JPH0410086Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a trailing rear suspension for an automobile, and more particularly to a trailing rear suspension that uses torsion bar springs to reduce the shock received by the rear wheels and transmit it to the vehicle body.

A rear suspension in which a torsion bar spring is assembled to a trailing rear suspension is known. Automobiles equipped with such a rear suspension must have a lower floor and body frame in order to increase the cabin space in order to improve the comfort of the rear seats. However, if this is done, a problem arises in that the external arm, which is the vehicle side end of the trailing arm, interferes with the body frame when the wheel strokes upward.
This is similar to the conventional external arm 1, as shown in Figure 6.
This is because the body frame 2 is made of a long plate extending straight in the horizontal direction, and a portion a of the upper side thereof abuts against the body frame 2. Therefore, as shown in Figure 7,
By using an external arm 1' whose central portion is curved downward, interference with the body frame 2 can be avoided. Incidentally, these external arms 1 and 1' have a torsion bar 4 attached to each of the rotation center sides via a retainer 3, and a wheel 5 is attached to the external facing wall (vehicle side end side wall) b side of the rotation end side. An internal arm (not shown) is integrally connected to the internal arm (not shown). The swing axis of the semi-trailing arm connecting the pin joint of the internal arm and the pivot portion of the external arm 1 does not coincide with the axis of the torsion bar (see FIG. 5). Therefore, the flat plate portion of the external arm 1 absorbs torsional deformation due to external force applied from the wheel 5 side. Incidentally, in the case of the external arm 1, the center line l of its shape is a straight line, and this center line l coincides with the action center line X of forced displacement (twisting) applied from the wheel 5 side. On the other hand, in the case of a curved external arm 1', the center line l1 of its shape is curved, and this center line l1 intersects the center line X of the forced displacement (torsion) applied from the wheel 5 side. Therefore, when each outer arm 1, 1' receives a forced displacement about the action center line X, stress is generated in the welded portion A with the collar-shaped retainer 3 based on the displacement. At this time, in the case of the straight external arm 1, the center line of action coincides with the center line of action Twisting around the line X causes stress concentration in the θ _O direction, which is the direction of the shape center line l'. For example, according to the stress measurement conducted by the present invention using an external arm with a predetermined shape, the fourth
As shown by the broken line B in the figure, a concentrated area where the stress is at a high level occurs in the direction of θ _O =45°.

When the curved outer arm 1' is used to improve comfort, stress concentration occurs in a part of the welded portion A of the retainer. As a result, this portion tends to lack durability, making it impossible to put the thus curved outer arm 1' into practical use. An object of the present invention is to provide a trailing rear suspension that can eliminate the above-mentioned problems.

A trailing rear suspension to which the present invention is applied will be explained with reference to FIG.

The collar portion 121 of the retainer 12 that connects the torsion bar spring 11 is welded to the flat plate portion 101 on the rotation center side of the horizontally long external trailing arm 10.
An internal trailing arm 13 is attached to the pivoting end 102 of the
and a rear wheel 15 is pivotally connected to the external facing wall 14 on the rotating end 102 side, and the external trailing arm 10 is formed so that its center is curved downward, and A long hole 16 as a stress relaxation hole is formed at a position on the flat plate portion 101 near the welded portion A to the weld portion 121.

Such a trailing rear suspension prevents interference with the vehicle body frame by curving the external trailing arm 10 that connects the torsion bar spring 11 and the rear wheel 15. The stress concentration occurring at the welded portion A with the retainer 12 can be removed through the elongated hole 16 as a stress relaxation hole.

The trailing rear suspension as an embodiment of the present invention shown in FIG. 1 is a semi-trailing rear suspension for a passenger car (not shown).
That is, the left and right ends (only the left end is shown) of the cross member 17, which is long in the vehicle width direction, are each bolted to a mounting member (not shown) on the bottom side of the vehicle body using a connecting member 18. As shown in FIG. 5, the left and right ends of the cross member 17 are provided with semi-trailing arms arranged in the longitudinal direction of the vehicle to support wheels at the rear and bifurcated at the front. That is, at this left and right end, there are a pair of external trailing arms (hereinafter simply referred to as external arms) 10 on the external side and the internal side (i.e., the vehicle side end side and the vehicle center side) and an internal trailing arm (hereinafter simply referred to as the internal side). (denoted as arm)1
Pivotally connect each rotation center of 3. On the other hand, external arm 1
A vehicle body frame 21, which is fixed to the bottom wall of the vehicle body and is long in the front-rear direction, is provided above the vehicle body frame 21. Note that, in FIG. 2, the left side of the vehicle body frame 21 has changed its position to the front of the external arm 10, and the right side has changed its position to the rear side of the external arm 10 from the front. Here, the cross member 17 has a cylindrical shape, and a torsion bar spring (hereinafter simply referred to as a torsion bar) 11 having a fixed end on the center side of the vehicle is fitted inside the cross member 17, and an outer arm rubber bush 19 is attached to the side end of the cross member 17. It is pivotally supported on the inner wall of the intervening cross member 17 (see FIG. 3).
A retainer 12 is attached to the tip end of the torsion bar 11 and is spline-coupled.
The entire outer periphery of the collar portion 121 is welded to the flat plate portion 101 on the rotation center side of the external arm 10. As shown in FIG.
is fixed to the rotating end of the The internal arm 13 is not perpendicular to the cross member 17 and maintains a predetermined cross angle α, thereby preventing the rear wheel 15 from swinging in the vehicle width direction. The rotation center side of the internal arm 13 is pivoted to the pivot member 171 of the cross member 17 via a long pin 20 (see FIG. 1) in the same direction as the longitudinal direction of the cross member 17, and the rotation end of the internal arm 13 is extends independently further rearward than that of the external arm to form a rigid plate portion 131, and a rear wheel 15 is pivotally connected to the external facing wall 14 of this rigid plate portion via a spindle (not shown).

