Vehicle undercarriage

Abstract

To provide a vehicle lower structure that improves straight-line stability while reducing the installation space for leaf springs in the vehicle width direction. [Solution] A vehicle undercarriage structure having a pair of side members 5, 6 arranged at intervals in the vehicle width direction and extending in the fore-and-aft direction of the vehicle, leaf springs 11 arranged so as to extend in the fore-and-aft direction of the vehicle along the pair of side members 5, 6 and support the axles of the vehicle's rear wheels, and a connecting shaft 23 that swingably connects the front end of the leaf spring 11 to the side members 5, 6, and the connecting shaft 23 is arranged inclined toward the front of the vehicle and inward in the vehicle width direction.

Description

[Technical Field]

[0001] The present invention relates to a support structure for a leaf spring suspension device in a vehicle undercarriage. [Background technology]

[0002] Many vehicles, such as pickup trucks, that are heavily loaded or frequently travel on rough roads employ leaf spring suspension systems. Leaf spring suspension systems have plate-shaped leaf springs attached to a pair of side members that extend in the longitudinal direction of the vehicle and are spaced apart in the transverse direction of the vehicle. The leaf spring has its front and rear ends supported by side members so as to be able to swing up and down, and its center portion supports the axle.

[0003] Leaf springs are usually arranged to extend in the longitudinal direction of the vehicle parallel to the side members, but for example, Patent Document 1 proposes a vehicle in which the leaf springs supporting the rear axle are arranged at an angle relative to the side members. As a result, when an external force is applied, such as when the vehicle is hit by a crosswind while traveling, the direction of the rear wheels is displaced in a direction against the external force, improving the vehicle's straight-line running performance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-270626 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, the long leaf spring is arranged at an angle relative to the fore-and-aft direction of the vehicle, which requires installation space in the vehicle width direction and may encroach on the installation space for other vehicle structures such as tires. The present invention has been made to solve such problems, and aims to provide a vehicle undercarriage structure that improves straight-line stability while reducing the installation space required for leaf springs in the vehicle width direction. [Means for solving the problem]

[0006] In order to achieve the above object, the undercarriage of a vehicle of the present invention includes a pair of side members arranged at an interval in the vehicle width direction and extending in the longitudinal direction of the vehicle; a leaf spring extending in the longitudinal direction of the vehicle along the pair of side members, with front and rear ends supported by the side members so as to be swingable in the up and down direction, and supporting an axle of a rear wheel of the vehicle; and a front connecting shaft swingably connecting the front end of the leaf spring to the side member. The front connecting shaft is disposed so as to be inclined toward the front of the vehicle and toward the inside in the vehicle width direction. [Effects of the Invention]

[0007] According to the vehicle undercarriage structure of the present invention, the front connecting shaft that connects the front end of the leaf spring supporting the rear axle to the side member is inclined with respect to the vehicle width direction, so that when the vehicle is subjected to an external force such as a crosswind, the rear wheel axle (rear axle) is displaced in a direction against the external force, thereby improving the running stability of the vehicle. Furthermore, since the leaf springs are arranged to extend in the fore-and-aft direction of the vehicle along the side members without being tilted from the fore-and-aft direction of the vehicle, the installation space required for the leaf springs in the vehicle width direction can be reduced, improving the ease of mounting the leaf springs on the vehicle. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a top view showing a schematic structure of a lower rear portion of a vehicle according to an embodiment of the present invention. [Figure 2] 1 is a side view showing a schematic structure of a lower rear portion of a vehicle according to an embodiment of the present invention. [Figure 3]FIG. 4 is a vertical cross-sectional view showing the structure of a support portion at the front end of a leaf spring. [Figure 4] FIG. 4 is a vertical cross-sectional view showing the structure of a support portion at the rear end of a leaf spring. [Figure 5] FIG. 10 is an explanatory diagram of the inclination of a support portion of a leaf spring. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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 rear lower part of a vehicle 1 according to an embodiment of the present invention. Fig. 2 is a side view showing a schematic structure of the rear lower part of a vehicle according to this embodiment. A vehicle 1 according to an embodiment of the present invention is a vehicle, such as a pickup truck, that is provided with a suspension device 8 using leaf springs 11 for the rear wheels.

