Vehicle frame structure

Abstract

A vehicle frame structure configured by connecting a pair of left and right side members by means of a cross member 10, wherein the side members 5 have an inner member 19 on the inside in the vehicle width direction and an outer member 20 on the outside in the vehicle width direction, the inner member 19 is configured by joining a rear inner member 19b at the rear of the vehicle and a front inner member 19a at the front of the vehicle, the rear inner member 19b is formed of a thin plate-like member that is thinner than the front inner member 19a, and the joined portion of the front inner member 19a and the rear inner member 19b is set forward of a center position in the front-to-rear width of the cross member 10, at the connecting portion of the side members 5 and the cross member 10.

Description

[Technical Field]

[0001] The present invention relates to a frame structure of a vehicle. [Background technology]

[0002] Vehicles such as pickup trucks are provided with a pair of side members spaced apart in the vehicle width direction as strength members, and the pair of side members are connected by multiple cross members extending substantially in the vehicle width direction to form a chassis frame.

[0003] Furthermore, many vehicles with relatively heavy loads, such as pickup trucks, use leaf springs as suspension devices. The front and rear ends of the leaf springs are supported by side members so as to be able to swing. For example, in Patent Document 1, the rear end of the leaf spring is supported by the side member via a shackle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-79033 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to ensure strength and rigidity while reducing weight, side members are often made of steel plate with a rectangular box-like or U-shaped cross section. Furthermore, there is a demand for reducing the thickness of the subframe as much as possible in order to reduce the weight of the vehicle.

[0006] However, since large loads are input from the leaf springs and cargo boxes to the connecting portions of the side members with the shackles and the portions where the mounting brackets are located, it is particularly important to ensure sufficient rigidity and strength at these portions.

[0007] The present invention has been made to solve such problems, and aims to provide a vehicle frame structure that can reduce the weight of a vehicle having a chassis frame formed by connecting a pair of left and right side members with a cross member while ensuring the rigidity of the side members. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the vehicle frame structure of the present invention comprises a pair of side members arranged at intervals in the vehicle width direction and extending in the fore-and-aft direction of the vehicle, and a cross member extending in the vehicle width direction and connecting the pair of side members, wherein the side members have an inner member on the inside in the vehicle width direction and an outer member on the outside in the vehicle width direction, and the inner member is constructed by joining a first member on the rear side of the vehicle and a second member on the front side of the vehicle that is longer than the first member, and the cross member is connected so as to cover the joint between the first member and the second member in the inner member, and the joint between the first member and the second member is forward of the center position of the vehicle fore-and-aft width of the cross member.

[0009] This allows the inner member to be divided into the first member and the second member, thereby shortening the component length, thereby improving the component yield and reducing the component cost. Furthermore, since the cross member is connected so as to cover the joint between the first member and the second member, the strength of the side member at the joint between the first member and the second member can be ensured. Furthermore, by locating the joint between the first and second members at the front side, which is more susceptible to twisting deformation than the rear side of the cross member when the vehicle is traveling on rough roads, for example, and by firmly fixing this joint, the rigidity of the entire frame, including the side members and cross member, can be efficiently improved and deformation can be suppressed.

[0010] Preferably, the cross member is positioned at the rearmost of multiple cross members provided on the vehicle that connect the pair of side members, and the first member is thinner than at least the portion of the second member adjacent to the first member. This reduces the thickness of the first member that extends rearward from the rearmost cross member, thereby reducing the weight of the side member and making it easier to absorb collision loads by causing the first member to collapse in the event of a rear-end vehicle collision.

[0011] Preferably, the first member is formed to be thinner than a portion of the outer member adjacent to the outer side of the first member in the vehicle width direction, and a portion of the first member is formed to be wider in the vehicle width direction than the outer member adjacent to the outer side of the first member in the vehicle width direction. As a result, by having a portion of the first member that is thinner than the outer member and wider in the vehicle width direction, the side member can be made more likely to crush at the thinner portion of the first member in the event of a rear-end collision, thereby further improving impact absorption in the event of a rear-end collision.

