IMPROVEMENTS IN MOTOR VEHICLE SUSPENSIONS

Abstract: The invention relates to a motor vehicle suspension sys­ tem (1) of the type comprising a transverse bar (2) connected at its ends to the central parts of two longitudinal arms (4) each of which is connected at one end to the motor vehicle body and at its opposite end carries a mounting for a respec­ tive wheel (8). According to the invention, at least one end of the transverse bar (2) is located within a respective seat (10) in the corresponding longitudinal arm (4) with the interposition of a sleeve (11) of elastomeric material, the internal surface of the sleeve adhering to the transverse bar (2) and the external surface adhering to the surface of the seat (10) in the longitud­ inal arm, whereby, in use, the transverse bar (2) transmits torsion and resists bending. The sleeve (11) of elastomeric material may be provided at only one end of the transverse bar (2) (in which case the other end is fitted into a seat in the respective longitudinal arm) or at both ends. In the first case, the twisting moments about the axis of the transverse bar (2) caused by oscillations of the longitudinal arms (4) of the sus­ pension are discharged entirely, or at least substantially, by the single sleeve of elastomeric material. In the second case the twisting moments are discharged by the two sleeves (11) of elastomeric material, being divided between them.

Description: "Improvements in motor vehicle suspensions" The present invention relates to a suspension system for motor vehicles, of the type comprising a transverse bar connected at its ends to the central parts of two longitudinal arms each of which is connected at one end to the motor vehicle body and at its opposite end carries a mounting for a respective wheel, each longitudinal arm being further provided with means for the attachment of a respective spring and a respective shockabsorber forming part of the suspension In known suspension systems of the type specified above, the transverse bar is rigidly connected at its ends to the two longitudinal arms, whereby it is subject to resilient torsional deformations which are added to those due to bending. In order to allow the correct operation of the suspension, the transverse bar is consti tuted by ar. element with an open cross-section, which makes the manufacture )f the transverse bar relatively complicated and expensive and the fixing of the ends of the transverse bar (usually by welding) to the longitudinal arms complicated and expensive. The object of the present invention is to provide a suspension system of the type specified above which is simple and cheap to construct and assemble, and is highly reliable. In order to achieve this object, the invention provides a suspension system of the type specified above, characterised in that at least one end of the transverse bar is located within a respective seat in the corresponding longitudinal arm with the interposition of a sleeve of elastomeric material, the internal surface of the sleeve adhering to the transverse bar and the external surface adhering to the surface of the seat in the longitudinal arm, whereby, in use, the transverse bar is subject substantially solely to bending, the torsional movements produced by the suspension in use being absorbed by deformation of the elastomeric material. According to a first embodiment of the invention, the transverse bar has a sleeve of elastomeric material at only one end whereby, in use, the twisting moments about the axis of the transverse bar caused by the osscillations of the two longitudinal arms of the suspension are discharged entirely, or at least substantially, by the single sleeve of elastomeric material. In a second embodiment, the transverse bar has a sleeve of elastomeric material at both ends, whereby, in use, the twisting moments about the axis of the transverse bar caused by oscillations of the two longitudinal arms of the suspension are discharged entirely, or at least substantially, by the two sleeves of elastomeric material, being divided between them. A further characteristic of the suspension systemaccording to the invention lies in the fact that adjacent the ends of the or each sleeve of elastomeric material are located two annular supports which are interposed between the transverse bar and the respective seat in the longitudinal arm and prevent oscillations of the longitudinal arm about an axis perpendicular to the axis of the bar. This prevents any relative movements between the two 1 longitudinal arms, with the exception of rotations about the axis of the transverse bar. The two annular supports may be constituted, for example, by two plain bearings of a material with a low coefficient of friction (for example, plastics material), by two rolling bearings, or by any other solution adapted to allow the rotation of a longitudinal arm relative to the transverse bar with no, or at least very little, working clearance. In a preferred embodiment of the invention, the transverse bar is constituted by a circular-section tube of steel or light alloy (preferably made by extrusion). Further characteristics and advantages of the present invention will emerge from the description which follows with reference to the appended drawings, provided 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 illustrates a detail of the suspension system of Figure 1 in section and on an enlarged scale, and Figure 3 illustrates a variant of Figure 2. The drawings illustrate, by way of example, a rear suspension 1 for a front-wheel drive motor vehicle. The suspension 1 includes a transverse bar 2 constituted by a circular-section tube 2 of steel or light alloy (preferably made by extrusion), the ends 3 of which are connected (in a manner which will be described in detail below) to the central parts of two longitudinal arms 4 each of which has one end 5 articulated about an axis 6 to the body of the motor vehicle (not illus trated) and its opposite end 7 carrying the mounting for a respective rear wheel 8 of the motor vehicle. Each longitudinal arm 4 has means for the attachment of a suspension spring 9 and the respective shockabsorber Figure 2 illustrates, in section, one end 3 of the tube constituting the transverse bar 2 mounted within a seat 10 in the corresponding longitudinal arm 4 with the interposition of a rubber sleeve 11, of known type, having a tubular metal insert Ila (the metal insert lla is necessary in case the twisting moments which the sleeve 11 must transmit are high). The inner surface of the sleeve 11 adheres to the transverse bar 2 and its outer surface adheres to the surface of the seat 10. In the example illustrated, this is achieved simply by force-fitting the sleeve 11. The sleeve is interposed axially between two annular supports 12 which, in use, prevent oscillations of the longitudinal arm 4 relative to the transverse bar 2 about an axis perpendicular to the axis of the bar, and which are constituted by two rolling bearings of sealed type (to prevent grease from the bearings damaging the rubber of the sleeve 11). Instead of the rolling bearings 12, it is also possible to use plain bearings constituted by a material with a low coefficient of friction, for example, a plastics material, or metal rings provided internally with a wearresistant material. In the example illustrated the seat 10 in the longitudinal arm 4 housing the transverse bar 2 is constituted by a blind hole formed in this arm. However. it could also be constituted by a through hole closed at one end by a cover fixed to the longitudinal arm 4 by screws. The sleeve 11 of elastomeric material and the two annular supports 12 adjacent the ends thereof are locked between a shoulder 2a of the bar (which may also be constituted by ring welded to the bar) and a resilient ring 13 mounted on the end of the bar. The outer rings of the rolling bearings 12 bear respectively against an annular cover 17 fixed by screws 18 to the longitudinal arm 4 and a spacing ring 14 fitted fully into the seat 10. The cover 17 has an annular sealing washer 19 surrounding the bar 2. The two longitudinal arms 4 may be connected together by means of a tie rod 20. Each end of the tie rod 20 has a flanged element 24 fixed by screws 25 (for example, three screws at 120 ) to the end wall of the seat 10 in the arm 4. Thus, the twisting moments induced by oscillations of the longitudinal arms are also discharged by the tie rod 20. In a further embodiment of the invention, the sleeve 11 is not used and the twisting moments are discharged entirely by the tie rod 20. In the variant of Figure 3, the tie rod 20 has a grooved end portion 26 fitted for axial sliding movement in an internally-grooved ring 27 which is inserted in a hole 28 in the arm 4 and is provided with a flange 29 secured by bolts 30 to the arm 4. The tie rod 20 has a screw-threaded tang 31 on which an adjustment nut 32 is engaged. The sleeve 11 of elastomeric material may be pro vided at only one end of the transverse bar 2 or at both ends. In the first case, the twisting moments about the axis of the transverse bar 2 caused by oscillations of the longitudinal arms 4 about their axes of articulation 6 are discharged entirely, or at least substantially, by the single sleeve of elastomeric material. In the second case, these twisting moments are discharged by both the sleeves, being divided between them. The transverse bar may be formed of steel or light alloy. In the latter case, it is preferably made by extrusion. The structure described above has particular advantages of simplicity and economy of manufacture and facility and quickness of assembly. Since the twisting moments exerted on the suspension are discharged by each sleeve of elastomeric material, the transverse. bar has only to resist the bending forces and may. thus be formed from a tubular element, to the advantage of simplicity and economy.

