GB2284865A

GB2284865A - Resiliently mounted plain bearing

Info

Publication number: GB2284865A
Application number: GB9325870A
Authority: GB
Inventors: Garry James Preece
Original assignee: Jaguar Cars Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 1993-12-17
Filing date: 1993-12-17
Publication date: 1995-06-21
Also published as: GB9325870D0

Abstract

A bearing (10) Comprises an inner rigid bush (11) and an outer bush (15) rotatably mounted thereon, the inner bush extending axially beyond at least one end of the outer bush. An elastomeric sleeve (20) is formed on the external surface of the outer bush, the elastomeric sleeve having a sealing formation (21) which engages the external surface of the inner bush. A low friction coating is formed on the external surface of the inner bush where it is engaged by the outer bush and by the sealing formation. <IMAGE>

Description

BEARINGS The present invention relates to bearings and in particular to elastically mounted journal bearings.

Elastically mounted journal bearings as commonly used in vehicle suspension systems, typically comprise an inner rigid bush arranged rotatably in an outer bush. An elastomeric sleeve is moulded to the external surface of the outer bush by which the outer bush may be compliantly mounted in a bearing housing. It has been proposed to provide a low friction lining between the surfaces of the inner and outer bushes. Furthermore, sealing means have been proposed to prevent ingress of dust and moisture between the relatively rotating surfaces of the inner and outer bushes.

The present invention provides an improved form of this type of bearing.

According to one aspect of the present invention a bearing comprises an inner rigid bush and an outer bush rotatably mounted on the inner bush, the inner bush extending axially beyond at least one end of the outer bush, an elastomeric sleeve being formed on the external surface of the outer bush, the elastomeric sleeve having a sealing formation which engages the external surface of the inner bush where it extends axially beyond the outer bush, a low friction coating being formed on the external surface of the inner bush where it is engaged by the outer bush and by the sealing formation.

The present invention thus provides a low friction bearing with sealing means to prevent the ingress of dirt or moisture and has the advantage over previously proposed bearings in that the sealing means engages against a low friction surface and hence the life of the seal will be prolonged its performance will be improved and noise generation reduced.

According to a preferred embodiment of the present invention, the elastomeric sleeve may be provided with thrust formations which will engage against a radial surface of the bearing housing to accommodate end loading of the bearing.

An embodiment of the invention is now described, by way of example only, with reference to the accompanying drawings in which: Figure 1 illustrates in cross-sectional elevation, a bearing in accordance with the present invention; and Figure 2 is a part-sectional plan view of the inner mounting of a wishbone of a vehicle suspension using a pair of bearings as illustrated in Figure 1.

As illustrated in Figure 1, a bearing 10 comprises an inner bush 11 made of metal. The inner bush 11 has an internal bore 12 through which a bolt may extend to secure the inner bush 11 to suitable support means (not shown). The inner bush 11 is provided with a flange 13 at one end.

An outer bush 15 of tubular formation with a flange 16 at the end corresponding to the flange 13 of the inner bush 11, is mounted on the external surface of the inner bush 11 so that the inner surface of the outer bush 15 rotatably engages the external surface of the inner bush 11 and the opposed radial faces of flanges 13 and 16 slidably engage.

A moulded elastomeric sleeve 20 is bonded to the external surface of the outer bush 15. Elastomeric sleeve 20 has an annular seal formation 21 which extends beyond the flange 16 of the outer bush 15 and into sealing engagement with a recessed portion 14 of the flange 13 of inner bush 11.

A further annular formation 22 extends coaxially of the main body portion 23 of elastomeric sleeve 20 from the end thereof adjacent flange 16 of the outer bush 15, on the opposite side of the flange 16 to the seal formation 21.

The external surface of the inner bush 11 and its flange formation 13 are coated with a low friction material.

This may be in the form of an epoxy resin coating or paint which is loaded with a low friction material such as PTFE or molybdenum disulphide. Such materials are commercially available as Emralon plan and Molycote and may be applied by spraying techniques, dip or cathodic painting processes. The thickness of the coating is preferably from 0.005 to 0.05 mm.

