WO1987002109A1

WO1987002109A1 - Spring end assembly

Info

Publication number: WO1987002109A1
Application number: PCT/GB1986/000532
Authority: WO
Inventors: Arthur Ernest Deville
Original assignee: Gkn Technology Limited
Priority date: 1985-09-26
Filing date: 1986-09-09
Publication date: 1987-04-09
Also published as: GB8803007D0; EP0270546A1; GB2199636A; GB8523788D0; JPS63501523A

Abstract

An assembly of an end portion (14, 34) of a leaf spring of fibre-reinforced plastics material, of increasing thickness and decreasing width towards its free end, and a housing enclosing the end portion and formed of two elements (18, 19; 28, 29; 36, 37) secured together and of a shape interfitting with the end portion so as not to move thereon. The elements may be pressings welded together, and are further provided with means (23, 40) for receiving a part such as a steering swivel joint.

Description

SPRING END ASSEMBLY

This invention relates to an assembly by which the end of a leaf spring made of composite, fibre-reinforced plastics, material is to be secured to a vehicle suspension component.

The invention has been devised in relation to a suspension of the kind disclosed in published International Patent Application O83/01758. That suspension comprises a spring in the form of an elongate leaf which extends transversely of the vehicle and is supported relative to the vehicle structure for pivotal movement about two axes extending generally transversely of the spring (i.e. longitudinally of the vehicle) between the ends of the spring. The ends of the spring are connected to wheel carrier members by joints which, for the vehicle's front wheels, are steering swivel joints. End portions of the spring, outboard of the points of pivotal support of the spring, are of increasing width and decreasing thickness towards their free ends, so that such portions of the spring are substantially rigid and act as wishbones or lower suspension links, while the part of the spring between its pivotal support bends resiliently to provide springing and also an anti-roll effect. The present invention, however, is applicable more generally to leaf springs in vehicle suspensions.

One problem which arises in relation to springs made of composite material is that of connection of the spring to other components. Expedients such as drilling holes in the spring to receive fasteners such as bolts or rivets are undesirable, because they interrupt the fibres of the spring upon which the spring's integrity and performance depend.

It is the object of the present invention to provide for connection of the end of a leaf spring to a component of a vehicle suspension, without causing such problems.

According to the invention, we provide an assembly comprising a leaf spring of fibre-reinforced plastics material and a housing at least partially enclosing an end portion of a leaf spring, said housing comprising two elements secured together and of a configuration which interfits with the spring end portion to prevent relative movement of the housing and spring, and further comprising means for attachment to a vehicle suspension component.

In a spring whose thickness increases and width decreases towards its free end, it will be appreciated that provided the housing is a close fit on the end portion of the spring, it is impossible for the housing to become detached from or even move at all on the spring.

For a strong and permanent connection, the elements forming the housing may be welded together, preferably between complementary abutting flange portions thereof so that the welding can be carried out at a sufficient distance from the surface of the spring not to cause heat damage thereto. Additionally, such flange portions assist the rigidity of the assembly.

An adhesive and/or filler substance may be provided between the housing and end portion of the spring. In addition to filling any voids which may exist between the spring and housing due to production tolerances, such a substance prevents penetration of dirt or water to the inside of the housing, which otherwise would be a potential source of wear or corrosion.

The invention will now be described by way of example with reference to the accompanying drawings, of which :-

Figure 1 is a diagrammatic view of a spring to which the invention is applicable;

Figure 2 is a plan view of one embodiment of assembly according to the invention;

Figure 3 is an elevation of the assembly of Figure 2;

Figure 4 is a cross-section on the line 4-4 of

Figure 3;

Figure 5 is a plan view of a further embodiment of assembly according to the invention;

Figure 6 is an elevation of the assembly of Figure 5;

Figure 7 is a cross-section on the lines 7-7 of Figure 6;

Figure 8 is a plan view of yet another embodiment of assembly according to the invention;

Figure 9 is a longitudinal section through the embodiment of Figure 8; Figure 10 is a sec tion on the line 10-10 of Figure

9 .

Referring firstly to Figure 1 of the drawings, there is shown a spring 12 in the form of an elongate leaf of composite, fibre-reinforced plastics, material. The spring is intended to be used in a vehicle suspension of the kind disclosed in published international patent application no. O83/01758. The spring comprises a central portion 13 and two end portions 14, the central portion being of constant cross-sectional shape throughout its length and the end portions being of increasing thickness and decreasing width towards their free ends. To facilitate its manufacture by a process such as pultrusion, the spring may be of constant cross-sectional area throughout its length (except where its extremities are chamferred as described hereafter) . As used in a suspension of the kind above referred to, the spring is supported relative to the vehicle structure at the two transition regions between the central and end portions of the spring, f.or generally pivotal movement relative to the vehicle about respective axes extending transversely of the spring, i.e. longitudinally of the vehicle. The free ends of the spring are connected to wheel carrier members, not shown, by way of swivel joints, not shown, and the end portions 14 of the spring act as suspension links or wishbones, being relatively rigid by virtue of their increasing thickness. The central portion 13 of the spring bends resiliently to provide springing in use.

In Figure 1, the free ends of the end portions 14 of the spring are provided with assemblies indicated generally at 15 by which the swivel joints are attached to the spring. Embodiments of such assemblies will now be described.

