GB2191619A

GB2191619A - Means for detecting pneumatic tyre deflation

Info

Publication number: GB2191619A
Application number: GB08712652A
Authority: GB
Inventors: Albert William Brown
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-06-10
Filing date: 1987-05-29
Publication date: 1987-12-16
Also published as: GB8712652D0

Abstract

Such means are provided for detecting the deflation of a pneumatic tyre on a road wheel of a road vehicle whilst the vehicle is in motion. A probe 11 is mounted on a wheel mounting. The probe extends downwardly, and is of adjustable length to be normally spaced above the ground 18. If the tyre is being deflated, the tip 15 of the probe moves through a distance until it contacts the ground. This causes the probe to pivot against a spring 20 about a mounting 23 in a casing 12 containing an electric switch 27 to operate the switch. This causes a visible and/or audible warning 33 to provide the driver with an indication of the deflated tyre. <IMAGE>

Description

SPECIFICATION Means for detecting pneumatic tyre deflation This invention relates to the provision of means for detecting the deflation of a pneumatic tyre on a road wheel of a road vehiclewhilstthevehicle is in motion.

According to the present invention, a detector comprises a probe for being normally mounted ata wheel mounting to be out of contact with the ground, but to be brought into contact with the ground if the mounting drops in consequence of whole or partial deflation ofthetyre.

For example, the probe may be arranged to close an electrical contact in responseto its engagement with the ground, and thereby to complete a circuit in a warning system, producing a visible or audible warning signal in the interior of the vehicle to warn the driver of the deflation.

The invention is particularly, although not exclusively, applicable to vehicles fitted with the so-called "total mobility" pneumatic tyres which, even when ruptured by a "blow out", can continue to be driven on safely and almost normally even though partially or wholly deflated. Such "total mobility" tyres have especially wide tread, and may betemporarily self-sealing and partially self-reflating after a rupture or puncture, so that the tyre remains on the wheel rim despite the reduction in air pressure and the vehicle can continue to be driven safely on a partially deflated tyre for many miles, without serious danger or impairment of the handling of the vehicle.

The present invention provides a means of warning the driver of a vehicle fitted with "total mobility" tyres that one of his tyres has become partially or wholly deflated, since he might otherwise not be able to detect such deflation from any change inthevehiclehandling and he might remain ignorant of the deflation for a considerable period of time.

Similarly, the invention is applicable to lorries or other vehicles having wheels in pairs, where if one tyre deflates, the other carries an increased pressure, and may blow out if the driver is not warned to replace the deflated tyre. There would be a detector on each wheel of each pair. Awarning to the driver couldbeavisual and/oranaudiblewarning.

The invention includes a vehicle with a detector mounted at each wheel, and includes the method of detecting deflation of the tyre using the detector.

From another aspect of the invention, the detector comprises a casing containing an electric switch and a pivotally mounted probe projecting from the casing, the probe being normally spring-biassed against a stop, but arranged, when pivotted away from the stop, to operate the switch.

The invention may be carried into practice in various ways, but one specific embodiment will now be described by way of example with reference to the accompanying drawings, in which Figure lisa front elevation of a vehicle wheel fitted with deflation warning means; and Figure2 is a sketch showing the construction of the warning means as seen in the direction ofthe arrow II in Figure 1, and its electrical connections.

A lorry is fitted adjacent each of its wheel axles with an elongate downwardly-directed substantially-vertical probe 11 which is pivotally mounted in a casing 12, which is in turn mounted on an axle bearing 13, either directly orthrough a rigid bracket.

The probe 11 is in upper and lower sections of solid nylon or other plastic, which can slide relatively to each other by virtue of a conventional pin and slot connection 15 to set the length of the probe, such that with the pneumatic tyre 17 ofthatwheel fully inflated, the tip 15 ofthe probe will be a given distance (markedx in the drawings) above the surfaceoftheground 18. If, however, the tyre 17 deflates partially or wholly to a reduced air pressure as indicated at 19suchthatthewheel rim descends vertically through a distance greaterthan x, the tip of the probe 15 will contact the ground surface 18.