[0012] Preferably, the first member is configured so that its width in the vehicle width direction increases toward the rear of the vehicle. This makes it possible to further reduce the weight of the rear portion of the side member and also makes the rear portion of the side member more easily crushable in the event of a rear collision, thereby further improving impact absorption.

[0013] Preferably, the width of the rear end of the first member in the vehicle width direction is the same as the width of the rear end of the side member in the vehicle width direction. As a result, by making the rear end portion of the side member substantially the first member, it is possible to further reduce the weight of the side member.

[0014] Preferably, the side member further has a reinforcement extending in the vehicle width direction inside and connecting the inner walls of both side surfaces in the vehicle width direction, and the reinforcement is arranged at the front and rear positions of the vehicle at the connection points between the side member and the cross member. This allows the reinforcement to improve the rigidity and strength of the connection between the side member and the cross member. [Effects of the Invention]

[0015] According to the vehicle frame structure of the present invention, the component length of the inner member can be shortened, reducing component costs, and the cross member can ensure the rigidity of the side member at the joint between the first member and the second member.

[0016] Furthermore, because the joint between the first member and the second member is located forward of the center position of the cross member's front-to-rear width, the joint between the first member and the second member is located at a location that is relatively prone to torsional deformation at the joint between the side member and the cross member. By firmly fixing this joint, the rigidity of the entire frame, including the side member and the cross member, can be efficiently improved and deformation can be suppressed. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a perspective view showing a schematic structure of a rear lower part of a vehicle according to an embodiment of the present invention; [Figure 2] 1 is a perspective view showing a schematic structure of a chassis frame of a vehicle according to an embodiment of the present invention; [Figure 3] FIG. 2 is a perspective view showing the structure of a mounting portion for a cargo box at the rear portion of the side member according to the embodiment. [Figure 4] FIG. 2 is a perspective view showing the structure of the vicinity of the connection portion between the left side member and the rearmost cross member according to the present embodiment. [Figure 5] FIG. 2 is a top view showing the structure of the vicinity of the connection portion between the left side member and the rearmost cross member according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing a schematic structure of the lower rear part of a vehicle 1 according to an embodiment of the present invention. Fig. 2 is a perspective view showing a schematic structure of a chassis frame 2 of the vehicle 1 according to this embodiment. Fig. 3 is a perspective view showing a structure of a mounting portion for a luggage box 4 at the rear of a side member according to this embodiment.

[0019] A vehicle 1 in one embodiment employing the frame structure of the present invention is a vehicle equipped with a cargo box 4 and a suspension device 8 with leaf springs 11, such as a pickup truck.

[0020] 1 and 2, a vehicle 1 is provided with a pair of side members 5, 6 that extend in the vehicle longitudinal direction and are spaced apart in the vehicle width direction. The pair of side members 5, 6 are connected by a plurality of cross members to form a chassis frame 2. The cross members extend in the vehicle width direction and are arranged at intervals in the vehicle longitudinal direction. A cargo box 4 is placed on the chassis frame 2. The cargo box 4 is fixed to a mount bracket 3 fixed to side members 5 and 6 with bolts and nuts (not shown).

[0021] A plurality of mount brackets 3 are provided at intervals in the longitudinal direction of the vehicle on the outer sides of the side members 5, 6 in the vehicle width direction. Of the plurality of mount brackets 3, the mount bracket 3 located at the rearmost position of the vehicle is provided near the front-rear position of the rearmost cross member 10.

[0022] The axles of the rear wheels 7 of the vehicle 1 are suspended by a suspension device 8 using leaf springs 11 . The leaf springs 11 are disposed below the side members 5, 6 so as to extend in the direction in which the side members 5, 6 extend, i.e., in the longitudinal direction of the vehicle. The front ends of the leaf springs 11 are supported by the side members 5, 6 via front connecting shafts (not shown) so as to be rotatable in the vertical direction of the vehicle.

