IMPROVEMENTS IN SUSPENSION SYSTEMS FOR MOTOR VEHICLES

Abstract: The invention relates to a suspension system for motor vehicles of the type including a transverse bar (8) connected at its ends to the central parts of two longitudinal arms (2), each of which is articulated at one end to the body of the motor vehicle about a transverse axis (4), and at its opposite end has a bearing (6) for a wheel. In this invention, the said transverse bar is constituted by a tublar component which has a substantially circular, open cross-section and is fixed at each end in a cooperating seat in the respective longitudi­ nal arm (2) by means of a series of radial bolts (14) which engage that part of the transverse bar (8) diametrally op­ posite the aperture in the bar itself. Within each end of the transverse bar (8) there is a tile-shaped locking element (17) provided with a series of nuts (18) which are engaged by the ends of the said radial fixing bolts (14). This tile-shaped ele­ ment which may, for example, extend through an angle of about 180°, has a cross-section the thickness whereof de­ creases progressively from its centre towards its ends. Thus the ends of the bar (8) are locked in the respective longitudi­ nal arms without causing discontinuous stresses in the bar itself.

Description: Improvements in suspension systems for motor vehicles The present invention relates to motor-vehicle suspension systems, of the type including: a pair of longitudinal arms, each of which is articulated at one end to the body of the motor vehicle about a transverse axis and at its opposite end has a bearing for a wheel, each arm having attachment means for a respective spring and a respective shock absorber, and a transverse bar rigidly fixed at its ends to the central partsof the two longitudinal arms. According to the conventional method, each longitudinal arm includes a central support which is generally made from welded sheet metal and has a relatively complicated structure. This central support is welded to the respective end of the torsion bar, which is also of sheet metal. The end portions of each longitudinal arm are constituted by two elements welded to the said central support on opposite sides thereof. The aim of the present invention is to create a suspension system of the type specified at the beginning of the present description which has a structure which is simpler, more reliable, less expensive and lighter than previous systems. The main characteristic of the suspension system according to the invention lies in the fact that the aforementioned transverse bar is constituted by a tubular component which has a substantiallycircular, open cross-section, and is fixed at each end within a cooperating seat in the respective longitudinal arm by means of a series of radial bolts which engage the zone of the transverse bar diametrally opposite the aperture in the bar, and in that, within each end of the transverse bar there is a tile-shaped locking element provided with a series of nuts which are engaged by the ends of the said fixing bolts, the said tile-shaped element having a cross section which decreases progressively in thickness from its centre towards its ends. As a result of the said characteristics, the transverse bar has the properties of flexural rigidity and torsional flexibility needed for the suspension to function properly and,at the same time, each end of the bar is locked correctly to the respective longitudinal arm without generating discontinous stresses in the bar itself. Further characteristics and advantages of the present invention will become apparent from the description which follows with reference to the appended drawings, supplied purely by way of non-limiting example, in which: Figure 1 is a schematic plan view of a suspension system according to the invention, Figure 2 is a section taken on line II of Figure 1, Figure 3 is a side view of the suspension system of Figures 1 and 2, Figure 4 shows, on an enlarged scale, a detail of Figure 2,and Figure 5 is a section taken on arrow V of Figure 3. In the drawings, reference numeral 1 generally indicates a rear suspension system for a motor vehicle with front-wheel drive. The suspension system 1 includes a pair of longitudinal arms 2 each of which has one end 3 articulated to the body of the motor vehicle' (not illustrated) about a transverse axis 4, and one end 5 furnished with a bearing 6 for a wheel 7 (illustrated in broken outline in the drawings). In the present description and in the following claims, the term "longitudinal" is used with reference to a direction parallel to the direction of forward movement of the motor vehicle, and the term"transverse" is used to mean a horizontal direction perpendicular to the said longitudinal direction. The longitudinal arms 2 can be made, in known manner, either by casting (from cast iron or light alloy) or by pressing (from steel or light alloy). The suspension system 1 also includes a transverse torsion bar 8 rigidly fixed at each end to a central part 9 of the respective longitudinal arm 2. Each longitudinal arm 2 also has a zone 10 for supporting a spring and a shock absorber which form part of the suspension. The transverse bar 8 consists of a tubular component, for example of light alloy,having a substantiallycircular open section (see Figure 5). The two longitudinal edges of the bar 8 defining the aperture therein extend the entire length of the bar and are indicated 8a. When the bar is assembled in a motor vehicle, the said aperture in the bar faces downwardly. As illustrated in detail in Figures 4 and 5, each end of the transverse bar 8 is fitted into a cylindrical seat 11 in the respective longitudinal arm 2, preferably with the interposition of a metal tube 12 closed at its outer end by a disc 13. In the embodiment illustrated, each end of the transverse bar 8 is locked in its seat 11 by three radially extending bolts 14. Each bolt 14 has a head 14a bearing,with the interposition of a washer 15, on the bottom of a respective seat 16 formed in the external surface of the longitudinal arm 2. Each bolt 14 passes through the wall of the longitudinal arm 2 defining the seat 11, the tube 12 and the transverse bar 8, at a point on the latter which is diametrally opposite the aperture in the bar itself. Within each end of the transverse bar 8 there is a tile-shaped locking element 17. To the internal surface of this element are welded three nuts 18 which are engaged by the bolts 14 so as to press the locking element 17 against the internal surface of the bar 8 so as to lock the latter in its seat. The tile-shaped locking element may extend through any angle but preferably extends through about 1800, as in the case illustrated in the drawings. The cross section of the tile-shaped element 17 has a thickness which diminishes progressively from its centre towards its ends (see Figure 5). Thus the bar is locked securely in its seat in the respective longitudinal arm without discontinuous stresses being generated in the bar. Whilst the motor vehicle is in motion, oscillations of the wheels 7 about the transverse axis 4 are permitted by the movements of the longitudinal arms 2 which cause the transverse bar 8 to bend and twist. The structure of the transverse bar described above allows the torsional and flexional characteristics of the bar to be varied during the design stage by variation of three parameters: the diameter of the bar, its thickness and the width of the aperture; allowing its use in various applications in the field of motor vehicles and light vehicles. Naturally, without altering the principle of the invention, constructional details and embodiments may be varied widely with respect to that described and illustrated, purely by way of example, without thereby departing from the scope of the present invention.

