Torsion beam suspension structure of a vehicle

Abstract

To provide a torsion beam type suspension structure of a vehicle that is able to improve lateral rigidity by suppressing fluctuation in a vehicle width direction without disturbing vertical movement of a suspension.SOLUTION: A torsion beam type suspension structure 1 includes right and left lateral rods 13 arranged between rear ends 11B of right and left trailing arms 11 and a vehicle body. An arm-side end 13A of each lateral rod 13 is held by an arm-side holding portion 14 provided on a rear-end 11B of each trailing arm 11, and a vehicle-body-side end 13B of each lateral rod 13 is held by a vehicle-body-side holding portion 15 provided at a vehicle-width-direction central portion of the vehicle body. The vehicle-body-side holding portion 15 has left and right slit grooves 15A extending at least in a vehicle vertical direction and formed at an interval in the vehicle width direction and holds the vehicle-body-side ends 13B of the respective lateral rods 13 so as to be movable independently on the left and right sides, along respective longitudinal directions of the slit grooves 15A.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a torsion beam suspension structure for a vehicle. [Background technology]

[0002] Torsion beam suspension structures used in automobiles and other vehicles are fixed to the vehicle body at only two points, the left and right trailing arms, making it difficult to ensure rigidity in the vehicle width direction (lateral rigidity), which is an important function of suspension. Therefore, as one prior art technique for ensuring lateral rigidity in a torsion beam suspension, a suspension structure employing a Watts link mechanism is known (see, for example, Patent Document 1). In a conventional torsion beam suspension structure using a Watts link mechanism, fluctuations in the suspension width direction (left-right difference) are absorbed via left and right lateral rods (tie rods) and Watts links. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-93992 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the torsion beam suspension structure using the conventional Watt link mechanism, the operation of the Watt link mechanism does not fully respond to fluctuations in the suspension, which can result in mechanical obstruction of the suspension's vertical movement. Furthermore, in conventional structures, rubber bushings are sometimes used at the lateral rod connection points, but deterioration of these rubber bushings can reduce the effectiveness of the lateral rods and Watt links in improving lateral rigidity.

[0005] The present invention has been made with the above points in mind, and aims to provide a torsion beam suspension structure for a vehicle that can improve lateral rigidity by suppressing fluctuations in the vehicle width direction without interfering with the vertical movement of the suspension. [Means for solving the problem]

[0006] In order to achieve the above object, one aspect of the present invention provides a torsion beam suspension structure for a vehicle, comprising a pair of left and right trailing arms extending in the fore-and-aft direction of the vehicle, with front ends journaled to the vehicle body and swingable up and down, and a torsion beam suspended between the trailing arms. This torsion beam suspension structure for a vehicle comprises a pair of left and right lateral rods respectively disposed between the rear ends of the trailing arms and the vehicle body, a pair of left and right arm-side holders provided at the rear ends of the trailing arms and holding the arm-side ends of the lateral rods, respectively, and a vehicle-body-side holder provided in the vehicle width center portion of the vehicle body and holding the vehicle-body-side ends of the lateral rods, the vehicle-body-side holders having a pair of left and right slit grooves extending at least in the vehicle up-and-down direction and spaced apart in the vehicle width direction, and configured to hold the vehicle-body-side ends of the lateral rods independently of each other along the longitudinal direction of the slit grooves. [Effects of the Invention]

[0007] According to the torsion beam suspension structure for a vehicle of the present invention, when the left and right trailing arms move in different directions due to the roll of the vehicle body while the vehicle is moving, the vehicle body side ends of the left and right lateral rods are displaced along the longitudinal direction of the slit grooves, thereby suppressing movement in the vehicle width direction without interfering with the vertical movement of the suspension, thereby improving lateral rigidity. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing a torsion beam suspension structure for a vehicle according to an embodiment of the present invention; [Figure 2]FIG. 2 is a bottom view of the rear part of a vehicle to which the torsion beam suspension structure according to the embodiment is applied, viewed from below. [Figure 3] 2 is a side view of the torsion beam suspension structure of FIG. 1 as viewed from the left side of the vehicle. [Figure 4] 2 is an enlarged perspective view showing the periphery of a vehicle body side holding portion in FIG. 1. FIG. [Figure 5] 5 is a front view of the vehicle body-side holding portion of FIG. 4 as viewed from the front side of the vehicle. [Figure 6] FIG. 5 is a cross-sectional view taken along the line AA in FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing a torsion beam suspension structure for a vehicle according to one embodiment of the present invention. FIG. 2 is a bottom view of the rear of a vehicle to which the torsion beam suspension structure according to this embodiment is applied, as viewed from below. FIG. 3 is a side view of the torsion beam suspension structure of FIG. 1, as viewed from the left side of the vehicle. In the drawings described below, the arrow Fr direction indicates the front in the vehicle's longitudinal direction, the arrow O direction indicates the outward direction in the vehicle's width direction, and the arrow U direction indicates the upward direction in the vehicle's vertical direction. In addition, the terms "left and right" in the description of the embodiments correspond to the left and right when looking at the front of the vehicle from inside the vehicle cabin.