[0023] The rear end of the leaf spring 11 is supported by the side members 5, 6 via a shackle 12 so as to be rotatable in the vertical direction of the vehicle. The shackle 12 is supported by the side members 5, 6 behind and in the vicinity of the cross member 10.

[0024] The shackle 12 is connected to the side members 5, 6 by a shackle pin 41 inserted into an insertion hole 13 extending in the vehicle width direction provided in the side wall of the side members 5, 6, and is supported so as to be rotatable around the insertion hole 13, and is also structured to support the rear end of the leaf spring 11 so as to be rotatable around an axis extending in the vehicle width direction.

[0025] The side members 5, 6 are formed by butting together and welding both ends of an inner member 19 and an outer member 20, which are formed by bending sheet metal into a U-shape. The side members 5, 6 are hollow with a box-shaped longitudinal cross section, and have an upper wall 21, a lower wall 22, an inner wall 23, and an outer wall 24. The upper wall 21 and the lower wall 22 have weld lines 25 where the inner member 19 and the outer member 20 are butted together.

[0026] The cross member 10 is hollow and has a box-shaped cross section at the top and bottom, and has an upper wall 26, a lower wall 27, a front wall 28, and a rear wall 29. The end of the cross member 10 abuts against an inner wall 23 of the side member on the inner side in the vehicle width direction and is fixed by welding.

[0027] As shown in Figure 3, the mount bracket 3 has a U-shaped cross section and includes an upper wall 30 and two support side walls 31, 32. The mount bracket 3 is arranged so that the upper wall 30 and the support side walls 31, 32 extend perpendicularly in the vehicle width direction from the outer side walls 24 of the side members 5, 6. The upper wall 30 of the mount bracket 3 is arranged to extend horizontally of the vehicle 1 at approximately the same vertical height as the upper walls 21 of the side members 5, 6, and the two support side walls 31, 32 are arranged side by side and spaced apart in the vehicle fore-and-aft direction. Therefore, the mount bracket 3 is arranged so that the opening of the U-shaped cross section faces downward.

[0028] The ends of the support side walls 31, 32 of the mount bracket 3 facing the side members 5, 6 are bent perpendicularly outward in the vehicle longitudinal direction to form outer flange portions 35. The outer flange portions 35 are fitted to the outer wall 24 of the side member, and their outer peripheries are fixed to the outer wall 24 by welding. The outer flange portions 35 of the mount bracket 3 have their outer ends cut out in a substantially semicircular shape to form cutout portions 36.

[0029] A bolt hole 37 is provided in the upper wall 30 of the mounting bracket 3, and a bolt is inserted into and fastened together with a bolt hole provided in a strength member at the bottom of the cargo box 4 or a bolt hole provided in the mounting bracket fixed to the bottom of the cargo box 4, thereby detachably fixing the cargo box 4 to the side members 5 and 6 via the mounting bracket 3.

[0030] 4 and 5 show the structure near the connection portion between the side member 5 and the cross member 10 according to the embodiment of the present invention, with Fig. 4 being a perspective view and Fig. 5 being a top view. Fig. 4 is a view of the connection portion between the left side member 5 in the vehicle width direction and the rearmost cross member 10, viewed from approximately the center in the vehicle width direction and from the rear.

[0031] The side member 5 is provided with a tubular portion 40 near the rear of the cross member 10, which connects the shackle 12. The tubular portion 40 is a cylindrical member whose axis extends in the vehicle width direction and is disposed so as to penetrate the side member 5, and has an insertion hole 13 formed therein into which a circular rod-shaped shackle pin 41 is inserted. The shackle 12 has a pair of plate members disposed so that one end thereof sandwiches the side member 5 on the left and right, and one end of the shackle 12 is supported by the side member 5 by the shackle pin 41 so as to be rotatable in the front-rear direction. Both ends of the tubular portion 40 are disposed so as to protrude slightly outward from the side walls (inner wall 23, outer wall 24) of the side member 5, and are fixed to the side walls of the side member 5 by, for example, welding.

