JP6464825B2 - Torsion beam suspension - Google Patents

Description

  The present invention relates to a torsion beam type suspension including a long torsion beam and a trailing arm joined to an end of the torsion beam.

2. Description of the Related Art In recent years, a torsion beam in which a pair of left and right trailing arms are joined to the left and right ends of a long torsion beam that extends in the vehicle width direction in order to achieve reduction in weight, space saving, and cost reduction of an automobile. A suspension is used.
In addition, in order to achieve further weight reduction in order to improve the fuel efficiency of automobiles, the material of automobile parts has been replaced from iron to light metal alloys, and light metal alloys are also used in torsion beam suspensions that are suspension parts. Is being promoted.

  In Patent Document 1, a trailing arm is made of an aluminum alloy die-casting casting, and is pivotally supported by a vehicle body, a wheel suspension for suspending a wheel, a spring support for supporting a coil spring, and a shock absorber. A torsion beam type suspension is disclosed in which a shock mounting portion to which the armor is attached is integrally formed, and the trailing arm and an aluminum torsion beam are joined by welding.

JP 2010-69963 A

By the way, the torsion beam is input with a torsional load caused by the roll caused by the left and right wheels stroking in the opposite phase, so that an appropriate rigidity is required. On the other hand, since a lateral load, a longitudinal load, and a vertical load are input to the trailing arm, rigidity that can withstand these loads is required.
Therefore, a torsion beam suspension, which is a joined body of a torsion beam and a trailing arm, receives lateral loads, longitudinal loads, vertical loads, and torsional loads (hereinafter simply referred to as loads) from the trailing arms connected to wheels and the like. It will be input repeatedly.

However, the torsion beam suspension of Patent Document 1 described above has the following problems.
The trailing arm of Patent Document 1 has a pivotal support portion, a wheel suspension portion, a spring support portion, and a shock attachment portion, and the wheel suspension portion, the spring support portion, and the shock attachment portion are located on the vehicle rear side of the torsion beam. Therefore, the bending rigidity in the vehicle width direction on the vehicle front side of the trailing arm is low, and the bending rigidity is high on the vehicle rear side of the trailing arm. Therefore, when a vertical load is input to the torsion beam, there is a possibility that stress concentrates on the vehicle front side of the joint portion between the trailing arm and the torsion beam.

In addition, the light alloy aluminum die-cast material for producing the trailing arm of Patent Document 1 is inferior in impact performance to a steel plate, so that it breaks at the time of impact, and the fracture surface may damage peripheral parts. For example, since the fuel tank is arranged on the vehicle front side of the torsion beam, if the torsion beam breaks due to a collision from the rear of the vehicle, the fuel tank may be damaged by the fracture surface.
Furthermore, since the torsion beam of Patent Document 1 is formed in a closed cross-sectional shape extending in the vehicle width direction, a weld end exists at the joint between the torsion beam and the trailing arm. For this reason, when a load is applied to the torsion beam or the trailing arm to cause deformation, stress may concentrate on the weld end. In particular, the vicinity of the welded portion between the torsion beam and the trailing arm is softened due to the heat effect of welding, and is easily broken.

  The present invention has been made in view of such a situation, and an object thereof is to reduce stress concentration generated in a joint portion between a torsion beam and a trailing arm while suppressing an increase in weight. The object is to provide a torsion beam suspension.

In order to solve the above-described problems of the prior art, in the present invention, a long torsion beam and a light alloy-made trailing arm are joined, and a joint portion between the torsion beam and the trailing arm is provided. In the torsion beam type suspension, a part of the vehicle front side of the lower surface of the trailing arm at the joint is positioned below the vehicle with respect to the vehicle rear side of the lower surface of the trailing arm at the joint.

  In one aspect of the torsion beam suspension, the trailing arm has a lower surface, and the lower surface of the trailing arm has at least a horizontal portion and an inclined portion.