[0010] A torsion beam suspension structure 1 according to this embodiment is applied to, for example, a rear suspension structure that supports left and right wheels (rear wheels in this case) 2 of a vehicle such as an automobile. As shown in FIGS. 1 to 3, the torsion beam suspension structure 1 includes a pair of left and right trailing arms 11, a torsion beam 12 installed between each trailing arm 11, a pair of left and right lateral rods 13 respectively disposed between each trailing arm 11 and the vehicle body, a pair of left and right arm-side holders 14 that hold arm-side ends 13A of each lateral rod 13, and a vehicle-body-side holder 15 that holds vehicle-body-side ends 13B of each lateral rod 13. The dashed lines in FIG. 1 indicate the outline of the left and right wheels 2.

[0011] The left and right trailing arms 11 each extend in the longitudinal direction of the vehicle. The front end 11A of each trailing arm 11 is journaled via a rubber bushing or the like to a floor side member 3 (FIG. 2), which constitutes a frame member of the vehicle body. The direction of the support axis A1 of each trailing arm 11 is inclined slightly toward the rear of the vehicle as it extends outward in the vehicle width direction, as viewed from below (FIG. 2). Each trailing arm 11 can swing up and down around the support axis A1. A wheel 2 is rotatably attached to the rear end 11B of each trailing arm 11 via a hub carrier (not shown). The direction of the rotation axis (axle) A2 of the wheel 2 is approximately parallel to the vehicle width direction. A spring mounting portion 11C is provided on the inside rear of each trailing arm 11. The lower end of a coil spring (not shown) is fixed to the spring mounting portion 11C. In addition, the lower end of a shock absorber (not shown) is fixed around the spring mounting portion 11C of each trailing arm 11. The upper ends of the coil springs and shock absorbers are fixed to rear side members 4 (FIG. 2) that form the frame members of the vehicle body.

[0012] The torsion beam 12 extends in the vehicle width direction, and both ends in the vehicle width direction are fixed to the front-rear middle parts of the left and right trailing arms 11, respectively. A torsion bar (not shown) is housed inside the torsion beam 12. The torsion bar acts as a spring by utilizing its restoring force against torsional deformation. By installing the torsion beam 12 between the left and right trailing arms 11, when the left and right wheels 2 try to move up and down in opposite directions, the torsion bar twists, and this restoring force prevents the wheels from moving in the opposite directions. This suppresses excessive roll of the vehicle body.

[0013] The left and right lateral rods 13 are each made of a rod-shaped metal member extending in the vehicle width direction. The left lateral rod 13 is disposed between the rear end 11B of the left trailing arm 11 and the vehicle body fixed part 5 located in the center of the vehicle width direction. The right lateral rod 13 is disposed between the rear end 11B of the right trailing arm 11 and the vehicle body fixed part 5. Connecting means such as ball joints are provided at both longitudinal ends of each lateral rod 13. The arm-side end 13A of each lateral rod 13 is connected to the rear end 11B of the trailing arm 11 via an arm-side holder 14. The vehicle body-side end 13B of each lateral rod 13 is connected to the vehicle body fixed part 5 via a vehicle body-side holder 15.

[0014] The left and right arm-side holders 14 are provided on the rear end portions 11B of the left and right trailing arms 11, respectively. In this embodiment, each arm-side holder 14 is fixed to the underside of the rear end portion 11B of the trailing arm 11 so as to be located below the rotation axis A2 of the wheel 2 (FIG. 3). Each arm-side holder 14 has a rod-shaped connecting member 14A extending from the rear end portion 11B of the trailing arm 11 toward the rear of the vehicle, as viewed from below the vehicle (FIG. 2). In this embodiment, the connecting member 14A extends at a slight angle downward as it approaches the rear of the vehicle, as viewed from the side of the vehicle (FIG. 3). A ball joint or the like provided on the arm-side end portion 13A of the lateral rod 13 is rotatably connected to an intermediate portion of the connecting member 14A in the extending direction. The left and right arm-side holders 14 as described above hold the arm-side end portions 13A of the left and right lateral rods 13 to the rear end portions 11B of the left and right trailing arms 11, respectively.