[0032] The inner end of the tubular portion 40 is provided with a reinforcing portion 45 that protrudes radially outward from the outer peripheral wall of the tubular portion 40. The reinforcing portion 45 is a plate-like member having a hole into which the inner end of the tubular portion 40 is inserted, and is fixed around its entire periphery by welding to the outer peripheral surface of the inner end of the tubular portion 40. The reinforcing portion 45 also comes into contact with the inner wall 23 of the side member 5 and is fixed by welding. Therefore, one end of the tubular portion 40 is fixed to the side member 5 via the reinforcing portion 45.

[0033] Furthermore, the reinforcing portion 45 extends linearly toward the front of the vehicle along the inner surface of the side member 5 to a position close to the rear wall 29 of the cross member 10. The support side wall 31 on the rear side of the vehicle's rearmost mounting bracket 3 is located in a fore-and-aft position between the rear wall 29 of the vehicle's rearmost cross member 10 and the front end of the reinforcing portion 45. The reinforcing portion 45 may extend toward the front of the vehicle until it comes into contact with the rear wall 29 of the cross member 10. The rear wall 29 of the cross member 10, the front end of the reinforcing portion 45, and the support side wall 31 on the rear side of the vehicle's rearmost mounting bracket 3 may be located in approximately the same or nearby positions in the fore-and-aft of the vehicle.

[0034] Furthermore, the inner member 19 on the inside of the side member 5 in the vehicle width direction is divided into a front inner member 19a (second member) on the vehicle front side and a rear inner member 19b (first member) on the vehicle rear side between the front wall 28 and rear wall 29 of the cross member 10 and at a position forward of the center position in the fore-and-aft direction of the cross member 10. The rear end of the front inner member 19a and the front end of the rear inner member 19b are joined by welding (joint 38). Furthermore, the rear inner member 19b is formed to have a thickness thinner than that of the front inner member 19a and the outer member 20.

[0035] Furthermore, the rear inner member 19b gradually becomes longer in a linear manner in the vehicle width direction as it extends rearward from the cylindrical portion 40, and accordingly, the rear portion of the outer member 20 gradually becomes shorter in the vehicle width direction as it extends rearward from the cylindrical portion 40. As a result, the proportion of the side member 5 taken up by the rear inner member 19b becomes larger than that of the outer member 20 as it extends rearward from the cylindrical portion 40 toward the vehicle rear. At the rear end of the side member 5, the outer member 20 has only the outer wall 24 without substantially having the upper wall 21 or lower wall 22, and the vehicle width of the rear inner member 19b is substantially the same as the vehicle width of the side member 5.

[0036] Two reinforcements 50, 51 are provided within the side member 5 near the connection with the cross member 10, and are spaced apart from each other in the vehicle longitudinal direction, which is the extension direction of the side member 5, to reinforce the side member 5.

[0037] The reinforcements 50, 51 are rectangular thick plate members, and the entire periphery thereof is welded and fixed to the inner wall of the side member 5. That is, the reinforcements 50, 51 have the effect of supporting the inner wall of the side member 5 and improving the strength and rigidity of the side member 5.

[0038] The vehicle rear side reinforcement 50 is disposed in a longitudinal position between the rear wall 29 of the cross member 10 at the rearmost position of the vehicle and the front end of the reinforcing portion 45. The vehicle rear side reinforcement 50 may be disposed in approximately the same or nearby longitudinal positions as the rear wall 29 of the cross member 10, the front end of the reinforcing portion 45, and the support side wall 31 on the vehicle rear side of the mount bracket 3.

[0039] On the other hand, the reinforcement 51 on the front side of the vehicle is positioned slightly rearward of the front wall 28 of the cross member 10 and slightly forward of the joint 38 between the front inner member 19a and the rear inner member 19b.

