IMPROVEMENTS IN MOTOR VEHICLE SUSPENSIONS

Abstract: In a motor vehicle suspension of the type comprising two trailing arms (2) connected intermediate their ends by a cross member (3) which is resiliently deformable under torsion, the cross member (3) is fixed by bolts (11) or rivets to each of the two trailing arms (2). Preferably, the cross member (3) has a cross-section substantially in the form of an inverted V and has end portions each of which has a flat rebated upper sur­ face in which holes for engagement by the bolts of rivets are formed, each flat surface being located close to the neutral axis of the V section, In a preferred embodiment, a layer of adhesive (21) is interposed between the coupling surfaces of the trailing arms (2) and the cross member (3),

Description: The present invention relates to motor-vehicle suspensions of the type indicated in the pre-characterising portion of the attached claim 1. A suspension of this type is known from EP-A-0 133 829. This known suspension has a torsion bar connecting the two trailing arms, a further torsion bar, and a cross-member which also connects the two trailing arms to each other. This cross-member has its end portions welded to the trailing arms and has a V-shaped cross-section with its cavity facing substantially forwardly of the vehicle. The object of the present invention is to provide a suspension of the type specified above which has a simple and reliable structure, while at the same time being easy and cheap to manufacture. The main characteristic of the suspension according to the invention is indicated in the characterising portion of the attached claim 1. By virtue of this characteristic, the welding operation which is necessary in the suspension of the prior art is avoided, so that assembly of the suspension is easy and economic. Moreover, due to the location of the flat rebated surfaces of the cross-member in sensible proximity to the neutral axis of the V section, the forces to which the bolts or rivets are subject as a result of resilient torsional deformations of the cross-member during movement of the motor-vehicle are considerably reduced. Furthermore, in a preferred embodiment, the two trailing arms are each constituted by two sheet metal half-shells having coupling surfaces welded together and having holes for engagement by the bolts or rivets. Preferably, a layer of adhesive is also interposed between the coupling surfaces of the trailing arms and the ends of the cross member in order to improve the strength of structure. Further characteristics and advantages of the invention will become apparent 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 partial perspective view of a motor vehicle suspension according to the invention, Figure 2 is an exploded perspective view of the suspension of Figure 1, and Figure 3 is a sectional view taken on the line III-III of Figure 1. The drawings illustrate, by way of example, a rear suspension 1 for a front-wheel-drive vehicle including two identical trailing arms 2 (only one of these arms is illustrated in the drawings) connected together at their intermediate zones by a cross member 3 which is resiliently deformable under torsion. Each arm 2 carries a bush 4 at one end for articulation to the body of the motor vehicle and a mounting 5 at its other end for the respective wheel. In the embodiment illustrated, the structure of each arm 2 is constituted by two sheet metal half-shells 6,7 (Figure 2) welded together along coupling surfaces constituted by longitudinal lateral flanges 6a, 7a. The two sheet metal half-shells 6, 7 are also welded to the wheel mounting 5, the bush 4 for articulation to the body, as well as an auxiliary member 8 having an upwardly-projecting frusto-conical portion 9 which is welded to a flat surface 6b of the upper element 6 of each arm 2. The appendage 9 is provided for centering the suspension spring associated with each arm 2. In a conventional manner, each of the two trailing arms also has an associated shock absorber. The cross member 3 is constituted by an elongate sheet metal element having a cross-section substantially in the form of an inverted V with a flat rebated upper surface 10 at each end (Figure 2 illustrates only one end of the cross member 3, the opposite end being identical). According to the invention, each end of the cross member 3 is connected to the respective trailing arm 2 by bolts or rivets. The embodiment illustrated relates to the case in which the connections are achieved by three screws 11 which engage holes 12, 13, 14 (Figure 2) formed in the respective coupling surfaces 6a, 7a and 10 of the two half-shells 6, 7 constituting each trailing arm 2 and of the cross member 3. The flat surface 10 is located sensible on the neutral axis 15 (Figure 2) of the cross-section of the element 3 so as to reduce considerably the forces to which the connecting members are subject as a result of the torsional resilient deformations of the cross member 3 which occur when the two trailing arms 2 oscillate differently. The coupling surface of the lower half shell 7 of the arms 2 and the coupling surface 10 of the cross member 3 also have dished portions 16, 17 which cooperate with each other to facilitate the correct coupling of the elements. The screws 11 cooperate with bolts 18 which bear against the lower surface of the cross member 3 with the interposition of a plate 19 and a washer 20. It is clear, however, that these constructional details could be varied widely with respect to that described and illustrated purely by way of example. Again in the embodiment illustrated, a layer of adhesive 21 is interposed between the coupling surfaces of the lower half-shell 7 of the arm 2 and the cross member 3, which improves the strength of the structure. By virtue of the characteristics described above, the suspension according to the invention has a simple and reliable structure which at the same time is easy and cheap to manufacture, particularly compared with known solutions in which the fixing is achieved by welding of the cross member 3 to the two trailing arms 2. Naturally, the principle of the invention remaining the same, the forms of embodiment and details of construction may be varied widely with respect to that described purely by way of example, without thereby departing from the scope of the present invention, as defining by the claims.

Claims: 1. Motor-vehicle suspension of the type including a pair of trailing arms (2) articulated at one of their ends to the body of the motor-vehicle and carrying wheel mountings (5) at their opposite ends, and a cross-member (3) constituted by an elongate sheet metal element with a V-shaped cross-section, which is resiliently deformable under torsion and interconnects the intermediate zones of the two arms (2), each arm (2) being provided with means (8,9) for supporting a respective spring and a respective shock absorber, wherein the cross-member (3) has end portions each with a flat upper surface (10) fixed to the respective trailing arm (2), characterised in that said cross-member (3) is the only existing connection between the two trailing arms (2) and is arranged with the cavity of its V-shaped cross-section facing downwardly, said upper surface (10) of each end portion of the cross-member (3) being a rebated surface located sensibly on the neutral axis (15) of the V section, said end portions being fixed to the trailing arms (2) by bolts or rivets (11, 18) engaging holes (14) formed in said flat rebated upper surface (10). 2. Suspension according to Claim 1, characterised in that each of the two trailing arms (2) is constituted by two sheet metal half-shells (6, 7) having coupling surfaces (6a, 7a) welded together and having the holes (12, 13) for engagement by the bolts (11, 18) or rivets. 3. Suspension according to Claim 2, characterised in that a layer of adhesive (21) is interposed between the coupling surfaces of the trailing arms (2) and the cross member (3). 4. Suspension according to Claim 1, characterised in that the said flat surface (10) of the cross member and the corresponding coupling surface of the respective trailing arm (2) have dished portions (16,17) which cooperate with each other to facilitate the correct coupling of these elements.

Inventors: DI GIUSTO, NEVIO, GANDIGLIO, ROMOLO
Applicants: FIAT AUTO S.P.A.
Application year: 1987
Main classification: B60G21
IPC codes: B60G7, B60G21