GB2258195A

GB2258195A - Pneumatic tyre assembly

Info

Publication number: GB2258195A
Application number: GB9215923A
Authority: GB
Inventors: Robin Hamilton
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-07-27
Filing date: 1992-07-27
Publication date: 1993-02-03
Also published as: GB9116259D0; GB9215923D0

Abstract

A pneumatic tyre assembly 10 comprises a tyre 14 containing a flexible partition 16 which divides the space within the tyre 14 into an outer chamber 18 and an inner chamber 20. Valves 22, 24 allow air to be introduced independently into either chamber 18, 20. A change of pressure within one of the chambers may be at least partly compensated by a change of volume of the other chamber. This mitigates the effects of a puncture in the tyre 14, or a failure of either valve 22, 24. A pump 34 and a control circuit 30 may be mounted on the wheel to which the tyre assembly is fitted, the pump being actuated by rotation of the wheel, or the pump 34 and control circuit 30 may be mounted on a vehicle with which the wheel is associated. The control circuit 30 can transmit signals, for example to the vehicle driver, by mechanical, audible, electrical, radio or magnetic means to indicate the state of the tyre or to give an alarm. The control circuit 30 may also receive signals, for example from the driver, to cause a change of tyre pressure. <IMAGE>

Description

Tyre Pressure Control and Tyre Safety The present invention relates to the control of tyre pressure in vehicle tyres, and to tyre safety.

Vehicle tyre manufacturers specify recommended operating pressures for their tyres. These recommended pressures depend on the circumstances of use. For example, higher pressures are usually specified for high speed use, or use when large loads are being carried. It is important to keep tyre pressures at or close to these recommended values in order to reduce wear on the tyre and to reduce fuel consumption of the vehicle. Furthermore, vehicle handling, the comfort of passengers and the safety performance of a tyre can all be adversely affected by incorrect tyre pressure.

It is however difficult to maintain tyre pressures at the recommended values. The pressure can increase significantly after a long period of use at high speed, when the tyre will be hot. Significant changes in the load require compensation in the tyre pressure, but many drivers do not make the necessary change, preferring to rely on using a pressure which is a compromise value.

This can lead to a compromise in the performance of the tyre.

It is an object of the present invention to address these difficulties.

Sudden tyre failure, such as a blowout arising from a puncture, can be catastrohpic due to a collapse in the shape of the tyre, leading to a lack of control of the vehicle. The invention seeks to overcome this difficulty. The arrangements to be described can help control the shape of the tyre, allowing the driver to slow down under control.

The invention provides a pneumatic tyre assembly comprising a tyre and flexible partition means which, in use, divide the space within the tyre into at least first and second chambers, and valve means operable to inflate either chamber independently of the other, whereby a change of pressure within one of the chambers may be at least partly compensated by a change of volume of the other chamber.

The tyre assembly may further comprise an inner tube, the partition means being located within the inner tube to provide the said chambers within the inner tube.

One of the chambers is preferably located between the partition means and a wheel on which the assembly is mounted, and the second chamber is located between the partition means and the tyre.

The partition means may comprise a sheet of elastic material, such as rubber.

First and second valve means are preferably associated with respective chambers. The first and second valve means may be mounted diametrically opposite one another on the wheel on which the assembly is mounted.

Alternatively, the valve means may be operable to inflate either chamber selectively. The valve means may be so arranged as to inflate one of the chambers until a first pre-determined pressure is reached, and thereafter to inflate the other chamber.

Control means are preferably operable to control the pressure in the tyre, to maintain a preset pressure, by causing one or both chambers to be inflated or deflated. The preset pressure may be set by remote control. Control means may monitor the pressures in the chambers and generate a signal indicative of the pressures or an abnormality in the pressures. The control means may monitor the pressure difference between the chambers in order to detect an abnormality. The control means is preferably operable to close the valve means in the event of an abnormality. The said generated signal may be provided to a remote location to provide an alarm signal in the event of an abnormality. The signals may be transmitted to or from the remote location. They may be transmitted by mechanical, audible, electrical, radio, magnetic or other means.

