Vehicle frame structure

Abstract

The objective is to obtain a vehicle frame structure that can suppress twisting of the cross member section and improve the handling stability of the vehicle while it is in motion. [Solution] The vehicle frame structure 10 is integrally formed by casting and comprises a pair of left and right rear side members 30, a cross member portion 38, and a first rib 50. The cross member portion 38 has both ends 38A in the vehicle width direction connected to the mounting portion 36 of the suspension member and is curved convexly toward the front of the vehicle. The first rib 50 connects both ends 44A of the front wall portion 44 and the intermediate portion 46A of the rear wall portion 46 of the cross member portion 38 along the vehicle width direction. This improves the rigidity of the cross member portion 38 itself and makes it possible to suppress twisting of the cross member portion 38. Here, the torsional rigidity during vehicle driving can be effectively increased even in the curved cross member portion 38, and the handling stability during vehicle driving can be improved.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 below discloses a technique related to the lower structure of the rear part of a vehicle. In this prior art, in the rear part of the vehicle, a luggage compartment is provided between a pair of left and right rear side members, and both ends of a rear cross member extending in the vehicle width direction with respect to the pair of left and right rear side members are respectively connected to the front side of the vehicle of this luggage compartment. Here, since a jacking load from the suspension member is transmitted to a skeletal part such as a side member to which the suspension member is connected, the jacking load is transmitted to the cross member connected to the skeletal part.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] On the other hand, it has been considered to integrally form a skeletal part such as a side member and a cross member (hereinafter referred to as "cross member part") by casting. However, in some vehicles, in order to avoid interference with the load carried on the lower part of the vehicle, the cross member part is formed in a curved shape along the vehicle front - rear direction. In this case, compared with the case where the cross member part is formed linearly, the torsional rigidity in the cross member part decreases with respect to the jacking load transmitted from the suspension member, and there is a possibility of adversely affecting the handling stability during vehicle running.

[0005] In consideration of the above facts, an object of the present invention is to obtain a vehicle skeletal structure part capable of suppressing the torsion of the cross member part and improving the handling stability during vehicle running. [Means for solving the problem]

[0006] The vehicle frame structure according to the first embodiment is a vehicle frame structure integrally formed by casting and comprises a pair of left and right frame parts provided on the rear and widthwise sides of the vehicle and extending in the longitudinal direction of the vehicle, each having a mounting part to which a suspension member is attached; a cross member part extending in the widthwise direction of the vehicle, with both ends in the widthwise direction of the vehicle connected to the pair of mounting parts, and having a rear wall part that constitutes the rear end of the vehicle, and at least the rear wall part being curved convexly toward the front of the vehicle; and a first rib connecting the end in the widthwise direction of the cross member part and the curved rear wall part along the widthwise direction of the vehicle.

[0007] The vehicle frame structure according to the first embodiment is integrally formed by casting and comprises a pair of left and right frame sections, a cross member section, and a first rib. The pair of left and right frame sections are provided on the rear and widthwise sides of the vehicle and extend in the longitudinal direction of the vehicle, and each has a mounting section to which a suspension member is attached. The cross member section extends in the widthwise direction of the vehicle, and both ends of the cross member section in the widthwise direction are connected to the pair of mounting sections, and has a rear wall section that forms the rear end of the vehicle, and at least the rear wall section is curved convexly toward the front of the vehicle. Furthermore, the first rib connects the end of the cross member section in the widthwise direction and the curved rear wall section along the widthwise direction of the vehicle.

[0008] Thus, in this embodiment, by providing a first rib in the cross member portion that connects the end portion in the vehicle width direction with the curved rear wall portion in the vehicle width direction, the rigidity of the cross member portion itself is improved and twisting of the cross member portion is suppressed. Furthermore, by providing the first rib in the cross member portion connected to the suspension member mounting portion, the first rib is added as an additional transmission path for the upward load during vehicle driving.

[0009] With the above configuration, in this embodiment, the load transmitted to the cross member is distributed, and as a result, twisting of the cross member can be further suppressed. In other words, in this embodiment, the torsional rigidity during vehicle operation can be effectively increased even in the curved cross member, and the handling stability during vehicle operation can be improved.

[0010] In this context, "the end of the cross member in the vehicle width direction" being "connected to the mounting part" means that at least a portion of the end of the cross member in the vehicle width direction overlaps with the mounting part when viewed from the vehicle width direction. Therefore, the end of the cross member in the vehicle width direction and the mounting part do not necessarily have to be directly connected.

[0011] Furthermore, the "first rib" here can be provided on the inner or outer surface of the cross member when the cross-sectional shape of the cross member is an open cross-section, but when the cross-sectional shape is a closed cross-section, it is provided on the outer surface of the cross member.

