Torsion beam type suspension

Abstract

To provide a torsion beam type suspension which can ease concentration of stress occurring in a tip located at the inner side in a vehicle width direction of a reinforcement member.SOLUTION: In a torsion beam type suspension, at least an outer edge of a taper part and outer edges of a pair of branch parts are welded to a torsion beam and first welding beads are formed along the outer edge of the taper part and the outer edges of the pair of branch parts. The pair of branch parts has first enlarged parts in which a space between the pair of branch parts gradually increases toward the inner side in a vehicle width direction. Each first welding bead extends to at least the first enlarged part and extends to a position different from a tip of the first enlarged part.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[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. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-65543 Summary of the Invention [Problem to be solved by the invention]

[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. [Means for solving the problem]

[0006] (1) A torsion beam suspension according to at least one embodiment of the present invention comprises a torsion beam extending along 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, and the beam portion gradually narrows in the vehicle longitudinal direction toward the inside of the vehicle width direction. and a pair of branch portions branching into two in the vehicle longitudinal direction from the tapered portion toward the inside in the vehicle width direction, at least an outer edge of the tapered portion and an outer edge of the pair of branches are welded to the torsion beam, and a first weld bead is formed along the outer edge of the tapered portion and the outer edges of the pair of branches, the pair of branch portions have an expanding portion where the spacing between the pair of branch portions gradually expands toward the inside in the vehicle width direction, and the first weld bead extends at least into the expanding portion, and to a position different from the tip of the expanding portion. a torsion beam suspension having a tapered portion that gradually narrows in the vehicle fore-and-aft direction from the trunk toward the inside of the vehicle width direction, and a pair of branch portions that branch into two in the vehicle fore-and-aft direction from the tapered portion toward the inside of the vehicle width direction, at least the outer edges of the tapered portion and the outer edges of the pair of branches are welded to the torsion beam, and a first weld bead is formed along the outside of the tapered portion and the outside of the pair of branches, and the pair of branches have a first expansion portion where the spacing between the pair of branches gradually increases toward the inside of the vehicle width direction, and the first weld bead extends to at least the first expansion portion, and to a position different from the tip of the first expansion portion.

[0007] According to the above-described configuration (1), the distance (the distance between the fulcrums) between the pair of branches in the first enlarged portion gradually increases toward the inside in the vehicle width direction. This allows the torsion beam to more easily deform between the pair of branches in the first enlarged portion, making it easier for the torsion beam to follow the displacement of the trailing arm. This reduces the load acting on the pair of branches in the first enlarged portion, and also reduces the stress generated in the pair of branches. As a result, the concentration of stress generated in the torsion beam at the tips (the tips on the inside in the vehicle width direction) of the pair of branches (reinforcement members) can be alleviated. Furthermore, the first weld bead extends at least to the first enlarged portion, extending to a position different from the tips of the first enlarged portion (the pair of branches), thereby alleviating a sudden change in rigidity at the tips of the pair of branches. This allows the concentration of stress generated in the torsion beam at the tips (the tips on the inside in the vehicle width direction) of the pair of branches (reinforcement members) to be alleviated.

[0008] (2) In some embodiments, in the configuration of (1) above, the starting point of the first expanded portion is provided at the center of the pair of branch portions in the vehicle width direction.

[0009] According to the above configuration (2), the rigidity of the torsion beam can be ensured on the outer side in the vehicle width direction of the center of the pair of branch portions in the vehicle width direction, while the torsion beam can be easily deformed on the inner side in the vehicle width direction.

[0010] (3) In some embodiments, in the configuration of (1) or (2) above, the 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.

[0011] According to the above configuration (3), deformation of the torsion beam is suppressed at the branch portion, so that stress generated in the weld beads formed on the outer edges of the pair of branch portions can be reduced.

[0012] (4) In some embodiments, in the configuration of (1) or (2) above, the first expansion portion has an inclined portion on the outer side of the tip of the first expansion portion that faces inward relative to the extension direction of the first expansion portion, and the first weld bead is formed beyond the inclined portion and toward the inside in the vehicle width direction.