[0010] As shown in Fig. 1, vehicle 1 is equipped with a pair of side members 5, 6 that extend in the longitudinal direction of the vehicle and are spaced apart in the vehicle width direction. The pair of side members 5, 6 are connected by multiple cross members to form chassis frame 2. The cross members include cross member 10a located in front of rear wheels 7 of vehicle 1, cross member 10b located near the axle of rear wheels 7 (rear axle 9) in the longitudinal direction of the vehicle, and cross member 10c located behind rear wheels 7.

[0011] The cross members 10a, 10b, and 10c extend in the vehicle width direction and are disposed at intervals from one another in the vehicle front-rear direction. For example, a cargo box is placed on the chassis frame 2. The cargo box is fixed by bolts and nuts via a plurality of mounting brackets (not shown) fixed to the side members 5 and 6.

[0012] A rear axle 9 of the vehicle 1 is suspended from side members 5 and 6 by a suspension device 8 having leaf springs 11 and shock absorbers 14a and 14b. The leaf springs 11 are made up of multiple stacked rectangular plate-shaped spring members. 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.

[0013] The front end of the leaf spring 11 is supported by the side members 5 and 6 so as to be rotatable in the vertical direction of the vehicle. The rear end of the leaf spring 11 is supported by the side members 5, 6 via a shackle 12 (link member) 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 rear cross member 10c.

[0014] The support portion at the front end of the leaf spring 11 is located lower than the support portion at the rear end (the connection portion with the shackle 12). The side members 5 and 6 and the cross members 10a, 10b, and 10c are hollow and have a box-shaped longitudinal cross section. The ends of the cross members 10a, 10b, and 10c abut against the inner side walls of the side members 5 and 6 on the inner side in the vehicle width direction and are fixed by welding.

[0015] The cross member 10a is disposed in the vicinity of the support portion of the front end of the leaf spring 11 at a position in the front and rear of the vehicle, and the cross member 10c is disposed in the vicinity of the support portion of the rear end of the leaf spring 11 at a position in the front and rear of the vehicle. Fig. 3 is a vertical cross-sectional view showing the structure of the support portion at the front end of the leaf spring 11. Fig. 4 is a vertical cross-sectional view showing the structure of the support portion at the rear end of the leaf spring 11. Fig. 5 is an explanatory diagram of the inclination of the support portion of the leaf spring 11. Fig. 3 is a cross-sectional view of the A-A portion shown in Fig. 2. Fig. 4 is a cross-sectional view of the B-B portion shown in Fig. 2. Fig. 5 is a top view of the leaf spring 11 and its support portion.

[0016] 2 and 3, a cylindrical eye 20 is fixed to the front end of the leaf spring 11. As shown in Fig. 3, the eye 20 is inserted between a pair of support brackets 21 and 22 extending downward from both the left and right side surfaces of the side members 5 and 6, and is supported swingably by a bolt-shaped connecting shaft 23 (front connecting shaft). Between the eye 20 and the connecting shaft 23 are a cylindrical steel collar 24 and a bushing 25 formed into a cylindrical shape from an elastic material such as rubber and placed between the collar 24 and the eye 20.

[0017] The pair of support brackets 21, 22 have holes 26, 27 arranged coaxially. The collar 24 has an axial length such that it can be inserted between the pair of support brackets 21, 22 with almost no gap between them, and the eye 20 and bushing 25 have approximately the same axial length but are shorter than the collar 24. Bushings 28, 29 (stoppers) formed into annular plates from an elastic member are provided between both ends of the eye 20 and bushing 25 and the pair of support brackets 21, 22. The bushing 25 and the bushings 28, 29 are preferably configured to be able to engage with each other.

[0018] The bushings 28 and 29 have an outer diameter that is approximately the same as the outer diameter of the eye 20, and the collar 24 is inserted into a hole in the center. The axial length of the eye 20 and bush 25 when equipped with bushes 28, 29 at both ends is set to a length that allows them to swing around the connecting shaft 23 and collar 24 between a pair of support brackets 21, 22, but is substantially unable to move in the axial direction.

[0019] When assembling the front end of the leaf spring 11 to the side member 5, the collar 24 and bushing 25 are inserted into the eye 20, and then the bushing 25 is inserted between the pair of support brackets 21 and 22 with bushings 28 and 29 engaged on both sides of the bushing 25. Then, the shaft hole of the collar 24 is aligned with the holes 26 and 27, and the connecting shaft 23 is inserted through one of the holes 26 and passes through. A nut 30 is then fastened to the tip of the connecting shaft 23 protruding from the hole 27, whereby the front end of the leaf spring 11 is supported by the side member 5 so as to be swingable around the axis of the connecting shaft 23.

