Vehicle undercarriage

Abstract

To lower the floor of a vehicle.SOLUTION: A vehicle lower structure 1 includes an axle 3, a side rail 4, and a bound stopper 5. The bound stopper 5 has a pair of mountain portions 53, 53 spaced apart in a vehicle front-rear direction D2, and a valley portion 54 positioned between the pair of mountain portions 53, 53 in the vehicle front-rear direction D2. Each of the pair of mountain portions 53, 53 extends down below the valley portion 54 in a vehicle vertical direction D1. The axle 3 includes a pair of end contact portions 34, 34 disposed below the pair of mountain portions 53, 53 in the vehicle vertical direction D1, and a center contact portion 35 disposed below the valley portion 54 in the vehicle vertical direction D1.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle undercarriage. [Background technology]

[0002] In vehicles such as trucks, bound stoppers are sometimes provided on the side rails to absorb impacts transmitted from the axles to the side rails and to prevent direct collisions between the axles and the side rails (see, for example, Patent Document 1). These conventional bound stoppers are positioned above the axles in the vertical direction of the vehicle and extend downward in the vertical direction of the vehicle from the underside of the side member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-006633 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for lower vehicle floors in vehicles such as trucks in order to ensure a sufficient load capacity for cargo, etc. In response to this demand, it is conceivable to reduce the dimension of the bound stopper in the vertical direction of the vehicle.

[0005] However, conventional bound stoppers require a height in the vertical direction of the vehicle to function as an impact absorbing portion and a height in the vertical direction of the vehicle to function as an interference prevention portion, which places a limit on how small they can be made in the vertical direction of the vehicle. The impact absorbing portion is a portion that performs an impact absorbing function by absorbing the impact transmitted from the axle to the side rail, and the interference prevention portion is a portion that performs an interference prevention function by preventing a direct collision between the axle and the side rail.

[0006] Therefore, an object of the present invention is to provide a vehicle underbody structure that can lower the floor of a vehicle. [Means for solving the problem]

[0007] The vehicle undercarriage structure of the present invention comprises an axle to which wheels are attached, a side rail extending in the fore-and-aft direction of the vehicle and movable in the up-and-down direction of the vehicle relative to the axle, and a bound stopper attached to the side rail to restrict movement of the side rail in the up-and-down direction of the vehicle relative to the axle, the bound stopper having a pair of peaks spaced apart in the fore-and-aft direction of the vehicle and a valley portion located between the pair of peaks in the fore-and-aft direction of the vehicle, each of the pair of peaks extending lower in the up-and-down direction of the vehicle than the valley portion, and the axle having a pair of end abutments located below the pair of peaks in the up-and-down direction of the vehicle and a central abutment located below the valley portion in the up-and-down direction of the vehicle.

[0008] In this vehicle undercarriage structure, as the side rail moves relative to the axle in the vertical direction of the vehicle, the pair of peaks of the bound stopper abut against the pair of end abutment portions of the axle, and the valley portion of the bound stopper abuts against the central abutment portion of the axle. This restricts the movement of the side rail relative to the axle in the vertical direction of the vehicle. Because each of the pair of peaks extends lower in the vertical direction of the vehicle than the valley portion, it primarily functions as an impact absorbing portion that absorbs impact transmitted from the axle to the side rail. Meanwhile, because the valley portion is shorter in the vertical direction of the vehicle than the pair of peaks, it primarily functions as an interference prevention portion that prevents direct collision between the central abutment portion of the axle and the side rail. In this way, the portion of the bound stopper that primarily functions as an impact absorbing portion and the portion that primarily functions as an interference prevention portion can be separated in the fore-aft direction of the vehicle, allowing the dimension of the bound stopper in the vertical direction of the vehicle to be reduced. This allows for a lower vehicle floor. Furthermore, since the pair of peaks and the pair of end abutment portions are located on both sides of the valley portion and the central abutment portion in the fore-and-aft direction of the vehicle, when the bound stopper abuts against the axle, it is possible to prevent the axle from twisting around its axis.

[0009] In the vehicle up-down direction, the upper ends of the pair of end abutment portions may be located lower than the upper end of the central abutment portion. In this vehicle undercarriage structure, since the upper ends of the pair of end abutment portions are located lower than the upper end of the central abutment portion in the vehicle up-down direction, the pair of ridges can be arranged to straddle the axle in the vehicle fore-aft direction. This makes it possible to further reduce the vehicle floor.

