GB2110999A

GB2110999A - Vehicle suspension element

Info

Publication number: GB2110999A
Application number: GB08137293A
Authority: GB
Inventors: Vittorio Donn; Osvaldo Fasano
Original assignee: RIV SKF Officine di Villar Perosa SpA; RIV Officine di Villar Perosa SpA
Current assignee: SKF Industrie SpA
Priority date: 1981-12-07
Filing date: 1981-12-10
Publication date: 1983-06-29
Also published as: FR2518935A1; DE3148388A1

Abstract

A suspension comprising an elastically deformable element (1) is described, this is provided with a first beam (2) disposed transversely to the chassis and a pair of second beams (3) each of which projects from one end of the first beam (2), and a connection element (31) fixed to the said second beams (3) and operable to transmit the displacement of each of these latter to the other. <IMAGE>

Description

SPECIFICATION A suspension for the wheels of a vehicle The present invention relates to a structurally simple and compact suspension for the wheels of a vehicle, which is able to store a high elastic potential energy and is provided with other favourable properties which can contribute to significantly improving the road holding and the comfort of the ride of the vehicle.

As is known, suspensions of conventional type normally comprise assemblies of springs of various types, such as semi-elliptic, cylindrical helix or tosion bar types, with which there are usually associated systems of levers which are variously connected together and operable to support the stub axle of the wheel and to allow this to move in a predetermined manner with respect to the chassis of the vehicle.

Conventional suspensions of the indicated type have numerous disadvantages.

Firstly, these are constructionally rather complex both because of the type of springs with which they are provided and the required method for their assembly into the suspension, but also, above all, because of the presence of the said systems of levers which, in particular in the case of the steering wheels of the vehicle, constitute the actual linkage which is operable to guide the displacements of the stub axle of the wheel in the most correct manner possible with respect to the chassis.

Moreover, such suspensions are rather bulky due to the dimensions both of the springs and of some of the parts of the above mentioned lever systems, and these therefore pose not insignificant problems for their housing. Again, in many cases, the elastic potential energy which can be stored in the springs of the suspension is not very great with the consequence of having little comfort in the ride. Finally, whenever it is desired to adjust the position of the wheels with respect to the vehicle's chassis, for example to adjust the distance of the axes of these from the chassis itself, it is necessary to perform suitable adjustments on the said lever systems with the consequence of also varying the wheel geometry.It is, in fact, known that an adjustment performed for varying the distance of a wheel from the chassis can give rise to different angles of camber and toe-in of the wheel from those which the wheel had before the adjustment.

The object of the present invention is that of providing a structurally simple and compact suspension for the wheels of a vehicle, which will be free from the above mentioned disadvantages.

The suspension of the invention is characterised by the fact that it comprises at least one elastically deformable element provided with a first elastically deformable beam which can be arranged with its axis transversely with respect to the vehicle's chassis, a pair of second elastically deformable beams each of which projects from a corresponding end of the said first beam and has an axis which forms with the axis of this latter an angle greater than or equal to 900 and which can support at its end the stub axle of a wheel, the said first elastically deformable element being connected to the chassis of the vehicle substantially by means of a fixed coupling between the said chassis and a central region of the said first beam and substantially by means of pivots disposed between the said chassis and at least a pair of end regions of the said first beam, a connection element acting mechanically to connect two corresponding regions of the said second beams or the ends of the said first beam, the said connection element substantially comprising a third beam the axis of which is substantially parallel to that of the said first beam in such a way that a load applied to the axle of one of the said wheels causes a substantially flexural deformation of the associated second beam and a substantially torsional deformation of the section of the said first beam lying betwee the second beam and the said central region of the first beam, and such that the said connection element tends substantially to transmit to the other second beam the same flexural deformation which the said loaded second beam experiences.

For a better understanding of the structural characteristics of the present invention and of the advantages which derive from it, several embodiments of the invention will now be described with reference to the attached drawings in which: Figure lisa schematic plan view of the suspension of the invention, corresponding to a first embodiment thereof; Figure 2 is a section of the suspension of Figure 1, taken on the line ll-ll, in which it is illustrated in different configurations; Figure 3 is a section of the suspension of Figure 1, taken on the line Ill-Ill; Figure 4 is a plan view of a part of a second embodiment of the suspension; Figure 5 is a plan view of a constructional detail of the suspension; Figure 6 is a section of the detail of Figure 5, taken on the line VI-VI;; Figure 7 is a partially sectioned side view of a part of the suspension of the invention utilised for the support of the steering wheel.