[0020] 1 and 5, the leaf spring 11 is installed so as to extend in the fore-and-aft direction of the vehicle along the side members 5, 6, but the eye 20 at the front end of the leaf spring 11 is arranged so as to be inclined with respect to the vehicle width direction, which is perpendicular to the extension direction of the leaf spring 11. In accordance with the inclination of this eye 20, the support brackets 21, 22 are inclined near the holes 26, 27, and the axis CLa passing through the holes 26, 27 is arranged so as to be inclined with respect to the vehicle width direction of the side members 5, 6. More specifically, the axis of the eye 20, i.e., the support axis at the front end of the leaf spring 11, is inclined with the inner side in the vehicle width direction toward the front of the vehicle.

[0021] As shown in Figures 2 and 4, a cylindrical eye 35 is fixed to the rear end of the leaf spring 11. As shown in Figure 4, the shackle 12 that connects the eye 35 to the side member 5 has a pair of side walls 12a, 12b that extend downward and sandwich both left and right side walls of the side member 5. The upper parts (one ends) of the side walls 12a, 12b are provided with holes 37, 38 into which a bolt-shaped connecting shaft 36 (first rear connecting shaft) is inserted. The lower parts (other ends) of the side walls 12a, 12b are provided with holes 40, 41 into which a bolt-shaped connecting shaft 39 (second rear connecting shaft) is inserted.

[0022] One end of the shackle 12 is swingably supported on the side member 5 by a connecting shaft 36, and the eye 35 is swingably supported on the other end of the shackle 12 by a connecting shaft 39. The connecting shafts 36 and 39 have axes parallel to each other and are both arranged to extend in the vehicle width direction. A cylindrical boss portion 45 having an axis extending in the vehicle width direction and penetrating both left and right side walls of the side member 5 is fixed to the side member 5. Both ends of the boss portion 45 protrude outward beyond both left and right side walls of the side member 5. The connecting shaft 36 is inserted into the boss portion 45.

[0023] Between the connecting shaft 36 and the boss portion 45, a bushing 46 (46a, 46b: first bushing) formed into a cylindrical shape by an elastic member is interposed. The bushing 46 (46a, 46b) is divided into left and right portions near the center in the vehicle width direction of the side member 5. Both ends of the bushing 46 protrude outward beyond the boss portion 45, and these outwardly protruding portions further protrude radially outward over the entire periphery and are provided with flange portions 47a, 47b.

[0024] The axial length of the boss portion 45, which is the sum of the left and right bushings 46a, 46b, is set so that it can swing around the connecting shaft 36 between the upper part of the shackle 12. In addition, the flange portions 47a, 47b are arranged to be sandwiched between both ends of the boss portion 45 and the side walls 12a, 12b of the shackle 12, and the distance between the side walls 12a, 12b at the upper end of the shackle 12, the axial length of the boss portion 45, and the axial thicknesses of the flange portions 47a, 47b of the bushings 46a and 46b are set to an extent that relative movement between the boss portion 45 and the upper part of the shackle 12 in the vehicle width direction is almost impossible.

[0025] At the connection between the lower end of the shackle 12 and the eye 35 at the rear end of the leaf spring 11, Between the connecting shaft 39 and the eye 35, a bushing 50 (50a, 50b: second bushing) formed into a cylindrical shape by an elastic member is interposed. The bushing 50 (50a, 50b) is divided into left and right halves near the center of the vehicle width direction of the eye 35. Both ends of the bushing 50 protrude axially outward beyond the eye 35, and these outwardly protruding portions further protrude radially outward along the entire circumference and are provided with flange portions 51a, 51b.

[0026] The axial length of the bushing 50, which is the combination of the left and right bushings 50a, 50b, is set so that it can swing around the connecting shaft 39 between the side walls 12a, 12b at the lower end of the shackle 12. In addition, the flange portions 51a, 51b are arranged to be sandwiched between both ends of the eye 35 and the side walls 12a, 12b at the lower end of the shackle 12, and the spacing between the side walls 12a, 12b at the lower end of the shackle 12, the axial length of the eye 35, and the axial thicknesses of the flange portions 51a of the bushing 50a and 51b of the bushing 50b are set to an extent that relative movement between the eye 35 and the lower end of the shackle 12 in the vehicle width direction is substantially impossible.