[0010] The length from the lower ends of the pair of peaks to the lower end of the valley in the vehicle vertical direction may be longer than the length from the upper ends of the pair of end contact portions to the upper end of the central contact portion in the vehicle vertical direction. In this vehicle undercarriage structure, the length in the vehicle vertical direction between the lower ends of the pair of peaks and the lower ends of the valley is longer than the length in the vehicle vertical direction between the upper ends of the pair of end contact portions and the upper end of the central contact portion, so the pair of peaks can abut against the axle before the valleys. As a result, in the bound stopper, only the pair of peaks, which mainly function as impact absorbing portions, can elastically contract until the valleys abut against the axle 3, thereby reducing the impact of the axle on the side rail. [Effects of the Invention]

[0011] According to the present invention, it is possible to achieve a low floor of a vehicle. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing a main part of a vehicle underbody structure according to an embodiment; [Figure 2] FIG. 2 is a schematic cross-sectional view taken along line II-II shown in FIG. [Figure 3] 10 is a schematic diagram illustrating a state in which a bound stopper of a main part of a vehicle undercarriage structure according to an embodiment comes into contact with an axle. FIG. [Figure 4] FIG. 4 is a schematic cross-sectional view taken along line IV-IV shown in FIG. [Figure 5] 10 is a graph showing an example of the relationship between a suspension stroke and a load input to a side rail. [Figure 6]FIG. 10 is a side view showing a bound stopper of a modified example. [Figure 7] FIG. 10 is a side view showing a bound stopper of a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same or equivalent elements will be designated by the same reference numerals, and redundant description will be omitted.

[0014] FIG. 1 is a schematic diagram showing a main part of a vehicle underbody structure according to an embodiment. FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. 1. As shown in FIGS. 1 and 2, the vehicle underbody structure 1 according to this embodiment constitutes a part of a vehicle 2 and includes an axle 3, a side rail 4, and a bound stopper 5. The vehicle 2 is not particularly limited, but in this embodiment, it is a vehicle such as a truck with a cabin located at the front and a cargo bed located at the rear. In the following description, directions such as up / down and front / rear refer to directions in the vehicle 2. For example, the up / down direction refers to the up / down direction in the vehicle up / down direction D1, and the front / rear direction refers to the front / rear direction in the vehicle fore / aft direction D2.

[0015] The axle 3 is a rear axle (dead axle) to which rear wheels 6 are attached. Here, a typical vehicle such as a truck is a rear-wheel drive vehicle that drives the rear wheels. For this reason, the rear axle (axle housing) which is the drive shaft has a hollow cross-sectional structure, and a differential gear, drive shaft (axle shaft), etc. are stored inside it. In contrast, the vehicle 2 of this embodiment is a front-wheel drive vehicle that drives the front wheels, and the axle 3 which is the rear axle of the driven shaft is a dead axle that has a solid cross-sectional structure. The axle 3 will be described in detail later.

[0016] The side rails 4 are frames of the vehicle 2 that extend in the vehicle longitudinal direction D2. Two side rails 4 are arranged on the vehicle 2 so as to face each other in the vehicle width direction D3. The side rails 4 have a U-shaped cross section that opens inward in the vehicle width direction D3. The side rails 4 are supported by a suspension (not shown) so as to be movable relative to the axle 3 in the vehicle vertical direction D1. In other words, the axle 3 and the side rails 4 are movable relative to each other in the vehicle vertical direction D1 as the suspension strokes.

[0017] The bound stoppers 5 are members attached to the side rails 4 to restrict movement of the side rails 4 relative to the axles 3 in the vehicle up-down direction D1. The bound stoppers 5 are attached to each of the two side rails 4. The bound stoppers 5 have a bracket 51 and an elastic portion 52.

[0018] Bracket 51 holds elastic portion 52 and is attached to the underside of side rail 4. Bracket 51 is formed in the shape of a thin flat plate that fits along the underside of side rail 4. Bracket 51 is made of, for example, metal. Elastic portion 52 is held by bracket 51 by, for example, adhesive bonding or fitting. Bracket 51 can be attached to side rail 4 by, for example, bolting using stud bolts, welding, or the like.