Referring now to Figures 2, 3 and 4 of the drawings, there is shown the free end of a spring end portion 14. The increasing thickness and decreasing width of the end portion is clearly shown, although the extremity of the spring has its upper and lower surfaces chamferred at 16 and its end provided with a part-cylindrical recess 17. The free end portion of the spring is enclosed within a housing comprising two sheet metal pressings 18, 19 which are of a shape which closely corresponds to that of the free end portion of the spring. The pressings 18, 19 have respective flanges 20, 21 which abut one another and are secured together, e.g. by spot welding as indicated at 22 in Figure 1. A tubular socket 23 for a swivel joint lies within the recess 17 at the end of the spring, and is there welded to the pressings 18, 19.

Because of the increasing thickness and decreasing width of the spring end portion 14, to which shape the pressings 18, 19 closely conform, it will be appreciated that theoretically no relative movement is possible between the spring and the welded assembly of pressings IS, 19 and socket 23.. To allow for production tolerances, and to ensure that fretting between the spring and pressings will not occur in use, the pressings may be so dimensioned that they are pre-stressed by application of a suitable force thereto prior to and during the welding together of their flanges 20, 21.

In the assembly according to Figures 2 to 4, the flanges 20, 21 increase the rigidity of the assembly.

The spot welding together of the flanges does not present a great risk of damage to the fibre-reinforced plastics material of the spring, since the overall heat input is not great and is not immediately adjacent to the spring's surface. However, it will be appreciated that alternative expedients could be used for fastening the flanges together, e.g. by seam welding therebetween or possibly by use of fasteners such as bolts or rivets if it might be desired to dismantle the assembly.

Referring now to Figures 5, 6 and 7 of the drawings, there is shown an assembly which is generally similar to that of Figures 2 to 4, in that the end portion 14 of the spring, which is of the same configuration, fits within a housing comprising an upper pressing 28 and a lower pressing 29. In this case, however, the pressings have portions 30, 31, respectively, which overlap the other pressing and are secured thereto by welding.

Referring now to Figures 8 to 10 of the drawings, there is shown a spring end portion 34 which is of the same general configuration as that of the previous embodiments, i.e. of decreasing width and increasing thickness towards its free end. The extreme end portion of the spring has a chamferre^*d surface at 35.

The end portion of the spring is enclosed within a housing comprising an upper pressing 36 and a lower pressing 37. Pressing 36 has side wall portions 38 which extend downwardly beyond the lower surface of the spring, and pressing 37 has downwardly depending flanges 39 which are a close fit between the wall portions 38. The end of lower pressing 37 is formed as a part-cylindrical wall 40 for receiving a swivel joint part indicated in outline at 41. The pressings 36, 37 are joined together to hold the spring therebetween by welding between the wall portions 38 and flanges 39, as shown in Figure 10 of the drawings. As for the embodiments previously described, the pressings 36, 37 are preferably welded together while being pressed towards one another firmly to embrace the spring and to take up clearances due to production tolerances. In the embodiment of Figures 8 to 10, the configuration of wall portions 38 and flanges 39, extending in the direction in which the pressings 36, 37 are applied to the spring, is such that irrespective of minor dimensional changes in the thickness of the spring end portion, there will always be adjacent surfaces at which welding can be carried out.

In all the embodiments above described, further to reduce the possibility of clearances existing or developing between the spring end portion and the housing enclosing it, a substance in flowable form may be introduced between the spring and pressings constituting the housing, which substance sets when the pressings have been secured together. Such a substance may be an adhesive, and may be injected through one or more apertures provided in the pressings after the pressings have been secured together. Alternatively, such a substance could merely be placed on the spring surface prior to the application of the pressings thereto.

As an alternative to the use of an adhesive, a plastics material may be introduced between the pressings and spring. Particularly, a material such as an appropriate type of nylon may be introduced by a reaction injection moulding process. In addition to taking up clearances during initial assembly, the use of adhesive or a plastics material in this matter also has the advantage of preventing penetration of dirt and/or water to the interior of the pressings enclosing the end portion of the spring. This is advantageous in reducing the possibility of corrosion occuring, which is particularly important in a spring used in vehicle suspension.

It will be appreciated that the invention is applicable to springs used for purposes other than in vehicle suspensions.

Claims

CT/GB86/00532CLAIMS

1. An assembly (15) comprising a leaf spring (12) of fibre-reinforced plastics material and a housing at least partially enclosing an end portion (14, 34) of the leaf spring, said housing comprising two elements (18, 19; 28, 29; 36, 37) secured together and of a configuration which interfits with the spring end portion (14, 34) to prevent relative movement of the housing and spring, and further comprising means (23, 40) for attachment to a vehicle suspension component.

2. An assembly according to Claim 1 further characterised in that the thickness of the spring end portion (14, 34) increases and its width decreases towards its free end.

3. An assembly according to Claim 1 or Claim 2 further characterised in that the elements (18, 19; 36, 37) are secured together at complementary abutting flange portions (20, 21; 38, 39) thereof.

4. An assembly according to Claim 3 further characterised in that said flange portions (38, 39) extend in the direction in which the elements (36, 37) are applied to the spring.

5. An assembly according to Claim 1 or Claim 2 further characterised in that the elements (28, 29) are secured together at overlapping portions (30, 31) thereof.

6. An assembly according to any one of the preceding claims further characte ised in that the elements (18, 19; 28, 29; 36, 37) are welded together.

7. An assembly according to any one of the preceding claims further characterised in that the elements (18, 19; 28, 29; 36, 37) are pre-stressed when secured together .

8. An assembly according to any one of the preceding claims further characterised in that an adhesive and/or filler substance is present between said housing and end portion of the spring.

9. An assembly according to Claim 8 further characterised in that said substance has been introduced after securement of said elements together.