[0012] The vehicle frame structure according to the second embodiment is the vehicle frame structure according to the first embodiment, wherein the cross member portion has an open cross-sectional shape that is open to one side in the vertical direction of the vehicle, and the first rib extends along the vehicle width direction inside the cross member portion.

[0013] In the vehicle frame structure according to the second embodiment, the cross member portion has an open cross-sectional shape that is open to one side in the vertical direction of the vehicle, and the first rib extends along the vehicle width direction inside the cross member portion and connects the rear wall portion and the end portion of the cross member portion in the vehicle width direction along the vehicle width direction.

[0014] Therefore, in this embodiment, when an upward load is applied while the vehicle is in motion, the distortion of the rear wall portion of the cross member portion prevents the opening of the cross member portion (the angle between the back wall portion and the rear wall portion of the cross member portion from becoming obtuse), thereby contributing to the handling stability while the vehicle is in motion. The cross member portion has an open cross section shape with the upper side of the vehicle open, or an open cross section shape with the lower side of the vehicle open.

[0015] In the third embodiment, the vehicle frame structure is such that, in the first embodiment or the second embodiment, the first rib is connected to the front wall portion that constitutes the front end of the vehicle at the vehicle width direction end of the cross member portion.

[0016] In the vehicle frame structure according to the third embodiment, at the vehicle width direction end of the cross member portion, the first rib connects to the front wall portion that constitutes the front end of the vehicle, thereby bridging the front wall portion and the rear wall portion of the cross member portion by the first rib. As a result, in this embodiment, the rigidity of the cross member portion itself is further improved, and the opening of the cross section of the cross member portion is more effectively suppressed.

[0017] The vehicle frame structure according to the fourth embodiment is a vehicle frame structure according to any one of the first to third embodiments, wherein the first rib is formed continuously along the vehicle width direction, is connected to the front wall at both ends in the vehicle width direction, and is connected to the rear wall at the middle part in the vehicle width direction.

[0018] In the vehicle frame structure according to the fourth embodiment, the first rib is formed continuously along the vehicle width direction, connecting to the front wall at both ends in the vehicle width direction and connecting to the rear wall in the middle of the vehicle width direction. By forming the first rib continuously along the vehicle width direction in this way, it is possible to further improve the rigidity of the cross member portion along the vehicle width direction compared to when the first rib is divided in the vehicle width direction.

[0019] The vehicle frame structure part according to the fifth aspect is the vehicle frame structure part according to any one of the first to fourth aspects, in which a plurality of second ribs that connect the front wall part and the rear wall part, which constitute the front end on the vehicle front side in the cross member part, in the shortest possible way are provided along the vehicle width direction.

[0020] In the vehicle frame structure part according to the fifth aspect, by providing a plurality of second ribs that connect the front wall part, which constitutes the front end on the vehicle front side in the cross member part, and the rear wall part, which constitutes the rear end on the vehicle rear side, in the shortest possible way along the vehicle width direction, it becomes possible to more effectively suppress the opening of the open cross section of the cross member part compared to the case where the second rib is not provided.

[0021] The vehicle frame structure part according to the sixth aspect is the vehicle frame structure part according to any one of the first to fifth aspects, in which a third rib that connects the front wall part and the rear wall part, which constitute the front end on the vehicle front side in the cross member part, in a truss shape is provided.

[0022] In the vehicle frame structure part according to the sixth aspect, by providing a third rib that connects the front wall part, which constitutes the front end on the vehicle front side in the cross member part, and the rear wall part, which constitutes the rear end on the vehicle rear side, in a truss shape, it becomes possible to more effectively suppress the opening of the open cross section of the cross member part compared to the case where the third rib is not provided.

[0023] Here, in this aspect, since the third rib is connected in a truss shape, the rigidity against the load along the vehicle front-rear direction in the cross member part is further improved, and it becomes possible to transmit the impact load input from the vehicle rear side along the vehicle width direction via the third rib.

[0024] The vehicle frame structure part according to the seventh aspect is the vehicle frame structure part according to the fifth aspect, in which the central part in the vehicle front-rear direction of the second rib is lower than both end parts on the vehicle front-rear direction sides.

[0025] In the vehicle skeletal structure part according to the seventh aspect, the second rib has a central part in the vehicle front-rear direction that is lower than both end parts in the vehicle front-rear direction. As a result, in the second rib, compared with the case where it is formed at the same height along the vehicle front-rear direction, it becomes possible to improve the cooling efficiency during the molding of the vehicle skeletal structure part.

[0026] The vehicle skeletal structure part according to the eighth aspect is the vehicle skeletal structure part according to any one of the first to seventh aspects, and the cross member part is arranged on the front side of the spare tire storage part provided in the lower part of the vehicle.

[0027] In the rear part of the vehicle, a spare tire storage part may be provided. In this case, since the spare tire storage part is formed according to the shape of the spare tire, a substantially columnar concave part is formed, and the front side in the spare tire storage part has an arc shape in plan view.