The external surface of the inner bush 11 engaged by the circumferential and radial faces of the outer bush 15 and by the sealing formation 21 are coated with the dry lubricant, so as to provide low frictional engagement between the engaging surfaces of the inner and outer bushes 11, 15 and of the sealing formation 21 with the recessed portion 14 of the inner bush 11.

Bushes 10 of the type described above may be used in pairs to secure the inner mountings of a wishbone 30 of a vehicle suspension to the vehicle body. The wishbone 30 comprises a pair of arms 31 (only one shown) which come together at their outermost ends. As illustrated in Figure 2, a bearing housing 32 is provided at the inner end of each arm 31. The bearing housing 32 is a cylindrical formation with an axial bore 33. Bearings 10 of the form described above may be pressed into the axial bore 33, one from each end with the flanges 13, 16 of the bushes 11, 15 outermost. The diameter of the elastomeric sleeves 20 is greater than that of the internal diameter of the bore 33, so that the elastomeric sleeves 20 will be compressed. The bearings 10 are thus compliantly mounted in the bearing formations.

The axial length of the bearings 10 and the bearing housing 32 is such that when elastomeric formations 22 engage the ends of the bearing housing 32, the innermost ends of the bearings 10 will be spaced apart. The elastomeric formations 22 can thus be compressed axially to provide axial compliance of the inner wishbone mounting, due to axial loading.

The inner wishbone mounting is secured to a suitable bracket on the vehicle body by means of a bolt which passes through the central bore 12 of the inner bush 11.

The bearings 10 thus provide a low torque connection between the wishbone 30 and vehicle body whilst also providing the required degree of lateral and axial compliance between the wishbone 30 and vehicle body.

The inner bush 11 may typically be made from steel although due to the low frictional engagement between the inner and outer bushes 11 and 15, soft materials such as aluminium, alloys, plastics or plastic composites which will give weight reduction and flexibility of manufacture may alternatively be used. The outer bush 15 may be made from any material which will provide dimensional stability, for example stainless steel, aluminium or carbon fibre reinforced epoxy resins. The elastomeric sleeve 20 may be made of natural or synthetic rubber.

In addition to coating the external surface of the inner bush 11 with low friction material, the surfaces of the outer bush 15 which engage the inner bush 11 may also be coated with low friction material. The sliding inferface may also be improved by the addition of grease or other lubricants.

Claims

1. A bearing comprising an inner rigid bush and an outer bush rotatably mounted on the inner bush, the inner bush extending axially beyond at least one end of the outer bush, an elastomeric sleeve being formed one the external surface of the outer bush, the elastomeric sleeve having a sealing formation which engages the external surface of the inner bush where it extends axially beyond the outer bush, a low friction coating being formed on the external surface of the inner bush where it is engaged by the outer bush and by the sealing formation.

2. A bearing according to Claim 1 in which the outer surface of the inner bush defines cylindrical and radial surfaces, the inner surface of the outer bush having corresponding cylindrical and radial surfaces which make sliding engagement with those of the inner bush.

3. A bearing according to Claim 2 in which the inner bush has a flange formation adjacent one end, the outer bush having a corresponding flange formation, the sealing formation extending over the flange formation of the outer bush and into engagement with the flange formation of the inner bush.

4. A bearing according to any one of the preceding claims in which the whole of the external surface of the inner bush is coated with a low friction material.

5. A bearing according to any one of the preceding claims in which the surfaces of the outer bush which engage the inner bush are coated with a low friction material.

6. A bearing according to any one of the preceding claims in which the low friction material comprises an epoxy resin coating or paint which is loaded with low friction material.

7. A bearing according to Claim 6 in which the low friction material is PTFE or molybdenum disulphide.

8. A bearing according to any one of the preceding claims in which the elastomeric sleeve is provided with thrust formations which may be compressed against a bearing housing to accommodate end loading of the bearing.

9. A bearing substantially as described herein with reference to and as shown in Figures 1 and 2 of the accompanying drawings.