DE4021569A1 - Wheel; suspension system for vehicle - is formed as parallelograph to improve drive characteristics - Google Patents

Abstract

The wheel suspension system is for a vehicle. It has two elastically mounted rigid connecting arms (16,18) with a flexible cross strut (24) arranged in between. A second cross strut (34) having a smaller bending moment is rranged in front of the first strut in the sense of the direction of travel (X) to form a parallelogram with the connecting arms and the first strut. USE/ADVANTAGE - Suspension system which gives improved elasto-kinematic behavious, esp. when negotiating curves.

Description

The invention relates to a wheel suspension for motor vehicles according to the Preamble of claim 1.

Such wheel suspensions are used as torsion beam axles (e.g. book "Chassis technology: basics", J. Reimpell, Vogel-Verlag Würzburg 1986, Pages 59 ff.) And have become familiar with vehicles of the A and B class proven many times over; they are characterized by a simple robust con structure with favorable kinematic properties.

To reduce the tendency to curl, especially in sporty designs Chassis it is also known to stabilize the Ver Bundlenker axles by inserting an additional torsion bar reinforce (see above book, page 19). The torsion bar is there within the cross-sectional profile of the cross strut.

To specifically influence the self-steering behavior when driving through curves rivers, lane-correcting camps have also been proposed (cf. Book, page 61), the side forces on the wheels in particular one Counteract oversteer.

The object of the invention is to provide the generic wheel suspension means with regard to their elastokinematic behavior especially when driving through bends.

This object is achieved with the characterizing features of claim 1 solved. Advantageous and expedient next Formations of the invention can be found in the further claims.  

Through the measures according to the invention, a kind of handlebar parallelo created grams, formed from sections of the trailing arm, the cross strut and the second strut, which has the kinematic properties the suspension so influenced that, for example, an oversteer is reduced when cornering. This is achieved on the one hand by the stiffening effect of the "parallelogram" because whose nodes are fixed connections that frame the axis stiffen the composite. In addition, there is an opposing inclination between cross strut and strut that determine the elastokinematic behavior or affects the self-steering behavior of the axle favorably and in particular counteracts the "going into lane" of the wheel on the outside of the curve. The corrective tracking behavior can be determined by the ratio of Ab stands between cross strut and second strut or preferably at one Execution according to claim 2 by the ratio of the distances Lenkerla ger to cross strut and handlebar bearing to be adjusted to the second strut.

The second strut can also be advantageous if appropriately designed act as an additional stabilizer, so that starting from a wheel suspension with additional stabilizer either omitted and can be replaced by the second strut, whereby the invention almost without additional effort, or a second additional stabilizer is created.

The second strut is preferably according to claim 3 in the vicinity of the elastic the bearings of the trailing arms arranged so that they turn in slants to a lesser extent than the cross strut. This allows the second strut next to the occurring torsion without problems and in the frame whose elastic deformation absorb the bending moments that this embossed due to the inclined position of the rigid cross strut will.

Although the strut in the context of the requirements of claim 1 is an arbitrary may have cross-sectional profile, e.g. B. C, V or U-shaped, or a preferably flat spring leaf can be (high transverse rigidity with a relatively low bending moment when tilted in curves)  a torsion bar is proposed according to claims 4 to 6, which by Welding, or preferably by screwing, simple and in this form has been tried and tested as a stabilizer.

Several embodiments of the invention are in the following with wide ren details explained. The schematic drawing shows in

Fig. 1 is a plan view of a wheel suspension for a motor vehicle comprising longitudinal arms, which are interconnected by a transverse strut and a second strut,

Fig. 2 is a view according to arrow X of FIG. 1 on the wheel suspension, and

Fig. 3 is a side view of the wheel suspension according to Fig. 1;

Fig. 4 is a further plan view of a suspension system similar to FIG. 1, but with a greater distance between the handlebars and second bearings strut

Fig. 5 again shows a view X of Fig. 4,

Fig. 6 is a side view of the wheel suspension according to Fig. 4;

Fig. 7 is a plan view of the construction of a partially shown wheel suspension according to FIG. 1 with a screwed second strut.