[0028] In the vehicle skeletal structure part according to the eighth aspect, the cross member part is arranged on the front side of the spare tire storage part provided in the lower part of the vehicle, and it can be curved to avoid interference with the spare tire storage part according to the shape of the spare tire storage part.

[0029] In the first aspect, even in the curved cross member part, the torsional rigidity during vehicle running can be effectively increased, and the handling stability during vehicle running can be improved. Therefore, it becomes possible to arrange a curved cross member part on the front side of the spare tire storage part provided in the lower part of the vehicle. As a result, in this aspect, it becomes possible to improve the handling stability during vehicle running while improving the efficiency of the layout of the lower part of the vehicle.

[0030] Herein, the vehicle frame structure according to the ninth embodiment may be a vehicle frame structure integrally formed by casting, comprising: a pair of frame parts provided on the rear and widthwise sides of the vehicle, positioned inside the left and right rear wheel houses and extending in the longitudinal direction of the vehicle; a cross member portion having a rear wall portion that connects the left and right rear wheel houses and forms the rear end of the vehicle, with at least the rear wall portion being curved convexly toward the front of the vehicle; and a first rib that connects the widthwise end of the cross member portion and the curved rear wall portion along the widthwise direction of the vehicle.

[0031] As a result, in this embodiment, the torsional rigidity of the cross member section connecting the left and right rear wheelhouses is improved, making it possible to improve the handling stability when the vehicle is in motion.

[0032] Furthermore, the vehicle frame structure according to the tenth embodiment may include a vehicle frame structure integrally formed by casting, comprising: a pair of frame parts provided on the rear and widthwise sides of the vehicle, extending in the longitudinal direction of the vehicle and having inclined parts that extend diagonally inward in the widthwise direction as they move toward the rear of the vehicle; a cross member part that extends in the widthwise direction of the vehicle, with both ends in the widthwise direction of the vehicle connected to the inclined parts and having a rear wall part that constitutes the rear end of the vehicle, and at least the rear wall part being curved convexly toward the front of the vehicle; and a first rib that connects the end of the cross member part in the widthwise direction and the curved rear wall part along the widthwise direction of the vehicle.

[0033] As a result, in this embodiment, the torsional rigidity is improved by the first rib connecting the vehicle width direction end of the cross member portion connected to the suspension member mounting portion and the rear wall portion of the cross member portion which is convex toward the front of the vehicle, thereby improving the handling stability when the vehicle is in motion. [Effects of the Invention]

[0034] As described above, the vehicle frame structure according to the present invention can suppress twisting of the cross member portion and improve the handling stability of the vehicle while it is in motion. [Brief explanation of the drawing]

[0035] [Figure 1] This is a bottom view of the rear of a vehicle to which the vehicle frame structure according to this embodiment is applied. [Figure 2] This is a bottom view corresponding to Figure 1, which shows Modification Example 1. [Figure 3] This is an enlarged perspective view of a key part showing the shape of the first rib, which constitutes a part of the vehicle frame structure according to this embodiment. [Figure 4] This is a bottom view corresponding to Figure 1, which shows a modified example 2. [Figure 5] Figures (A) to (E) are schematic bottom views showing the configuration of the first rib, which constitutes a part of the vehicle frame structure according to this embodiment. [Figure 6] This is a bottom view corresponding to Figure 1, which shows Modification 3. [Figure 7] Figures (A) to (C) are schematic bottom views showing the shape of a cross member portion that constitutes a part of the vehicle frame structure according to this embodiment. [Figure 8] This is a schematic cross-sectional view taken along section AA in Figure 1. [Modes for carrying out the invention]

[0036] A vehicle frame structure according to one embodiment of the present invention will be described. In each figure, arrows FR indicate the front side in the longitudinal direction of the vehicle, arrow RH indicates the right side of the vehicle, and arrow UP indicates the upper side in the vertical direction of the vehicle. Hereafter, when simply referring to the longitudinal, left-right, and up-down directions, unless otherwise specified, they refer to the longitudinal direction of the vehicle, the left-right direction (vehicle width direction), and the up-down direction of the vehicle.

[0037] <Configuration of the vehicle's frame structure> First, the configuration of the vehicle frame structure according to this embodiment will be described.

[0038] Figure 1 shows a bottom view of the rear (rear of the vehicle) 14 side of a vehicle 12 to which the vehicle frame structure 10 according to this embodiment is applied, viewed from below. Figure 8 shows a schematic cross-sectional view when cut along line AA shown in Figure 1. Since the vehicle frame structure 10 is configured symmetrically, in the following description, only the configuration of one side may be explained, and the description of the other side may be omitted. In addition, in each figure, the same reference numeral is used for a pair of left and right components. Furthermore, in each figure, some reference numerals may be omitted.