The partition means may be so arranged as to collapse against the valve means in the event of partial deflation of a chamber between the partition means and a wheel, to prevent further deflation. The partition means may be arranged to expand against the tyre walls in the event of deflation of the chamber between the partition means and the tyre walls, to support the tyre walls and assist in maintaining the shape of the tyre.

The assembly preferably further comprises gas supply means operable to supply gas to one or both chambers. The gas is preferably air. The gas supply means preferably comprises a pump. The pump means are preferably carried by the wheel on which the assembly is mounted. The pump means may be powered by rotation of the said wheel. The pump means are preferably controlled by control means operable to maintain a preset pressure in the tyre.

The control means is preferably operable to increase or release pressure from one or both chambers.

The pump means may be controlled in dependence on a signal, preferably received from the driver of a vehicle to which the assembly is fitted, the signal indicating the desired pressure within the tyre.

In a second aspect, the invention provides a pneumatic tyre assembly for a vehicle, comprising a tyre, valve means and gas supply means, the valve means and gas supply means being operable to change the pressure in the tyre assembly while the vehicle is stationary or in motion.

The gas supply means may be mounted at a fixed position on the vehicle and may be mounted on the wheel on which the tyre assembly is mounted. In the latter case, the gas supply means is preferably powered by rotation of the said wheel.

The assembly preferably comprises control means operable to control operation of the gas supply means in dependence on the tyre pressure. The control means may control the gas supply means in dependence on the desired tyre pressure.

The gas supply means preferably comprises pump means.

The tyre assembly of the second aspect may incorporate any or all of the features of the first aspect of the invention.

According to a third aspect of the invention, there is provided a pneumatic tyre assembly comprising a tyre and control means operable to monitor the pressure within the tyre and to transmit a signal to a remote location, the signal indicating the pressure within the tyre or an abnormality in the pressure. The signal may be transmitted to an occupant of a vehicle to which the tyre assembly is fitted. The signal is preferably transmitted by mechanical, audible, electrical, radio, magnetic or other means.

The control means is preferably operable to change the pressure in the tyre by operation of valve means and/or gas supply means, such as pump means. The control means may be operable in response to instructions received from an occupant of a vehicle to which the tyre assembly is fitted, these signals being received by mechanical, audible, electrical, radio, magnetic or other means.

The tyre assembly of the third aspect may incorporate any or all of the features of the first aspect of the invention.

Embodiments of the present invention will now be described in more detail, by way of example only, and with reference to the accompanying drawings in which: Fig. 1 is a schematic section along the diameter of a wheel carrying a tyre assembly according to the present invention, the tyre being tubeless; and Fig. 2 is a similar schematic view in relation to a tyre with an inner tube.

Turning to Fig. 1, there is shown a pneumatic tyre assembly indicated generally at 10, mounted on a vehicle wheel 12. Hub mounting arrangements for the wheel 12 are not shown, in the interests of clarity. The tyre assembly 10 comprises a tyre 14 and a flexible partition 16. The partition 16 divides the space within the tyre 14 into an outer chamber 18 and an inner chamber 20.

Additional partitions could further divide the space.

The valve means at 22 and 24 are operable to introduce air independently into either chamber 18,20. A change of pressure within one of the chambers 18,20 may be at least partly compensated by a change of volume of the other chamber.

In more detail, the wheel 12 has a rim 26 which supports a standard tubeless tyre 14 in conventional manner. Within the space inside the tyre 14, there is a partition 16, for instance a small inner tube, which separates the first chamber 18 from the second chamber 20. A conventional valve 22 is mounted in the rim 26 to allow the outer chamber 18 to be inflated. A second valve 24 allows the inner chamber 20 to be inflated.

Consequently, air may be introduced independently into either chamber. The valves 22,24 are mounted diametrically opposite each other on the rim 26, in order to assist in balancing the wheel.