The suspension of the invention comprises at least one elastically deformable element, generally indicated 1, which is substantially constituted by a first beam 2 the longitudinal axis of which is disposed substantially transversely with respect to the vehicle, that is to say in a direction orthogonal to that along which the vehicle itself moves; this element is further constituted by a pair of second beams 3 each of which projects from a corresponding end of the first beam 2 and has an axis which forms an angle which is greater than or equal to with the axis of the first beam as is clearly seen in Figure 1 which is a plan view from above of the said deformable element.Conveniently, as has been illustrated in this Figure, the axis of each beam 3 forms an angle of substantially 45" with that of the beam 1. Each of the said beams 2 and 3 has a substantially rectangular section and, therefore, this element is in reality, constituted by an assembly of three plates disposed in such a way as to form a U; the width in plan of each beam 3 can reduce gradually from the region of attachment with the beam 2 towards its free end 4 to which there can be connected, in any convenient manner, the stub axle 5 for a wheel.

The elastically deformable element 1 is connected to the vehicle chassis by means of a fixed coupling between the central region 6 of the first beam 2 and a suitable attachment region 7 (Figure 3) of the chassis itself. This fixed attachment can be formed in any manner whatsoever, for example by means of a support 8 of a type such as that of the embodiment illustrated in Figures 1,3 and 4, comprising a pair of small plates 9 and 10 between which the central region 6 of the first beam 2 is clamped by means of captive bolts 13 (Figure 13) which simultaneously fix the small plates themselves to the attachment region 7 of the chassis.

For a purpose which will be illustrated further below, the support 8 is conveniently provided with means for allowing the adjustment of the distance between the support itself and the chassis, which, in the illustrated embodiment, comprise a pair of abutment seats 14 and 15formed in the small plate 10, the first of which is substantially turnable about an axis parallel to that of the beam 2 (orthogonal to the plane of the drawing of Figure 3) and the second of which can be suitably spaced from the attachment region 7, for example by means of adjustment spacers 16. Conveniently, for a correct positioning between the elastically deformable element and the support a locating peg or pin 17 can be provided.

The elastically deformable element is moreover connected to the chassis by means of a pair of pivots which can be of the spherical type as has been illustrated in the embodiment of Figures 1,2,4 and 7, for cylindrical as has been illustrated in the embodiment of Figures 5 and 6. In the first case, each of these, indicated 18, is operable to connect one end of the first beam 2, to the chassis; as is clearly seen in Figure 2 it can be constituted by a pair of resilient bushes 19, 20 made of a deformable material for example rubber, each of which has a spherical surface 23.The bush 19 is provided with an annular projection 24 which can be inserted into a corresponding hole in the first beam 2, and a captive bolt (stud) 25 locks the said bushes to a region 26 (Figure 2) of the chassis, in this way constituting a ball joint forthefirst beam 2.

In the second case, that is to say in which the said pivots are cylindrical, each of these comprises a support 27 (Figures 5 and 6) fixed to the chassis and substantially defining a seat into which there is introduced an axial projection 28 (Figure 5) of the first beam 2; between this latter and the said seat there is arranged a filling 29 (Figure 6) of a resiliently deformable material, for example rubber.

The suspension further includes a connection element 31 operable mechanically to connect together tvvo corresponding regions 32 (Figure 1) of the second beams 3, or else the two ends of the first beam 2, and which serves to transmit, to a certain extent and in a manner which will be described, the deformation which has been produced in one of the said regions (or ends) to the other. This connection element 31 substantially comprises a third beam 33 (Figures 1 and 3) and a pair of arms 34, each of which projects from one end of the beam itself.As is clearly seen in Figures 1 and 3, the sections of the third beam 33 and the associated arms 34 are conveniently rectangular and the form and dimensions of these are chosen in such a way that the connection element defined thereby also has a U-shape form and the said arms can be substantially superimposed, in plan, on the corresponding second beams 3.

Each arm 34 of the connection element 31 is rigidly connected, in any convenient manner, with a region of a corresponding second beam 3; in the case of the illustrated embodiment, the end of each arm 34 (Figure 3) is connected at the free end to a corresponding second beam 3 by means of a sleeve 35 formed of the same plate of which both the elastically deformable element 1 and the connection element 31 are made, which in this case are obtained from a single sheet metal blank; the sleeve 35 can be conveniently utilised, by means of the interposition of a bush 36 of deformable material (Figure 1) for the support of the end of an axle 37 provided with supports 5 for the wheels.

In this constructional arrangement, between the second beams 3 and the associated arms 34 there is positioned a pad 38 of deformable material having its upper and lower surfaces 42,43 connected, in any way, to the corresponding surfaces of the beams and the arms; if the material of such pads is rubber the said connection can be made by means of vulcanisation.

