BACKGROUND At present with modern vehicles which can travel at relatively high speeds over modern roads with smooth and quietly running engines, one of the few remaining problems to be overcome is the question of road noise.

Road noise is understood to be created by vibrations transmitted from road surface to the cab of a motor vehicle. Varying different types and quality of road surface create different levels of vibration and noise which ideally should be reduced if not eliminated.

The applicant understands that the source of this noise is created by the tyre acting in much the same fashion as a stereo speaker cone when it vibrates in and out.

The applicant considers the action of a vehicle tyre moving over each and every bump on a road surface causes the same effect and sound. These impact movements of the tyre surface invade the internal pressurised air space of the tyre to be converted into a myriad of sound waves amplified into shock waves by the high pressure of the inflated tyre. The magnitude of these shock waves are increased or decreased according to vehicle speed and the condition of the road. The shock waves hammer and ricochet with considerable force around the interior surface of the tyre and the exposed areas of a wheel rim which is normally constructed from steel or another metal alloy. The vibrations are then transmitted through the wheel rims, discs, wheel bearings and suspension culminating in an irritating noise in the vehicle cab. The irritating noise not only spoils radio listening but can affect people susceptible to headaches.

One attempt to eiiminate this problem is for car manufacturers to heaviiy pad the interior body panels. This adds markedly to manufacturing cost.

An object of the present invention is to incorporate a simple modification which will substantially reduce, if not eliminate road noise or to reduce road noise to a more acceptable level.

Further objects and advantages of the invention will become apparent from the following description which is given by way of example only.

DISCLOSURE OF THE INVENTION According to a broadest aspect of the invention there is provided a noise barrier in a road wheel assembly.

The barrier can be made from any suitable noise absorbing/deadening material manufactured to exacting safety specifications as far as width, thickness and retention are required. A solid synthetic or natural rubber or plastics material which is an extremely poor medium for transmitting vibrations can be used.

Preferably a specially prepared durable rubber extruded and vulcanised between two steel or other metal rings or plates situated between a road wheel rim and a wheel hub assembly is suitable.

The invention can be incorporated into a new wheel or as a modification to an existing wheel which should in no way affect the balance of the wheel. In fact wheel balance may be improved due to a self centring effect created by the noise barrier material.

Examples of the invention will now be described with reference to the accompanying drawings: DESCRIPTION OF THE DRAWINGS Figure 1 shows diagrammatically a cross-section through part of an example of wheel assembly incorporating the present invention; Figure 2 shows a cross-section through an alternative construction of wheel assembly incorporating the present invention; Figure 3 shows a part section through yet another alternative construction of wheel assembly showing the actual size of a 1 5 inch wheel rim incorporating the present invention; and Figure 4 shows a part section through a construction of wheel assembly for a cast aluminium alloy wheel.

DESCRIPTION OF THE PREFERRED EXAMPLES All the examples of the invention will be described with reference to a standard wheel assembly for a vehicle, the wheel assembly has a tyre 6 to be mounted relative to a wheel bearing 1. The wheel bearing 1 is linked in known manner via a metal disc 2 portion of the wheel assembly which would normally have associated therewith an annular rim 3.

In the first example shown in Figure 1 the annular rim 3 has sandwiched between it and a wheel rim 5 an annular strip of durable natural/synthetic rubber 4. The rubber strip 4 is vulcanised to both the wheel rim 5 and the rim 3. The tyre 6 is fitted in the normal way to the wheel rim 5.

In the second example shown in Figure 2 the wheel is constructed with two discs which are joined together by a vulcanised rubber plate 4.

In the third example in Figure 3 a part section through a 1 5 inch wheel is shown.

The wheel is constructed from a 1 5 inch wheel rim 5 and a modified rim 3. The rim 3 is a cut-down and compressed 1 5 inch rim with both side walls (not shown) originaily attached at 8 and 9 removed. The rim 3 is welded to a ledge section 10 on the periphery of the disc 2.

In the fourth example shown in Figure 4 the wheel is constructed from two parts, namely a central hub section 11 and a wheel rim 1 2. The hub section 11 has a profile suitable for attachment to a wheel hub (not shown) by way of studs which are aligned with holes (not shown) on centre lines 13 (only one of which can be seen) in disc portion 14.

The wheel rim 1 2 is profiled to have a pneumatic tyre (not shown) fitted and the external profile may of any suitable construction and shape which is cast from the same or similar metal alloy material as the section 11. The section 11 and rim 1 2 are held together by rubber 1 5 which is vulcanised to the parts.

The wheel assembly is formed by placing the hub section 11 and wheel rim 1 2 in position in or on a jig/mechanism so that under heat and pressure the rubber is forced into the space therebetween to be vulcanised to the surfaces 1 6 and 1 7 respectively of the hub section 11 and wheel rim 1 2.

In practice operating stresses would expose the noise barrier formed by the rubber 4 to driving, braking, cornering and weight supporting forces. The most effective position in the wheel assembly for this noise barrier would seem to be as close as possible to the noise source. In the examples the barrier is farthermost away from the hub has been chosen for as little stress as possible and that is between the wheel rim and the wheel disc. The applicant is confident that the forces can be taken care of in the strength of the vulcanising contact between the rubber barrier and the wheel rims.

Bearing in mind the quality of modern vulcanising, the applicant considers this will be satisfactory. However, strict quality control measures are essential.

There are other advantages to having this rubber bushing built into motor vehicle wheels apart from the major advantage of muting pneumatic tyre noise entering the vehicle cab. The rubber is an added shock absorbent assisting in taking impact stress off the wheel assemblies, suspensions and also serves to increase the life of the wheel bearings. It should help to protect the vehicle transmission from shock through the mechanical drive to the road. It will also assist in automatically keeping the wheels in balance and giving a smoother ride. The applicant believes it will transform the ride of a standard car into a more luxurious model.

Prior to extruding the rubber between the two parts of the rim it will be necessary to have a special jig manufactured to set the rim and disc assembles in correct concentric positions and also to arrange for correct location between the hub and rim.

Where in the aforegoing description mechanical equivalents are available it is to be appreciated that they can be substituted for the named components.

Thus by this invention there is provided a wheel noise reduction assembly.

Particular examples of the invention have been described and it is envisaged that improvements and modifications can take place with departing from the scope of the appended claims.