropriately.

[0063] In addition, the rear body structure 1 has improved rigidity in the central part of the vehicle width direction due to the reinforcing rib 39, which suppresses deformation of the rear floor panel main body due to rear-end collision load and allows the rear-end collision load to be transmitted more effectively.

[0064] Furthermore, the vehicle rear body structure 1 distributes the rear collision load to the multiple front and rear ribs 32, 37 by the annular ribs 33, 38, so that the rear collision load can be transmitted more effectively.

[0065] A vehicle rear structure 1 according to an embodiment of the present invention is a vehicle rear structure 1 that integrally includes, by die-cast molding, a pair of left and right rear wheel housing sections 10 and a rear floor panel section 20 that connects the pair of left and right rear wheel housing sections 10. The rear floor panel section 20 is provided at the rear of the rear floor panel section 20 and includes a rear frame connecting section 26 to which a rear frame 40 is connected, and a load transmission rib that extends inward in the vehicle width direction from in front of the rear frame connecting section 26 toward the front. Therefore, the vehicle rear structure 1 is able to transmit a rear collision load toward the center of the vehicle body by the load transmission rib, and can distribute the rear collision load over a wide area of ​​the rear floor panel section 20. In other words, the vehicle rear structure 1 is able to withstand a rear collision load without reinforcement by a frame member or the like, thereby achieving weight reduction and improved rear collision load transmission performance and collision energy absorption performance.

[0066] In the vehicle rear body structure 1, the load transmission rib is connected to the rear frame connecting portion 26. Therefore, the vehicle rear body structure 1 can more suitably achieve improvements in rear-impact load transmission performance and collision energy absorption performance.

[0067] In the vehicle rear body structure 1, the load transmission rib includes an upper rib formed on the upper surface of the rear floor panel portion 20 and a lower rib formed on the lower surface of the rear floor panel portion 20. Therefore, in the vehicle rear body structure 1, the load transmission ribs are formed on both the upper and lower surfaces of the rear floor panel portion 20, which realizes a strong load transmission path and further improves the rear-impact load transmission performance and collision energy absorption performance.

[0068] The lower rib is higher than the upper rib in the vehicle rear structure 1. Therefore, the vehicle rear structure 1 can efficiently transmit a rear collision load by making the lower rib, which receives a load in a tensile direction, higher than the upper rib.

[0069] The number of the lower ribs is greater than the number of the upper ribs in the vehicle rear structure 1. Therefore, the vehicle rear structure 1 can efficiently transmit a rear collision load by providing more lower ribs that receive a load in the tensile direction than the upper ribs.

[0070] In the vehicle rear structure 1, the load transmission ribs are formed so as to extend inward in the vehicle width direction as they extend forward at an angle of 30 degrees or less with respect to the fore-and-aft direction. Therefore, the vehicle rear structure 1 can suppress deformation of the load transmission ribs and achieve efficient transmission of rear-end collision loads.

[0071] In the vehicle rear body structure 1, the rear floor panel portion 20 is formed at the rear frame connecting portion 26 and includes a drive unit mounting portion 27 to which the drive unit 4, which is disposed below the rear floor panel portion 20, is mounted. Therefore, the vehicle rear body structure 1 can firmly hold the drive unit 4 because the drive unit 4 is mounted at the portion where the rear frame 40 is connected.

[0072] In the vehicle rear body structure 1, the rear floor panel 20 includes the pair of left and right load transmission ribs and a reinforcing rib 39 formed between the pair of left and right load transmission ribs. Therefore, the vehicle rear body structure 1 can improve the rigidity of the rear floor panel 20 and further improve the collision energy absorption performance.

[0073] In the vehicle rear structure 1, the reinforcing rib 39 is formed so as to connect the pair of left and right load transmission ribs together. Therefore, the vehicle rear structure 1 can further improve the rigidity of the rear floor panel portion 20.

[0074] In the vehicle rear structure 1, the rear floor panel portion 20 includes the plurality of load transmission ribs and the annular rib 38 that connects the plurality of load transmission ribs. Therefore, the vehicle rear structure 1 can suitably distribute a rear collision load via the annular rib 38.

[0075] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified as appropriate within the scope of the present invention.

[0076] DESCRIPTION OF SYMBOLS 1 Vehicle rear body structure 2 Die-cast portion 3 Rear wheel 4 Drive unit 10 Rear wheel house portion 11 Bulging portion (rear wheel house main body portion) 20 Rear floor panel portion 21 Upper wall portion (rear floor panel main body portion) 22 Front wall portion (rear floor panel main body portion) 23 First lower wall portion (rear floor panel main body portion) 24 Rear wall portion (rear floor panel main body portion) 25 Second lower wall portion (rear floor panel main body portion) 25a Cutout portion 26 Rear frame connecting portion 26a Opposing wall portion 26b Outer wall portion 26c Inner wall portion 26d Lower wall portion 27 Drive unit mounting portion 31 Left and right ribs 32 Front and rear ribs 32a, 32c Front and rear ribs (load transmission ribs, upper ribs) 33 Annular rib 34 Opposing rib 36 Left and right ribs 37 Front and rear ribs 37a, 37b, 37c Front and rear ribs (load transmission ribs, lower ribs) 38 Annular rib 39 Reinforcement rib 40 Rear frame 41 Front end portion X Jig

Claims

1. A vehicle rear structure comprising a pair of left and right rear wheel housing sections and a rear floor panel section connecting the pair of left and right rear wheel housing sections, which are integrally formed by die-cast molding, wherein the rear floor panel section is provided at the rear of the rear floor panel section and comprises: a rear frame connecting section to which a rear frame is connected; and a load transmission rib extending from in front of the rear frame connecting section inward in the vehicle width direction as it moves forward.

2. The rear vehicle body structure according to claim 1, wherein the load transmission rib is connected to the rear frame connecting portion.

3. The rear vehicle body structure described in claim 1, characterized in that the load transmission rib comprises an upper rib formed on the upper surface of the rear floor panel portion, and a lower rib formed on the lower surface of the rear floor panel portion.

4. The vehicle rear body structure according to claim 3, wherein the lower rib is higher than the upper rib.

5. The vehicle rear body structure according to claim 3, wherein the number of said lower ribs is greater than the number of said upper ribs.

6. A rear vehicle body structure according to claim 1, characterized in that the load transmission rib is formed so as to extend inward in the vehicle width direction as it extends forward at an angle of 30 degrees or less relative to the fore-and-aft direction.

7. A rear vehicle body structure as described in any one of claims 1 to 5, characterized in that the rear floor panel portion is formed in the rear frame connection portion and has a drive unit mounting portion to which a drive unit arranged below the rear floor panel portion is attached.

8. A vehicle rear structure as described in any one of claims 1 to 5, characterized in that the rear floor panel portion comprises a pair of left and right load transmission ribs and a reinforcing rib formed between the pair of left and right load transmission ribs.

9. The rear vehicle body structure according to claim 8, wherein the reinforcing rib is formed so as to connect the pair of left and right load transmission ribs.

10. A vehicle rear structure as described in any one of claims 1 to 5, characterized in that the rear floor panel portion comprises: a plurality of the load transmission ribs; and an annular rib connecting the plurality of the load transmission ribs.

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