[0013] According to the above configuration (4), delay in heat propagation can be suppressed when arc welding the outer tip of the first expanded portion. This can prevent an unmelted portion from occurring at the tip of the first expanded portion. Furthermore, by providing an inclined portion at the outer tip of the first expanded portion, the tip of the first expanded portion is tapered, which reduces the rigidity of the tip of the first expanded portion and reduces the difference in rigidity with the torsion beam, thereby suppressing stress concentration in the first weld bead.

[0014] (5) In some embodiments, in the configuration of (1) or (2) above, the pair of branch portions have a second expansion portion in which the spacing between the pair of branch portions gradually increases from the starting point of the first expansion portion toward the outside 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 described in (1) or (2) above, the torsion beam has a hole extending along the vehicle width direction on the inner side of the pair of reinforcement members in the vehicle width direction.

[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 first enlarged portion (reinforcement member) can be reduced, thereby reducing the stress acting on the torsion beam at the tip (torsion beam) on the inner side in the vehicle width direction of the reinforcement member. [Effects of the Invention]

[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. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view of a torsion beam suspension according to an embodiment of the present invention, viewed from below and in front of a vehicle. [Figure 2] FIG. 2 is a diagram illustrating a reinforcement member welded to a torsion beam of a torsion beam suspension according to an embodiment of the present invention. [Figure 3] FIG. 2 is a diagram illustrating a reinforcement member welded to a torsion beam of a torsion beam suspension according to an embodiment of the present invention. [Figure 4] FIG. 2 is a diagram illustrating a reinforcement member welded to a torsion beam of a torsion beam suspension according to an embodiment of the present invention. [Figure 5] 1 is a view of a torsion beam suspension according to an embodiment as viewed from below a vehicle. DETAILED DESCRIPTION OF THE INVENTION

[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, it comprises a torsion beam 11 extending along the vehicle width direction, a pair of trailing arms 13 and 15 fixed to one end and the other end of the torsion beam 11, and a pair of reinforcement members 17 and 19 extending from each of the pair of trailing arms 13 and 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 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 bearing portion 21 (23) and the wheel support portion 25 (27) (coupled axle type). In the pair of trailing arms 13, 15 according to the embodiment, the bearing portion 21 (23) is located more inward in the vehicle width direction than the wheel support portion 25 (27) and is formed to protrude outward in the vehicle width direction from the bearing portion 21 (23) toward the wheel support portion 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 the 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 FIGS. 2 to 4, the beam portion 41 includes a trunk portion 45, a tapered portion 47 that gradually narrows in the vehicle longitudinal direction toward the inner side in the vehicle width direction from the trunk portion 45, and a pair of branch portions 49 and 51 that branch into two in the vehicle longitudinal direction toward the inner side in the vehicle width direction from the tapered portion 47. The trunk portion 45 is a portion having a constant width in the vehicle longitudinal direction, and the tapered portion 47 is a portion that narrows in width at a predetermined ratio in the vehicle longitudinal direction toward the inner side in the vehicle width direction from the trunk portion 45. The predetermined ratio may be constant or may vary. The pair of branch portions 49 and 51 have a constant width in a direction orthogonal to the extending direction, but are not limited thereto and may gradually narrow.

[0028] At least the outer edges of the tapered portion 47 and the pair of branch portions 49 and 51 are welded to the torsion beam 11 by arc welding, and a weld bead (first weld bead) 53 is formed along the outer edges of the tapered portion 47 and the pair of branch portions 49 and 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 and 51 are welded to the torsion beam 11 by arc welding, and a weld bead 53 is 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 and 51.

[0029] The pair of branch portions 49 and 51 have a widened portion (first widened portion) 55 in which the interval D between the pair of branch portions 49 and 51 gradually widens (D1 < D2) toward the inner side in the vehicle width direction, and the weld bead 53 extends at least to the widened portion 55 and extends to a position different from the tip of the widened portion 55.

