GB2341153A

GB2341153A - Maintaining tyre inflation

Info

Publication number: GB2341153A
Application number: GB9819336A
Authority: GB
Inventors: David Adie
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-09-07
Filing date: 1998-09-07
Publication date: 2000-03-08
Also published as: GB9819336D0

Abstract

A device 1 for maintaining tyre inflation comprises an oversized inflatable tube 2 of tough, flexible and thin plastic material located on a wheel rim 3 within a tyre 4. As a puncture occurs through piercing of the tyre 4 by a sharp object 5, the inflatable tube 2 forms itself around the sharp object 5 and seals off air leak points 6 in the tyre 4. The tube 2 may be in its inflated form prior to a puncture of the tyre 4 or may be deployed from a folded form (9, Fig 3) using air supplied by a pump when a puncture of the tyre occurs. A pressure sensor 7 linked to control panel instrumentation informs the driver of the puncture.

Description

2341153 Device for Maintaining Tyre Inflation The present invention

relates to an inflatable device fitted inside a vehicle tyre cavity as a means of keeping the tyre inflated following a puncture. The device provides a lightweight means of keeping the punctured tyre inflated Without having to stop the vehicle and removes the need to carry a spare wheel within the vehicle.

The resulting advantages of the device are:

- more storage space available within the vehicle due to the elimination of the spare wheel; - reduced fuel consumption due to the difference in weight between the lightweight device and the previously used spare wheel; - reduced exhaust emissions from the vehicle due to reduced fuel consumption; - increasedconvenience through not having to stop and change a wheel, particularly in uncomfortable surroundings andlor conditions; increased personal security through not having to stop in isolated areas, particularly at night.

Systems for dealing with a puncture already exist in different forms.

The most common puncture handling system is the straightforward replacement concept whereby a spare wheel is used to substitute the original wheel holding the damaged tyre. This concept is coming under increasing scrutiny driven by environmental legislation pressure to reduce the weight of vehicles and subsequently lower fuel consumption and corresponding exhaust emissions.The elimination of the spare wheel would contribute to achieving these goals. Additionally the spare wheel has a restricting effect on vehicAe design flexibility and demands space which could be utilised for other purposes such as further storage. capacity.

An existing alternative to the spare wheel is the injection of a rubber compound solution inside the tyre which hardens and thereby seals the puncture hole. This method has limitations regarding the size of hole which can be effectively sealed and puncture holes of over 5mm are not repairable with this concept.

Another concept is the run-flat tyre comprising a plastic ring fitted within the tyre cavity to the wheel rim which prevents the tyre from slipping off the wheel and allows the driver to continue travelling without having to fit a spare wheel. The drawbacks to this approach are that: a) with four solid plastic rings each of larger-than-wheel diameter the device is not particularly lightweight; b) one wheel is smaller than the others following a puncture; and c) the punctured tyre no longer provides pneumatic shock-absorption.

The reinforced-sidewall tyre is another approach which allows the driver to continue without replacing the damaged tyre. Again, as with the runflat ring, the driving conditions are abnormal with no pneumatic shockabsorption. Additionally the distance able to be travelled is limited and the concept removes the normal-condition performance of flexible sided tyres.

It is an object of the present invention to provide an inexpensive, lightweight inflatable device in the form of an oversize inner-tube of tough, thin, flexible plastic material fitted to a vehicle wheel rim Within the tyre cavity, which deploys through the supply of compressed air, which has a potential fully-inflated size larger than the tyre cavity, but which when inflated is restricted in size to the form of the tyre cavity, which prevents air from escaping from the tyre and thereby maintains normal tyre pressure within the tyre cavity to keep the tyre in a fully-functional, operational condition until a tyre replacement point is reached without having to carry out tyre replacement or to stop the vehicle, which eliminates the need to carry a spare wheel, and which can inform the driver of a puncture through control-instrument information.

Inflatable tubes inside tyres were previously used in the history of tyre development as a means of providing support shape to the tyre without allowing air to escape through non-airtight areas between the tyre and the wheel rim.

Gradually these inner tubes which were made of rubber became redundant through the introduction of improved-fit tubeless tyres.

The difference between the present invention and previous inner tubes is that the present invention: a) does not necessarily have to be inflated for normal operating conditions; b) is capable of being inflated while the vehicle is moving; c) is not made of rubber, rather of a tough, thin, flexible plastic material such as certain forms of polyethelene; and d) does not have a tight fit against the inner walls of the tyre, rather it is designed to have excess surface area due to it's oversize which creates tension absorbing folds.

