GB2189749A

GB2189749A - Wheel rim for a run-flat pneumatic tyre

Info

Publication number: GB2189749A
Application number: GB08610677A
Authority: GB
Inventors: Yi Jye Tony Shiah
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-05-01
Filing date: 1986-05-01
Publication date: 1987-11-04
Also published as: GB8610677D0

Abstract

The wheel rim 11 has a profile which has a greater radius at mid-section 11b than at the edges 11a such that, on loss of tyre pressure, the greater radius mid-section runs on the tread of the tyre and keeps the edges of the rim from damaging the side walls of the tyre. A helical adapter 13, Fig. 4, may be threaded on to a conventional rim to provide a raised surface in the mid-section of the rim. The adapter may be made of metal, hard rubber or nylon. <IMAGE>

Description

SPECIFICATION Wheel rim for a pneumatic tyre This invention relates to wheel rims for pneumatic tyres.

A perennial problem with pneumatic tyres as used on automobiles, airplanes and the like, is loss oftyre pressure whetherthrough puncture, blow-out, or valvefailure. Numerous attempts have been madeto alleviate this problem, but they require the use of special tyres or special rims, which are expensive.

The conventional solution for automobiles is to carry a spare wheel which is put on when a tyrefails in use. The spare wheel is bulky and expensive, and usually has to be deployed in roadside conditions frequently in bad weather and at night. Moreover, at today's high automobile speeds, the vehicle may travel a considerable distance before coming to rest, during which time the fail tyre has quite likely suffered irreparable damage. Most seriously, however,thefailed tyre, especially if it is a fronttyre, causes steering problems, and failed tyres have on that account been responsible for many serious, often fatal automobile accidents. The risk involved in a landing wheel tyrefailure on an airplane is obvious.

The fact that the conventional solution is still very much the accepted one, for all its faults, does not speakwell for the special tyres or rims that have been proposed as alternatives. Such alternatives include tyres that are to some extent self-sealing so that they only partially deflate and can continue, perhaps at reduced speed, for a get-you-home orto a garage distance where replacement or repair can be effected more easily than by the roadside. Another alternative is the provision of a lubricant on the inner wall ofthetyre so that it is betterableto stand upto the harsh treatment it gets when running flat. Such alternatives have in general not been priced attractively in comparison to the conventional provision of a spare wheel.

The present invention provides a new solution to the problem by which even conventional wheel rims and tyres can at moderate expense be adapted to reduce the risk, cost and inconvenience associated with tyre failure.

The invention comprises a wheel rim fora pneumatictyre having side walls and a tread portion, said rim having a profile which has a greater radius at mid-section than at the edges such that on loss of tyre pressure the greater radius mid-section runs on the tread portion and keeps the edges from damaging the side walls.

The wheel rim may comprise a conventional rim and an adaptor mounted thereon effectively to enlarge the profile at mid-section. Said adapter may comprise a helical member that can be threaded on to the rim over one edge thereof and which sits on the lesser radius mid-section ofthe conventional rim toenlargethe profile there.

Said adaptor may be secured to the rim, and may be of metal and be welded to the said lesser-radius mid-section ofthe rim.

The adaptor may, however, be of a flexible material such as hard rubberornylon, and maythen be held on said rim by its resilience.

The adaptor may be ofhollowconstruction.

Embodiments of wheel rims according to the invention will now be described with reference to the accompanying drawings, in which" Figure 1 is an axial section through a conventional automobile wheel rim modified by an adaptor according to the invention, Figure2 is a diagrammatic illustration of a conventional rim with (a) an inflated tyre and (b) a flat tyre.

Figure 3 is a diagrammatic illustration like Figure 2 with a rim according to the invention, and Figure 4 is a view of an adaptor being threaded on to a conventional wheel rim.

The drawings illustrate a wheel rim 11 fora pneumatictyre 12 having side walls 12a and atread 12b,the rim 11 having a profilewhich has a greater radius at mid-section 11 b than at the edges 11 c such that on loss of tyre pressure the greater radius mid-section 11 b runs on the tread portion 1 2b and keeps the edges 11 a from damaging the side walls 12a.

This is seen by comparing Figure 3 with Figure 2.

Figure 2 illustrates a conventional rim 11'(a) with the tyre 12 inflated and (b) with thetyre 1 2flat. The edges 1 la' ofthe rim are shown running on the sidewalls 12awhich have collapsed and which are consequently bearing high pressure loadingsfrom the sharp edges 1 la' ofthe rim 11' and are being damaged thereby.More seriously,the collapsed tyre 12' is unstable and can be displaced completely to one side ofthe rim 11' so that one ofthe edges 1 la' is running directly on the road surface which can damagetheedge-which in tubeless tyres is an important part ofthe seal -frequently beyond repair, necessitating complete wheel replacement.

In contrast, Figure 3 shows how the tyre 12 behaves on loss of pressure when the wheel rim has a greater radius at mid-section 11 b than at the edges 11 a. The thread 1 2b of the tyre is held flat againstthe road surface, the greater radius mid-section 11 b of the rim 11 running directlyon thetread. The edges 1 a ofthe rim 11 cannot come into contact with the road surface and do not damage the side walls 12a of thetyre 12,which remains substantially stable on the rim 11.

Figure 1 shows a conventional automobile wheel rim 11 in axial section with a mid-section 11 c of lesser radius than the edges 11 a. This conventional rim 11 is however modified in accordance with the invention byan adapter 13 in the form of a helical member that can be threaded on to the rim 11 over one edge 1 1a thereof and which sits on the lesser radius mid-section 11 c effectively to enlargethe profile there.

This adaptor 13 is of steel and is secured to the rim 11 bywelding.The adaptoris itseif of hollow construction, actually having a U-shaped profile.

Instead of metal, hard rubber or nyion or like resilient material can be used for the adaptor, which can by their resilience alone be held on the said rim 11, although such adaptors could also be secured by adhesive.

Figure 4 shows an adaptor 13 being threaded on to a conventional rim 11.

Accordingly, the many millions of wheel rims in current use can be readily converted by such simple and readily and inexpensively fitted adaptor means to perform safely and conveniently according to the invention in the event of tyre pressure loss. An automobile can be safely driven with a deflated tyre for maybe up to 100km, certainly far enough to get home orto a garagefor repair.

Claims

1. Awheel rimfora pneumatictyre having side walls and a tread portion, said rim having a profile which has a greater radius at mid-section than at the edges such that on loss of tyre pressure the greater radius mid-section runs on the tread portion and keeps the edges from damaging the side walls.

2. Awheel rim according to claim 1, comprising a conventional rim and an adaptor mounted thereon effectively to enlarge the profile at mid-section.

3. Awheel rim according to claim 2, said adaptor comprising a helical memberthatcan be threaded on to the rim over one edge thereof and which sits on the lesser radius mid-section ofthe conventional rim to enlargethe profile there.

4. Awheel rim according to claim 3, said adaptor being secured to the rim.

5. Awheel rim according to claim 3 or claim 4, said adaptor being of metal and being welded to the said lesser radius mid-section of the rim.

6. Awheel rim according to claim 3 or claim 4, said adaptor being of a flexible material such as hard rubber or nylon.

7. A wheel rim according to claim 6, said adaptor being held on said rim by its resilience.

8. Awheel rim according to anyone of claims 2 to 7, said adaptor being of hollow construction.

9. Awheel rim substantially as hereinbefore described with reference to the accompanying drawings.