  Furthermore, in one aspect of the torsion beam suspension, the lower surface of the trailing arm has at least two horizontal portions and an inclined portion in part, and the inclined portion is between the two horizontal portions. Is arranged.

  Further, in one aspect of the torsion beam type suspension, the torsion beam is formed in a concave shape with the opening side facing downward along the longitudinal direction, and the trailing arm is disposed to overlap the concave inner surface side of the end of the torsion beam, At least the end of the torsion beam and the overlapping portion of the trailing arm are joined, and the end of the trailing arm and the overlapping portion of the torsion beam are joined, and the trailing arm is connected to the torsion beam. Inclined so that the cross-sectional area gradually becomes smaller.

In one aspect of the torsion beam suspension, the height of the trailing arm in the direction perpendicular to the reference line extending in the longitudinal direction of the torsion beam is substantially the same as the height of the torsion beam in the direction perpendicular to the reference line. Is set.

  Further, in one aspect of the torsion beam suspension, the inclined portion and the center of curvature of the hole portion provided on the torsion beam side of the trailing arm coincide with each other.

  In one aspect of the torsion beam suspension, the trailing arm is formed by casting.

As described above, torsion beam suspension according to the present invention includes a torsion beam elongated, and Torre ring arm of light alloy are joined, has a junction between the said torsion beam Torre ring arm, the joint Since a part of the vehicle front side of the lower surface of the trailing arm in the portion is located on the vehicle lower side with respect to the vehicle rear side of the lower surface of the trailing arm in the joint portion, Of the lower part, the part located further below the lower part on the rear side of the vehicle will contribute to improving the rigidity on the front side of the vehicle, reducing stress concentration on the front side of the vehicle when a vertical load is applied to the torsion beam can do. Moreover, only the weight of the lower part of the trailing arm on the front side of the vehicle, which is located further below the lower part of the rear side of the vehicle, can be increased, and there is no need to increase the thickness. Stress concentration can be reduced while suppressing.

In one aspect of the torsion beam suspension, the trailing arm has a lower surface, and the lower surface of the trailing arm has at least a horizontal portion and an inclined portion. The angle between the torsion beam and the bottom surface of the trailing arm is larger than when the bottom surface of the trailing arm is inclined when the angle is substantially horizontal. This reduces stress concentration on the side of the trailing arm and makes it difficult to break. be able to.
Moreover, since the trailing arm has a substantially closed cross-sectional structure, a core (sand core or salt core) is required to form the trailing arm by casting, and the junction between the trailing arm and the torsion beam is required. In this case, by providing the horizontal portion on the lower surface of the trailing arm, the angle of the end portion of the core is larger and gentler than in the case where the horizontal portion is not provided. Therefore, according to one aspect of the present invention, the corner shape of the end of the core can be easily manufactured, so that the productivity of the core can be improved. In addition, when the core is stored or transported, the occurrence of chipping at the corner portion at the end of the core can be suppressed, and the product cost of the trailing arm can be reduced.

  Further, in one aspect of the torsion beam suspension, the lower surface of the trailing arm has at least two horizontal portions and an inclined portion, and the inclined portion is between the two horizontal portions. Therefore, by setting the lower surface of the trailing arm as the horizontal portion-the inclined portion-the horizontal portion, the inclined portion of the trailing arm can be made a weak portion against the load applied in the vehicle front-rear direction. As a result, in the event of a collision from the rear of the vehicle, not the joint between the torsion beam and the trailing arm, but the inclined portion of the trailing arm can be broken. That is, by breaking the lower surface of the trailing arm at the time of a collision from the rear of the vehicle, the fracture surface of the torsion beam does not go to the fuel tank arranged on the vehicle front side of the torsion beam, so the fracture surface of the torsion beam hits This can prevent the fuel tank from being damaged. In addition, the surface area of the lower surface of the trailing arm can be increased by setting the lower surface of the trailing arm to be horizontal portion-inclined portion-horizontal portion. Therefore, the heat dissipation performance of the muffler disposed in the vicinity of the trailing arm can be improved.

