CA1045964A - Inner tube assembly for run-flat tires - Google Patents

Abstract

Abstract of the Disclosure An inner tube assembly for a pneumatic tire, comprising a primary annular tube, a secondary annular tube surrounding the primary annular tube, an annular primary tube-restraining band interpositioned between the primary and secondary tubes, and valves intercommunicat-ing the primary and secondary tubes with one another, is disclosed. The foregoing abstract is neither intended to define the invention disclosed in the specification, nor is it intended to limit the scope of the invention in any way.

Description

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Backg~ound of t~le Invention The present invention relates :in general to the provision of an inner tube safet~ system .for a partially puncture-proof, vehicular, pneumatic -tire of the "run-flat" varietyO More particularly, the present invention relates to a pneumatic tire comprising means for par- :
titioning the interior thereof into two inflatable annu- ~' lar chambers, one o~ which surrounds the other so if :~
punctured will deflate to the exclusion of deflation of '~
the inner chamber it surrounds.
It is already known to provide an inner tube ' safety system for pneumatic tires that comprises~
a) a so-called primary, radially internalj con-tinuous, endless annular inner tube made Qf a substan-tially inextensible flexible rnaterial in order to maintain a substantially constan~ crossectional perimeter, the tube being adapted to surround contiguously and fit into '~:
the well of a vehicular wh~e~ rim,. the tube having an outside diameter that, in its mounted inflated state, is ' substantially lass than the inside diameter of the crown region of an inflated tire the tube is to be associated '.~
with, the tube having a conv~nt~onal ln~lation valve de- .;
signed to pass through said rim; and `' b,) at least;on~ systern o~ a so-called secondar~
radially externai inner tube means made of elastically ;' .
expansible or dilatable material, circumferentially sur~
rounding completely,'contiguously, and substantially con- .`.`'~ ' cent.rically the primary inner tube, and filling out, in the mounted state, the balance or the rema'ining.volume of the available inner space of the tire7 the secondary inner tube means being connected, preferably detachably and -' .. . . : . . . .. . . . . ................... .. . . .
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~ermeticallyg with the prlmar r lnner tube by at l~a~t ~ne 1'~pecial valve" capable o~ ning automatically to communicate the interior~ of the primary and secondary tube ~y~t~ wi~h one another ~herl they are under a mu tual pressure equil~bPiu~ ~d (2) closlng automatieally ~hen the sec~ndæry or outer ~ube m~an~ i~ p~ulctured ana loses its pressure equllibriu~n with the primary or ir~er tub~. Such a "special lralve" (~r valve~ ls disclo~ed ln the c~pe~di~g Canadlan Patent Applicatloll Seri~ No9 1~ 256,669, of Arldre M. :13ev~enne and ~ilbert I.. Ig~a, fi~ed July 9, 19769 a~d assigned to Uniroyal~O a Societe Anon~
wh~ch as~tgnee ls the ~une ass~gnee o~ the in~taIlt appll-cation~
~I!he above kncl~n s~rst~ attented by the draw back o~ requiring ~ strusture o~ relativel~ con~plex a~d .
co~tly prima~r ir~er tube constituent materlal ~u~ to it8 ~ceseara1 lnextensibility property.
Summar~r o~ the In~rentio~
~h~ maia obJect o~ the pre~ent inventl~ is, there-2~ ore, tQ el~mlna~ ~uch drawl~ac}~s by crea~lng a syst~m that use~ with respect to the primary ins~er tube, a non-reinr~or¢ed ordinarr i~ner tube material that i~ pre~erdbly ela~tlc~lly extcn~ibl~, ~uch a~ ~or in~ a pneu-matic tire inner tubc ~r a motorcyclc ~heel or thc likeO
This i8 achi~ved by sl~ulta~e~siy providing ~ae~n~ de-signed t~ limit th~ circum~erential e~ sion of such a primar r ir~er tub~
For this pu~po~e, the lnn~r t~be syst~ in accord-~ce ~ith th~ prese~t invention co~prises an ordlnary radlally internal primary in~ler tub~ made o~ a ~le~ible ~ -material that is exteneible ~r dilatable upon lrli~lati~n, _2- ;