Fig. 1 shows a sketch of a wheel suspension 10 for the rear, non-driven wheels 12 , 14 of a motor vehicle, not shown, with a left and a right trailing arm 16 , 18, which at L ₁ and L ₂ via elastic bearings 20 , 22 on Structure are hinged.

The trailing arms 16 , 18, which are rigid in construction, are firmly connected to one another via a torsionally rigid, rigid cross strut 24 , with gusset plates 26 , 28 ensuring a rigid connection. The cross strut 24 may have a C, V or U-shaped cross-sectional profile; it is designed in such a way that it can absorb the bending forces and moments exerted by the trailing arms without damaging deformation. The connection points between the trailing arms 16 , 18 and the cross strut 24 are designated A ₁ and A ₂ .

At C ₁ and C ₂ axle journals 30 , 32 are attached to the free ends of the trailing arms 16 , 18 and support the wheels via corresponding roller bearings.

In the direction of travel (arrow X), a second strut 34 is arranged in front of the link bearings L ₁ and L _{2, which} is firmly connected to sections of the trailing arms protruding beyond the link bearings L ₁ , L ₂ . The strut 34 is formed by a round cross-section, full torsion bar made of spring steel. The connection points between the second strut 34 and the trailing arms 16 , 18 are denoted by S ₁ and S ₂ .

The suspension 10 described acts when the wheels 12 , 14 deflect on the same side as a rigid axle, the pivot axis 36 of which runs through the bearing points L ₁ , L ₂ . Track and camber changes do not occur.

When the wheels 12 , 14 reciprocate, the wheel suspension 10 acts like a semi-trailing arm axis, the pivot axis of which runs in each case approximately through a bearing point L ₁ or L ₂ and through the center of thrust (see dashed line 38 ) of the cross strut 24 .

Passes the motor vehicle, for example, a right turn, so the trailing arms 16 , 18 as ge as shown in Figures 2 and 3 shows ge. For the sake of better illustration, however, it is not the curling tendency of the structure that is drawn, but the road line 40 is laid at an angle.

When driving through this right turn occur on the wheels 12 , 14 side forces (arrows 42 ), the wheel suspension 10 due to the elasticity of the bearing points L ₁ , L ₂ and due to the inevitable elasticity in the axle assembly (trailing arm 16 , 18 , cross strut 24 ) brace in the sense of an oversteering tendency or generate a corresponding self-steering movement of the wheels 12 , 14 .

This tendency counteracts the second strut 34 , which also acts as a stabilizer. In addition to the stiffening effect, the second strut 34, together with the cross strut 24 and the intermediate sections of the trailing arms 16 , 18, forming a type of stiff parallelism of the handlebars, the strut 34 is less inclined than the cross strut 24 (see FIG. 2 or in FIG. 3, the distance between the points A _1, A ₂ at points S _1, S _2). This different inclined position of the two struts 24 , 34 causes a targeted self-steering on the trailing arms 16 , 18 or a toe in the wheel suspension 10th In particular, the inside wheel 14 now exerts an understeering tendency, while the outside wheel 12 is deflected slightly in the oversteering sense, but this self-steering movement is far less than with a comparable wheel suspension 10 without the second strut 34 .

The self-steering movements can be seen in FIG. 1 in comparison to the dash-dotted lines 44, 46 , which represent the structural position of the wheels 12 , 14 in the unloaded state. The tendency of the structure of the motor vehicle to curl is determined by the stabilizing effect of the cross strut 24 and by the stabilizing effect of the second strut 34 . The suspension provided between the structure and the wheels is not shown in the exemplary embodiment. While the cross-member 24 is flexurally stiff, the strut 34 and the torsion bar, a relative to the strut 24 reduced bending moment on, so that defined at wech selseitigem springs of the wheels 12, 14 of the camber of the wheels 12, 14 solely by the cross brace 24 .