[0019] The elastic portion 52 elastically deforms to restrict movement of the side rail 4 relative to the axle 3 in the vehicle up-down direction D1. The elastic portion 52 functions as an impact absorbing portion that absorbs impact transmitted from the axle 3 to the side rail 4, and also functions as an interference prevention portion that prevents a direct collision between the axle 3 and the side rail 4. The elastic portion 52 is formed of an elastically deformable elastic member. For example, rubber is used as the elastic portion 52. The elastic portion 52 has a pair of peaks 53 and a valley 54. The pair of peaks 53 mainly function as an impact absorbing portion that absorbs impact transmitted from the axle 3 to the side rail 4. The valley 54 mainly functions as an interference prevention portion that prevents a direct collision between the axle 3 and the side rail 4. However, the pair of peaks 53 may also function as an interference prevention portion. Similarly, the valley 54 may also function as an impact absorbing portion.

[0020] The pair of peaks 53, 53 are arranged in the vehicle fore-and-aft direction D2 so as to be spaced apart from each other. That is, one peak 53 and the other peak 53 are arranged in the vehicle fore-and-aft direction D2 so as to be spaced apart from each other. Each of the pair of peaks 53, 53 extends downward from the bracket 51. While each of the peaks 53, 53 may be formed in a columnar shape, it is preferable that it be formed in a frustum shape that tapers downward. The frustum shape may be, for example, a quadrangular pyramid shape or a circular cone shape.

[0021] The valley portion 54 is located between the pair of peaks 53, 53 in the vehicle longitudinal direction D2. The valley portion 54 extends in a flat plate shape from one peak 53 to the other peak 53 along the bracket 51. Each of the pair of peaks 53, 53 extends below the valley portion 54. In other words, the dimension (height) of the pair of peaks 53, 53 in the vehicle vertical direction D1 is greater than the dimension (thickness) of the valley portion 54 in the vehicle vertical direction D1.

[0022] The axle 3 has an attachment portion 31 , a contact portion 32 , and a bent portion 33 .

[0023] The mounting portion 31 is located at the end of the axle 3 in the vehicle width direction D3, and is the portion to which the rear wheel 6 is attached. The abutment portion 32 is the portion with which the bound stopper 5 abuts when the side rail 4 moves in the vehicle up-down direction D1 relative to the axle 3. The abutment portion 32 is located inward of the mounting portion 31 in the vehicle width direction D3 and extends in the vehicle width direction D3. The bent portion 33 is located between the mounting portion 31 and the abutment portion 32, and is a portion that is bent so that the abutment portion 32 is located below the wheel axle of the rear wheel 6. Therefore, the abutment portion 32 is located below the wheel axle of the rear wheel 6.

[0024] The contact portion 32 has a pair of end contact portions 34 , 34 and a central contact portion 35 .

[0025] The pair of end abutment portions 34, 34 are portions with which the pair of peaks 53, 53 of the bound stopper 5 abut when the side rail 4 moves in the vehicle up-down direction D1 relative to the axle 3. The pair of end abutment portions 34, 34 are disposed below the pair of peaks 53, 53. In other words, one end abutment portion 34 is disposed below one peak 53, and the other end abutment portion 34 is disposed below the other peak 53. Therefore, when the side rail 4 moves in the vehicle up-down direction D1 relative to the axle 3, the upper ends 34A, 34A of the pair of end abutment portions 34, 34 abut against the lower ends 53A, 53A of the pair of peaks 53, 53.

[0026] The central contact portion 35 is a portion with which the valley portion 54 of the bound stopper 5 abuts when the side rail 4 moves in the vehicle up-down direction D1 relative to the axle 3. The central contact portion 35 is located below the valley portion 54 of the bound stopper 5. Therefore, when the side rail 4 moves in the vehicle up-down direction D1 relative to the axle 3, the upper end 35A of the central contact portion 35 abuts against the lower end 54A of the valley portion 54.