  Furthermore, in one aspect of the torsion beam type suspension, the torsion beam is formed in a concave shape with the opening side facing downward along the longitudinal direction, and the trailing arm is disposed to overlap the concave inner surface side of the end of the torsion beam, At least the end of the torsion beam and the overlapping portion of the trailing arm are joined, and the end of the trailing arm and the overlapping portion of the torsion beam are joined, and the trailing arm is connected to the torsion beam. Since the cross-sectional area is inclined so as to gradually become smaller, the rigidity of the joint portion of the trailing arm and the torsion beam changes gradually, and when stress is applied, stress is applied to a specific part. You can prevent the situation of concentration.

In one aspect of the torsion beam suspension, the height of the trailing arm in the direction perpendicular to the reference line extending in the longitudinal direction of the torsion beam is substantially the same as the height of the torsion beam in the direction perpendicular to the reference line. As a result, there is no step at the radial outside of the torsion beam at the junction between the torsion beam and the torsion beam, and the torsion beam and the trailing arm can be easily joined, and stress is applied to the step portion. Concentration can be prevented, and the durability performance of the joint can be improved.

  Furthermore, in one aspect of the torsion beam type suspension, the inclined portion and the curved center of the hole portion provided on the torsion beam side of the trailing arm are coincident with each other, so that the junction between the trailing arm and the torsion beam In this case, a low-strength portion is formed in the shape, and at the time of collision from the rear of the vehicle, not the welded joint between the trailing arm and the torsion beam, but the inclined portion of the trailing arm (the center of curvature of the hole). ) Can be reliably broken. Therefore, as in the above aspect of the torsion beam suspension, by breaking the lower surface of the trailing arm at the time of collision from the rear of the vehicle, the fracture surface of the torsion beam and the trailing arm does not go toward the fuel tank, and the torsion beam and the trailing ring Since the fracture surface of the arm does not hit the fuel tank, it is possible to reliably prevent the fuel tank from being damaged.

  Further, in one aspect of the torsion beam type suspension, since the trailing arm is formed by casting, the corner shape of the end portion of the core can be easily manufactured as in the one aspect of the torsion beam type suspension. The productivity of the core can be improved, and chipping of the corner-shaped portion at the end of the core that occurs during storage and transportation of the core can be suppressed. In addition, since the surface area of the lower surface of the trailing arm can be increased, the heat dissipation performance of the muffler disposed in the vicinity of the trailing arm can be improved.

It is the perspective view which looked at the vehicle to which the torsion beam type suspension concerning the embodiment of the present invention was applied from the front. It is a disassembled perspective view which shows the torsion beam type suspension which concerns on embodiment of this invention. FIG. 3 is an enlarged view of a portion Z in FIG. 2, and is a perspective view for explaining an input load to a torsion beam. It is the perspective view which looked at the state before joining the torsion beam and the trailing arm of the torsion beam type suspension concerning the embodiment of the present invention from the upper part. It is the perspective view which looked at the trailing arm of the torsion beam type suspension concerning the embodiment of the present invention from the upper part. FIG. 2 is a plan view showing a positional relationship between a torsion beam, a fuel tank, and a muffler as viewed from above the entire torsion beam suspension according to the embodiment of the present invention. FIG. 7 is a side view showing the torsion beam in cross section as viewed from the direction of the arrow V1 in FIG. It is the XX sectional view taken on the line in FIG. (A) is sectional drawing which cut | disconnected the torsion beam type suspension arm according to the embodiment of the present invention perpendicularly to the vehicle width direction, and (b) shows the conventional torsion beam type suspension arm in the vehicle width direction. It is sectional drawing cut | disconnected perpendicularly | vertically with respect to it. FIG. 7 is a cross-sectional view showing a junction between a torsion beam and a trailing arm, as viewed from the direction of arrow V2 in FIG. 6. It is the perspective view which looked at the hole part of the torsion beam from the vehicle lower side in the junction part of the torsion beam and the trailing arm of the torsion beam type suspension which concerns on embodiment of this invention. FIG. 5 is a cross-sectional view of a torsion beam type suspension arm according to another embodiment of the present invention cut perpendicularly to the vehicle width direction.