[0015] The vehicle body-side holding portion 15 is provided in the vehicle widthwise center portion of the vehicle body fixed portion 5, which is installed between the left and right rear side members 4 (FIGS. 1 and 2). In this embodiment, the vehicle body-side holding portion 15 is located below the support axis A1 of the front end portion 11A of each trailing arm 11 in a side view of the vehicle (FIG. 3). The vehicle body-side holding portion 15 has a pair of left and right slit grooves 15A that extend at least in the vehicle up-down direction and are spaced apart in the vehicle width direction (FIG. 1). The vehicle body-side holding portion 15 is configured to hold the vehicle body-side end portions 13B of each lateral rod 13 so that the left and right ends can move independently along the longitudinal direction of each slit groove 15A. Details of the vehicle body-side holding portion 15 will be described later.

[0016] The vehicle body fixing portion 5 has a beam portion 5A and an extension portion 5B. The beam portion 5A extends in the vehicle width direction between the left and right rear side members 4 (Figure 2). The beam portion 5A is bent so that its middle portion in the vehicle width direction is located lower on the vehicle than both side portions. The extension portion 5B extends from the middle portion in the vehicle width direction of the beam portion 5A toward the front of the vehicle. A vehicle body side holding portion 15 is fixed to the front end of the extension portion 5B with bolts or the like. Fixing members 5C for fixing to the left and right rear side members 4 are welded to both end portions in the vehicle width direction of the beam portion 5A, respectively. Each fixing member 5C is fixed to the lower surface of the respective rear side member 4 with bolts or the like.

[0017] Here, the specific configuration of the vehicle body side holding portion 15 will be described in detail. Fig. 4 is an enlarged perspective view of the periphery of the vehicle body side holding portion 15 in Fig. 1. Fig. 5 is a front view of the vehicle body side holding portion 15 in Fig. 4 as seen from the front side of the vehicle. Fig. 6 is a cross-sectional view taken along line AA in Fig. 4.

[0018] 4 to 6, in the vehicle body side holding portion 15 in this embodiment, for example, each of the left and right slit grooves 15A described above is formed by a combination of an inner member 15B and an outer member 15C.

[0019] The inner member 15B has a front surface and a rear surface arranged with a gap in the vehicle front-rear direction, an upper surface connecting the upper end of the front surface to the upper end of the rear surface, a lower surface connecting the lower end of the front surface to the lower end of the rear surface, and side surfaces connecting the inner end of the front surface in the vehicle width direction to the inner end of the rear surface in the vehicle width direction. The inner member 15B opens outward in the vehicle width direction. The front surface and the rear surface of the inner member 15B each have a notch corresponding to the shape of the slit groove 15A, which is formed from the outer side in the vehicle width direction.

[0020] The outer member 15C has a front and rear surface spaced apart in the vehicle longitudinal direction, an upper surface connecting the upper end of the front surface to the upper end of the rear surface, and a lower surface connecting the lower end of the front surface to the lower end of the rear surface. The outer member 15C opens inward and outward in the vehicle width direction. The inner edges of the front and rear surfaces of the outer member 15C in the vehicle width direction are each provided with an inclined portion corresponding to the shape of the slit groove 15A. The outer member 15C is assembled to the inner member 15B so as to surround the outer portion of the inner member 15B in the vehicle width direction. The combination of the inner member 15B and the outer member 15C is fixed to the front end of the extension portion 5B of the vehicle body fixing portion 5 using an upper mounting plate 15D and a lower mounting plate 15E with bolts or the like.

[0021] In this embodiment, the left and right slit grooves 15A of the vehicle body-side holding portion 15 are formed by arranging notches on the front and rear surfaces of the inner member 15B and inclined portions of the vehicle widthwise inner edges of the front and rear surfaces of the outer member 15C facing each other, forming a substantially parallelogram shape with a predetermined width in the vehicle width direction and extending in a slanted outward direction in the vehicle width direction toward the bottom of the vehicle. That is, the notches on the front and rear surfaces of the inner member 15B form the upper and lower edges and the vehicle widthwise inner oblique sides of the slit groove 15A. Furthermore, the inclined portions of the vehicle widthwise inner edges of the front and rear surfaces of the outer member 15C form the vehicle widthwise outer oblique sides of the slit groove 15A. The front and rear ends of a ball joint or the like provided at the vehicle body-side end 13B of the left lateral rod 13 are inserted into the left slit groove 15A. Further, the front and rear ends of a ball joint or the like provided at the vehicle body side end 13B of the right lateral rod 13 are inserted into the right slit groove 15A.