[0030] As long as the spacing D between the pair of branch portions 49, 51 in the expanded portion 55 gradually increases toward the inside in the vehicle width direction, the expansion rate of the spacing D may be small as shown in Fig. 2, or may be large as shown in Figs. 3 and 4. Furthermore, the expanded portion 55 may be such that the spacing D between the pair of branch portions 49, 51 increases toward the vehicle width direction at a predetermined rate and the inner edge is formed in an arc shape as shown in Figs. 2 and 3, or such that the spacing D between the pair of branch portions 49, 51 increases toward the vehicle width direction at a constant rate and the inner edge is formed in a straight line as shown in Fig. 4.

[0031] As shown in FIGS. 2 and 3, the starting point of the expanded portion 55 is provided at the center of the pair of branch portions 49, 51 in the vehicle width direction, but as shown in FIG. 4, it is not limited to this.

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

[0033] 2 to 4, the inner edge of branch portion 61, where 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] As shown in FIG. 2, the expanded portion 55 has an inclined portion 57 on the outer side of the tip of the expanded portion 55 that faces inward relative to the extension direction of the expanded portion 55, and the weld bead 53 is formed beyond the inclined portion 57 and on the inner side in the vehicle width direction.

[0035] As shown in FIGS. 2 and 3, the pair of branch portions 49, 51 have an enlarged portion (second enlarged portion) 67 in which the distance between the pair of branch portions 49, 51 gradually increases from the starting point of the enlarged portion 55 toward the outside in the vehicle width direction.

[0036] As shown in FIG. 4, the pair of branch portions 49, 51 may have a parallel portion 65 at which the distance D (D1) between the pair of branch portions 49, 51 is constant, but the parallel portion 65 is not essential.

[0037] 5, the torsion beam 11 has holes 69 and 71 extending along the vehicle width direction on the vehicle width direction inner sides of the pair of reinforcement members 17 and 19. The holes 69 and 71 are a pair, but are not limited to this.

[0038] [Effect of torsion beam suspension] According to the torsion beam suspension 1 of this embodiment, the distance D (the distance between the fulcrums) between the pair of branches 49, 51 gradually increases toward the inside in the vehicle width direction at the expanded portion 55, which makes it easier for the torsion beam 11 to deform between the pair of branches 49, 51 at the expanded portion 55 and makes it easier for the torsion beam 11 to follow the displacement of the trailing arms 13, 15. This reduces the load acting on the pair of branches 49, 51 at the expanded portion 55, and also reduces the stress generated in the pair of branches 49, 51. As a result, it is possible to alleviate the concentration of stress generated in the torsion beam 11 at the tips (the tips on the inside in the vehicle width direction) of the pair of branches 49, 51 (reinforcement members 17, 19). Furthermore, weld bead 53 extends to at least expanded portion 55 and to a position different from the tips of expanded portion 55 (the pair of branch portions 49, 51), thereby mitigating a sudden change in rigidity at the tips of the pair of branch portions 49, 51. This makes it possible to mitigate the concentration of stress that occurs in torsion beam 11 at the tips (the tips on the inner side in the vehicle width direction) of the pair of branch portions 49, 51 (reinforcement members 17, 19).

[0039] Furthermore, by locating the starting point of the expansion portion 55 at the vehicle width center of the pair of branch portions 49, 51, the rigidity of the torsion beam 11 can be ensured on the vehicle width outer side of the vehicle width center of the pair of branch portions 49, 51, while making it easier to deform the torsion beam 11 on the vehicle width inner side.

[0040] In addition, the inner edge of branch portion 61, where the pair of branch portions 49, 51 branch off, is welded to torsion beam 11, and a weld bead 63 is formed along the inner edge of branch portion 61, thereby suppressing deformation of torsion beam 11 at branch portion 61, and thereby reducing stress generated in weld bead 53 formed on the outer edge of the pair of branch portions 49, 51.