The partition 16 is made of a sheet of elastic material such as rubber. This allows it to expand or contract according to any pressure difference between the chambers 18,20, so that the pressure difference is at least partially compensated by increases or decreases in the volumes of the two chambers.

The assembly also comprises a control circuit 30 which is connected by means indicated schematically at 32 to the inner valve 24. The connection 32 allows the control circuit 30 to monitor the pressure within the inner chamber 20.

The assembly also comprises a small pump 34 mounted at or near the centre of the hub 36 of the wheel 12 or elsewhere. The pump 34 is connected at 38 to the control circuit 30 and can pump air under control of the control circuit 30 through the connection 32 to the valve 24.

The connection 32 also allows the control circuit 30 to open the valve to release air from the inner chamber 20.

The control circuit 30 may be arranged to generate a signal indicative of any abnormality in the tyre pressure and this signal can be transmitted, as indicated at 40, to a remote location by any suitable mechanical, audible, electrical, radio, magnetic or other means. The transmission is preferably to a location at which the driver or other vehicle occupant can read the signal in order to be advised of the state of the tyre, and may be used to generate an alarm.

In use, the two chambers 18,20 will be under pressure and the partition 16 will have stretched to substantially equalise these pressures. Thus, in normal use, operation of the pump 34 is not required. However, if the pressure within the tyre begins to change from the desired pressure, the control circuit 30 will sense this and either reduce the tyre pressure, or operate the pump to increase the tyre pressure through the valve 24. For instance, as the tyre heats up during normal use, the pressure will tend to increase and this can be compensated by releasing air. Alternatively, if the pressure reduces, for instance because the tyre begins to cool, additional air can be pumped in to restore the correct pressure.

If the control circuit 30 senses that there is an abnormality in tyre pressure, for instance because air is being constantly required, a warning can be transmitted to alert the driver to the abnormality. For instance, in the event of a slight leak, air will be constantly required to compensate for the leak.

Alternatively, the controller 30 may be provided with sensors (not shown) which allow it to monitor abnormalities by comparing the difference in pressures between the two chambers 18,20. In normal use, this difference will be minimal, but if the outer chamber 18 becomes badly deflated, the partition 16 will stretch considerably, and this increased tension in the partition 16 can result in an increased pressure difference between the chambers 18,20.

In the event of a rapid tyre deflation, such as that caused by a puncture, the outer chamber 18 will lose virtually all pressure virtually instantaneously. This causes the inner chamber 20 to expand to fill the whole of the interior of the tyre 14. This may help to seal the puncture, even if the partition 16 is ruptured. Once the inner chamber has expanded, the pressure within the tyre will be significantly less as a result of the expansion of the chamber 20, but it is expected that a practical arrangement could be designed to provide sufficient pressure to maintain the stability of the tyre while the vehicle is brought to a halt. It is to be noted that unlike a conventional inner tube, the partition 16 is at least partially protected from puncture by virtue of the outer chamber 18, which separates the partition 16 from the tyre 14.

If the partition 16 does become punctured, or the inner valve 24 fails or the control circuit 30 fails, the controller 30 can be designed to fail safe by shutting off the inner valve 24 automatically, for instance when a minimum pressure is detected in the inner chamber 20. It may also be possible to arrange the partition 16 to collapse against the valve 24 so as to seal it off and prevent further deflation through the valve 24.

It can be seen from Fig. 1 that the pump 34 is located at or near the centre of the hub 36, but could be elsewhere. It is envisaged that the pump 34 may be powered by rotation of the hub 36. For instance, the pump 34 can consist of a central core 42 which rotates with the hub 36 inside a collar 44, the relative rotation of these elements giving rise to a driving force for the pump.

A small electric dynamo (not shown) may also be mounted on the hub 36, to generate electrical power for the control means or valves.

In addition to transmitting signals from the control circuit 30 to a vehicle occupant, it is envisaged that the control circuit 30 can receive signals transmitted under the control of the occupant (preferably the driver), to instruct a change in tyre pressure for instance because of a change in driving conditions.