[0040] The reinforcement 50 has a two-part structure composed of an inner reinforcement 50a fixed to the inner member 19 and an outer reinforcement 50b fixed to the outer member 20. The inner reinforcement 51a is fixed to the inside of the inner member 19 by welding, and the outer reinforcement 51b is fixed to the inside of the outer member 20 by welding. In the above embodiment, the structure of the side member 5 on the left side of the vehicle has been described, but the side member 6 on the right side of the vehicle may also be made to have a similar structure that is symmetrical on the left and right sides.

[0041] As described above, in this embodiment, the side members 5, 6 are each made up of the inner member 19 on the inside in the vehicle width direction and the outer member 20 on the outside in the vehicle width direction. Furthermore, the inner member 19 is formed by welding together parts that are separated in the vehicle fore-and-aft direction, such as the front inner member 19a on the front side of the vehicle and the rear inner member 19b on the rear side of the vehicle. This allows the component length of the inner member 19 to be shortened, thereby improving the component yield and reducing the component cost.

[0042] Furthermore, at the connection between the inner member 19 and the cross member 10, more specifically, the front inner member 19a and the rear inner member 19b are joined at the front-to-rear position of the vehicle between the front wall 28 and rear wall 29 of the cross member 10, and the cross member 10 is connected so as to cover the joint 38 between the front inner member 19a and the rear inner member 19b, thereby ensuring the strength and rigidity of the side members 5 and 6.

[0043] The inner member 19 is formed by joining a rear inner member 19b located at the rear of the vehicle and a front inner member 19a located at the front of the vehicle and longer than the rear inner member 19b. Therefore, for example, when subjected to an input from the rear tires during off-road driving, the front periphery of the connection between the side members 5, 6 and the cross member 10 is more likely to undergo torsional deformation than the rear periphery. This configuration places the joint where the front inner member 19a and the rear inner member 19b overlap each other in the front portion of the connection between the side members 5, 6 and the cross member 10, where deformation is likely to occur, i.e., forward of the center position of the cross member 10 in the vehicle longitudinal direction width near the rear tires, which contributes more to torsional rigidity. This efficiently improves the rigidity of the entire chassis frame 2, including the side members 5, 6 and the cross member 10, and suppresses deformation.

[0044] Furthermore, the cross member 10 at the front-rear position where the front inner member 19a and the rear inner member 19b are joined is the rearmost of the multiple cross members of the vehicle 1, so the plate thickness of the rear inner member 19b, which extends rearward from the rearmost cross member 10, is thinner than that of the front inner member 19a. This reduces the weight of the inner member 19, and therefore the side members 5 and 6, and also makes it easier to absorb the collision load by the rear inner member 19b collapsing in the event of a rear-end collision.

[0045] Furthermore, since the outer member 20 has a thickness greater than that of the rear inner member 19b, the rear inner member 19b has a thinner thickness, which contributes to weight reduction, while the outer member 20 ensures the necessary rigidity and strength.

[0046] The width in the vehicle width direction of the rear inner member 19b is approximately the same as the width in the vehicle width direction of the outer member 20 at the connection position with the cross member 10, and the width in the vehicle width direction increases toward the rear end rearward of the cylindrical portion 40. Therefore, rearward of the cylindrical portion 40, the width in the vehicle width direction of the rear inner member 19b, which has a thin plate thickness, is equal to or greater than the width in the vehicle width direction of the outer member 20, making it easier for the side members 5, 6 to collapse. This improves impact absorption in the event of a rear collision.

[0047] In particular, at the rear ends of the side members 5, 6, the width of the rear inner member 19b in the vehicle width direction is approximately the same as the width of the side members 5, 6 in the vehicle width direction, so the rear portions of the side members 5, 6 can be made even lighter.

[0048] Furthermore, the width of the front inner member 19a in the vehicle width direction increases linearly rather than stepwise toward the rear ends of the side members 5, 6, which can suppress stress concentration in the side members 5, 6. Therefore, the rear ends of the side members 5, 6 are more likely to crush uniformly during a rear-end collision, further improving impact absorption.