The key principle of the present invention lies in the over-sizing of the inflatable tube allied to the toughness of the tube material. When a sharp object pierces the tyre outer wall, any tightly fitting inner tube which is already inflated within the tyre cavity, or any inner tube which is subsequently inflated as a result of the piercing, is also likely to be pierced as the surface of the inflated tube meets the sharp object. However, when an inflated device is significantly larger than the tyre cavity, and of an appropriate, tough but thin material such as Tyvek polyethelene, the inflating device does not get pierced but rather wraps itself to the form of the sharp object and seals any air gaps around it.

The device can be fitted in a basic version with the tube pre-deployed in an inflated form within the tyre cavity prior to a puncture, or alternatively in a more advanced version with the tube held in a folded, flat form ready to be deployed in the event of a puncture.

In the advanced version atthe moment of puncture, a ptesture sensor notes the sudden drop in tyre pressure and the inflatable device, which is located on the wheel rim inside the tyre cavity, is deployed. Air is supplied to the device by a small, lightweight, central, on board compressor and lightweight tubing of for example polypropylene which runs respectively through each wheel rim to the inflation device.

The driver is informed of the puncture by a signal display on the instrument panel and knows that the damaged tyre has to be replaced at the next opportunity.

In the basic version the tube is pre-deployed and no compressor or air supply pipeline are required. The tube is inflated through the tyre inlet valve and kept in deployed mode continually regardless of whether a puncture occurs or not.

The advantage of the more advanced version is the provision of further security should the tyre still be losing some pressure after the deployment of the inflatable tube. The compressor would continue to supply air to the leaking tyre and allow uninterrupted travel.

Several degrees of complexity can be provided between the basic and advanced versions according to market requirements. For example due to the low weight and space requirement of the inflatable tube, further back- up tubes may be fitted without increasing cost or weight dramatically. More than one inflatable tube per tyre would allow in the event of an extreme case, where the primary inflating tube was damaged and leaking, to maintain air pressure through the air supply from the compressor, stop the vehicle to remove any problematic object before activating the secondary tube and continuing the journey.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:- Figure 1 shows a section through the tyre cavity with the basic version tube held in deployed mode prior to a puncture.

Figure 2 shows the basic version tube wrapped around a puncture-causing object and maintaining the air-tightness of the tyre cavity.

Figure 3 shows a section through the tyre cavity with the advanced version inflatable tube held in position.

Figure 4 shows a partial side view section of the advance version tube in position in deflated, folded condition; Figure 5 shows a section through the tyre cavity with the advance version tube inflating and wrapping around a puncture causing sharp object.

Figure 6 shows a schematic of the compressor and air supply circuit.

According to the invention a tyre inflation device 1 comprises an inflatable tube 2 of tough, flexible and thin plastic material located on a wheel rim 3 within a tyre 4. As a puncture occurs through a piercing of the tyre 4 by a sharp object 5 the inflatable tube 2 forms itself around the sharp object 5 and seals-off air leak points 6 in the tyre 4. A pressure sensor 7 linked to control panel instrumentation informs the driver of the puncture and it's status.

In an advanced version of the invention an inflation device 8 comprises an inflatable tube 9 of tough, flexible and thin plastic material located in a deflated, folded condition on a wheel rim 3 within a tyre 4. As a puncture occurs through a piercing of the tyre 4 by a sharp object 5 a pressure sensor 7 notes the sharp drop in air pressure within the tyre 4 and activates a central compressor 10 which supplies air to the inflatable tube 9 by an airline 11. The inflatable tube is deployed within the tyre 4 and forms itself around the sharp object 5 and seals- off air leak points 6 in the tyre 4. A pressure sensor 7 linked to control panel instrumentation informs the driver of the puncture and if s status.

Claims

1. An inexpensive, lightweight inflatable device in the form of an oversize inner-tube of tough, thin, flexible plastic material fitted to a vehicle wheel rim Within the tyre cavity, which deploys through the supply of compressed air, which has a potential fully-inflated size larger than the tyre cavity, but which when inflated is restricted in size to the form of the tyre cavity, which prevents air from escaping from the tyre and thereby maintains normal tyre pressure within the tyre cavity to keep the tyre in a fully-functional, operational condition until a tyre replacement point is reached without having to carry out tyre replacement or to stop the vehicle, which eliminates the need to carry a spare wheel, and which can inform the driver of a puncture through control-instrument information.

2. A device as claimed in Claim 1 wherein the inflatable tube is fitted in a folded, deflated, flat form to the wheel rim and is deployed through the supply of compressed air from a central compressor and air pipeline when a puncture is registered by a tyre-pressure sensor within the tyre cavity.

3. A device as claimed in Claim 1 wherein more than one inflatable tube is fitted.

4. A device as claimed in Claims 1 and 2 which is modified in dimension to suit the application to motorbike tyres.

5. A device as claimed in Claims 1 and 2 which is modified in dimension to suit the application to bicycle tyres.