OA10074A - Tyre fault warning device - Google Patents

Description

010074 "TYPE PMJLT WMttCaC DEVÏCE*' PESCRIPTIOWi

The présent invention relates to a tyre fault waming devisa, espe-cially but not exdusively £$; the tyres of totor-cars and liÿxt oomnercialvehiclea.

As is well known, the maintenance of tha. tyres of a vehiole at th»OQ^-^t operating pressure is of paramount iôportanoe to tha safety of the.vehiole «ben driving -s indeed to this end manufacturera reconxnend thatthe vehiole tyres are chnrjwd far tho oucrout pressure prier to oannencinga joumey. Kowever, due to various reasens e.g. slow punctures, deformedwheel rûns, etc, tyres dan loeë pressure. Also, where there is overheatingat a wheel a dangerous situation can arise.

Op until now there pas been no satisfactory and oonvenient means ofwaming drivées of thesè' tyfb fault situations, while tha vehiole is onthe move.

It is the principal ûbjdct of the présent invention to provide a tyre , I · * fault waming devine which cçn be oonveniently ixstalled, bot which issatisfactory and' reliablç in operation.

Aooording to tha érèseuç invention, a tyre fault waming devise com-prises a fault waming means 'hdapted to be fitted at or inoorparated in a ?t ·.’·*· dl tyre valve, said fault waming jneans includinq radie signal means to trans-mit a radio signal for réception by raœiver means, said receiver meanslncluding fault indicating menas, and switch means zesponsive to pressure • . jt* ·*’ and/or tenperature conditions" in a tyre to activate said radio signalmeans far the issue of a £adio waming signal..

Preferably said ewitfch means are located in a f bot port of a tyrevalve; and preferably sâid Switch means are housed in a chaobar at saidfoot part, said chantoer ^nchiding a wall which is aoveble on Changingpressure and/or tenperafitte conditions in a tyre to actuate said switchmeans. Preferably said wàll is carried by a flwrihle ring mariber» andpreferably eaid-*all· «apaisée d ponvex dise of hi-metal meterial.

In a preferred entoodirenf, electrical power means far the radio signalmeans ineludes a battery housed in a removable cap of the tyre valve,electrical îeads to theradiosighal means being inoorparated in the valvebody and the cap. The cap çan’fee.secured to the valve body by a fitting Λ . means adapted to ensure thait tha laads to the radio signal means are can- - 2 - 010074 piste when the cap is fitted. Breferably the cap carries an ærial pf theradio signal means.

The recerving meànS can Include suitable warning means such as a lightor aurai warning (e.g. buzzer), and preferably these means include alatching device to maintaiii’ ti» warning indication, even whsn thewarning signal ceases. '

An embodiment of the présent invention will now be described by wayof exemple with. refererioe to the acconpanying drawings whereins

Fig. 1 shows a side-viçw of a high performance notor-car fitted witha tyre-fault warning System in accordance with the présent invention;

Fig. 2 shows schématisai 1y the radio transmission arrangement for warning signais in the warning System of Fig, 1;

Fig. 3 shows a cross-sectional elevatiohal view of a tyre and whsel• ♦ · rim portion including a tyre fsuit transmitting device of the System;

Fig. 4 shows a cross-sectional view of the fault transmitting deviceof Fig. 3 to a larger scale;

Fig. 5 shôws a detail q£ Fig. 4 to a larger scale; and

Fig. € shows thé inStrunsnt panel of the car of Fig. 1 fitted withtyre fault warning indicâtors.

Referring to the dràwings, a System for indicating tyre fault condi-tions, specifically pressure loss and overheating in the tyres, conprisestyre inflation valves which are in the form of spécial fault sensing andsignal transmitting valves 1, ând an æri al, pick-up 11 which. runs between the wheels 15 of the vehicle and which transmits fault signais from the ·* . ’ ’’ valves 1 to fault indicating iheans 2 installed, for exarqple, on the vehiclesinstrument panel or at saine other position whepe it will be possible forthe driver of the vehicle. to see a fault warning indication issued by theindicating means 2. The jndicating means 2 comprises a radio signalreceiver (Fig. 2) and warning indicating mean&amp;< such as a light or abuzzer. A separate warning light can be provided far each tyre so thatthe faulty tyre can be prêdsely identified· The valves 1 hâve the fui*.—tiens of sensing when tyré pressure falls by a predetermined aununt andtransmitting a warning radio signal when this reduced pressure conditionis reached, and similarly transmitting a warning signal when these is over-heating at the tyre.