[0022] The left and right slit grooves 15A of the vehicle body-side holding portion 15 are formed in a fan-shaped (figure eight) form with their lower ends positioned more outward in the vehicle width direction than their upper ends in a front view of the vehicle. In other words, the left and right slit grooves 15A are arranged symmetrically in the vehicle width direction with a gap therebetween, and are formed so that the gap widens toward the bottom of the vehicle. Specifically, the left and right slit grooves 15A in this embodiment are formed so that the angle α between their respective longitudinal directions (the direction of the center line L indicated by the dashed dotted line in FIG. 5) and the horizontal direction is within a range of 45° to 75° in a front view of the vehicle.

[0023] Furthermore, the left and right slit grooves 15A of the vehicle body-side holding portion 15 are formed so as to extend at an angle toward the rear of the vehicle as they move upward in a side view of the vehicle (FIG. 6). Specifically, the left and right slit grooves 15A in this embodiment are formed so that the angle formed between the longitudinal direction (the direction of the center line L indicated by the dashed dotted line in FIG. 6) and the horizontal direction is within a range of 75° to 90° in a side view of the vehicle.

[0024] The total longitudinal length and inclination angles α and β of the left and right slit grooves 15A of the vehicle body-side holder 15 as described above can be designed according to a slide curve that represents how the vehicle body-side ends 13B of the lateral rod 13 are displaced in response to movement of the left and right trailing arms 11 on which the torsion beam 12 is installed. The slide curve can be obtained, for example, by calculating the trajectories of the vehicle body-side ends 13B of the left and right lateral rods 13 based on the trajectories of the left and right arm-side holders 14 when the left and right trailing arms 11 are moved in opposite directions between the full bump position and full rebound position of the suspension stroke.

[0025] Next, the operation of the torsion beam suspension structure 1 according to this embodiment will be described. In the torsion beam suspension structure 1 described above, the vehicle body side ends 13B of the pair of left and right lateral rods 13 are held by a vehicle body side holder 15 provided in the center of the vehicle width direction, and the vehicle body side holder 15 has a pair of left and right slit grooves 15A extending at least in the vehicle up-down direction and spaced apart in the vehicle width direction, and is configured to hold the vehicle body side ends 13B of each lateral rod 13 so that they can move independently along the longitudinal direction of each slit groove 15A. With this structure, when the rear ends 11B of the left and right trailing arms 11 move in different directions due to roll of the vehicle body while the vehicle is traveling, the vehicle body side ends 13B of the left and right lateral rods 13 are displaced along the longitudinal direction of the slit grooves 15A, respectively. Therefore, movement of the suspension in the vehicle width direction can be suppressed without interfering with movement of the suspension in the up-down direction, and lateral rigidity can be improved.

[0026] In addition, because the left and right lateral rods 13 are connected to the arm-side holders 14 and vehicle-body-side holders 15 by ball joints or the like, it is possible to avoid a reduction in the effect of improving lateral rigidity due to deterioration of the rubber bushings used at the lateral rod connection points, etc., as in the conventional structure described above. Furthermore, because the left and right lateral rods 13 suppress fluctuations in the suspension in the vehicle width direction, it is possible to reduce the hardness of the rubber bushings used to pivotally support the front ends 11A of the left and right trailing arms 11 to the vehicle body (floor side members 3), thereby achieving a comfortable ride.

[0027] In the torsion beam suspension structure 1 according to this embodiment, each arm-side retaining portion 14 is located below the rotation axis A2 of the wheel 2, the vehicle body-side retaining portion 15 is located below the support axis A1 of the front end 11A of each trailing arm 11, and each slit groove 15A is formed in a fan-shaped configuration such that its lower end is positioned outward in the vehicle width direction relative to its upper end when viewed from the front of the vehicle. This configuration effectively reduces the vehicle width displacement of each trailing arm 11 without interfering with the up-and-down movement of the suspension due to the movement of the left and right lateral rods 13 when the left and right trailing arms 11 move in different directions, such as during vehicle roll, thereby effectively improving lateral rigidity. In particular, by setting the angle between the longitudinal direction of each slit groove 15A and the horizontal direction to be between 45° and 75° when viewed from the front of the vehicle, it is possible to accurately reduce the vehicle width displacement of each trailing arm 11.