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and an endless~ continuous annular retainer element, pre-~erably removable, made of a relatively flexible, but substantially inextensibl~, material having an insid~ dia-meter that is subs~antially equal to the maximum specified outside diameter t~,at the primary inner tube is to define in its standard inflated mounted and operating configura-tion. The retainer element is in the form of a hoop or collar that retains the inner primary tube in a specified maximum diametral condition annularly spaced from the inner crown region of the tire it is to be disp~sed into. The latter said annular space is to be filled by a secondary tube system or means that is separated from the primary tube via the retainer element.
The retainer element forms in this way a parti-tioning wall pro~iding a respective radlally external bearing surface ~or the primary inner tube and a radially `~`
intern~l bearing surface for the secondary tube means, the axial extent or width of the said retainer element being at least equal to the span of the internal space of the ;
~0 pneumatic tire in its inflated operating configuration at the site that the retainer elemeNt is to be ernployed.
It will be understood that the aforementioned "special"
valves that lnterconnect the primary tube to the secondary tube means project th~ou~h appropriate open-ln~; provided in the retainer element.
According to another characteristic of the present in~ention~ the afore~aid annular retainer element is made of a synthetic plastic material such as~ preferabl~
polyurethan~ whose hardness is preferably selectively variable within wide limits, for instance between a Shore . ... .
... .
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A hardne 8 ~3 of 30 and 90 unlt~ .
According to yet another character~stlc ~r the pre~ent ~nvention, the a~ore3ald annu~ar re~ainer el~mer~t i8 made o~ a~tlricial or syn~hetic rubber or o~ a thermo-pla~tic Rynthetlc elastomer known in th~ trade under the trademark de~ignation "U~IROYAL TPR" ~hich i8 ~nd~wed in pa~lcular with the prop~rt~es ~:f a vulcaniz0d rubber and, ln particular, ~ith }~gh heat resl~tance.
According to yet another characteristlc of tha presenlt ir~e~tion, the afor~said retain~r ele~enit i8 manu-~actured from an inJection molded material, in partlcular under pre~ure.
qhe pre~e~t i~ven~ion, there~ore~ o~fers the ad-~antag~ o~ a eubstantial reduction in the cost of the afore~aid inner tube system a~ a re~ult o~ a ~ubstantial reducti~n ln the manu~acturing cost o~ the primary inner tu~e, and by the concomitant creation o~ an annular re-tainer element constituting a ~pacer element ~nterposi-tioned between the primary ir~er tube and the secondary i~er tube mea~, the retainer elemant being likewise made oY a sub~ance that i8 rela~i~ely inexpen~ive and simple tQ manu~actureO Such de~lg~ bene*its are ~btained without impairing either the e~iciency, depcndabilit~
~r op~ra~ve ~a~ety oP the ~yst~m~

Bri~r Da~cripti~n o~ the nrawi~s me pre~en~ in~ntion will be better under~tood ~ .
~rom ~he ~ollowing detaiJ.ed description thereo~ taken in eonJunction wlth ~he dra~rings~ in ~ch:
Fig. 1 ~s an enlarged, fragmentary, vertical, cross-~ectional view of the tube s;ystem o~ ~he present in~rention; all~

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F~ g . 2 i~ a per~pectlve view c>~ ~he retalner el6-~ent of the pre~ent in~en~lon.

Detailed De~crl tion of the Inverl~ion _ P
Re~erring now to the drawlngs, there i~ 111UB~
trated in Fig. 1 a pneumat~c tire 1 that ~s mo~ted on a w~eel rim 2. q~he p.neu~atic tire 1 i~ coD~prlsed o~ a croom ragion 3 surrounded by a tread 4. The ~idewalls are rein- -forced by a pair of a~ular beads 5, by m~ans o~ whlch the ;:
tire 1 ls mounted on the ~heel rlm 2~ Wheel rlm 2 in~
cludes a ~rell or drop cen~er 8, a pair oi bead ~eats 10 ~ :and a pa~r o~ flanges 9. Confined in the tire 1 is a ;
radially internal pri~ary inner tube 6 and a radlally .~
external secondary inner tube 70 . :
me pr1ma~r lnner tu~e 6 18 made ~rom an e~cten3ible or dilatable ~lexible material, in particular a materlal ;`
tha~ is elaeticall~ dilatable or exten~ibl~ when ~nflated.
The *u~e 6 i~ surrounded ~ubstantially coaxially by an:- :
annular retainer ele~nt 43 extending from one lnternal` `
tire sidewall to tb~ oppo~ite lnternal sidewall. Because 2~ the prim3r~ tube m~an~ 6 lles partially radially coexten-~irelg with and axlall~ between the beads 5 o~ ~he tire, ln~lation pres~ure within the primar~ tube cau~e~ cause~
~t to bear ~gain~t the bcad~ 5 and brac~ th~m a~a~n~t th~
r~diall~-~x~endlng portlone. o~ tha ~langes 9 o~ rim 2.
Z5 A conven~ional ~iller valve 11 i8 provided to allow in-; ;
flation of pr~m~ry tube means 6. The retainer elem~nt 43 is l~terpositioned between the radiall~ internal periphery of t~e secondary inner tube 7 and the radlal-ly external peripher~ of the primary lnner tube 60 me retatner element 43 (Fig. 2) is provi~dèd with .... . , .. ~ , -6~ 59~;4 clrcwl~ferenti~lly ~paced apart orlfice~ 44, the ce~ters of whiCh are sitUatea in ~he median equat0rial plane Or th~ retalner element 43. ~Che number oi such lDri~lce~
44 correspond~ to the number of ~pecial ~ral~r~5 13 con-nectlng and lnterconnunicatlng the seconda~g lnn~r tube 7 with primary inr~er tube 6. The speclal val~e~ 13 are of th~ typ~ disclosed in the a~or~DIontloned Ca~adian Pate~t Applicatlon No. 2569669 whlch remain open a~ g ~ there i~ a pressure equllibrium ln the tubes 6 a~d 7, 1~ and ~hleh cl~e whe~ ~¢h ~qull~brlum 18 103t~ ~r example, when the tube 7 is pu~ctur~d. Clearly the valve~ 13 proJ~et thr~u~h the ~pertur~s 44 to i~terc~munieate the `~
tubes 6 a~d 70 In thi~ regard, it wlll be understood that~ the tube 7 ~ay be co~prised oi a plurallty or di~-crete9 ~epara~ely in n atable chamber~ each of which is as~ociated with a r~spectiv~ one o~ the valv~s 13.
The r~tainer el~me~t 43 i~ subst~ntlally cylin- .
drical or h~op-sh~ped, and i~ axially coexten~ive with : `
th~ tubes 6 a~d 7 at the partlng llne th~rebetween. The 2~ opp~9it9 ~nd~ cr the rotai~er el~ment 43 are each provided with a~ a~nular or r~i~ed ~lango 45 th~t ~8 at least sub- . ;
otantially trun¢ated or con~sh~ped ~nd divorge~t~ Th~
two ~lang~ 45 are preferably su~Btantially symmetrlcal wi~h re~pa~t to ~he ~edian oquatorlal pla~o o~ tho re~ er element 43. The retainer ele~ent 43 i~ ~ade pre~erably o~ .