[0039] As shown in Figure 1, a pair of left and right rockers 18 extend in the longitudinal direction of the vehicle from the side (vehicle side) 16 of the vehicle 12. Between the left and right rockers 18, a floor section 22, which constitutes the floor surface of the vehicle interior 20 (see Figure 8), extends in the longitudinal direction and the vehicle width direction. On the rear end 18A side of the rocker 18, a floor cross member 24 extends in the vehicle width direction below the floor section 22 between the left and right rockers 18.

[0040] Furthermore, wheelhouse sections 28, which serve as rear wheelhouses where the rear wheels 26 are positioned, are provided on the rear side of each of the left and right rockers 18. Rear side members (framework sections) 30 extend in the vehicle's longitudinal direction from the inside of the left and right wheelhouse sections 28 in the vehicle's width direction.

[0041] Each of the left and right rear side members 30 has an inclined portion 31 that extends diagonally inward in the vehicle width direction as it moves towards the rear of the vehicle, and each of the left and right rear side members 30 has a connecting portion 32 in the front-rear direction of the vehicle to which the rear end 18A of the rocker 18 and the end 24A of the floor cross member 24 in the extending direction (vehicle width direction) are connected.

[0042] By providing the floor cross member 24 and the connecting portion 32 as separate components, the materials can be changed between the floor cross member 24 and the connecting portion 32, and the design flexibility of the connecting portion 32 is improved. Note that this connecting portion 32 is not necessarily required; a gap may be provided between the front end 30A of the rear side member 30 and the end 24A of the floor cross member 24. Alternatively, the front end 30A of the rear side member 30 may be connected to the rear end 18A of the rocker 18 and the end 24A of the floor cross member 24.

[0043] Furthermore, the left and right rear side members 30 are each provided with mounting portions 36 for attaching the suspension members 34 (see Figure 8). A cross member portion 38 extends in the vehicle width direction, connecting the left and right wheelhouse portions 28 and the left and right mounting portions 36 (as will be described later). Note that the cross member portion 38 is shown with dots to make its shape easier to understand.

[0044] Between the left and right rear side members 30, a rear floor panel 40, which forms the floor surface at the rear of the vehicle body, extends in the longitudinal and width directions of the vehicle. This rear floor panel 40 forms the floor surface of the luggage space, and a roughly cylindrical storage compartment (spare tire storage compartment) 42 is recessed in the front part of the rear floor panel 40 in the width direction of the vehicle, opening upwards towards the vehicle. A spare tire (not shown) can be stored in this storage compartment 42. The storage compartment 42 is closed by a cover provided on its upper edge.

[0045] Thus, the front side of the rear floor panel 40 is provided with a storage compartment 42 for accommodating a spare tire. For this reason, the aforementioned cross member portion 38 is curved in a convex shape toward the front of the vehicle, following the shape of the storage compartment 42.

[0046] Here, the cross member portion 38 is integrally formed with the wheel house portion 28 and the rear side member 30 by, for example, aluminum die casting. In this embodiment, for example, the wheel house portion 28 and the rear side member 30 have an open cross-sectional shape with the outer side in the vehicle width direction open, and the cross member portion 38 has an open cross-sectional shape with the lower side of the vehicle open.

[0047] The shape of the cross member portion 38 will be described in detail. For example, the cross member portion 38 has a cross-sectional shape that is approximately an inverted U-shape when cut along the vehicle's longitudinal and vertical directions. The cross member portion 38 is composed of a front wall portion 44 that forms the front end in the vehicle's longitudinal direction, a rear wall portion 46 that forms the rear end in the vehicle's longitudinal direction, and a rear wall portion 48 that connects the upper ends of the front wall portion 44 and the rear wall portion 46. Both ends of the cross member portion 38 in the vehicle's width direction are connected to the side wall portions 30B that extend along the vehicle's longitudinal and vertical directions in the rear side member 30. Furthermore, the front wall portion 44 and the rear wall portion 46 of the cross member portion 38 are curved convexly toward the front of the vehicle and are arranged on approximately concentric circles.

[0048] Furthermore, in this embodiment, the mounting portion 36 of the suspension member 34 (see Figure 8) is provided on the extension of the front wall portion 44 of the cross member portion 38. In other words, in this embodiment, at least a portion of both ends 38A of the cross member portion 38 in the extending direction (vehicle width direction) overlaps with the mounting portion 36 when viewed from the vehicle width direction. To give a specific example, in this embodiment, both ends 38A of the cross member portion 38 in the vehicle width direction are connected to a pair of mounting portions 36 via the side wall portion 30B of the rear side member 30 and the lower wall portion 30C that extends along the vehicle longitudinal direction and vehicle width direction in the rear side member 30.

[0049] Furthermore, within the cross member section 38, there is a first rib 50 that is erected (hangs down) from the rear wall section 48 and connects both ends 44A in the vehicle width direction of the front wall section 44 of the cross member section 38 and the intermediate section 46A in the vehicle width direction of the rear wall section 46 of the cross member section 38 along the vehicle width direction.