Claims: CLAIMS: 1. Motor vehicle suspension system comprising a transverse bar (2) connected at its end to the central parts of two longitudinal arms (4) each of which is connected at one end to the motor vehicle body and at its opposite end (7) carries a mounting for a respective wheel (8), each longitudinal arm (4) being further provided with means for the attachment of a respective spring and a respective shock-absorber forming part of the suspension, characterised in that at least one end (3) of the transverse bar (2) is located within a respective seat (10) in the corresponding longitudinal arm (4) with the interposition of a sleeve (11) of elastomeric material, the internal surface of the sleeve adhering to the transverse bar (2) and the external surface adhering to the surface of the seat (10) in the longitudinal arm, whereby, in use, the transverse bar (2) is subject substantially solely to bending. 2. Suspension system according to Claim 1, characterised in that the transverse bar (2) has a sleeve (11) of elastomeric material at only one end, whereby, in use, the twisting moments about the axis of the transverse bar (2) caused by oscillations of the two longitudinal arms (4) of the suspension are discharged entirely, or at least substantially, by the single sleeve (11) of elastomeric material. 3. Suspension system according to Claim 1, characterised in that the transverse bar has a sleeve (11)of elas tomeric material at both ends, whereby, in use, the twisting moments about the axis of the transverse bar (2) caused by oscillations of the two longitudinal arms (4) of the suspension are discharged entirely, or at least substantially, by the two sleeves (11) of elastomeric material, being divided between them. 4. Suspension system according to Claim 1, characterised in that adjacent the ends of the or each sleeve (11) of elastomeric material are located two annular supports (12) which are interposed between the transverse bar (2) and the respective seat (10) in the longitudinal bar (4) and prevent oscillations of the transverse bar (2) about an axis perpendicular to the axis of the bar. 5. Suspension system according to Claim 4, characterised in that the two supports are constituted by two rolling bearings. 6. Suspension system according to Claim 4, characterised in that the two supports are two plain bearings (12) constituted by rings of a material having a low coefficient of friction. 7. Suspension system according to Claim 1, characterised in that the transverse bar (2) is constituted by a circular-section tube. 8. Suspension system according to Claim 1, characterised in that the transverse bar (2) is of steel. 9. Suspension system according to Claim 1, characterised in that the transverse bar (2) is of light alloy. 10. Suspension system according to Claim 1, characterised in that the transverse bar (2) is made by extrusion. 11. Suspension system according to Claim 1, characterised in that the two longitudinal arms (4) are connected together by means of a tie rod (20) located coaxially within the transverse bar (2). 12. Suspension system according to Claim 11 characterised in that each end of the tie rod (20) is connected to a respective longitudinal arm for rotation, whereby the twisting moments are discharged at least partly by the tie rod. 13. Suspension system according to Claim 1, characterised in that the seat for the transverse bar (2) in the longitudinal arm (4) is closed by an annular cover (17) screwed onto the longitudinal arm (4) and provided with an annular sealing washer which surrounds the transverse bar.

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