In an alternative arrangement, it is envisaged that the valves 22,24 could be replaced by a single composite valve which can direct air to either chamber 18,20 under control of the control circuit 30. This eliminates the need to provide an additional valve mounting hole in the rim 26. A composite valve may be arranged to operate automatically to supply pressure to the outer chamber 18 until a pre-determined pressure is reached, and then to inflate the inner chamber 20. The composite valve could provide means for monitoring the pressure difference between the two chambers.

It will be apparent that the overall pressure in the tyre is governed by the conditions of the two chambers 18,20. Consequently, when first inflating the tyre, it is envisaged that the outer chamber 18 will be inflated to a pressure slightly below the desired working pressure and that the inner chamber 20 will then be inflated until the working pressure is reached. This method of inflation ensures that the partition 16 is kept well away from the walls of the tyre 14 during normal use.

Fig. 2 shows how the apparatus previously described can be used in relation to a tyre which uses an inner tube. The only difference between the assemblies shown in Figs. 1 and 2 is the presence of an inner tube 50 and consequently, corresponding numerals are used in relation to other elements. The inner tube 50, when inflated, abuts the tyre 14 over the whole inner surface of the tyre. Consequently, the outer chamber 18 is formed within the inner tube 50, between the inner tube 50 and the partition 16. The inner chamber 20 is formed, as before, between the partition 16 and the rim 26. The operation of the apparatus shown in Fig. 2 is precisely the same as the operation described above in relation to Fig. 1 and the same constructions and alternatives can be used.

Many variations and modifications can be made without departing from the spirit and scope of the present invention. For instance, the pump 34 and the control circuit 30, have been described as mounted on the hub 36 but one or both could alternatively be mounted at a fixed position on the vehicle on which the wheel 12 is mounted. Rotating couplings would then be required between the fixed components and the components of the wheel or components mounted on a wheel. It is also envisaged that the pump 34, or the control circuit 30, could be used alone or together in relation to a conventional tyre assembly which does not incorporate the partition 16. In that case, the advantages of tyre pressure monitoring would be obtained without the increased safety provided by the presence of the partition 16. Alternatively, the partition 16 can be used to provide the increased safety, without using a control circuit 30 or pump 34 to provide constant automatic monitoring of tyre pressure.

This specification refers to tyres as "pneumatic" because it is expected that in most situations the tyre will be inflated with air. However, other gases could be used, and the term "pneumatic tyre" is not intended to be restricted to air-filled tyres.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

1. A pneumatic tyre assembly comprising a tyre and flexible partition means which, in use, divide the space within the tyre into at least first and second chambers, and valve means operable to inflate either chamber independently of the other, whereby a change of pressure within one of the chambers may be at least partly compensated by a change of volume of the other chamber.

2. An assembly according to claim 1, further comprising an inner tube, the partition means being located within the inner tube to provide the said chambers within the inner tube.

3. An assembly according to claim 1 or 2, wherein one of the chambers is located between the partition means and a wheel on which the assembly is mounted, and the second chamber is located between the partition means and the tyre.

4. An assembly according to claim 1, 2 or 3, wherein the partition means comprises a sheet of elastic material, such as rubber.

5. An assembly according to any preceding claim, wherein first and second valve means are associated with respective chambers.

6. An assembly according to claim 5, wherein the first and second valve means are mounted diametrically opposite one another on the wheel on which the assembly is mounted.

7. An assembly according to any of claims 1 to 4, wherein the valve means are operable to inflate either chamber selectively.

8. An assembly according to any preceding claim, wherein the valve means is so arranged as to inflate one of the chambers until a first pre-determined pressure is reached, and thereafter to inflate the other chamber.

9. An assembly according to any preceding claim, wherein control means is operable to control the pressure in the tyre, to maintain a preset pressure, by causing one or both chambers to be inflated or deflated.

10. An assembly according to claim 9, wherein the preset pressure is set by remote control.

11. An assembly according to any preceding claim, further comprising control means operable to monitor the pressures in the chambers and to generate a signal indicative of the pressures or an abnormality in the pressures.