[0050] Here, in the cross member portion 38, for example, the front wall portion 44 and the rear wall portion 46 are formed at approximately the same height, and the first rib 50 is formed at approximately the same height as the front wall portion 44 and the rear wall portion 46. For this reason, the first rib 50 has a roughly rectangular shape when viewed from the front side in the longitudinal direction of the vehicle. In addition, the front wall portion 44 and the rear wall portion 46 of the cross member portion 38 do not necessarily need to be formed at the same height, and the shape of the first rib 50 can be appropriately changed depending on the heights of the front wall portion 44 and the rear wall portion 46.

[0051] <Function and Effects of Vehicle Frame Structures> Next, the operation and effects of the vehicle frame structure according to this embodiment will be described.

[0052] In this embodiment, the vehicle frame structure 10 shown in Figure 1 is integrally formed by casting, and the vehicle frame structure 10 is composed of a pair of left and right rear side members 30, a cross member portion 38, and a first rib 50. The pair of left and right rear side members 30 have mounting portions 36 to which the suspension member 34 (see Figure 8) is attached, and the cross member portion 38 is such that at least a portion of both ends 38A in the vehicle width direction overlaps with the mounting portion 36 when viewed from the vehicle width direction (connected to the mounting portion 36). Furthermore, the cross member portion 38 is curved convexly toward the front of the vehicle, and the first rib 50 connects (connects) both ends 44A of the front wall portion 44 (in the vehicle width direction) and the intermediate portion 46A of the rear wall portion 46 (in the vehicle width direction) along the vehicle width direction.

[0053] Thus, in this embodiment, the cross member portion 38 is provided with a first rib 50 that connects both ends 44A of the front wall portion 44 and the intermediate portion 46A of the rear wall portion 46 along the vehicle width direction. This improves the rigidity of the cross member portion 38 itself and makes it possible to suppress twisting of the cross member portion 38.

[0054] Furthermore, by providing the first rib 50 in the cross member portion 38 connected to the mounting portion 36 of the suspension member 34, the first rib 50 is added to the transmission path of the upward load during vehicle travel, in addition to the front wall portion 44, rear wall portion 46, and back wall portion 48. As a result, in this embodiment, the load transmitted to the cross member portion 38 is distributed, and consequently, twisting of the cross member portion 38 can be further suppressed.

[0055] In other words, in this embodiment, the torsional rigidity of the curved cross member portion 38 during vehicle travel can be effectively increased, thereby improving handling stability during vehicle travel. Furthermore, by increasing the rigidity of the cross member portion 38, sufficient resistance can be obtained against the load applied during a side collision of the vehicle 12.

[0056] Furthermore, in this embodiment, the cross member portion 38 has an open cross-sectional shape that is open to the lower side of the vehicle, and the first rib 50 extends along the vehicle width direction inside the cross member portion 38, connecting both ends 44A of the front wall portion 44 of the cross member portion 38 and the intermediate portion 46A of the rear wall portion 46 of the cross member portion 38 along the vehicle width direction.

[0057] Therefore, in this embodiment, when an upward load is applied while the vehicle 12 is in motion, for example, the angle between the rear wall portion 48 and the back wall portion 46 of the cross member portion 38 becomes obtuse due to the distortion of the rear wall portion 46 of the cross member portion 38, thereby suppressing the opening of the cross section of the cross member portion 38 and contributing to steering stability while the vehicle is in motion.

[0058] Furthermore, in this embodiment, the front wall portion 44 and the rear wall portion 46 of the cross member portion 38 are curved in a convex shape toward the front of the vehicle and are arranged on substantially concentric circles. In addition, a first rib 50 is provided within the cross member portion 38 that connects both ends 44A in the vehicle width direction of the front wall portion 44 and the intermediate portion 46A in the vehicle width direction of the rear wall portion 46 of the cross member portion 38 along the vehicle width direction.

[0059] Thus, in this embodiment, within the cross member portion 38, the rigidity of the cross member portion 38 is further improved by connecting the front wall portion 44A in the vehicle width direction with the intermediate portion 46A in the vehicle width direction with the rear wall portion 46 of the cross member portion 38 via the first rib 50. Furthermore, this suppresses the formation of obtuse angles between the front wall portion 44 and the rear wall portion 48, and between the rear wall portion 46 and the rear wall portion 48 of the cross member portion 38, thereby more effectively preventing the opening of the cross section of the cross member portion 38.

[0060] In this embodiment, the cross member portion 38 is positioned in front of the housing portion 42 provided in the lower part of the vehicle 52, and is curved in a convex shape toward the front of the vehicle to match the shape of the housing portion 42. In this embodiment, the torsional rigidity during vehicle operation can be effectively increased even in the curved cross member portion 38, and the steering stability of the vehicle 12 during vehicle operation can be improved. Therefore, it is possible to position the curved cross member portion 38 in front of the housing portion 42 to avoid interference with the housing portion 42. As a result, in this embodiment, it is possible to improve the steering stability during vehicle operation while improving the efficiency of the layout of the lower part of the vehicle 52.