[0041] Furthermore, by having an inclined portion 57 facing inward relative to the extension direction of the expanded portion 55 on the outer side of the tip of the expanded portion 55, it is possible to suppress delay in heat propagation when arc welding the outer side of the tip of the expanded portion 55. This makes it possible to suppress the occurrence of an unmelted portion at the tip of the expanded portion 55. Furthermore, by providing an inclined portion 57 on the outer side of the tip of the expanded portion 55, the tip of the expanded portion 55 becomes tapered, which reduces the rigidity of the tip of the expanded portion 55 and reduces the difference in rigidity with the torsion beam 11, thereby suppressing the concentration of stress occurring in the weld bead 53.

[0042] In addition, the pair of branch portions 49, 51 have an expansion portion 67 in which the distance between the pair of branch portions 49, 51 gradually increases from the starting point of the expansion portion 55 toward the outside in the vehicle width direction, thereby making the branch portion 61 where the pair of branch portions 49, 51 branch off larger, and making it easier to weld the branch portion 61 to the torsion beam 11.

[0043] Furthermore, the torsion beam 11 has holes 69, 71 extending along the vehicle width direction on the inner side of the pair of reinforcement members 17, 19 in the vehicle width direction, which makes it easier for the torsion beam 11 to deform and reduces the load acting on the tip (the tip on the inner side in the vehicle width direction) of the expanded portion 55 (reinforcement members 17, 19).This also reduces the stress acting on the torsion beam 11 at the tip (torsion beam 11) on the inner side in the vehicle width direction of the reinforcement members 17, 19.

[0044] 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. [Explanation of symbols]

[0045] 1 Torsion beam suspension 11 Torsion beam 13,15 Trailing arm 17,19 Reinforcement member 21,23 Bearing section 25,27 Wheel support 29,31 Bracket 33.35 Bracket 37,39 Arm section 41,43 Beam section 45 Executive 47 Tapered section 49,51 Branch 53 Weld bead (first weld bead) 55 Expansion section (first expansion section) 57 Slope 61 Branch 63 Weld bead (second weld bead) 67 Expansion section (second expansion section) 69,71 holes PV swing axis (pivot) AX axle D, D1, D2 interval

Claims

1. 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; a pair of reinforcement members extending from the pair of trailing arms to the torsion beam; Equipped with Each of the pair of reinforcement members is an arm portion fixed to the trailing arm; a beam portion fixed to the torsion beam; Including, The beam portion is a tapered portion that gradually narrows in the vehicle front-rear direction toward the inside in the vehicle width direction; a pair of branch portions branching into two in the vehicle front-rear direction from the tapered portion toward the inside in the vehicle width direction; and At least an outer edge of the tapered portion and an outer edge of the pair of branch portions are welded to the torsion beam, and a first weld bead is formed along the outer edge of the tapered portion and the outer edges of the pair of branch portions, The pair of branch portions have a first expanding portion in which the distance between the pair of branch portions gradually expands toward the inside in the vehicle width direction, A torsion beam suspension, wherein the first weld bead extends to at least the first enlarged portion and to a position different from the tip of the first enlarged portion.

2. The torsion beam suspension according to claim 1 , wherein the first enlarged portion has a starting point at a center of the pair of branch portions in the vehicle width direction.

3. 3. The torsion beam suspension according to claim 1, wherein an inner edge of a 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.

4. the first enlarged portion has an inclined portion on the outer side of a tip end of the first enlarged portion, the inclined portion facing inward with respect to an extension direction of the first enlarged portion, The torsion beam suspension according to claim 1 or 2, wherein the first weld bead is formed beyond the inclined portion and on an inner side in the vehicle width direction.

5. 3. The torsion beam suspension according to claim 1, wherein the pair of branch portions have second enlarged portions in which the spacing between the pair of branch portions gradually increases from the starting point of the first enlarged portion toward the outside in the vehicle width direction.

6. 3. The torsion beam suspension according to claim 1, wherein the torsion beam has holes extending along the vehicle width direction on inner sides of the pair of reinforcement members in the vehicle width direction.

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