COMPOSITE SPRINGS

Abstract: An assembly of a fibre reinforced composite leaf spring with layers of longitudinally oriented fibres spaced from one another by a core portion of randomly oriented fibres, and a component such as an axle beam, the component being clamped to the spring and located length wise of the spring by a locating member which engages with a formation extending at least partially through the core portion of the spring but which does not interrupt the longitudinal fibres thereof. Interruption of the longitudinally oriented fibres is thus avoided.

Description: Composite Springs This invention relates to leaf springs made of fibre reinforced composite material, comprising layers of fibres at least the majority of which extend longitudinally of the spring spaced from one another in the direction of bending of the spring by a core portion of randomly oriented fibres, all the fibres being set in a resin material. Such leaf springs will hereinafter be referred to as leaf springs of the kind specified. More particularly, the invention relates to the securing to a spring of the kind specified, in the central region thereof, of a component such as a vehicle axle. The properties of such a spring depend, inter alia on the longitudinally extending fibres thereof not being interrupted by whatever expedient is used to attach the component to the spring. According to the present invention, we provide an assembly comprising a leaf spring of the kind specified, a component secured thereto by clamping means at least partially embracing the spring, and a locating member engaging with a formation extending at least partially through the core portion of the spring, said locating member also engaging the component and/or clamping means to prevent movement of the component longitudinally of the spring. It has been found that the properties of a spring of the kind specified are not adversely affected by the provision of a bore or other formation extending transversly through the core portion of the spring, since the longitudinally extending fibres remain unaffected thereby. The use of such a formation to provide for location of the component which is secured to the spring by the clamp means thus is an improvement upon any construction utilising bolts or the like penetrating the spring in its primary direction of bending. The locating member may comprise a plate extending across the width of the spring and having upstanding lugs which lie against the sides of the spring, a bolt passing through said lugs and the core portion of the spring. The plate may have a formation which engages the component to be attached to the spring. The clamping means may comprise U-bolts. An alternative form of locating member, in the form of a plate, provided at each side of the spring, may fit between the U-bolts. These and other features of the invention will now be described by way of example with reference to the accompanying drawings, of which Figure 1 is a side elevation of one form of assembly according to the invention. Figure 2 is a perspective view of part of a further embodiment of the invention. Referring firstly to Figure 1, the assembly there illustrated comprises a leaf spring 10 which has spaced layers 11, 12 of fibres the majority of which extend longitudinally of the spring and a core portion 13 of randomly oriented fibres. All the fibres are set in a matrix of a cured resin material, e.g. an epoxy resin, and in one construction of such a spring proposed hitherto the fibres which are longitudinally oriented may be wholly or partly carbon fibres while the fibres in the core portion are glass fibres. An axle beam 14 is secured to the spring by U shape clamping bolts 15, 16 which embrace the spring. On the upper surface of the spring these bolts clamp to the spring a sheet metal component 17 which carries a bump stop 18, and a spacer 19. Between the axle beam and the lower surface of the spring 10 is interposed a wedge shaped element 20 which provides for a desired orientation of the axle beam relative to the spring. If the axle beam were to be required to lie against the spring, the wedge-shaped element 20 would be omitted. To each side -of the spring 10 is secured a locating plate 21, by a bolt 22 extending transversly through an aperture in the core portion 13 of the spring. The plates 22 are a close fit between the U bolts 15, 16, and thus prevent undesired movement of the axle beam longitudinally of the spring. Referring now to Figure 2, there is illustrated in outline only a spring 30. A locating member is provided in the form of a plate 31 with upwardly extending lugs 32 which lie against the sides of the spring. A bolt, not shown, is passed through the lugs 32 and the core portion of the spring to secure the locating member to the spring. An axle beam is clamped to the spring by U shaped bolts as in Figure 1 or any suitable alternative clamping means, and a dowel peg 33 on the underside of the locating member engages the axle beam to prevent movement of the latter longitudinally of the spring. In this case, the clamping means takes no part in longitudinal location of the axle beam relative to the spring. If the spring is of a rectangular shape in cross section, having sharp corners, spacing washers may be disposed between the lugs 32 and the sides of the spring. This is because a plate 31, which normally will be made by bending sheet metal, cannot be formed with a sharp right angled section in the internal angle between the lugs 32 and flat part of the plate 31. If the corners of the spring, as viewed in cross section, are rounded, both the plate 31 and lugs 32 may lie closely against the spring. In this embodiment also there may be provided one or more spacers between the actual beam and the spring, or, if required, a wedge shaped element as shown in Figure 1. Although the particular embodiment described above is the securing of an axle beam to a spring, it will be appreciated that the invention is applicable to the securing of other components to a spring where similar or analogous conditions apply.

Claims: CLAIMS 4 , w s 1. An assembly comprising a leaf spring (10) made of layers of fibres (11? 12) at least the majority of which extend longitudinally of the spring, spaced from one another from the direction of bending of the spring by a core portion (13) of randomly oriented fibres, all the fibres being set in a resin material, and a component (14) secured to the spring by clamping means (15, 16) at least partially embracing the spring, characterised by a locating member (21, 22, 31) engaging with a formation extending at least partially through the core portion (13) of the spring and also engaging the clamping means (15, 16) and/or component (14) to prevent movement of the component longitudinally of the spring. 2. An assembly according to Claim 1 further characterised in that the locating member comprises a plate (31) extending across the width of the spring and having lugs (32) which lie against the sides of the spring, a fastener passing laterally through said lugs and an aperture through the core portion of the spring. 3. An assembly according to Claim 2 further characterised in that said plate has a formation (33) which engages the component to be attached to the spring. 4. An assembly according to any one of the preceding claims further characterised in that said clamping means comprises U shaped bolts (15, 16). 5. An assembly according to Claim 4 further characterised in that a locating member (21) is provided at each side of the spring, and fits between said U shaped bolts. 6. An assembly according to any one of the preceding claims further characterised in that said component (14) is an axle beam. 7. A method of attaching a component to a leaf spring comprising layers of fibres (11, 12) at least the majority of which extend longitudinally of the spring spaced from one another in the direction of bending of the spring by a core portion (13) of randomly oriented fibres, all the fibres being set in a resin material, characterised by providing a locating member (21, 22, 31) and engaging same with a formation extending at least partially through the core portion (13) of the spring, engaging the locating member (21, 22, 31) with said component (14) and/or with a clamping means, (15, 16) and securing the component to the spring by said clamping means.

Inventors: DIMMOCK, JOHN, HARRIS, LEIGHTON RICHARD
Applicants: GKN GROUP SERVICES LIMITED
Application year: 1981
Main classification: B60G11
IPC codes: F16F1, B60G11