Hereinafter, the present invention will be described in detail based on illustrated embodiments.
1 to 11 show a torsion beam suspension according to an embodiment of the present invention. In FIG. 2, the arrow Fr indicates the front of the vehicle, the arrow W indicates the vehicle width direction, and the arrow U indicates the upper side of the vehicle. In FIG. 3, an arrow F1 indicates a vertical load at the tire ground contact point G, an arrow F2 indicates a longitudinal load at the tire ground contact point G, and an arrow F3 indicates a lateral load direction at the tire ground contact point G.

As shown in FIG. 1, a vehicle 1 according to an embodiment of the present invention is a four-wheel type automobile, and includes a torsion beam type suspension 2 as a rear suspension, and left and right wheels are interposed via the torsion beam type suspension 2. 3 are suspended from the vehicle body 4 respectively.
The torsion beam suspension 2 of the present embodiment, as shown in FIGS. 2 to 4, is provided with a long torsion beam 5 that extends in the vehicle width direction and both left and right ends of the torsion beam 5. A pair of left and right trailing arms 6 are provided. A spring 7 and a shock absorber 8 are attached to the trailing arm 6 and are suspended from the vehicle body 4.
As shown in FIGS. 2 to 5, the trailing arm 6 of this embodiment is an integrally formed part made of cast aluminum using a non-ferrous alloy such as a light metal alloy, and has a closed cross-sectional shape with a hollow structure. Is formed. The trailing arm 6 has a beam joint portion 6a extending in the vehicle width direction at one end, and a front arm portion 6b and a rear arm portion 6c extending in the vehicle front-rear direction are provided on the other end side of the beam joint portion 6a. It has been.

As shown in FIGS. 2 to 11, the beam joining portion 6 a of the trailing arm 6 is a joining portion with the torsion beam 5 to be overlapped, and a step corresponding to the thickness of the torsion beam 5 is provided. ing. Thereby, in a state where the end portion of the torsion beam 5 is overlapped with the beam joint portion 6 a of the trailing arm 6, the outer peripheral portion of the torsion beam 5 and the outer peripheral portion of the trailing arm 6 are substantially flat (flat). It is configured.
Further, the beam joint portion 6a is inclined in the vehicle width direction from the vehicle inner side to the vehicle outer side so that the upper part of the vehicle is located on the inner side (vehicle center side) and the lower part of the vehicle is located on the outer side of the vehicle. The cross-sectional area of the beam joint portion 6a is set smaller as it is located on the vehicle inner side. Further, in the beam joining portion 6a, an oblong hole portion 60 extending in the vehicle width direction is provided on the lower surface of the trailing arm 6 on the torsion beam 5 side. The beam joining portion 6a has a structure capable of welding the two ends of the trailing arm side on the vehicle outer side and the end portion on the torsion beam side on the vehicle inner side. The torsion arm 6 and the torsion beam 5 are welded and brazed. Bonding or friction stir welding (FSW) is used for wire bonding, and bead W1 and W2 of the bonding portion are formed on the outer periphery of the overlapping portion. The bead W2 of the joint portion is inclined so that the vehicle upper side is located on the vehicle inner side and the vehicle lower side is located on the vehicle outer side as viewed from the rear of the vehicle (in the direction of arrow V2 in FIG. 6).