[0027] Upper ends 34A, 34A of the pair of end abutment portions 34, 34 are located lower than an upper end 35A of the central abutment portion 35. For example, the pair of end abutment portions 34, 34 may extend forward and rearward from a lower end portion of the central abutment portion 35. In this case, the cross section of the abutment portion 32 in the vehicle longitudinal direction D2 and the vehicle vertical direction D1 is formed into an inverted T shape, with the central portion extending in the vehicle vertical direction D1 forming the central abutment portion 35, and the portions extending forward and rearward from the lower end portion of the central abutment portion 35 forming the pair of end abutment portions 34, 34.

[0028] Fig. 3 is a schematic diagram showing a state in which a bound stopper of a main part of a vehicle undercarriage according to an embodiment abuts against an axle. Fig. 4 is a schematic cross-sectional view taken along line IV-IV in Fig. 3. As shown in Figs. 1 to 4, a length L1 from the lower ends 53A, 53A of the pair of peaks 53, 53 to the lower end 54A of the valley 54 in the vehicle up-down direction D1 is longer than a length L2 from the upper ends 34A, 34A of the pair of end contact portions 34, 34 to the upper end 35A of the central contact portion 35 in the vehicle up-down direction D1. In other words, when the pair of peaks 53, 53 abut against the pair of end contact portions 34, 34, a gap G corresponding to the difference (L2 - L1) between the length L1 and the length L2 is generated between the valley 54 and the central contact portion 35 in the vehicle up-down direction D1.

[0029] Therefore, when the side rail 4 moves in the vehicle up-down direction D1 relative to the axle 3, first, the pair of end abutment portions 34, 34 abuts against the pair of peaks 53, 53, causing the pair of peaks 53, 53 to begin elastic contraction. After the pair of peaks 53, 53 elastically contracts by the difference (L2-L1) between the length L1 and the length L2, the center abutment portion 35 abuts against the valley portion 54, causing the valley portion 54 to begin elastic contraction.

[0030] FIG. 5 is a graph showing an example of the relationship between suspension stroke and load input to the side rail. In FIG. 5, S1 indicates the suspension stroke when the pair of end contact portions 34, 34 contact the pair of peaks 53, 53, and S2 indicates the suspension stroke when the center contact portion 35 contacts the valley portion 54. As shown in FIG. 5, in the region of stroke greater than S2, not only the pair of peaks 53, 53, which primarily function as shock absorbers, but also the valley portion 54, which primarily functions as an interference prevention portion, elastically contracts. This increases the rate at which the load input from the axle 3 to the side rail 4 increases relative to the suspension stroke. However, in the region from S1 to S2, only the pair of peaks 53, 53, which primarily function as shock absorbers, elastically contracts. This decreases the rate at which the load input from the axle 3 to the side rail 4 increases relative to the suspension stroke, reducing the impact of the axle 3 on the side rail 4.

[0031] As described above, in the vehicle undercarriage structure 1 according to this embodiment, as the side rail 4 moves in the vehicle up-down direction D1 relative to the axle 3, the pair of peaks 53, 53 of the bound stopper 5 come into contact with the pair of end abutment portions 34, 34 of the axle 3, and the valley portion 54 of the bound stopper 5 comes into contact with the central abutment portion 35 of the axle 3. This restricts movement of the side rail 4 in the vehicle up-down direction D1 relative to the axle 3. Here, because each of the pair of peaks 53, 53 extends lower than the valley portion 54, the pair of peaks 53, 53 mainly function as impact absorbing portions that absorb impact transmitted from the axle 3 to the side rail 4. On the other hand, because the length of the valley portion 54 in the vehicle up-down direction D1 is shorter than the pair of peaks 53, 53, the pair of peaks 53, 53 mainly function as an interference prevention portion that prevents direct collision between the central abutment portion 35 of the axle 3 and the side rail 4. In this way, in the bound stopper 5, the portion that primarily functions as an impact absorbing portion and the portion that primarily functions as an interference preventing portion can be separated in the vehicle fore-and-aft direction D2, so the dimension of the bound stopper 5 in the vehicle up-and-down direction D1 can be reduced, thereby enabling a lower floor of the vehicle 2. Furthermore, because the pair of peaks 53, 53 and the pair of end abutment portions 34, 34 are located on both sides of the valley portion 54 and the central abutment portion 35 in the vehicle fore-and-aft direction D2, it is possible to prevent the axle 3 from twisting about its axis when the bound stopper 5 abuts against the axle 3.