[0028] Furthermore, in the torsion beam suspension structure 1 according to this embodiment, each slit groove 15A extends at an angle rearward as it extends upward in a side view of the vehicle, thereby precisely suppressing only the displacement of each trailing arm 11 in the vehicle width direction, thereby more effectively improving lateral rigidity. In particular, by setting the angle between the longitudinal direction of each slit groove 15A and the horizontal direction to be within the range of 75° to 90° in a side view of the vehicle, only the displacement of each trailing arm 11 in the vehicle width direction can be suppressed with even greater precision.

[0029] Although the present invention has been described above with reference to an embodiment, it is not limited to the above embodiment, and various modifications and variations are possible based on the technical concept of the present invention. For example, in the above embodiment, an example was described in which the left and right slit grooves 15A of the vehicle body side holding portion 15 are each formed by a combination of an inner member 15B and an outer member 15C, but the left and right slit grooves may each be formed by a single member or a combination of three or more members. It is also possible to form the left and right slit grooves using a common member.

[0030] Furthermore, in the above-described embodiment, an example has been shown in which the left and right arm-side holders 14 are located below the rotation axis A2 of the wheel 2, but each arm-side holder 14 may be located above the rotation axis A2. Similarly, an example has been shown in which the vehicle body-side holder 15 is located below the support axis A1 of the front end 11A of each trailing arm 11, but the vehicle body-side holder 15 may be located above the support axis A1. In this case, it is only necessary to calculate a slide curve for the vehicle body-side end portions 13B of the left and right lateral rods 13 according to the respective positions of the left and right arm-side holders 14 and the vehicle body-side holder 15, and then optimize the overall longitudinal lengths and inclination angles α and β of the left and right slit grooves of the vehicle body-side holder 15 according to the slide curve. [Explanation of symbols]

[0031] 1...Torsion beam suspension structure 2...wheels 3...Floor side member 4...Rear side member 5...Vehicle body fixing part 5A…beam part 5B...Extension part 5C...Fixing member 11...trailing arm 11A...front end 11B…Rear end 11C...Spring installation section 12...Torsion beam 13...Lateral rod 13A...Arm side end 13B...Car body side end 14...Arm side holding part 14A...Connecting member 15...Vehicle body side holding part 15A...Slit groove 15B...Inner member 15C...Outer member 15D...Upper mounting plate 15E...Lower mounting plate A1...Trailing arm support shaft A2...Wheel rotation axis L: Center line of the slit groove in the longitudinal direction α: Angle between the longitudinal direction of the slit groove and the horizontal direction (viewed from the front of the vehicle) β: Angle between the longitudinal direction of the slit groove and the horizontal direction (viewed from the side of the vehicle)

Claims

1. A torsion beam suspension structure for a vehicle, comprising a pair of left and right trailing arms extending in the longitudinal direction of the vehicle, with their front ends journalled to the vehicle body and swingable up and down, and a torsion beam installed between the trailing arms, a pair of left and right lateral rods respectively disposed between the rear end of each trailing arm and the vehicle body; a pair of left and right arm-side holding portions provided at the rear end of each trailing arm and holding arm-side ends of each lateral rod; a vehicle body side holding portion provided in a vehicle width direction central portion of the vehicle body and holding a vehicle body side end portion of each of the lateral rods, A torsion beam suspension structure for a vehicle, characterized in that the vehicle body side holding portion has a pair of left and right slit grooves extending at least in the vertical direction of the vehicle and spaced apart in the vehicle width direction, and is configured to hold the vehicle body side ends of each lateral rod so that they can move independently on the left and right along the longitudinal direction of each slit groove.

2. each arm-side holding portion is located below the vehicle with respect to a rotation axis of a wheel rotatably supported via a hub carrier at the rear end of each trailing arm; the vehicle body side holding portion is located below the vehicle with respect to the support shaft of the front end portion of each trailing arm, 2. The torsion beam suspension structure for a vehicle according to claim 1, characterized in that each of the slit grooves is formed in a flared shape such that, when viewed from the front of the vehicle, the lower end of each groove is positioned more outward in the vehicle width direction than the upper end.

3. 3. The torsion beam suspension structure for a vehicle as described in claim 2, characterized in that the angle formed by each of the slit grooves between the longitudinal direction and the horizontal direction when viewed from the front of the vehicle is within the range of 45° or more and 75° or less.

4. 4. The torsion beam suspension structure for a vehicle according to claim 2, wherein each of the slit grooves extends obliquely rearward of the vehicle as it extends upward in a side view of the vehicle.

5. 5. The torsion beam suspension structure for a vehicle according to claim 4, wherein the angle formed by each of the slit grooves between the longitudinal direction and the horizontal direction in a side view of the vehicle is within a range of 75° or more and 90° or less.

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