Torsion beam-type suspension

Abstract

This torsion beam-type suspension is formed with a weld bead for welding a beam part and a torsion beam along the outer edges of a pair of branch parts. The pair of branch parts has tip parts that gradually narrow in the vehicle front-rear direction toward the inner side in the vehicle width direction. The weld bead extends at least along the tip parts and extends to positions different from the tip ends of the tip parts.

Description

Torsion beam suspension

[0001] The present disclosure relates to torsion beam suspensions.

[0002] Patent Document 1 discloses a torsion beam suspension. This torsion beam suspension includes a torsion beam extending in the vehicle width direction, a pair of trailing arms fixed to one end and the other end of the torsion beam, and a pair of reinforcement members extending from each of the pair of trailing arms to the torsion beam. Each of the pair of reinforcement members is welded to the torsion beam, and weld beads are formed along the outer edges of each of the pair of reinforcement members.

[0003] International Publication No. 2016 / 143625

[0004] In the torsion beam suspension disclosed in Patent Document 1, stress is concentrated in the torsion beam at the tip of the reinforcement member on the inside of the vehicle width direction, so repeated loads over a long period of time can cause cracks to form in the torsion beam at the tip of the reinforcement member on the inside of the vehicle width direction.

[0005] In view of the above circumstances, at least one embodiment of the present invention aims to provide a torsion beam suspension that can alleviate the concentration of stress that occurs in the torsion beam at the tip of the reinforcement member that is on the inner side in the vehicle width direction.

[0006] (1) A torsion beam suspension according to at least one embodiment of the present invention comprises a torsion beam extending along the vehicle width direction, a pair of trailing arms fixed to one end and the other end of the torsion beam, respectively, and a pair of reinforcement members extending from each of the pair of trailing arms to the torsion beam, wherein each of the pair of reinforcement members includes an arm portion fixed to the trailing arm and a beam portion fixed to the torsion beam, wherein the beam portion has a pair of branch portions that branch into two in the fore-and-aft direction of the vehicle from a midpoint in the vehicle width direction toward the inside of the vehicle width direction, and a first weld bead is formed along the outer edges of the pair of branches to weld the beam portion and the torsion beam, and each of the pair of branch portions has a tip portion that gradually narrows in the fore-and-aft direction of the vehicle toward the inside of the vehicle width direction, and the first weld bead extends at least along the tip portion to a position different from the tip of the tip portion.

[0007] According to the configuration (1) described above, the width of the tip portion gradually narrows in the vehicle longitudinal direction toward the vehicle width inward, so that the rigidity of the tip portion gradually decreases toward the vehicle width inward. Furthermore, the first weld bead extends at least along the tip portion and extends to a position different from the tips of the tip portions (pair of branch portions), so that a sudden change in rigidity at the tips of the pair of branch portions can be alleviated. This can alleviate stress concentration in the torsion beam at the tips (tips on the vehicle width inward) of the pair of branch portions (reinforcement members).

[0008] (2) In some embodiments, in the configuration of (1) above, the inner edge of the branch portion from which the pair of branches branch is welded to the torsion beam, and a second weld bead is formed along the inner edge of the branch portion.

[0009] According to the above configuration (2), deformation of the torsion beam is suppressed at the branch portion, so that stress generated in the weld beads formed along the outer edges of the pair of branch portions can be reduced.

[0010] (3) In some embodiments, in the configuration of (1) or (2) above, the tip portion has an outer inclined portion on the outer side of the tip portion that faces inward with respect to the extension direction of the tip portion.

[0011] According to the above configuration (3), it is possible to suppress a delay in heat propagation when arc welding the outside of the tip portion, thereby suppressing the occurrence of an unmelted portion at the tip portion.

[0012] (4) In some embodiments, in the configuration of (1) or (2) above, the tip portion has an inner inclined portion on the inside of the tip portion that faces outward with respect to the extension direction of the tip portion.

[0013] According to the configuration (4) above, by providing an inner inclined portion on the inside of the tip portion that faces inward relative to the extension direction of the tip portion, the tip portion can be gradually narrowed in the fore-and-aft direction of the vehicle toward the inside in the vehicle width direction.

[0014] (5) In some embodiments, in the configuration of (1) or (2) above, the pair of branch portions have an extension portion that is an inner portion of the pair of branch portions in the vehicle width direction and extends in the vehicle width direction, and an expansion portion that is an outer portion of the pair of branch portions in the vehicle width direction and is inclined with respect to the extension direction of the extension portion, so that the spacing between the pair of branch portions gradually becomes wider toward the outer side in the vehicle width direction.

[0015] According to the above configuration (5), the branch portion where the pair of branches are branched is large, and it is possible to easily weld the branch portion to the torsion beam.