[0061] <Modification of the above embodiment> Modifications of the above embodiment are described below.

[0062] (Variation 1) In the above embodiment, as shown in Figure 1, a first rib 50 is provided within the cross member portion 38 along the vehicle width direction. Here, as a modified example 1, as shown in Figure 2, a plurality of second ribs 54 are provided along the vehicle width direction, in addition to the first rib 50, to connect the front wall portion 44 and the rear wall portion 46 of the cross member portion 38 in substantially the shortest possible manner.

[0063] In Modification 1, the second rib 54 connects the front wall portion 44 and the rear wall portion 46 of the cross member portion 38 in approximately the shortest possible distance. Therefore, compared to the case where the second rib 54 is not provided, deformation of the front wall portion 44 and the rear wall portion 46 can be suppressed. In other words, in Modification 1, compared to the case where the second rib 54 is not provided, the angle formed by the rear wall portion 48 and the front wall portion 44 and the rear wall portion 46 is further suppressed from becoming obtuse, and the opening of the cross section of the cross member portion 38 can be prevented more effectively.

[0064] The second rib 54 may be formed to be approximately flush with the front wall 44 and rear wall 46 of the cross member portion 38, or, as shown in Figure 3, the central portion in the longitudinal direction of the vehicle may be lower than the height of the front wall 44 and rear wall 46. In Figure 3, the first rib 50 is omitted from the illustration to prioritize the visibility of the second rib 54.

[0065] Here, by forming the second rib 54 so that its height is approximately flush with the front wall portion 44 and the rear wall portion 46 along the vehicle's longitudinal direction, it becomes possible to effectively suppress the opening of the cross member portion 38's open cross section. On the other hand, by making the height of the central part of the second rib 54 in the vehicle's longitudinal direction lower than the height of the ends (front wall portion 44 side and rear wall portion 46 side) in the vehicle's longitudinal direction, it becomes possible to improve the cooling efficiency during the molding of the vehicle frame structure portion 10 compared to when the second rib 54 is formed at the same height along the vehicle's longitudinal direction. For this reason, the height of the second rib 54 may be changed according to its position in the vehicle's width direction on the cross member portion 38.

[0066] Furthermore, as shown in Figure 2, the second rib 54 may be provided in multiple locations over substantially the entire area of ​​the cross member portion 38 in the vehicle width direction, or it may be provided only in a part of the cross member portion 38, such as both ends 38A in the vehicle width direction of the cross member portion 38.

[0067] (Modification 2) Furthermore, as a second modification, as shown in Figure 4, a third rib 56 may be provided in addition to the first rib 50, connecting the front wall portion 44 and the rear wall portion 46 of the cross member portion 38 in a truss-like manner. By connecting the front wall portion 44 and the rear wall portion 46 of the cross member portion 38 with a truss-like third rib 56 in this way, it becomes possible to more effectively suppress the opening of the cross section of the cross member portion 38 compared to the case in which the third rib 56 is not provided.

[0068] Furthermore, in the modified example 2, a third rib 56 connecting in a truss-like manner is provided within the cross member portion 38, thereby further improving the rigidity of the cross member portion 38 against loads along the longitudinal direction of the vehicle, and enabling the transmission of impact loads input from the rear of the vehicle along the vehicle width direction via the third rib 56.

[0069] Furthermore, the third rib 56 may be formed to be approximately flush with the front wall 44 and rear wall 46 of the cross member portion 38, similar to the second rib 54 (see Figure 2), or its central portion in the vehicle's longitudinal direction may be lower than the height of the front wall 44 and rear wall 46. In addition, multiple third ribs 56 may be provided over substantially the entire vehicle width direction of the cross member portion 38, or they may be provided only on a part of the cross member portion 38, such as both ends 38A in the vehicle width direction of the cross member portion 38.

[0070] Furthermore, while the above-described modified examples 1 and 2 describe cases in which a second rib 54 and a third rib 56 are provided, the second rib 54 and the third rib 56 may be mixed within the cross member portion 38.

[0071] (Variation 3) In the above embodiment, as shown in Figures 1 and 5(A), the first rib 50 provided on the cross member portion 38 is connected to both ends 44A of the front wall portion 44 in the vehicle width direction at both ends 50A in the vehicle width direction. The first rib 50 is connected to the intermediate portion 46A of the rear wall portion 46 of the cross member portion 38 in the vehicle width direction at the central portion 50B in the vehicle width direction, and is formed continuously along the vehicle width direction. However, the first rib 50 only needs to connect the end portion 38A of the cross member portion 38 in the vehicle width direction and the curved rear wall portion 46 along the vehicle width direction, so it does not necessarily need to be formed continuously along the vehicle width direction. Figures 5(A) to 5(E) are schematic bottom views of the cross member portion 38.

