GB2166839A

GB2166839A - Leaf spring assemblies

Info

Publication number: GB2166839A
Application number: GB08526554A
Authority: GB
Inventors: Graham Hemmings; Steven Donowski
Original assignee: GKN Technology Ltd
Current assignee: GKN Technology Ltd
Priority date: 1984-11-08
Filing date: 1985-10-28
Publication date: 1986-05-14
Also published as: GB8526554D0; GB2166839B

Abstract

An assembly of two leaf spring elements 10, 11, preferably of fibre reinforced plastics, material, is secured together with a spacer therebetween, The spacer is in the form of first and second parts 12, 13 secured to the respective spring elements, the two parts having formations which interfit so that relative misalignment between the spring elements is resisted. The formations may be of dovetail (14) configuration as shown in plan in Fig. 3. Penetration of dirt to the spring surfaces is also prevented. The spacer parts are of slightly resilient rubber or plastics material. They may be secured to the leaf spring elements by adhesive, or by forming the parts in situ during moulding of the leaf spring elements. <IMAGE>

Description

SPECIFICATION Leaf spring assemblies This invention relates to an assembly of leaf spring elements, such elements being secured together in spaced generally parallel relationship. The invention is applicable primarily, although not exclusively, to such an assembly in which the leaf spring elements are made of composite, fibre reinforced plastics, material.

Such an assembly typically is used in a motor vehicle suspension. Two or more leaf spring elements are used where a single element does not give the required spring characteristics. The elements are usually held together by some form of clamping means, for example U bolts, and often some form of spacer, e.g. of a resilient material such as a suitable rubber or plastics material, is interposed between the leaf spring elements. This is particularly a requirement in the case of springs of composite material, since it assists in preventing penetration of abrasive dirt to the clamped spring surfaces which would cause wear in use.

A further problem which arises in such assemblies of leaf spring elements, particularly if they are only held together in their centre region and not constrained at other positions along their length, is that the spring elements can become misaligned relative to one another in the manner of the blades of a pair of scissors. This phenomenon is known as "scissoring". They can also become displaced from the required position longitudinally and transversely relative to one another. It is the object of the present invention to overcome or reduce these problems.

According to the invention, we provide an assembly of two leaf spring elements secured together in spaced generally parallel relationship with spacer means interposed between them, wherein said spacer means comprises a first part secured to one of said spring elements and a second part secured to the other of said spring elements, said parts having formations which interfit with one another to resist relative angular misalignment between said spring elements. Preferably said spacer means is of a resilient material.

In a spring assembly according to the invention, the interfitting engagement between the parts of the spacer means assists in preventing scissoring between the spring elements. In addition, the fact that the parts of the spacer means are secured to the respective spring elements effectively prevents penetration of abrasive dirt to the spring elements' surfaces thereunder. This is particularly advantageous where the springs are of composite material.

Preferably said interfitting formations have a thickness less than the thickness of each of said parts of said spacer means. Thus each of said parts is secured to its respective leaf spring element over its entire surface area.

Said formations may be in the form of a dovetail.

The invention will now be described by way of example with reference to the accompanying drawings, of which: Figure 1 is a side view of part of an assembly according to the invention; Figure 2 is a section on the line 2-2 of Fig.

1; , Figure 3 is a section on the line 3-3 of Fig.

2; Referring firstly to Fig. 1 there is shown part of an assembly comprising a first leaf spring element 10 and a second leaf spring element 11. The leaf spring elements are of elongate form, and only the central part thereof is shown. The spring elements may be of composite, fibre reinforced plastics, material. In a practical embodiment the leaf spring elements will be held together by some form of clamping means extending around them, e.g. comprising U bolts and suitable abutment plates, but such clamping means is not here illustrated.

Interposed between the surfaces of the spring elements is a spacer means which has a first part 12 and a second part 13. The parts 12, 13 are both rectangular in plan view, of the same dimensions as one another.

Considered across the width of the spring elements, each part of the spacer means has a portion which is of greater thickness and one which is of lesser thickness.

The greater thickness portion of the part 12 includes a dovetail shaped formation 14. This fits into a correspondingly shaped recess formation in the thicker portion of part 13. The two parts of the spacer means are thus engaged in a manner which resists misalignment there-between.

The parts 12, 13 are secured by use of a suitable adhesive to their respective spring elements. Thus the spring elements also are held in alignment with one another and scissoring, as well as relative longitudinal or transverse movement, is resisted. Further, penetration of abrasive dirt which could cause wear of the spring surfaces is prevented. To permit dismantling if required, the parts 12, 13 preferably are not secured by adhesive to one another.

The two parts of the spacer means are preferably of a slightly resilient material, e.g. an appropriate grade of rubber.or plastics material. As an alternative to securing them to the spring elements by adhesive, they may be secured by forming the part in situ on the spring element in a moulding process. Such a part may completely embrace the spring leaf element at its clamped connection.

It will be appreciated that interengaging formations of configuration other than the dovetail illustrated could be provided on the parts of the spacer. Any form of interfitting projec tion and recess, preferably not extending through the full thicknesses of the parts, could be provided.

Claims

1. An assembly of two leaf spring elements secured together in spaced generally parallel relationship with spacer means interposed therebetween, wherein said spacer means comprises a first part secured to one of said spring elements and a second part secured to the other of said spring elements, said parts having formations which interfit with one another to resist relative angular misalignment between said spring elements.

2. An assembly according to Claim 1 wherein said spacer means is of a resilient material.

3. An assembly according to Claim 1 or Claim 2 wherein said spacer means parts are secured to their respective spring elements by adhesive.

4. An assembly according to any one of the preceding claims wherein said formations extend for less than the full thickness of each of said parts.

5. An assembly according to any one of the preceding claims wherein said formations are in the form of a dovetail.

6. An assembly substantially as hereinbefore described with reference to the accompanying drawings.