[0016] (6) In some embodiments, in the configuration of (1) or (2) above, the torsion beam has a hole extending along the vehicle width direction between the pair of reinforcement members.

[0017] According to the above configuration (6), the torsion beam becomes more easily deformed, and the load acting on the tip (the tip on the inner side in the vehicle width direction) of the tip portion (reinforcement member) can be reduced, thereby reducing the stress acting on the torsion beam at the tip on the inner side in the vehicle width direction of the reinforcement member.

[0018] According to at least one embodiment of the present invention, it is possible to reduce the concentration of stress that occurs in the torsion beam at the tip of the reinforcement member that is located on the inner side in the vehicle width direction.

[0019] Fig. 1 is a perspective view of a torsion beam suspension according to an embodiment, as viewed from below and in front of a vehicle. Fig. 2 is a diagram schematically showing a reinforcement member welded to a torsion beam of a torsion beam suspension according to an embodiment. Fig. 3 is a diagram schematically showing a reinforcement member welded to a torsion beam of a torsion beam suspension according to an embodiment. Fig. 4 is a diagram schematically showing a reinforcement member welded to a torsion beam of a torsion beam suspension according to an embodiment. Fig. 5 is a diagram of a torsion beam suspension according to an embodiment, as viewed from below a vehicle.

[0020] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0021] [Torsion beam suspension] The torsion beam suspension 1 is a suspension used for the rear wheels of a front-wheel drive vehicle, and as shown in Figure 1, comprises a torsion beam 11 extending along the vehicle width direction, a pair of trailing arms 13, 15 fixed to one end and the other end of the torsion beam 11, and a pair of reinforcement members 17, 19 extending from each of the pair of trailing arms 13, 15 to the torsion beam 11.

[0022] [Torsion Beam] The torsion beam 11 is a cross beam that allows torsion. The torsion beam 11 according to the embodiment is a beam (U-beam) with a U-shaped cross section that opens downward in the vehicle height direction, but is not limited to this. The torsion beam 11 according to the embodiment is formed by bending a steel plate having a uniform thickness, but is not limited to this.

[0023] [Pair of Trailing Arms] The pair of trailing arms 13, 15 are bilaterally symmetrical, with a swing axis (pivot) PV located forward in the vehicle longitudinal direction and an axle AX located rearward. In the pair of trailing arms 13, 15 according to the embodiment, bearings 21, 23 supported by the swing axis PV are provided forward in the vehicle longitudinal direction, and wheel support portions 25, 27 are provided rearward. In the pair of trailing arms 13 (15) according to the embodiment, the torsion beam 11 is fixed between the bearings 21 (23) and the wheel support portions 25 (27) (coupled axle type). In the pair of trailing arms 13, 15 according to the embodiment, the bearings 21 (23) are located inward in the vehicle width direction relative to the wheel support portions 25 (27) and are formed to protrude outward in the vehicle width direction from the bearings 21 (23) toward the wheel support portions 25 (27).

[0024] Each of the pair of trailing arms 13, 15 according to the embodiment has a hollow structure formed by welding two members formed by bending steel plates of uniform thickness together, but is not limited to this. Each of the pair of trailing arms 13, 15 according to the embodiment is provided with brackets 29, 31 that support the lower ends of suspension coils (not shown) and brackets 33, 35 to which other components (not shown) are attached, but the brackets 33, 35 to which other components are attached are not essential.

[0025] [Pair of Reinforcement Members] The pair of reinforcement members 17, 19 are bilaterally symmetrical. The pair of reinforcement members 17, 19 according to the embodiment extend from each of the pair of trailing arms 13, 15 to the torsion beam 11 on the lower surface of each of the pair of trailing arms 13, 15 in the vehicle height direction, but this is not limited thereto, and the pair of reinforcement members 17, 19 may extend from each of the pair of trailing arms 13, 15 to the torsion beam 11 on the upper surface of each of the pair of trailing arms 13, 15 in the vehicle height direction. The pair of reinforcement members 17, 19 according to the embodiment are formed by bending steel plates having a uniform thickness, but this is not limited thereto.

[0026] Each of the pair of reinforcement members 17, 19 includes an arm portion 37, 39 fixed to the trailing arm 13, 15, and a beam portion 41, 43 fixed to the torsion beam 11. The arm portion 37 (39) according to the embodiment has a flat portion provided along the underside of the trailing arm 13 (15) and an inclined surface portion provided along the inner surface of the trailing arm 13 (15) in the vehicle width direction, and these portions are fixed to the trailing arm 13 (15). In the arm portion 37 (39) according to the embodiment, the outer edges of the flat portion and the inclined surface portion are welded to the trailing arm 13 (15) by arc welding, and weld beads (not shown) are formed along the outer edges of the flat portion and the inclined surface portion.

