Spring devices – Vehicle – Lever and nontorsion spring
Patent
1988-12-02
1990-05-22
Butler, Douglas C.
Spring devices
Vehicle
Lever and nontorsion spring
267 31, 267 361, 267165, 267149, 267260, 267227, F16F 136, F16F 1300, B60G 314, B60G 1506
Patent
active
049271245
DESCRIPTION:
BRIEF SUMMARY
This invention relates to springs comprising a strip of fibre-reinforced plastics material of zig-zag configuration, having a plurality of limbs connected by reflex portions and the longitudinal centre line of the strip lying substantially in a single plane. Such springs, which will hereafter be referred to as springs of the kind specified, are disclosed in International Patent Application Publication No. W085/00207. More particularly, the invention relates to arrangements by which such springs can be mounted for use.
Springs of the kind specified have been proposed for use in motor vehicle suspension systems, where the properties of such springs can be advantageous. As compared with steel coil springs, currently widely used in vehicle suspensions, springs of the kind specified can lead to a reduction in weight and certain installation advantages resulting from the reduced space occupied by the springs. A spring of the kind specified is used as a compression spring, loaded between mounting components secured to opposite end limbs of the spring. When the spring is loaded, the limbs thereof are moved closer together.
The problem the present invention aims to overcome will now be described with reference to FIGS. 1, 2 and 3 of the accompanying drawings, showing diagrammatically a spring of the kind specified.
The spring of the kind specified shown in FIG. 1 comprises a plurality of limbs 10, 11, 12, 13, 14, 15, 16, joined by reflex portions 17, 18, 19, 20, 21, 22. As manufactured, limbs 10, 12, 14 and 16 are substantially parallel to one another. Limbs 11, 13, 15 are parallel to one another and inclined to the other limbs. To use the spring in, for example, a vehicle suspension, the end limbs 10, 16 thereof are held captive within mounting members 23, 24. Hitherto it has been usual to orient such mounting members 23, 24 to suit the orientation of end limbs 10, 16 as the spring is manufactured and when no stress is applied thereto.
FIG. 2 illustrates diagrammatically the shape assumed by the spring when it has been loaded by opposed forces applied to the mounting members 23, 24, as indicated by arrows 25. The force is sufficient to cause compression of the spring along its length as a whole such that limbs 12, 13 and 14 lie substantially parallel to one another. However, because mounting members 23, 24 remain in the same orientation as when the spring is unloaded, they cause the reflex portions 18, 21 to be deformed to a greater extent than the other reflex portions. With increasing distance from reflex portion 18, limb 11 approaches limb 12 and with increasing distance from reflex portion 21 limb 14 approaches limb 15.
This has led to premature failure of springs, particularly at reflex portions 18, 21.
If the spring were not held with its end limbs 10, 16 in a fixed orientation, i.e. if limbs 10, 16 were pin jointed at their mid points as shown in FIG. 3, for pivotal movement about respective axes 26, 27 perpendicular to the plane of the drawing, the spring would be deformed as shown in FIG. 3 with all the reflex portions being deformed equally and the limbs all being parallel to one another at a particular value of applied load. Such pin jointing or pivotal mounting of the end limbs of a spring is not however possible in practice because the spring would be unstable, i.e. would have a tendency to become displaced transversely of the direction in which it is loaded.
It is the object of the present invention to overcome or at least reduce the problems above described.
The present invention therefore provides an assembly comprising a spring in the form of a strip of fibre-reinforced plastics material of zig-zag configuration, having a plurality of limbs connected by reflex portions with the longitudinal centre line of the strip lying substantially in a single plane; and mounting means holding end ones of said limbs so that the spring acts resiliently therebetween, wherein the mounting means of at least one of said end limbs holds the respective limb at an attitude which it would assume at least one value of sp
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Pollard Andrew
Spedding Colin E.
Butler Douglas C.
GKN Technology Limited
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