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~ ~459 6 4 an inextensible mat~ri~il that is, however~ flexible~
The provision of the flanges 1~5 is ad~antageous in the sense that they embrace and anchor the axially endmost portions of the tube 7.
As illustrated in Fig. l, there remains open two spaces 34 on each side between the pneumatic tire l, tL~e annular retainer eleme~k ~3, and the primary inner tube 6.
It is contemplated that such spaces 3L~ be filled with re-spective annular elements ~now shown). Such elements may - ~
be made of rubber or the l~ke appended to, for example~ the~: ;
wall structure of the tube 6. The appended annular elements would, preferably, be contoured to corrrespond:l~o the contour :
of the spaces 34, and may be vulcanized or otherwise af- ~ `
fixed to the tube 6.
Each special valve 13 has a body portion~ l4 con-strained in a respective rubber tube stub 15 that is for-med a~ part of the inner tube 6, the opposite end portion of each valve 13 being affixed to the outer or secondary inner tube 7. Pursuant to a preferred form of such an arrangement, each tube stub 15 is associated with its corresponding valve 13 in snap-fit, detachable relation.
For example, each tube stub may be provided with an in-ternal annular~ collar-like~ flange 46, and each cor-responding valve 13 may have an assoc:iated annular groo~e 47. ~ :
Having thus set forbh the nature of the present invention, it will be unders-tood that the foregoing des-cription of a preferred embodiment of the present invention: ~
is for purposes of illustration onl~, and that ~he various:: :
structural and operational features and relationships herein ~ :

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disclosed ar~ suscept~ble to a nu~b~r of modifications and chan~es none of ~Ihich ent~ils an~J departure ~rom the spirit and scope of the present invention as defined in the here~
to appended claims, . ., ,:

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Claims (5)

What is claimed is:

1. An inner tube assembly for a pneumatic tire, said assembly comprising an annular flexible extensi-ble primary tube means adapted to lie at least par-tially radially coextensively with and axially between the beads of the tire when the assembly is mounted in the tire, primary valve means connected to and communi-cating with the interior of said primary tube means, secondary tube means surrounding said primary tube means, secondary valve means interconnecting and com-municating with the interiors of said primary and secon-dary tube means, and an apertured, substantially inex-tensible, flexible annular band interposed between said primary and secondary tube means, said band being coex-tensive axially with said primary tube means and said secondary tube means at a parting line therebetween, said band having an axial extent at least equal to the span of the internal space of the tire in its inflated operating condition at the location occupied by said band in said operating condition, whereby said band will limit the circumferential expansion of said primary tube means to a specified amount upon the inflation of the latter via said primary valve means, said secondary valve means remaining open and intercommunicating through said apertured band the interiors of said primary and secondary tube means for as long as there remains an equilibrium of pressure therebetween, said secondary valve means including closure means for pneumatically isolating the interiors of said primary and secondary tube means from one another when there occurs a pressure drop in said secondary tube means relative to said pri-mary tube means.

2. An inner tube assembly as claimed in claim 1, wherein said band includes at each of the axially op-posite ends thereof a respective radially outwardly pro-jecting frusto-conical flange.

3. An inner tube assembly as claimed in claim 1 wherein said band is provided with a central, circum-ferential array of apertures corresponding in number to the number of said secondary valve means.

4. An inner tube assembly as claimed in claim 1, wherein said secondary tube means comprises a plurality of discrete, separately inflatable chambers, and wherein said secondary valve means comprises a plurality of sepa-rate valves each of said valves being connected to a respective one of said inflatable chambers.

5. An inner tube assembly as claimed in claim 1, wherein said secondary valve means includes a body ex-tending through an aperture in said band, said body is attached at one end thereof to said secondary tube means and said body is attached at the other end thereof to said primary tube means, so that said secondary tube means,said band and said primary tube means form an integral subassembly for installation in said tire.