[0027] As shown in Figures 2 to 4, the beam portion 41 has a trunk portion 45, a tapered portion (a transversely intermediate portion) 47 that gradually narrows in the vehicle longitudinal direction from the trunk portion 45 toward the vehicle transversely inward, and a pair of branch portions 49, 51 that branch into two in the vehicle longitudinal direction from the tapered portion 47 toward the vehicle transversely inward. The trunk portion 45 has a constant width in the vehicle longitudinal direction, and the tapered portion 47 narrows in width from the trunk portion 45 toward the vehicle transversely inward at a predetermined ratio in the vehicle longitudinal direction. The predetermined ratio may be constant or may vary. The pair of branch portions 49, 51 have a constant width in a direction perpendicular to the extension direction, but this is not limited thereto and may gradually narrow.

[0028] At least the outer edge of the tapered portion 47 and the outer edges of the pair of branch portions 49, 51 are welded to the torsion beam 11 by arc welding, and weld beads (first weld beads) 53 are formed along the outer edge of the tapered portion 47 and the outer edges of the pair of branch portions 49, 51. In the beam portion 41 according to the embodiment, the outer edge of the trunk portion 45, the outer edge of the tapered portion 47, and the outer edges of the pair of branch portions 49, 51 are welded to the torsion beam 11 by arc welding, and weld beads 53 are formed along the outer edge of the trunk portion 45, the outer edge of the tapered portion 47, and the outer edges of the pair of branch portions 49, 51.

[0029] Each of the pair of branch portions 49, 51 has a tip portion 55 that gradually narrows in the vehicle fore-and-aft direction toward the inner side in the vehicle width direction, and the weld bead 53 extends at least to the tip portion 55 and extends to a position different from the tip of the tip portion 55.

[0030] As long as the tip portion 55 gradually narrows in the vehicle longitudinal direction toward the inside in the vehicle width direction, it may have an outer inclined portion 57 on the outside of the tip portion 55 that faces inward with respect to the extending direction of the tip portion 55, as shown in Figures 2 and 3, or it may have an inner inclined portion 59 on the inside of the tip portion 55 that faces outward with respect to the extending direction of the tip portion 55, as shown in Figure 4. Furthermore, although not shown, it may have an outer inclined portion on the outside of the tip portion 55 that faces inward with respect to the extending direction of the tip portion 55, and an inner extending portion on the inside of the tip portion that faces outward with respect to the extending direction of the tip portion.

[0031] The outer inclined portion 57 and the inner inclined portion 59 each narrow linearly at a constant ratio in the extension direction, but may also each narrow arcuately at a predetermined ratio in the extension direction.

[0032] As shown in FIG. 2 , the weld bead 53 extends along the tip portion 55 and extends beyond the tip of the tip portion 55 inward in the vehicle width direction, but as shown in FIGS. 3 and 4 , the weld bead 53 may be positioned more inward in the vehicle width direction than the tip of the tip portion 55.

[0033] 2 to 4 , the inner edge of branch portion 61, from which pair of branch portions 49, 51 branch off, is welded to torsion beam 11, and a weld bead (second weld bead) 63 is formed along the inner edge of branch portion 61. The inner edge of branch portion 61 is arc-shaped, and weld bead 63 formed along the inner edge of branch portion 61 is also arc-shaped, but is not limited to this.

[0034] The pair of branches 49, 51 may have an extending portion 65 that is an inner portion of the pair of branches 49, 51 in the vehicle width direction and extends in the vehicle width direction, and an enlarged portion 67 that is an outer portion of the pair of branches 49, 51 in the vehicle width direction and is inclined with respect to the extending direction of the extending portion 65, so that the distance D between the pair of branches 49, 51 gradually increases outward in the vehicle width direction. For example, the extending portion 65 is such that the distance D between the pair of branches 49, 51 is constant (parallel), but is not limited to this.

[0035] 5, the torsion beam 11 has holes 69 and 71 extending along the vehicle width direction between the pair of reinforcement members 17 and 19. The holes 69 and 71 are a pair, but are not limited to this.

[0036] [Effects of the Torsion Beam Suspension] According to the torsion beam suspension 1 according to the embodiment, the tip 55 of each of the pair of branch portions 49, 51 of the reinforcement members 17, 19 gradually narrows in the vehicle longitudinal direction toward the vehicle widthwise inner side, so that the rigidity of the tip 55 gradually decreases toward the vehicle widthwise inner side. Furthermore, the weld bead 53 extends at least along the tip 55 to a position different from the tip of the tip 55 (the pair of branch portions 49, 51), thereby mitigating a sudden change in rigidity at the tip of the pair of branch portions 49, 51. This makes it possible to mitigate the concentration of stress occurring in the torsion beam 11 at the tip (the tip on the vehicle widthwise inner side) of the pair of branch portions 49, 51 (the reinforcement members 17, 19).