[0072] For example, as a third modification, as shown in Figures 6 and 5(B), the first rib 50 may be divided in the vehicle width direction at the intermediate portion 46A of the rear wall portion 46 in the vehicle width direction. Depending on the curvature of the front wall portion 44 and the rear wall portion 46 of the cross member portion 38, the ends 44A of the front wall portion 44 and the intermediate portion 46A of the rear wall portion 46 in the vehicle width direction may not be connected in a straight line. In such cases, it is also possible to divide the first rib 50.

[0073] In this example, the first rib 50 is formed along the vehicle width direction, but it may also be formed intersecting with respect to the vehicle width direction when connecting both ends 44A of the front wall portion 44 of the cross member portion 38 and the intermediate portion 46A of the rear wall portion 46 in the vehicle width direction.

[0074] (Modification 4) In this embodiment and modification 3, as shown in Figures 5(A) and (B), the ends 50A of the first rib 50 in the vehicle width direction are connected to the front wall 44. However, since the first rib 50 only needs to connect the end 38A of the cross member 38 and the rear wall 46 along the vehicle width direction, the ends 50A of the first rib 50 do not necessarily need to be connected to the front wall 44.

[0075] For example, as a modified example 4, as shown in Figure 5(C), the ends 58A of the first rib 58 in the vehicle width direction do not have to be connected to the front wall portion 44. In this case, for example, vertical wall portions (not shown) extending in the vehicle longitudinal direction and the vehicle vertical direction are provided at both ends of the cross member portion 38, and the ends of the first rib 58 in the vehicle width direction may be connected to these vertical wall portions.

[0076] If the vertical wall portion is not provided, it may be connected to the side wall portion 30B of the rear side member 30 shown in Figure 1. Also, although the first rib 58 is formed continuously along the vehicle width direction here, as in the modified example 3, the first rib 58 may be divided in the vehicle width direction at the intermediate portion 46A of the rear wall portion 46 in the vehicle width direction, as shown in Figure 5(D).

[0077] (Variation 5) Furthermore, in the above embodiment, as shown in Figure 7(A), the cross member portion 38 has a front wall portion 44 and a rear wall portion 46 arranged substantially concentrically and formed along substantially the same arc shape, but the shape of the cross member portion 38 is not limited to this.

[0078] For example, as a modified example 5, as shown in Figure 7(B), flange portions 62A and 64A extending along the vehicle width direction may be formed at both ends of the front wall portion 62 and the rear wall portion 64 in the vehicle width direction of the cross member portion 60. In this case, as shown in Figure 5(E), the first rib 66 includes the flange portion 64A of the front wall portion 62 and connects to the rear wall portion 46 of the cross member portion 60.

[0079] (Experimental variation 6) Furthermore, in the embodiments described above, as shown in Figures 7(A) and (B), the cross member portion 38 is formed with the front wall portion 44 and the rear wall portion 46 curved convexly toward the front of the vehicle. However, it is not limited to this, as it is sufficient that at least the rear wall portion 46 is curved convexly toward the front of the vehicle.

[0080] For example, as a modified example 6, the front wall portion 70 of the cross member portion 68 may be formed along the vehicle width direction, as shown in Figure 7(C). In this case, although not shown, the first rib may be formed so as to connect the end portion 70A of the front wall portion 70 and the intermediate portion 46A of the rear wall portion 46 in the vehicle width direction, respectively, while being divided in the vehicle width direction. Furthermore, the first rib does not necessarily have to be connected to the front wall portion 70; in this case, both ends of the first rib in the vehicle width direction are connected to the side wall portion 30B of the rear side member 30 shown in Figure 1.

[0081] In this invention, since the cross member portion is formed by casting, the degree of design freedom is greater compared to when it is formed by extrusion molding or the like. For this reason, the shape of the cross member portion can be changed as appropriate to shapes other than those shown in Figures 7(A) to (C).

[0082] <Supplementary information regarding the above embodiment> Supplementary information regarding the above embodiment is described below.

[0083] In this embodiment, the cross member portion 38 shown in Figure 1 has an open cross-sectional shape that opens to the lower side of the vehicle, but it is not limited to this, and may also have a shape that opens to the upper side of the vehicle. In Figure 1, the rear wall portion 48 of the cross member portion 38 connects the upper ends of the front wall portion 44 and the rear wall portion 46. On the other hand, in the case where the cross member portion 38 is open to the upper side of the vehicle, although not shown, the rear wall portion 48 of the cross member portion 38 will connect the lower ends of the front wall portion 44 and the rear wall portion 46. In this case, the first rib 50 may be provided inside the cross member portion 38 (on the inner surface side of the rear wall portion 48) or may be formed on the outer surface side of the rear wall portion 48.