FIGS. 4 to 6 show a substantially same wheel suspension 10 '(like features are provided with the same reference numerals), in which compared to Fig. 1 to 3, the distances between the La gerpunkten L _1, L ₂ of the trailing arms 16' , 18 'to the attachment points S ₁ , S _{2 of} the second strut 34 ' and the distances between the bearing points th L ₁ and L ₂ and the attachment points A ₁ , A _{2 of} the cross strut 24 'are changed. Thus, the sections of the trailing arms 16 ', 18 ' in the direction of travel (arrow X) before the bearing points L ₁ , L _{2 are} extended, so that the distances between L ₁ and S ₁ or L ₂ and S _{2 are} increased while the distances between L ₁ and A ₁ or L ₂ and A _{2 are} shortened.

This in turn causes a right turn with corre sponding lateral forces (arrows 42 ) on the wheels 12 , 14 and a corresponding roll tendency of the structure of the motor vehicle a larger inclination of the second strut 34 '(see. Figs. 2 and 5) and a ver wrinkled inclination of the cross strut 34 '. This results in a converging position of the trailing arms 16 ', 18 ' in the direction of travel or a toe-in of the wheels 12 , 14 , so that now the outer wheel 12 causes a significant understeer tendency of the wheel suspension 10 '. This is shown in FIG. 1 again in comparison with the dash-dot lines 44, 46 representing the construction position.

Fig. 7 shows a more detailed, but only partially shown se wheel suspension 10 '', which corresponds in principle to the wheel suspension shown in Figs. 1 to 3. The cross strut 24 '' is welded to the only partially shown, left trailing arm 16 '', the gusset plate 26 '' ensuring a rigid connection. The trailing arm 16 '' is pivotally held in a bracket 50 via the elastic bearing 20 '', the bracket 50 being welded to the body of the motor vehicle, not shown. The bearing 20 '' is a rubber-metal bearing that is composed of an inner sleeve 52 , an outer sleeve 54 and an intermediate rubber elastic ring 56 . The bearing 20 '' is formed as a so-called track-correcting bearing, as described, for example, in the book mentioned at the beginning, page 61. The in the longitudinal arms 16 '' inserted bearing 20 '' is held by a fastening screw 58 in the bracket 50 .

On the front 60 in the direction of the trailing arm 16 '', the torsion bar 34 '' is fastened as a second strut by means of one or more screws 62 . The screw 62 is, a flattened end of the strut 34 '' penetrating, screwed into an internal thread on the end face 60 . The right side, not shown, of the wheel suspension 10 '' can be imagined as a mirror image.

Claims (6)

1.Wheel suspension for motor vehicles, with two rigid trailing arms elastically articulated on the body, which carry axle journals for the wheels at their free ends, and with a torsionally soft, flexurally rigid cross strut, which is rigidly corner rigid between the bearing points of the trailing arms on the body and the axles the trailing arms is connected, characterized in that in the direction of travel in front of the cross strut ( 24 ) and at a distance from this a second, torsionally soft and less bending moment strut ( 34 ) is arranged, which with the first cross strut ( 24 ) and the trailing arms ( 16 , 18 ) forming a parallelogram is firmly connected to the trailing arms ( 16 , 18 ). 2. Wheel suspension according to claim 1, characterized in that the second strut ( 34 ) in the direction of travel in front of the bearings ( 20 , 22 ) of the trailing arms ( 16 , 18 ) is arranged on the body. 3. Wheel suspension according to claim 1 or 2, characterized in that the second strut ( 34 ) is arranged close to the bearing points of the trailing arms ( 16 , 18 ) on the body. 4. Wheel suspension according to one or more of claims 1 to 3, characterized in that the second strut ( 34 ) is formed by a rotating rod. 5. Wheel suspension according to one or more of the preceding Ansprü surface, characterized in that the second strut ( 34 ) is screwed at its ends to the trailing arms ( 16 , 18 ). 6. Wheel suspension according to one or more of claims 1 to 5, characterized in that the strut ( 34 ) on the lying in the direction of the motor vehicle free end faces ( 60 ) of the longitudinal link ( 16 , 18 ) is screwed.