  Moreover, the height of the trailing arm 6 in the direction perpendicular to the reference line C extending in the longitudinal direction of the torsion beam 5 is set to be substantially the same as the height of the torsion beam 5 in the direction perpendicular to the reference line C. That is, as shown in FIG. 10, the trailing arm 6 and the torsion beam 5 have substantially the same vertical dimension L in the vehicle vertical direction at the joint bead W1, and the torsion beam and the outer peripheral shape of the trailing arm 6 on the upper side of the vehicle. The outer peripheral shape of the vehicle upper side of 5 is formed identically. For this reason, since there is no step portion on the outer side in the radial direction of the torsion beam 5 at the junction between the torsion beam 6 and the torsion beam 5, the torsion beam 5 and the trailing arm 6 can be easily and reliably joined. It is possible to prevent stress from concentrating on the step portion.

In the torsion beam suspension 2 of the present embodiment, as shown in FIG. 8, the vehicle front side portion 61 (or at least a part thereof) of the trailing arm 6 may be the rear side of the trailing arm 6 at the beam joint 6a. A step S in the vertical direction of the vehicle is provided between the ends of the torsion beam side. The step S is formed by extending the front portion 61 of the trailing arm 6 toward the vehicle lower side.
Further, as shown in FIG. 9A, the trailing arm 6 in the beam joining portion 6a has a lower surface 63, and the lower surface 63 has at least a horizontal portion 63a and an inclined portion 63b. doing. When the lower surface 63 of the trailing arm 6 has a substantially horizontal horizontal portion 63a at the junction between the trailing arm 6 and the torsion beam 5, the lower surface 63 is inclined as shown in FIG. 9B. The angle between the torsion beam 5 and the lower surface 63 of the trailing arm 6 is larger at the angle θ1 with respect to the horizontal portion 63a than at the angle θ2 with respect to the inclined portion 63b (θ1> θ2). ). Thereby, the stress concentration on the trailing arm 6 side is relaxed, and the joint portion is not easily broken.

  Furthermore, as shown in FIG. 11, the hole 60 provided on the torsion beam 5 side of the trailing arm 6 is formed to have a smaller diameter as it is located at the end in the vehicle width direction (arrow W direction). When viewed from below, the inclined portion 63b of the lower surface 63 of the trailing arm 6 and the center of curvature of the hole 60 provided on the torsion beam 5 side of the trailing arm 6 coincide with each other. As a result, a low-strength portion is formed in the joint portion between the trailing arm 6 and the torsion beam 5, and when an impact load is applied from the rear of the vehicle at the time of collision, the trailing arm 6 and the torsion beam are formed. 6 is broken at the inclined portion 63b (the curved center of the hole portion 60) of the lower surface 63 of the trailing arm 6, not at the joint portion (the location of the beads W1, W2).

  The front arm portion 6b of the trailing arm 6 is provided with a bush press-fit portion 64 into which a tubular bush that is an elastic member is press-fitted. The bush press-fit portion 64 is a bracket 9 fixed to the vehicle body 4 side. It is attached to be able to swing through a fixing bolt 10. Further, the rear arm portion 6c of the trailing arm 6 is provided with a carrier 65 toward the outside of the vehicle, and at the corner in the vehicle width direction between the beam joint portion 6a and the rear arm portion 6c. A spring seat 66 and a shock absorber mounting portion 67 are provided. A hub 11 and a brake drum 12 are attached to the carrier 65, and the wheel 3 is rotatably supported. The spring seat 66 supports the lower end of the spring 7 attached to the vehicle body 4 at the upper end, and an attachment hole 66a is provided on the seat plate surface. Moreover, the trailing arm 6 is formed in a shape in which R is increased from the carrier 65 and the bush press-fit portion 64 to the beam joint portion 6a as a countermeasure against stress concentration.