[0037] In addition, the inner edge of the branch portion 61 where the pair of branch portions 49, 51 branch off is welded to the torsion beam 11, and a weld bead 63 is formed along the inner edge of the branch portion 61, thereby suppressing deformation of the torsion beam 11 at the branch portion 61, and thereby reducing the stress generated in the weld bead 53 formed along the outer edge of the pair of branch portions 49, 51.

[0038] Furthermore, tip portion 55 has outer inclined portion 57 on the outside of tip portion 55 that faces inward with respect to the extending direction of tip portion 55, thereby making it possible to suppress delay in heat propagation when arc welding the outside of tip portion 55. This makes it possible to suppress the occurrence of an unmelted portion at the tip of tip portion 55.

[0039] Furthermore, since the tip portion 55 has an inner inclined portion 59 on the inside of the tip portion 55 that faces outward relative to the extension direction of the tip portion 55, the tip portion 55 can be gradually narrowed in the fore-and-aft direction of the vehicle toward the inside in the vehicle width direction.

[0040] The pair of branches 49, 51 have an extension portion 65 which is the inner portion of the pair of branches 49, 51 in the vehicle width direction and extends in the vehicle width direction, and an expansion portion 67 which is the outer portion of the pair of branches 49, 51 in the vehicle width direction and is inclined with respect to the extension direction of the extension portion 65 so that the spacing between the pair of branches 49, 51 gradually widens toward the outer side in the vehicle width direction.This makes the branch portion 61 where the pair of branches 49, 51 branch off larger, making it easier to weld the branch portion 61 to the torsion beam 11.

[0041] The torsion beam 11 has holes 69, 71 extending in the vehicle width direction between the pair of reinforcement members 17, 19, which makes it easier for the torsion beam 11 to deform and reduces the load acting on the tips (the tips on the inner side in the vehicle width direction) of the tip portions 55 (reinforcement members 17, 19). This also reduces the stress acting on the torsion beam 11 at the tips on the inner side in the vehicle width direction of the reinforcement members 17, 19.

[0042] The present invention is not limited to the above-described embodiments, and includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0043] REFERENCE SIGNS LIST 1 Torsion beam suspension 11 Torsion beam 13, 15 Trailing arm 17, 19 Reinforcement member 21, 23 Bearing portion 25, 27 Wheel support portion 29, 31 Bracket 33, 35 Bracket 37, 39 Arm portion 41, 43 Beam portion 45 Trunk portion 47 Tapered portion (middle portion in vehicle width direction) 49, 51 Branch portion 53 Weld bead (first weld bead) 55 Tip portion 57 Outer inclined portion 59 Inner inclined portion 61 Branch portion 63 Weld bead (second weld bead) 65 Extension portion 67 Enlarged portion 69, 71 Hole PV Swing axis (pivot) AX Axle D Spacing

Claims

1. A torsion beam suspension comprising: a torsion beam extending in a vehicle width direction; a pair of trailing arms fixed to one end and the other end of the torsion beam, respectively; and a pair of reinforcement members extending from each of the pair of trailing arms to the torsion beam, wherein each of the pair of reinforcement members includes an arm portion fixed to the trailing arm and a beam portion fixed to the torsion beam, wherein the beam portion has a pair of branch portions that branch into two in the fore-and-aft direction of the vehicle from a midpoint in the vehicle width direction toward the inside of the vehicle width direction, and a first weld bead is formed along outer edges of the pair of branches to weld the beam portion and the torsion beam, wherein each of the pair of branch portions has a tip portion that gradually becomes narrower in the fore-and-aft direction of the vehicle toward the inside of the vehicle width direction, and the first weld bead extends at least along the tip portion to a position different from the tip of the tip portion.

2. A torsion beam suspension as set forth in claim 1, wherein an inner edge of the branch portion where the pair of branches branch off is welded to the torsion beam, and a second weld bead is formed along the inner edge of the branch portion.

3. A torsion beam suspension as set forth in claim 1 or 2, wherein the tip portion has an outer inclined portion on the outside of the tip portion that faces inward relative to the extension direction of the tip portion.

4. A torsion beam suspension as set forth in claim 1 or 2, wherein the tip portion has an inner inclined portion on the inside of the tip portion that faces outward relative to the extension direction of the tip portion.

5. A torsion beam suspension as claimed in claim 1 or 2, wherein the pair of branches have: an extending portion which is an inner portion of the pair of branches in the vehicle width direction and extends in the vehicle width direction; and an enlarged portion which is an outer portion of the pair of branches in the vehicle width direction and is inclined with respect to the extending direction of the extending portion so that the distance between the pair of branches gradually becomes wider towards the outside in the vehicle width direction.

6. The torsion beam suspension according to claim 1 or 2, wherein the torsion beam has a hole extending in the vehicle width direction between the pair of reinforcement members.

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