Torsion beam type suspension

Abstract

To provide a torsion beam type suspension which can ease concentration of stress occurring in a torsion beam at 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 a first welding bead is 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 a connection part which connects the pair of branch parts with each other at tips of the pair of branch parts. The first welding bead extends to a position different from a tip of the connection 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, wherein the beam portion has a tapered portion that gradually narrows in the vehicle fore-and-aft direction 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 edge 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 outer edge of the tapered portion and the outer edges of the pair of branches, wherein the pair of branches have connection portions at their tips that connect the pair of branches to each other, and the first weld bead extends to a position different from the tips of the connection portions.

[0007] According to the above configuration (1), the rigidity of the pair of branch tips is ensured, and movement of the pair of branch tips is suppressed. This reduces the stress generated in the torsion beam at the tips of the pair of branch tips (reinforcement members), and reduces the concentration of stress generated in the torsion beam at the tips of the reinforcement members. Furthermore, because the first weld bead extends to a position different from the tip of the connection part, it is possible to reduce a sudden change in rigidity at the tip of the connection part. This reduces the concentration of stress generated in the torsion beam at the tip of the connection part (reinforcement member) (the tip that is on the inner side in the vehicle width direction).

[0008] (2) In some embodiments, in the configuration of (1) above, the minimum width of the connection portion is the same as or narrower than the minimum width of each of the pair of branch portions, and the inner edge of the connection portion has an arc shape larger than the distance between the pair of branch portions.

[0009] According to the above configuration (2), it is possible to prevent the rigidity of the tip of the connection portion from becoming too high.

[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 inner edge of the branch portion, so that stress generated in the weld beads formed along the outside of the pair of branch portions can be reduced.

[0012] (4) In some embodiments, in the configuration described in (1) or (2) above, the torsion beam has holes extending along the vehicle width direction on the vehicle width direction inner sides of the pair of reinforcement members.

[0013] According to the above configuration (4), the torsion beam becomes more easily deformed, and the load acting on the tips (the tips on the inner side in the vehicle width direction) of the pair of branches (reinforcement members) can be reduced, which in turn reduces the stress acting on the torsion beam at the tips on the inner side in the vehicle width direction of the reinforcement members. [Effects of the Invention]

[0014] 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]

[0015] [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. 10 is a diagram schematically illustrating a branch portion of a reinforcement member according to an embodiment. [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

[0016] 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.

[0017] [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.

[0018] [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.

[0019] [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).

[0020] 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.

[0021] [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.

[0022] 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.

[0023] 2 and 3, the beam portion 41 has a trunk portion 45, a tapered portion 47 that gradually narrows in the vehicle longitudinal direction from the trunk portion 45 toward the vehicle widthwise 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 widthwise 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 widthwise 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.

[0024] 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.

[0025] The pair of branches 49, 51 have connecting portions 55 at the tips of the pair of branches 49, 51 that connect the pair of branches 49, 51 to each other, and the weld bead 53 extends to a position different from the tip of the connecting portion 55.

[0026] As shown in FIG. 2, weld bead 53 extends inward in the vehicle width direction beyond the tip of connecting portion 55, but as shown in FIG. 3, it may be positioned inward in the vehicle width direction from the tip of connecting portion 55.

[0027] As shown in FIG. 4, the minimum width Wmin of the connecting portion 55 is the same as or narrower than the minimum width of the pair of branch portions 49, 51, and the inner edge of the connecting portion 55 is arc-shaped with a diameter DA larger than the distance DI between the pair of branch portions 49, 51, but is not limited to this.

[0028] The pair of branch portions 49, 51 have narrowing portions 57 that gradually narrow from the inner edge of the connecting portion 55 toward the outer side in the vehicle width direction, but the narrowing portions 57 are not essential. The narrowing portions 57 are formed in an arc shape so that the inner edge of the connecting portion 55 and the inner edges of the pair of branch portions 49, 51 are smoothly connected, but the invention is not limited to this.

[0029] 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.

[0030] The pair of branch portions 49, 51 have an enlarged portion 67 where the distance DI between the pair of branch portions 49, 51 gradually increases outward in the vehicle width direction, but the enlarged portion 67 is not essential.

[0031] The outer tips of the pair of branch portions 49, 51 are formed in an arc shape toward the connecting portion 55, but this shape is not essential.

[0032] 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.

[0033] [Effect of torsion beam suspension] According to the torsion beam suspension 1 of this embodiment, the pair of branches 49, 51 have a connection portion 55 at their tips that connects the pair of branches 49, 51 to each other, ensuring rigidity at the tips of the pair of branches 49, 51 and suppressing movement of the tips of the pair of branches 49, 51. This reduces stress generated in the torsion beam 11 at the tips of the pair of branches 49, 51 (reinforcement members 17, 19) and alleviates stress concentration in the torsion beam 11 at the tips of the reinforcement members 17, 19. Furthermore, because the weld bead 53 extends to a position different from the tip of the connection portion 55, it is possible to alleviate a sudden change in rigidity at the tip of the connection portion 55. This makes it possible to alleviate stress concentration in the torsion beam 11 at the tip (the tip on the inner side in the vehicle width direction) of the connection portion 55 (reinforcement members 17, 19).

[0034] The minimum width of the connection portion 55 is the same as or narrower than the minimum width of each of the pair of branch portions 49, 51, and the inner edge of the connection portion 55 is made into an arc shape that is larger than the distance between the pair of branch portions 49, 51, thereby preventing the rigidity of the tip of the connection portion 55 from becoming too high.

[0035] 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.

[0036] 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 widens toward the outside in the vehicle width direction, so that the branch portion 61 where the pair of branch portions 49, 51 branch off becomes larger, making it easier to weld the branch portion 61 to the torsion beam 11.

[0037] 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 ends (the ends on the inner side in the vehicle width direction) of the connecting parts (reinforcement members 17, 19).This also reduces the stress acting on the torsion beam 11 at the ends (torsion beam 11) on the inner side in the vehicle width direction of the reinforcement members 17, 19.

[0038] 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]

[0039] 1 Torsion beam suspension 11 Torsion beam 13,15 Trailing arm 17,19 Reinforcement member 21,23 Bearing section 25,27 Wheel support part 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 Connection 57 Reduction part 61 Branch 63 Weld bead (second weld bead) 67 Enlarged section 69,71 holes PV swing axis (pivot) AX axle DA diameter DI 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 connecting portions at tips of the pair of branch portions that connect the pair of branch portions to each other, A torsion beam suspension, wherein the first weld bead extends to a position different from the tip of the connection portion.

2. 2. The torsion beam suspension according to claim 1, wherein the minimum width of the connection portion is equal to or narrower than the minimum width of each of the pair of branch portions, and the inner edge of the connection portion has an arc shape larger than the distance between the pair of branch portions.

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. 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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