  As shown in FIGS. 2 to 6, the torsion beam 5 of the present embodiment is formed in a concave shape with the opening side facing downward along the longitudinal direction. That is, the torsion beam 5 is a long molded product having a substantially U-shaped vertical section with the opening side disposed on the vehicle lower side, and is an integrally molded part made of an extruded aluminum material having an open sectional structure. Moreover, both left and right end portions in the vehicle width direction are formed as arm joint portions 5a that are joint portions with the trailing arm 6 to be abutted. The torsion beam 5 is not limited to a substantially U-shaped cross section, and may have a substantially C-shaped vertical section or a substantially V-shaped vertical section.

The beam joint 6a, which is the end of the torsion beam 6, is disposed so as to overlap the concave inner surface of the arm joint 5a, which is the end of the torsion beam 5, and is at least in contact with the arm joint 5a of the torsion beam 5. The beam joining portion 6a of the overlapping portion of the arm 6 is joined, and the beam joining portion 6a of the trailing arm 6 and the arm joining portion 5a of the overlapping portion of the torsion beam 5 are joined, and the outer periphery of the overlapping portion The bead W1 and W2 of the junction are formed.
Further, the tip portion of the arm joint portion 5a located outside the vehicle in the vehicle width direction is inclined so that the sectional area of the trailing arm 6 gradually decreases toward the torsion beam 5, as shown in FIG. An inclined surface 68 is provided. The inclined surface 68 is formed in an inclined shape outward in the vehicle width direction so that the front side of the vehicle is located outside the vehicle and the rear side of the vehicle is located inside the vehicle in plan view.
As a result, the cross-sectional area of the trailing arm 6 gradually decreases from the trailing arm 6 toward the torsion beam 5, and the change in rigidity of the joint between the trailing arm 6 and the torsion beam 5 becomes gradual. When added, stress is not concentrated on a specific part.

  On the other hand, in the vicinity of the vehicle front side of the torsion beam 5 of the present embodiment, as shown by the chain line in FIGS. 6 and 7, a fuel tank N that stores fuel such as gasoline is disposed over almost the entire width of the torsion beam 5 in the vehicle width direction. Has been. Further, an exhaust device M such as an exhaust pipe and a muffler for passing the combustion gas is disposed in the vicinity of the right side of the torsion beam 5 above the vehicle so as to extend in the vehicle front-rear direction.

Next, the operation and effect of the torsion beam suspension 2 according to the embodiment of the present invention will be described.
As shown in FIG. 8, the torsion beam suspension 2 of the present embodiment includes a long torsion beam 5 that extends in the vehicle width direction, and a beam joint portion between the arm joint portions 5 a at the left and right ends of the torsion beam 5. 6a, and a light alloy trailing arm 6 to be joined to each other, and at least a front portion 61 of the trailing arm 6 with respect to a rear portion 62 of the trailing arm 6 of the beam joining portion 6a. Since a step S in the vertical direction of the vehicle is provided between the ends of the torsion beam side located on the lower side of the vehicle, a further lower portion of the trailing arm 6 on the front side of the vehicle with respect to the rear portion 62 of the vehicle The portion 61 located on the lower side can improve the rigidity on the front side of the vehicle, and the response on the front side of the vehicle when a vertical load is applied to the torsion beam 5. It is possible to mitigate the concentration. Moreover, only the weight 61 of the lower portion of the trailing arm 6 on the front side of the vehicle, which is located further below the lower portion on the rear side of the vehicle, can be increased. Since there is no need to increase the wall thickness, stress concentration can be reduced while suppressing an increase in weight.

  Further, in the torsion beam suspension 2 of the present embodiment, as shown in FIG. 9A, the lower surface 63 of the trailing arm 6 formed in the closed cross-sectional shape of the hollow structure has the horizontal portion 63a and the inclined portion 63b. Therefore, the angle formed by the torsion beam 5 and the lower surface 63 of the trailing arm 6 with respect to the horizontal portion 63a is larger than the case where the lower surface 63 of the trailing arm 6 is inclined only by the inclined portion 63b. The angle θ1 can be formed larger than the angle θ2 with respect to the inclined portion 63b. Therefore, it is possible to alleviate stress concentration on the trailing arm 6 side, and it is possible to suppress breakage at the joint between the torsion beam 5 and the trailing arm 6. In addition, a core required for forming the trailing arm 6 having a closed cross-sectional shape with a hollow structure by casting is formed on the lower surface 63 of the trailing arm 6 at the joint between the trailing arm 6 and the torsion beam 5. By providing the horizontal portion 63a, the angle of the end portion is larger and gentler than in the case where the horizontal portion 63a is not provided, so that the corner shape of the end portion of the core can be easily manufactured and the core It is possible to suppress chipping at the corners of the end of the core that occurs during storage and transportation.