An annular welded portion A is formed in the flat plate portion 101 of the external arm 10, and a long hole 16 as a stress relaxation hole is formed near the welded portion. This elongated hole 16 is a through hole and is formed obliquely below the rotation center O of the external arm 10, that is, approximately above the shape center l1 of the external arm 10. Moreover, the elongated hole 16 is formed long along an arc concentric with the retainer 12. Prior to the formation of this long hole 16, for example, the fourth
A stress distribution diagram of the welded portion A is obtained as shown by the broken line in the figure. As a result, the stress concentration area d with high stress is determined, and the direction θ _O corresponding to the center of the area (here, the direction of the horizontal line is set as zero and is about 45°) is determined.
Based on this data, the position of the elongated hole 16, that is, the position and length L that can cover the stress concentration area d are determined. Furthermore, the radius of curvature of the width x of the hole is determined by taking into consideration the fact that processing and stress concentration around the elongated hole 16 is prevented. Assuming that a perfect circular hole H corresponding to the elongated hole 16 is formed (indicated by a dashed line in FIG. The stress in the vicinity (shown as h) becomes high, which actually causes a decrease in strength, making it inappropriate to form this perfect circular hole H.

When the trailing rear suspension in which such a long hole 16 is formed in the outer arm 10 operates, the rear wheel 15 is moved between the pin connection point P1 of the inner arm 13 and the center point of the outer arm bush 19.
The axis L0 that connects P2 is used as the slow axis for vertical stroke operation (see Figure 5). Note that this oscillation axis
l _O and the axis of the torsion bar form a predetermined angle.
Therefore, during stroke operation, the external arm 10 transmits the spring force of the torsion bar 11 to the rear wheel 15, and at the same time is twisted around the action center line X in the θ _X direction by the reaction force from the rear wheel 15. At this time, stress approximately proportional to the stroke of the rear wheel 15 is generated in the welded portion A. Note that the stress distribution in this welded portion A is as shown by the solid line in FIG. 4. In this case, even if the part of the welded part A facing the elongated hole 16 receives an external force due to torsion in the _θ ) to reduce further. In other words, the portion facing the elongated hole 16 that receives the largest torsional force no longer receives much torsion in the _θ be done. As a result, the distribution of stress occurring in the welded portion A is averaged.

As described above, the trailing rear suspension according to the present invention curves the external arm 10 in order to improve the comfort of the rear passenger compartment.
By forming the elongated hole 16, stress concentration at the welded portion A with the retainer 12, which occurs due to the curvature of the retainer 12, is eliminated. Therefore, if the trailing rear suspension according to the present invention is used, the external arm 1
This external arm can be curved without reducing the durability of the welded portion A on the vehicle body, thereby making it possible to create a vehicle body that improves the comfort of the rear seats.

[Brief explanation of drawings]

Figure 1 is a perspective view of essential parts of a trailing rear suspension as an embodiment of the present invention, and Figure 2 is a perspective view of the main parts of a trailing rear suspension as an embodiment of the present invention.
A front view of the external arm in the figure, Fig. 3 is a side view of the main part of the torsion bar using the same trailing rear suspension as above, Fig. 4 is a diagram showing the stress distribution occurring in the welded part A on the external arm, Fig. 5 6 is a schematic plan view of a semi-trailing rear suspension, and FIGS. 6 and 7 are front views of different conventional external arms. 10... External arm, 11... Torsion bar, 12... Retainer, 121... Flange, 13...
...inner arm, 14...external facing wall, 15...rear wheel, 16...elongated hole.

Claims (1)

[Scope of utility model registration request] An external arm is arranged in the longitudinal direction of the vehicle to support the wheels at the rear, and the front part is bifurcated into two parts. The external arm has a flat plate part that is long in the longitudinal direction of the vehicle body with the plate surface in the up-down direction, and a circular ring-shaped part for connecting a torsion bar spring to the front end of the flat plate part. In a trailing rear suspension in which the outer periphery of the retainer is welded and the axis of the torsion bar and the swing axis of the wheel form a certain angle, the external arm is formed so that its center is curved downward. and a stress relief hole is formed in the vicinity of the welded portion with the retainer, and the stress relief hole is located on the center line of the longitudinal shape of the outer arm, rearwardly and downwardly of the retainer, and is approximately concentric with the retainer. A trailing rear suspension characterized by a long hole formed along an arc.