The connection between the beams 3 and the arms 34 can be made in a different manner from that described, for example as in the embodiment of Figures 4 and 7 in which the elastically deformable element 1 and connection element 31 are made from two different blanks. In this constructional arrangement, which is particularly suitable for the support of the vehicle's steering wheels, between each second beam 3 and the associated arm 34 (Figures 4 and 7) there is interposed a further beam 44 which is fixed to the previously mentioned beams, for example by means of rivets 45.

In this case a projecting part 46 (Figure 7) of the beam 44 serves as an attachment for a ball joint 47 connected to one end of a shock absorber 48 the other end of which is connected, with the interposition of resilient washers 49, to the chassis; the stub axle 50 for a wheel is rigidly connected to the said shock absorber.

The behaviour of the suspension in operation is as follows.

When there is no load applied to the elastically deformable element 1, it can be supposed to assume the configuration indicated A in Figure 2, that is to say in which each second beam 3 has an initial flexural deformation and the angular position of each beam 2 has been adjusted with respect to the chassis (by adjusting the adjustment spacers 16) in such a way as to bring the path of the axis 0 of the stub axle 5 of the wheel to a lowermost position (indicated A) with respect to that which it adopts when the weight of the vehicle acts on the suspen sion.Therefore, when only such weight acts on the suspension, this weight, by acting on the end of each second beam 3 flexurally deforms it and simultaneously generates a torsional moment (equal to the product of the force exerted by the weight and the distance of this force from the longitudinal axis of the first beam 2) on each section of beam 2 which lies between the end of the beam itself and the support 8, which causes a rotation of the said end with respect to the support which constitutes a fixed mounting for the beam.

In these conditions the elastically deformable element 1 assumes a configuration indicated B in Figure 2, that is to say in which the axis 0 of the stub axle of the wheel rises to a predetermined position above the preceding one.

The force applied in use to the free end of each beam 3 increases the flexural and torsional deformations respectively of the beams 3 and 2, giving rise to the deformation indicated C in Figure 2, in which the said axis is located in an even higher position.

Although each beam 3 undergoes a substantially flexural deformation under the action of the force applied at the free end, it is however apparent that in each section thereof a torsional moment acts so that, therefore, this beam also deforms under the action of such stress; this platter, and therefore the associated deformation, is greater the larger the angle formed by the axis of each beam 3 with the longitudinal axis of the beam 2.

It is evident that the spherical hinges 18, or the cylindrical hinges 21, do not put any restraint on the torsion of the beam 2; this can be seen, in fact, in Figures 2 and 6; because of the spherical surfaces 23 of the bushes 19 and 20 (Figure 2) the free rotation of the ends of the beam 2 between the surfaces themselves is allowed, or else, because of the deformability of the filling 29 (Figure 6) the rotation of these ends within the support 27 is allowed.

During the said deformation of the elastically deformable element 1, the connection element 31 performs the function which in a normal suspension is performed by the so-called "torsion bar", which as is known, has the purpose of transmitting to the support members of one wheel at least part of the vertical displacement which is experienced by the other. In fact, the third beam 33, which connects the regions 32 of the beams 3 is able to perform the said function because this beam behaves substantially as a rigid (or slightly elastic) cross piece so as to transmit both displacements of one beam 3 to the other and reaction forces with the chassis through the pivots 18.

In the embodiment of the suspension of Figures 1, 2 and 5, the corresponding arm 34 of the connection element 31, which also deformsflexurally, can obviously contribute to the support of the loads which act on each beam 3; the rubber pad 38 itself also cooperates in the deformation since, as is seen in the deformation position C of Figure 2, forces of opposite sense (in the directions of the arrows of Figure 2) act in the plane of the principal faces thereof, which forces exert a shear stress and deformation on it. This pad therefore tends to bias each beam 3 towards the initial configuration of Figure 2.

An entirely similar behaviour to that described is seen in the suspension of the embodiment of Figure 7, which is envisaged for the support of steering wheels, in this case, in which there is a construction arrangement substantially according to the Mac Pherson scheme, displacements of the end 46 of each beam 44 are experienced, and therefore corres ponding displacements of the ball joints 47 of the shock absorbers 48 occur.

When it is desired to vary the trim of the wheels with respect to the chassis, for example by increas ing the distance of the wheels from the chassis to satisfy different requirements depending on the operating conditions, it is sufficient to vary the adjusment of the support 8. For this purpose it will be sufficient, after having released the studs 13, to make the plate 10 turn about the axis of the abutment seat 14 and vary the height of the adjust ment spacers 16; it is apparent that by pre-arranging suitable different adjustment means, possibly driven by a servo mechanism, such operation can be effected with notable simplicity and speed, or absolutely in an entirely automatic manner.

It is however important to note that the adjustment of the trim which can be obtained with the suspension of the invention does not give rise to any undesirable variation in the wheel geometry (such as variations in the chamber or toe-in) which have occurred whenever the configuration of the normal wheel support linkages associated with suspensions of conventional type have been altered even slightly.