  Further, in the torsion beam suspension 2 of the present embodiment, the torsion beam is formed in a concave shape with the opening side facing downward along the longitudinal direction, and the beam joint portion 6a of the trailing arm 6 is concave in the arm joint portion 5a of the torsion beam 5. The arm joint 5a of the torsion beam 5 and the beam joint 6a of the overlapping portion of the trailing arm 6 are joined to each other, and the arm of the overlapping portion of the beam joint 6a of the trailing arm 6 and the torsion beam 5 is disposed. The joint 5a is joined, and the beads W1 and W2 of the joint are formed on the outer periphery of the overlapping portion. Moreover, the beam joining portion 6 a of the trailing arm 6 has an inclined surface 68 that is inclined so that the cross-sectional area gradually decreases toward the torsion beam 5. Therefore, according to the torsion beam type suspension 2 of the present embodiment, the cross-sectional area of the trailing arm 6 gradually decreases from the trailing arm 6 toward the torsion beam 5, and the joining portion of the trailing arm 6 and the torsion beam 5 is obtained. Therefore, when stress is applied to the joint between the trailing arm 6 and the torsion beam 5, stress concentration on a specific portion can be alleviated.

In the torsion beam suspension 2 of the present embodiment, the height (dimension L) of the trailing arm 6 in the direction perpendicular to the reference line C extending in the longitudinal direction of the torsion beam 5 is the reference line C as shown in FIG. Since the height of the torsion beam 5 in the vertical direction is set to be substantially the same as that of the torsion beam 5, there is no step on the radially outer side of the torsion beam 5 at the junction between the torsion beam 6 and the torsion beam 5. Thus, when stress is applied to the joint between the trailing arm 6 and the torsion beam 5, it is possible to avoid the concentration of stress at the stepped portion or the like.
Furthermore, in the torsion beam suspension 2 of the present embodiment, as shown in FIG. 11, the curved portion 63b of the lower surface 63 of the trailing arm 6 and the hole 60 provided on the torsion beam 5 side of the trailing arm 6 are curved. Since the center coincides and a portion having a low strength is formed at the joint between the trailing arm 6 and the torsion beam 6, the trailing arm 6 and the torsion beam 5 It can be surely broken at the location of the inclined portion 63b instead of the joint portion. Therefore, according to the torsion beam type suspension 2 of the present embodiment, the lower surface 63 of the trailing arm 6 is broken at the time of a collision from the rear of the vehicle, and the fracture surface of the torsion beam 5 and the trailing arm 6 goes toward the fuel tank N. Therefore, the fracture surfaces of the torsion beam 5 and the trailing arm 6 do not hit the fuel tank N, and damage to the fuel tank N can be reliably prevented.