[0032] Furthermore, since the upper ends 34A, 34A of the pair of end contact portions 34, 34 are located lower than the upper end 35A of the central contact portion 35 in the vehicle up-down direction D1, the pair of ridges 53, 53 can be disposed so as to straddle the axle 3 in the vehicle front-rear direction D2. This allows the floor of the vehicle 2 to be further lowered.

[0033] Furthermore, since the length L1 in the vehicle vertical direction D1 between the lower ends 53A, 53A of the pair of peaks 53, 53 and the lower end 54A of the valley portion 54 is greater than the length L2 in the vehicle vertical direction D1 between the upper ends 34A, 34A of the pair of end abutment portions 34, 34 and the upper end 35A of the central abutment portion 35, the pair of peaks 53, 53 can abut against the axle 3 before the valley portion 54. As a result, in the bound stopper 5, only the pair of peaks 53, 53, which function mainly as impact absorbing portions, can elastically contract until the valley portion 54 abuts against the axle 3, thereby reducing the upward thrust from the axle 3 to the side rail 4.

[0034] The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment, and may be modified or applied to other things within the scope that does not change the gist described in each claim.

[0035] For example, in the above embodiment, the bound stopper is described as including a bracket and an elastic portion, but as long as the bound stopper can be attached to the side rail, it does not have to include a bracket.

[0036] Furthermore, in the above embodiment, the elastic portion of the bound stopper has been described as being one piece, but the elastic portion of the bound stopper may be composed of multiple members. For example, in the elastic portion 152 of the bound stopper 105 of a modified example shown in FIG. 6, the pair of peaks 153 and the valley 154 are composed of separate members. The pair of peaks 153 and the valley 154 are bonded to the bracket 51 to form the elastic portion 152. In addition, in the elastic portion 252 of the bound stopper 205 of a modified example shown in FIG. 7, the elastic portion 252 is composed of a base member 255 that forms a portion of the pair of peaks 253 on the bracket 51 side and the valley 254, and a pair of block members 256 that form the remaining portions of the pair of peaks 253. The base member 255 is bonded to the bracket 51, and the pair of block members 256 are bonded to the base member 255 to form the elastic portion 252. [Explanation of symbols]

[0037] 1...vehicle understructure, 2...vehicle, 3...axle, 4...side rail, 5...bound stopper, 6...rear wheel (wheel), 31...mounting portion, 32...contact portion, 33...bending portion, 34...end contact portion, 34A...upper end, 35...central contact portion, 35A...upper end, 51...bracket, 52...elastic portion, 53...peak portion, 53A...lower end, 54...valley portion, 54A...lower end, 105...bound stopper, 152...elastic portion, 153...peak portion, 154...valley portion, 205...bound stopper, 252...elastic portion, 253...peak portion, 254...valley portion, 255...base member, 256...block member, D1...vehicle up / down direction, D2...vehicle fore / aft direction, D3...vehicle width direction, G...gap.

Claims

1. an axle to which the wheels are attached; a side rail extending in a front-rear direction of the vehicle and movable in a vertical direction of the vehicle relative to the axle; a bound stopper attached to the side rail to restrict movement of the side rail relative to the axle in the vehicle up-down direction, the bound stopper has a pair of peaks spaced apart in the vehicle longitudinal direction and a valley located between the pair of peaks in the vehicle longitudinal direction, Each of the pair of peaks extends lower than the valley in the vehicle up-down direction, The axle has a pair of end abutment portions arranged below the pair of peaks in the vehicle vertical direction, and a central abutment portion arranged below the valleys in the vehicle vertical direction, a length from a lower end of the pair of peak portions to a lower end of the valley portion in the vehicle vertical direction is longer than a length from an upper end of the pair of end contact portions to an upper end of the central contact portion in the vehicle vertical direction; Vehicle undercarriage.

2. In the vehicle vertical direction, upper ends of the pair of end contact portions are located lower than an upper end of the central contact portion. The vehicle undercarriage structure according to claim 1.

3. the bound stopper has an elastic portion formed of an elastic member that is elastically deformable, The elastic portion has the pair of peaks and the valley. The vehicle underbody structure according to claim 1 or 2.

4. The pair of ridge portions have the same length in the vehicle vertical direction. The vehicle underbody structure according to any one of claims 1 to 3.

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