Referring itbre.especially to Figs. 3 to 5. the spécial tyre valve 1includes a main valve body 16 which is of high grade plastics materialhousing a conventional one-way valve device (i.e. Schrader) 17 in an air - 3 - 010074 duct 3, and the body 16 has a langer diameter foot portion 16A which en-ables the body 16 to be tightly secured to the wteel rim 18 by a locknut19, the body 16 being insertèd throuÿi the normal valve haie in thewheelrim 18 such that the Joot 16A is i ntcrnally located. A sealing ring2ü, positioned betweenthe foot 16A and the wheelrim 18 ensures thedesired sealing effect, while foot 16A inclndes extemally opening airpassages 3A cccmunicàting with duct 3. A spécial plastics cap 8 is fittedon the body 16 and inclndes lugs 8a whereby the cap is fitted to thebody 16 by a half tum baypnet action, and by this means the cap 8, canbe fitted in only one posistiûo on the body 16. The radio signal, indi-cating a tyre fault condition^ is generated by a radio circuit on aprinted circuit board 10, and the power for this circuit is tqken from aStnall battery 9 (e.g. mercury oeil type) located at the inner end of the % · . fc * « cap 8 via electrical circuit leads 21A, 21B, electrical contacts 8B beingprovided between the cap 8 and the body 16 on this circuit. Further, aswitch is located in this circuit 21A/B at the foot 16A cbnprising switchcontacts 4 and a switch closing head 13A. A tension spring 22 ensuresgood contact between the. battery 9 and the feed and retuzn Unes of thecircuit 21A/B.

Operation of the closing head 13A is effected by a pressure sensitiveactuator 12, responsive to tyre pressure. The pressure sensitive actuatar 12 comprises a flexible.ring seal 6 carried by a louer rim of the foot î' ?· ' 16A, while a convex bi-tnetal dise 12A is fitted' to the ring seal 6 wherebya sealed chantier 5, at atnospheric pressure is formed at the foot 16A. Arod member 13 has one end resting on the dise 12A while the other endcarries the closing head 13A, ooopression spring 7 urging the rod trenfaer 13 against the dise 12A.

Incofparated on the cap 9 is an aerial wentoer 8c far the transmissionof radio signais 5 to be picked rp by aerial 11 (Fig. 2), and this aerialmember 8c is connected to the, radio circuit at board 10 by lead 24. Thewaxning indicating means 2 (Fig. 2), inclndes the radio receiver 25, towhich. the aerial 11, is fitted and which is powered by the vehiole'sbattery (not shawn) via leads 26A, 26B, a latching unit 14, and faultindicator 27, including ON- indicator laap 28 and buzzer 29. B» latchingunit 14 has the functicn of maintaining the fault waming signal at lanp28, even when the warningradio signal ceases.

Existing tyres can bë converted to the new System sinply by renovingthe existing valves and replacérig these with the spécial valves. 1. 010074 - 4 - Το place the warning System in an operating mode, before inflation ofeach tyre 18A ?the contacts 4 encased in chpofeer 5 nre closod and when thetyxe is inriated to'a pre-set pressure (say 26 psi/1828 gm/cm2), the flexi-ble ring seal 6 empresses and pushes against the spring 7 to nove thehead 13A, and thereby open thé contacts 4 making a normally open circuit.

The tyre is then inflàted bÿ a further amount (say 3 psi/211 gm/αη2 to29 psi/2039 gm/αη?) to the nbrÎOTl running pressuL** q£ the tyxw ln question.

Mhen inflation is cmplated the spécial cap 8 oantaining the pwer cell9 is fitted to the valve body 16. t*. .· Tîiis cap 8 can onlÿ be fitted in one position by means of the halftum bayonet cap action to locate lugs 8a. The fitting of the cap 8energises the line frotn the battery 9 through the contacts 8b between thecap and the valve stem, thendpwn to the open switch contacts 4.