[0027] When assembling the rear end of the leaf spring 11 to the side member 5, for example, bushings 50a, 50b are inserted into the eye 35, and the eye 35 with the bushings 50a, 50b inserted is inserted between the side walls 12a, 12b of the shackle 12. Then, the holes of the bushings 50a, 50b are aligned with the holes 40, 41 of the shackle 12, and a connecting shaft 39 is inserted through one of the holes 41, and a nut 52 is fastened to the tip of the connecting shaft 39 protruding from the hole 40, whereby the end of the shackle 12 is supported on the rear end of the leaf spring 11 so as to be swingable around the axis of the connecting shaft 39.

[0028] Additionally, bushings 46a and 46b are inserted into boss portion 45 of side member 5. Then, the holes of bushings 46a and 46b are aligned with holes 37 and 38 of shackle 12, and connecting shaft 36 is inserted through one of holes 38. Nut 53 is fastened to the tip of connecting shaft 36 protruding from hole 37, whereby the upper end of shackle 12 is supported by side member 5 so as to be swingable around the axis of connecting shaft 36.

[0029] While the above description has been given of the suspension unit 8 on the left side of the vehicle, the suspension unit 8 on the right side of the vehicle is also symmetrical and has a similar structure. That is, the eye 20 at the front end of the right leaf spring 11 is arranged at an angle with respect to the vehicle width direction so that the inner side in the vehicle width direction faces the front of the vehicle. As described above, in this embodiment, the rear axle of the vehicle 1 is suspended by the leaf spring suspension device 8. The leaf spring suspension device 8 uses a long leaf spring 11, and is structured so that both longitudinal ends are supported by the vehicle body so as to be able to swing up and down, and the rear axle 9 is supported at the longitudinal center.

[0030] The leaf spring 11 is supported by a pair of side members 5, 6 that extend in the front-rear direction of the vehicle 1 and are spaced apart in the vehicle width direction, and is disposed below the side members 5, 6. In the vehicle 1 of this embodiment, the leaf spring 11 is arranged to extend in the fore-and-aft direction of the vehicle together with the side members 5 and 6, but the connecting shaft 23, which is the support shaft at the front end of the leaf spring 11, is inclined with respect to the vehicle width direction, and the connecting shaft 23 is arranged so as to be inclined toward the front side of the vehicle 1, facing inward in the vehicle width direction.

[0031] For example, if a crosswind hits the vehicle 1 from the right while the vehicle is traveling straight and causes it to drift to the left, the crosswind will cause the vehicle body to move leftward. At this time, a lateral force (in the vehicle width direction) is applied to the rear axle 9 via the rear wheel 7 to the right side. The leaf spring 11 has a front end and a rear end, but only the rear end is supported via a shackle 12, which is a link member, so when a lateral force is applied to the rear wheel 7, the front and rear sides are displaced to the same extent.

[0032] However, in this embodiment, since the connecting shaft 23, which is the support shaft on the front side of the leaf spring 11, is disposed at an angle so as to face outward relative to the vehicle width direction, when the driver steers the front wheels to the right as described above, the left leaf spring 11 is displaced so as to move forward more than the right leaf spring 11, and the rear axle 9 is displaced so as to be steered in the same direction as the steering direction, i.e., in the direction against an external force such as a crosswind. Therefore, the rear axle 9 automatically tilts to suppress turning due to an external force, thereby improving the driving stability of the vehicle 1. Furthermore, during turning, the rear wheels are turned inward in the turning direction due to a similar mechanism, which increases the cornering power of the rear wheels and improves cornering performance.

[0033] Furthermore, in this embodiment, the support axis of the front end of the leaf spring 11 is tilted relative to the vehicle width direction, and the leaf spring 11 itself is not tilted from the fore-and-aft direction of the vehicle 1, but is arranged to extend in the fore-and-aft direction of the vehicle 1 along the side members 5 and 6, thereby reducing the installation space required for the leaf spring 11 in the vehicle width direction and improving the mountability of the leaf spring 11 on the vehicle 1.

[0034] Since bushes 25, 46a, 46b, 50a, and 50b made of elastic material are interposed in the support portions of the front and rear ends of the leaf spring 11, vibrations of the rear axle 9 can be absorbed and transmission to the side members 5 and 6 can be suppressed. This improves the ride comfort of the vehicle 1. Additionally, bushes 28, 29 formed into annular plates and made of elastic material are provided between both ends of an eye 20 provided at the front end of the leaf spring 11 and a pair of support brackets 21, 22 provided on the side member 5, and these bushes 28, 29 restrain the front end of the leaf spring 11 from moving in the vehicle width direction relative to the side members 5, 6 beyond a predetermined amount. Therefore, because movement of the leaf spring 11 in the vehicle width direction with the front end as a fulcrum is restrained, tilting of the leaf spring 11 when the vehicle is subjected to a crosswind or the like can be suppressed, thereby suppressing swaying of the vehicle.