Claims: CLAIMS 1. Suspension system for motor vehicles, including: a pair of longitudinal arms (2), each of which is articulated at one end (3) to the body of the motor vehicle about a transverse axis (4), and at its opposite end (5) has a bearing (6) for a respective wheel (7), each longitudinal arm (2) also having attachment means for a spring and a shock absorber, and a transverse bar (8) rigidly fixed at its ends to the central parts (9) of the two longitudinal arms (2), characterised in that the transverse bar (8) is constituted by a tubular component with a substantially-circular open cross-section which is fixed at each end in a cooperating seat (11) in the respective longitudinal arm (2) by means of a series of radial bolts (14) which engage that zone of the transverse bar (8) diametrally opposite the aperture in the bar itself, and in that within each end of the transverse bar (8), there is a tile-shaped locking element (17) provided with a series of nuts (18) which are engaged by the said fixing bolts (14), the locking element (17) having a cross-section the thickness whereof decreases progressively from its centre towards its ends. 2. Suspension system according to Claim 1, characterised in that the tile-shaped locking element (17) extends through an angle of about 1800. 3. Suspension system according to Claim 1, characterised in that the axes of the fixing bolts (14) lie in the same radial plane which intersects the tile-shaped locking element (17) centrally. 4. Suspension system according to Claim 3, characterised in that, when fitted in a motor vehicle, that part of the transverse bar (8) which is engaged by the fixing bolts (14) is uppermost.

Inventors: MAY, PIER LUIGI
Applicants: FIAT AUTO S.P.A., TEKSID S.P.A.
Application year: 1984
Main classification: B60G21
IPC codes: B60G21