The variation in the trim described only produces slight displacements, in the same sense, of the front and rear axes of the wheels in the direction of movement of the vehicle, which obviously do not have any influence on the said geometry.

The suspension of the invention which has been described therefore offers numerous advantages with respect to conventional suspensions. First of all, its significant constructional simplicity, which can be obtained substantially from a single sheet steel blank (that of Figure 1) in which all the fundamental parts of the suspension are incorporated (elastic elements, "torsion bar", attachments for the wheels). Then, the considerable capacity to store elastic potential energy, due to the rational exploitation, from the point of view of the elasticity, of the various parts with which it is constituted; in fact, elastic potential energy is stored not only by flexural deformation of some of the parts thereof, such as the beams 3, but also by torsional deformation of parts (the beam 2) disposed transversely with respect to the chassis of the vehicle. Moreover, the possibility of varying the trim of the wheels with respect to the chassis in a simple and rapid manner, without deleteriously affecting the geometry of the wheels themselves is a further advantage.

It is evident that, as well as other obvious variations, the suspension described can also include several deformable elements 1 superimposed in such a way as to form a stack.

Claims

1. A suspension for the wheels of a vehicle, characterised by the fact that it comprises at least one elastically deformable element provided with a first elastically deformable beam which can be disposed with its axis transversely with respect to the chassis of the vehicle, a pair of second elastically deformable beams each of which projects from a corresponding end of the said first beam and has an axis which forms an angle equal to or greater than 90" with the axis of this latter and is able to support at its end the stub axle for a wheel, the said first elastically deformable element being connected to the chassis of the vehicle substantially by means of a fixed coupling between the said chassis and the central region of the said first beam and substantially by means of pivots disposed between the said chassis and at least one pair of end regions of the said first beam, a connection element operable to mechanically connect two corresponding regions of the said second beams or the ends of the said first beam, the said connection element substantially comprising a third beam the axis of which is substantially parallel to that of the said first beam in such a way that a load applied to the stub axle of one of the said wheels causes a substantially flexural deformation of the associated second beam and a substantially torsional deformation of the section of the said first beam lying between the said second beam and the said central region of the first beam, and such that the said connection element tends substantially to transmit to the other second beam the same flexural deformation which is experienced by the said loaded second beam.

2. A suspension according to Claim 1, characterised by the fact that the said first beam and each of the said second beams of the said elastically deformable element are constituted by a plate having a substantially rectangular section.

3. A suspension according to one of the preceding claims, characterised by the fact that the said connection element includes a pair of arms, each of which projects from one end of the said third beam and the axis of which forms an angle equal to or greater than 90" with the axis of the said third beam.

4. A suspension according to Claim 3, characterised by the fact that the said third beam and each of the said arms of the said connection element are constituted by a plate having a substantially rectangular section.

5. A suspension according to any preceding Claim, characterised by the fact that the said fixed connection between the said chassis and the said central region of the said first beam is formed by means of a support element provided with means for adjusting the distance of the support itself from the chassis in such a way that it is possible to vary the height of the wheels from the chassis itself by adjusting the said distance.

6. A suspension according to Claim 5, characterised by the fact that the said support includes a pair of small plates fixed together and between which the said first beam is disposed, at least one of the said small plates being provided with a pair of seats for abutment onto the said chassis, the said adjustment being effected by causing this plate to rotate with respect to one of the said seats and adjusting the distance of the other seat from the chassis itself.

7. A suspension according to Claim 5 or Claim 6, characterised by the fact that the said adjustment means are operated by a servo mechanism.

8. A suspension according to any preceding claim, characterised by the fact that each of the said second beams of the said elastically deformable element is connected to a corresponding said arm of said connection element.

9. A suspension according to any preceding claim, characterised by the fact that the dimensions of the said elastically deformable element and of the said connection element are such as to make the said second beams substantially superimposable over the said arms.

10. A suspension according to any of Claims 2 to 9, characterised by the fact that the said elastically deformable element and the said connection element are formed from a single sheet metal blank and the said two elements are connected at the end of each of the said second beams and each of the said arms.

11. A suspension according to Claim 10, characterised by the fact that between the said second beams and the said arms there is disposed a pad of deformable material.

12. Asuspension according to any preceding claim, characterised by the fact that the said pivots operable to connect the said first beam to the said chassis include a pair of ball joints.

13. A suspension according to any of Claims 1 to 8, characterised by the fact that the said pivots operable to connect the said first beam to the said chassis include a pair of cylindrical pivots the axis of each of which is substantially coincident with the axis of the said first beam.

14. A suspension for the wheels of a vehicle, substantially as described and illustrated in the attached drawings.