[0035] The rear end of the leaf spring 11 is connected to the side members 5, 6 via a shackle 12, and an eye 35 at the rear end of the leaf spring 11 and the shackle 12 are connected by a connecting shaft 39 extending in the vehicle width direction, and the shackle 12 and the side members 5, 6 are connected by a connecting shaft 36 extending in the vehicle width direction. Bushes 50a, 50b provided around the connecting shaft 39 and bushes 46a, 46b provided around the connecting shaft 36 have flange portions 47a, 47b, 51a, 51b whose ends protrude radially outward, and these flange portions 47a, 47b, 51a, 51b suppress relative movement in the vehicle width direction at the two connection points between the rear end of the leaf spring 11 and the side members 5, 6, so that movement of the rear end of the leaf spring 11 relative to the side members 5, 6 in the vehicle width direction is effectively suppressed. Therefore, when the vehicle is subjected to a crosswind or the like, the inclination of the leaf spring 11 can be suppressed, and the swaying of the vehicle can be more effectively suppressed.

[0036] Furthermore, the flange portions 47a, 47b, 51a, 51b are formed by protruding the ends of the bushes 46a, 46b, 50a, 50b radially outward, and therefore can function as stoppers that suppress movement of the leaf spring 11 in the vehicle width direction at the support portion with a simple configuration. Furthermore, the bushing 46a and flange portion 47a, the bushing 46b and flange portion 47b, the bushing 50a and flange portion 51a, and the bushing 50b and flange portion 51b are each integrally configured, which also reduces the number of parts.

[0037] The present invention is not limited to the above-described embodiments. The detailed structure of the suspension device 8 may be changed as appropriate. For example, the bushes 28, 29 and flanges 47a, 47b, 51a, 51b that function as stoppers may be partially provided. Furthermore, configurations other than the vehicle suspension device 8 can also be modified as appropriate.

[0038] The present invention can be widely applied to vehicles equipped with leaf springs as suspension devices. [Explanation of symbols]

[0039] 1 vehicle 5, 6 Side members 11 Leaf spring 12 Shackle (linking member) 23 Connecting shaft 28, 29 Bush (stopper) 36 Connection shaft (first rear connection shaft) 39 Connection shaft (second rear connection shaft) 46a, 46b Bush (1st Bush) 47a, 47b, 51a, 51b Flange part (stopper) 50a, 50b bushings (second bushings)

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 leaf spring extending in the front-rear direction of the vehicle along the pair of side members, with front and rear ends supported by the side members so as to be swingable in the up-down direction, and supporting an axle of a rear wheel of the vehicle; a front connecting shaft that swingably connects the front end of the leaf spring to the side member; A vehicle undercarriage having: The front connecting shaft is disposed inclined toward the front of the vehicle inward in the vehicle width direction. A vehicle undercarriage characterized by:

2. A bushing formed of an elastic member is interposed between the side member and the front end of the leaf spring, and between the side member and the rear end of the leaf spring.

2. The vehicle undercarriage according to claim 1.

3. a stopper for restricting movement of the end of the leaf spring relative to the side member in the vehicle width direction, the stopper being provided at least either between the side member and the front end of the leaf spring or between the side member and the rear end of the leaf spring; 3. The vehicle undercarriage according to claim 2.

4. The stopper is integrally formed with the bush.

4. The vehicle undercarriage according to claim 3.

5. The bushing is formed in a cylindrical shape, and the stopper is a flange-shaped portion that protrudes radially outward from the axial end of the bushing.

5. The vehicle undercarriage according to claim 4.

6. The side member and the rear end of the leaf spring are connected via a link member, a first rear connecting shaft that swingably connects the side member and one end of the link member; a second rear connecting shaft that swingably connects the rear end of the leaf spring and the other end of the link member, The bushing is a cylindrical first bushing disposed around the first rear connecting shaft and interposed between the side member and the first rear connecting shaft; a cylindrical second bushing that is disposed around the second rear connecting shaft and is interposed between the rear end of the leaf spring and the second rear connecting shaft, The stopper is provided on each of the first bush and the second bush.

6. The vehicle undercarriage according to claim 5.

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