The vehicle is thén ready far normal use, but if a tyre fault develops,causing a predetermined déflation (say 3 psi/211 gn/cm2 or more), then thecontacts 4 close which energises the radio transmitter circuit 10 whichin tum sends a radio signal via the aerial 8c, which is incorporated inthe valve cap 8, This signal is picked tp by the aerial 11 and passed tothe receiver 25 which causes thewaming light 28 for the appropriatewheel to flash, and the buzzer 29 to sound.

If, on the other hand, a fault develops which causes the tyre to over-heat rather than lose pressure, the bi-metal dise 12 will flex and causethe rod 13 to move dpwnto close the contacts, 4. ,thus sending a warningsignal to the driver, in the marner described above.

When a fault develops whiléthe vehicle is parked, the driver shall be35 soon as hé tümS the ignition key an, by virtue of the latching device 14 incorporated in thé warning means 2, setting the warningsignal.

Ri--jp.fi y therefore, with the tyre at the correct pressure and a safetenperature t-hpre is an open circuit. but. with a drop in pressure or arise in tenperature, then the circuit is closed and wams the driver througha radio link.

It is a f eature of the. arrangement that the radio warning signaltransmission can be restriçted tû a narrow envelope (e.g. 2 mettes wide)along the length of the vehicle, so that interférence problems with over-taking operating the same warning system can be avoided. The radio transmission freqpency will of course be selected to satisfy thepertinent régulations Of the country. 010074

Thus the présent invention provides a safe and relatively économiedevice which can be fitted easily and relatively quickly to a vehicle, byremerving the tyre valves aod replacing thêta with the spécial fault trans-mitting valves 1, the receivèr for the radio signais o£ the valves 1, including the àerial 11 being relatively easily installed in the vehicle.

Modifications are pf course possible. Unis it may be possible to use a power source otherthao a battery (9) in the device - for exanple a1 * piezo electric generator oould. be used producing the required power forthe device front vehicle vibration.

Referenoe is made t£~Uie applicants oo-pending application no. 8815550.2 filed 30 lune 1988 which describes a tyre fault waming devicein the form of unit bloçk fitted into an existing tyre valve, the deviceagain issuing a radio waming signal when tyre pressure falls to a pre-deterndned level or when onsatisfactory overheating occurs.

Claims (11)

1. -6- 010074

   1. A tyref auit'waming device comprising a faultwarning means to be carried by a vehicle wheel whereinthe fault warning means is adapted to be coupled to orincorporâted in a tyte Valve, the fault warning meansincluding radio signal means to transmit a radio signalfor réception by receiver means provided with faultindicating means, sensing means for location in a tyreresponsive to pressure and/or température conditions inthe tyre, and switch means actuable by said sensingmeans to activate said radio signal means for the issueof a radio warning signai, the switch means beinglocated in a housing so as to be shielded from the airin the tyre.
2. 2. A device according to claim 1, whorein salaswitch means are located in a foot part of a tyre valve.
3. 3. A device according to claim 2, wherein saidswitch means are housed in a chamber at said foot part,said chamber including a wall constituting said sensingmeans which is movable on changing pressure and/ortempérature conditions in a tyre to actuate said switchmeans.
4. 4. A device according to claim 3, wherein saidwall is carried by a flexible ring member.
5. 5. A device according to claim 2 or 3, whereinsaid wall comprises à convex dise of bimetal material.
6. 6. A device according to any one of the precedingdaims, wherein electrical power means for the radiosignal means are provided including a battery housed ina removable cap of the tyre valve, electrical leads tothe radio signai means being incorporated in the valve • body and the cap.
7. 7. A device according to claim 6, wherein the capis secured to the valve body by a fitting means adaptedto ensure that the leads to the radio signal means are 010074 - 7 - complété vhenthe cap is fitted.
8. 8. A device according to claim 6 or 7, wherein thecap çarries an aerialof the radio signal means.
9. 9. A device according to any one of -the precedingdaims, wherein the teôeiving means. include wamingmeans such as a light or aurai waming eg buzzer.
10. 10. A device according to claim 9, wherein saidwaming means includes a latching device to main tain thewaming indication; evért when the radio warning signalceases.
11. 11. A tyre fault earning device substantially ashereinbefore described with reference to and asillustrated in the acçompanying drawings.