Figure 2 shows how the probe 11 is mounted in the casing 12. The upper end of the probe 11 is moulded with a boss 22 having a bore which is a slide fit around an internally threaded post 23 moulded as a partofthecasing 12. The postthus acts as afulcrum enabling the probe 11 to pivot in the plane of Figure 2. A bent wire spring 20 has one end wound around the post 23 and the other end engaging the probe above the fulcrum 23 to urge the fulcrum anticlockwise in Figure 2 against a stop 24 which is a sleeve fitted around another post 25 corresponding to the post 23.

The upper end of the probe 11 is in contact with the operating lever 26 of a microswitch 27 mounted within the casing 12,when the probe is againstthe stop 24, and that is the normal condition when the lowertip 15 of the probe is above the ground 18. The size of the sleeve 24wi11 be selected in accordance with the desired amount of pivotal movement of the probe before the switch operates.

If, however, thetyre partially deflates so that the tip 15 comes into contact with the ground, as described above, the forward movement of the vehicle in the direction indicated at21 in Figure2will cause the probe to pivot about the fulcrum 23 so that the upper end of the probe will move the lever 26 against the operating button 28 of the microswitch and cause the microswitch to close.

The switch terminals 31 are connected through the wall of the casing 12, respectively to earth and to one terminal of the vehicle battery 32. The otherterminal of the battery is connected to an indicating lamp 33 mounted on the dashboard of the vehicle and connected to earth to complete the circuit.

The lamp is one of a cluster, each of which is connected to a casing mounted on a different wheel mounting. One other lamp and casing are shown in Figure 1.

As the tyre begins to deflate, it is likelythatthe probe will make intermittent contact with the ground for a short period, which will have the effect of causing the warning lamp to flash, which is considered to give the driver a mqre effective warning than if a warning light merely came on and remained on.

There could also be an audible warning initiated by closing of the switch.

The probe, being in the form of a moulded plastic bar, can be easily and cheaply replaced if is should break.

The casing may befixed at a point on the axle that is not connected to the vehicle body and thatwill not move with the suspension.

For heavier vehicles, such as lorries, caravans, and trailers, the casing can be fixed directly on the road spring underthe axle at a point nearest to road wheels where the distance between axle and road does not vary.

Claims

1. A pneurnatic tyre deflation detector comprising a probe for being normally mounted art a wheel mounting to be out of contact with the ground, but to be brought into contact with the ground if the mounting drops in consequence of whole or partial deflation of the tyre on the wheel concerned.

2. Adetectorasclaimed in Claim 1 inwhichthe probe is mounted in a casing containing an electrical switch in a mannerto operate the switch when deflected.

3. A detector as claimed in Claim 2 in which the probe is pivotally mounted in the casing.

4. A detector as claimed in Claim 3 in which the probe is spring-biassed against a stop in the casing.

5. A detector as claimed in any of the preceding claims, in which the probe is of elongate form of adjustable length.

6. A detector as claimed in any of the preceding claims, in which the probe is arranged, when brought into contact with the ground, to operate an electrical switch connected in the circuit with the battery ofthe vehicle having the wheel and an indicator lamp on the vehicle dashboard, or an audible warning device.

7. A vehicle having a number if wheels with pneumatictyres and having a detector as claimed in any of Claims 1 to 6 for each wheeí.

8. A method of detecting whole or partial deflation of a pneumatic tyre on a vehicle in which a probe, which is mounted to be normally out of contact with the ground, comes into contact with the ground when the tyre of an associated wheel becomes partially deflated and in consequence the probe is deflected and causes a warning to be given.

9. Awarning device comprising a casing containing an electric switch and a pivotally mounted probe projecting from the casing, the probe being normally spring-biassed against a stop, but arranged, when pivoted awayfrom the stop, to operate the switch.

10. A device as claimed in Claim 9 in which the casing is adapted for mounting on awheel hub or wheel mounting.

11. A pneumatic tyre deflation detector constructed and arranged substantially as herein specifically described with reference to the accompanying drawings.