[0049] Furthermore, two reinforcements 50, 51 are provided at a distance in the vehicle longitudinal direction within the side members 5, 6 near the connection portion with the cross member 10, thereby improving the strength and rigidity of the side members 5, 6 near the connection portion with the cross member 10. Therefore, even if stress occurs at the connection portion of the side members 5, 6, it is possible to suppress deformation of the cross section of the side members 5, 6. This improves the torsional rigidity of the side members 5, 6 and improves the handling stability of the vehicle.

[0050] Of the two reinforcements 50, 51 provided near the connection of the cross member 10, the reinforcement 51 on the front side of the vehicle is positioned near the joint 38 between the front inner member 19a and the rear inner member 19b, thereby improving the strength and rigidity of the side members 5, 6 near the joint 38 between the front inner member 19a and the rear inner member 19b.

[0051] Furthermore, outer flange portion 35 of mount bracket 3 has its outer end cut out in a substantially semicircular shape to form notch 36, which ensures a long welding length for fastening outer flange portion 35 to outer wall 24 of the side member. Furthermore, by extending the upper portion of outer flange portion 35 on the vehicle rear side so that it approaches tubular portion 40, the distance between the support portion of leaf spring 11 and mount bracket 3 can be shortened, thereby improving rigidity in the vicinity of tubular portion 40.

[0052] The present invention is not limited to the above-described embodiments. For example, in the above embodiment, the rear inner member 19b is thinner than the front inner member 19a and the outer member 20, but it may be thinner only in part.

[0053] In addition, in the above embodiment, the joint 38 between the front inner member 19a and the rear inner member 19b is located at the connection between the cross member 10 at the rear end of the vehicle and the side members 5 and 6, but the joint between the front inner member 19a and the rear inner member 19b may also be located at the connection between the cross member other than the cross member 10 at the rear end of the vehicle.

[0054] Furthermore, the detailed structures of the side members 5, 6, the cross member 10, etc. may be changed as appropriate. Regarding the vehicle 1, the present invention can be widely applied to vehicles having a chassis frame configured by connecting a pair of side members with a cross member. [Explanation of symbols]

[0055] 1 vehicle 5, 6 Side members 10 Cross member 19 Inner Member 19a Front inner member (second member) 19b Rear inner member (first member) 20 Outer Member 50, 51 Reinforce

Claims

1. a pair of side members arranged at an interval in a vehicle width direction of the vehicle and extending in a front-rear direction of the vehicle; a cross member extending in the vehicle width direction and connecting the pair of side members, The side member has an inner member on the inside in the vehicle width direction and an outer member on the outside in the vehicle width direction, The inner member is configured by joining a first member on the vehicle rear side and a second member on the vehicle front side that is longer than the first member, the cross member is connected to the inner member so as to cover a joint between the first member and the second member, A frame structure for a vehicle, characterized in that the joint between the first member and the second member is located forward of the center position of the cross member in the vehicle's fore-and-aft width.

2. The vehicle frame structure described in claim 1, characterized in that the cross member is positioned at the rearmost of the vehicle's multiple cross members that connect the pair of side members, and the first member is thinner than at least the portion of the second member adjacent to the first member.

3. The first member is formed to have a thickness thinner than a portion of the outer member adjacent to the outer side of the first member in the vehicle width direction, 3. The vehicle frame structure according to claim 1, wherein a portion of the first member is formed to be wider in the vehicle width direction than the outer member adjacent to the first member on the vehicle width direction outer side.

4. 4. The vehicle frame structure according to claim 3, wherein the first member is configured so that its width in the vehicle width direction increases toward the rear of the vehicle.

5. 5. The vehicle frame structure according to claim 3, wherein the width of the rear end of the first member in the vehicle width direction is the same as the width of the rear end of the side member in the vehicle width direction.

6. The side member further includes a reinforcement extending in a vehicle width direction therein and connecting inner walls of both side surfaces in the vehicle width direction, 6. The vehicle frame structure according to claim 1, wherein the reinforcement is disposed at a connection between the side member and the cross member.

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