12. An assembly according to claim 11, wherein the control means monitors the pressure difference between the chambers in order to detect an abnormality.

13. An assembly according to claim 11 or 12, wherein the control means is operable to close the valve means in the event of an abnormality.

14. An assembly according to any of claims 11 to 13, wherein the said generated signal is provided to a remote location to provide an alarm signal in the event of an abnormality.

15. An assembly according to any of claims 10 to 14, wherein the or a signal is transmitted to or from a remote location.

16. An assembly according to claim 15, wherein the signal is transmitted by mechanical, audible, electrical, radio, magnetic or other means.

17. An assembly according to any preceding claim, wherein the partition means is so arranged as to collapse against the valve means in the event of partial deflation of a chamber between the partition means and a wheel, to prevent further deflation.

18. An assembly according to any preceding claim, wherein the partition means are arranged to expand against the tyre walls in the event of deflation of the chamber between the partition means and the tyre walls, to support the tyre walls and assist in maintaining the shape of the tyre.

19. An assembly according to any preceding claim, further comprising gas supply means operable to supply gas to one or both chambers.

20. An assembly according to claim 19, wherein the gas is air.

21. An assembly according to claim 19 or 20, wherein the gas supply means comprises a pump.

22. An assembly according to claim 21, wherein the pump means are carried by the wheel on which the assembly is mounted.

23. An assembly according to claim 21 or 22, wherein the pump means are powered by rotation of the wheel on which the assembly is mounted.

24. An assembly according to claim 21, 22 or 23, wherein the pump means are controlled by control means operable to maintain a preset pressure in the tyre.

25. An assembly according to claim 24, wherein the control means is operable to increase or release pressure from one or both chambers.

26. An assembly according to any of claims 21 to 25, wherein the pump means are controlled in dependence on a signal indicating the desired pressure within the tyre.

27. A pneumatic tyre assembly for a vehicle, comprising a tyre, valve means and gas supply means, the valve means and gas supply means being operable to change the pressure in the tyre assembly while the vehicle is stationary or in motion.

28. An assembly according to claim 27, wherein the gas supply means is mounted at a fixed position on the vehicle.

29. An assembly according to claim 27 or 28, wherein the gas supply means is mounted on the wheel on which the tyre assembly is mounted.

30. An assembly according to claim 29, wherein the gas supply means is powered by rotation of the said wheel.

31. An assembly according to any of claims 27 to 30, comprising control means operable to control operation of the gas supply means in dependence on the tyre pressure.

32. An assembly according to claim 31, wherein the control means is operable to control the gas supply means in dependence on the desired tyre pressure.

33. An assembly according to any of claims 27 to 32, wherein the gas supply means comprises pump means.

34. A tyre assembly according to any of claims 27 to 33 and any of claims 1 to 26.

35. A pneumatic tyre assembly comprising a tyre and control means operable to monitor the pressure within the tyre and to transmit a signal to a remote location, the signal indicating the pressure within the tyre or an abnormality in the pressure.

36. An assembly according to claim 35, wherein the signal is transmitted to an occupant of a vehicle to which the tyre assembly is fitted.

37. An assembly according to claim 35 or 36, wherein the signal is transmitted by mechanical, audible, electrical, radio, magnetic or other means.

38. An assembly according to any of claims 35 to 37, wherein the control means is operable to change the pressure in the tyre by operation of valve means and/or gas supply means.

39. An assembly according to claim 38, wherein the gas supply means comprise pump means.

40. An assembly according to claim 38 or 39, wherein the control means are operable in response to instructions received from an occupant of a vehicle to which the tyre assembly is fitted.

41. An assembly according to claim 40, wherein the signals are received by mechanical, audible, electrical, radio, magnetic or other means.

42. An assembly according to any of claims 35 to 41 and any of claims 1 to 34.

43. A tyre assembly substantially as described above with reference to Fig. 1 or Fig. 2 of the accompanying drawings.

44. Any novel subject matter or combination including novel subject matter disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.