FIG. 12 shows a torsion beam suspension according to another embodiment of the present invention.
In the torsion beam suspension 2 of this embodiment, as shown in FIG. 12, the lower surface 63 of the rolling arm 6 has at least two horizontal portions 63a and inclined portions 63b along the vehicle longitudinal direction. The inclined portion 63b is disposed between the two horizontal portions 63a. That is, in the torsion beam suspension 2 of the present embodiment, the lower surface 63 of the trailing arm 6 is arranged as horizontal portion 63a-inclined portion 63b-horizontal portion 63a, so that the inclined portion 63b of the trailing arm 6 extends in the vehicle front-rear direction. Since it is configured as a weak part against the applied load, in the event of a collision from the rear of the vehicle, not the welded joint between the torsion beam 5 and the trailing arm 6 but the inclined part 63b of the trailing arm 6 is broken. Further, the fracture surface of the torsion beam 5 and the trailing arm 6 is prevented from going to the fuel tank N disposed on the front side of the vehicle, and the damage of the fuel tank N due to the collision of the fracture surface of the torsion beam 5 and the trailing arm 6 is prevented. be able to. In addition, by having two horizontal portions 63a and inclined portions 63b, it becomes possible to increase the surface area of the lower surface 63 of the trailing arm 6, and exhaust such as a muffler disposed in the vicinity of the trailing arm 6 The heat dissipation performance of the device M can be improved.
Other configurations and operational effects are the same as those of the torsion beam suspension 2 of the above embodiment.

  While the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made based on the technical idea of the present invention.

For example, in the above-described embodiment, the trailing arm 6 is formed by casting. However, the present invention is not limited to casting, and an aluminum plate may be press-worked and joined by pressing. Furthermore, what was joined using several types among casting, die-casting, press molding of an aluminum plate, an aluminum extrusion material, and aluminum casting may be used.
In the above-described embodiment, the torsion beam 5 is made of an extruded aluminum material. However, the torsion beam 5 may be made by press-molding an aluminum plate, cast or die-cast.
Furthermore, the same joining structure can be applied even if the material of the trailing arm 6 and the torsion beam 5 is not only aluminum but also a light metal such as magnesium.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Torsion beam type suspension 3 Wheel 4 Car body 5 Torsion beam 5a Arm joint part 6 Trailing arm 6a Beam joint part 60 Hole part 61 The vehicle front side part of the lower surface of a trailing arm 62 The vehicle rear side part of the lower surface of a trailing arm 63 Lower surface of the trailing arm 63a Horizontal portion 63b Inclined portion 68 Inclined surface of the trailing arm C Reference line extending in the longitudinal direction of the torsion beam L Vertical dimension of the trailing arm at the joint S Step difference W1, W2 Bead at the joint θ1 Angle of inclination

Claims (7)

In a torsion beam type suspension in which a long torsion beam and a light alloy trailing arm are joined, and a joint portion between the torsion beam and the trailing arm is provided,
A torsion beam, wherein a part of a vehicle front side of a lower surface of the trailing arm at the joint is located on a vehicle lower side with respect to a vehicle rear side of a lower surface of the trailing arm at the joint. Suspension.   The torsion beam suspension according to claim 1, wherein the trailing arm has a lower surface, and the lower surface of the trailing arm has at least a horizontal portion and an inclined portion.   The lower surface of the trailing arm has at least two horizontal portions and an inclined portion in part, and the inclined portion is disposed between the two horizontal portions. The torsion beam suspension according to claim 1.   The torsion beam is formed in a concave shape with the opening side facing downward along the longitudinal direction, and the trailing arm is disposed to overlap the concave inner surface side of the end of the torsion beam, and at least the end of the torsion beam and the trailing ring The overlapping portion of the arm is joined, and the end portion of the trailing arm and the overlapping portion of the torsion beam are joined so that the sectional area of the trailing arm gradually decreases toward the torsion beam. The torsion beam type suspension according to claim 2, wherein the torsion beam type suspension is inclined. The height of the trailing arm in a direction perpendicular to a reference line extending in a longitudinal direction of the torsion beam is set to be substantially the same as a height of the torsion beam in a direction perpendicular to the reference line. Item 5. The torsion beam suspension according to item 4.   The torsion beam suspension according to any one of claims 2 to 5, wherein the inclined portion and a curved center of a hole provided on the torsion beam side of the trailing arm coincide with each other.   The torsion beam suspension according to claim 1, wherein the trailing arm is formed by casting.

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