[0084] Furthermore, in this embodiment, the cross member portion 38 has a cross-sectional shape that is substantially inverted U-shaped when cut along the vehicle's longitudinal and vertical directions, and has an open cross-sectional shape that is open to the lower side of the vehicle. However, even if the open end of the cross member portion 38 is closed by a plate or the like, as long as it includes the first rib 50, it is included in the cross member portion of the present invention.

[0085] Furthermore, in this embodiment, the mounting portion 36 of the suspension member 34 (see Figure 8) is provided on the extension line of the front wall portion 44 of the cross member portion 38. However, this is not limited to this, as it is sufficient that at least a portion of both ends 38A of the cross member portion 38 overlaps with the mounting portion 36 when viewed from the vehicle width direction. For example, although not shown, the mounting portion 36 may be provided on the extension line of the rear wall portion 46 of the cross member portion 38, or the mounting portion 36 may be provided between the extension line of the front wall portion 44 and the extension line of the rear wall portion 46.

[0086] Furthermore, in the embodiments described above, the vehicle frame structure 10 shown in Figure 1 is described as an example in which the left and right rear side members 30, left and right wheelhouse sections 28, rear floor panel 40, and cross member section 38 are integrally formed by casting, but it is not limited to this. For example, the wheelhouse sections 28 and rear floor panel 40 may be formed separately.

[0087] In this way, by separating the wheelhouse section 28 and rear floor panel 40 from the vehicle frame structure section 10, which is integrally formed with the left and right rear side members 30 and cross member section 38, the number of parts increases, but it becomes possible to change the materials for the vehicle frame structure section 10, wheelhouse section 28 and rear floor panel 40. This allows for variations in the manufacturing methods for the vehicle frame structure section 10, wheelhouse section 28 and rear floor panel 40, improving design flexibility.

[0088] Furthermore, the present invention can be implemented with various modifications without departing from its essence. Of course, the scope of the present invention is not limited to the embodiments described above. [Explanation of Symbols]

[0089] 10. Vehicle frame structure 12 vehicles 30 Rear side member (framework) 34 Suspension Member 36 Mounting part 38 Cross Member Section 38A End portion (end portion of the cross member in the vehicle width direction) 42 Storage compartment (spare tire storage compartment) 44 Front wall section (cross member section) 44A End portion (end portion in the vehicle width direction on the front wall) 46 Rear wall section (cross member section) 46A Intermediate section (intermediate section in the vehicle width direction at the rear wall) 50 First Rib 50A end 52 Underbody of the vehicle 54. Second Rib 56 Third Rib 58. First Rib 58A End portion (end portion in the vehicle width direction on the front wall) 60 Cross member section 62 Front wall section (cross member section) 62A Flange section 64 Rear wall section (cross member section) 64A Flange section 66. First Rib 68 Cross Member Section 70 Front wall section (cross member section)

Claims

1. A vehicle frame structure integrally formed by casting, A pair of left and right skeletal parts are provided on the rear and sides in the vehicle width direction and extend in the vehicle longitudinal direction, each having a mounting part to which a suspension member is attached, A cross member portion that extends in the vehicle width direction, has both ends in the vehicle width direction connected to a pair of mounting portions, and has a rear wall portion that forms the rear end of the vehicle, and at least the rear wall portion is curved convexly toward the front of the vehicle, A first rib connects the end of the cross member portion in the vehicle width direction and the curved rear wall portion along the vehicle width direction, A vehicle frame structure that includes the following components.

2. The vehicle frame structure according to claim 1, wherein the cross member portion has an open cross-sectional shape that is open to one side in the vertical direction of the vehicle, and the first rib extends along the vehicle width direction inside the cross member portion.

3. The vehicle frame structure according to claim 2, wherein the first rib is connected to the front wall portion that constitutes the front end of the vehicle at the vehicle width direction end of the cross member portion.

4. The vehicle frame structure according to claim 3, wherein the first rib is formed continuously along the vehicle width direction, connects to the front wall at both ends in the vehicle width direction, and connects to the rear wall at the middle portion in the vehicle width direction.

5. The vehicle frame structure according to claim 1, wherein a plurality of second ribs are provided along the vehicle width direction, connecting the front wall portion and the rear wall portion that constitute the front end of the cross member portion of the vehicle in substantially the shortest possible manner.

6. The vehicle frame structure according to claim 1, wherein a third rib is provided that connects the front wall portion and the rear wall portion, which constitute the front end of the cross member portion on the vehicle side, in a truss-like manner.

7. The vehicle frame structure according to claim 5, wherein the second rib is lower at its central portion in the vehicle's longitudinal direction than at both ends in the vehicle's longitudinal direction.

8. The vehicle frame structure according to claim 1, wherein the cross member portion is located in front of the spare tire storage portion provided in the lower part of the vehicle.

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