GB2181700A - Tubular tyre for cycles in general and in particular for racing bicycles - Google Patents

Abstract

The tyre comprises a toroidal casing 2 incorporating an air chamber 3, a protective strip 5 between the casing 2 and a rim 41, and a tread 6. At or adjacent the radially innermost part of the casing, in the vicinity of the joined edges 11 of the casing 2 there is at least one circumferentially extending reinforcing ring 10 constituted by a plurality of filaments having a high tensile strength. The edges 11 are joined by stitching 12 and the rings 10 prevent the tyre coming off the rim on deflation. The rim may be provided with grooves for improving the housing and anchorage of the rings 10. <IMAGE>

Description

SPECIFICATION Tubulartyrefor cycles in general and in particularfor racing bicycles The present invention relates to a tubular pneumatic tyre suitable for cycles in general, and especially suitableforracing bicycles.

Bicycles for general use have wheels with rims shaped to receive and retain the wire beads of an outer cover which encloses an inflatable inner tube.

Racing bicycles, on the other hand, are usually fitted with tyres of a much lightertype known as "tubular" tyres, in which an airchamberorinnertube is entirely surrounded by a fabric casing, usually made of cotton, but sometimes silk.

The basic type oftubulartyre is generally constituted by a toroidal fabric casing which surrounds an air cham ber or inner tu be and wh ich is protected from abrasion against the rim of the wheei by an outer protective base tape and is provided on its radially outermost partwith a tread which, in the most valued tyres, incorporates or overlies one or more fabric layers for protection against punctures.

Many constructional improvements have already been introduced into the basic tubulartyre by utilising natural and/or synthetic yarns and/or rubbers, as well as a whole series of improvements which have been taken from othertechnologies.

The majority of these improvements were directed towards a reduction in the costs of production, to widening the use oftubulartyresthemselves, asweli as to making them more attractive to users by improving the performance of such tyres, particularly as far as their durability is concerned.

In particular, the bands forming the casing originally made from several pieces of rubberized fabric cut on the bias with an angle of about45% have sub- sequently been formed by superimposing at least two layers of closely adjacent ru bberised threads crossing one another, which are then cut on the bias and formed into a band. To form a toroidal casing from such a band the circular edges were initially brought together and sealed, with the possible fitting of a sealing band; subsequently, however, the edges have been joined by sewing them together after having first preiiminarily hemmed them either externally or internally. Again an inner protective band may be positioned between the sewn edges and the air chamber.Sewing the edgestogethertoformthetor- oidal casing also has the advantage of making it possible, by unstitching, to gain access to the innertube to effect repairs after a puncture which was not possible with a sealed casing. It is also possible to change a valve if this becomes necessary.

Fabrics were also provided to give some protection against punctures; initially these were constituted by strips disposed both internally and externally of the casing in the region ofthetread, but subsequently they became, as for example is illustrated in Italian Patent application No. 22 158 A/84 by the same applicant, true and proper fabric layers without discontinuities, which extend circumferentially and are disposed to protect not only the region of the tread, but possibly also the side walls, going as far as to link up and join with-the base tape or being interposed between the edges and folded over with these.

This latter fabric, if made with the warp threads of the weave disposed radially, that is to say, orthogonal to the direction of movement, acts to reinforce the tyre cross-section, reducing deformation thereof, as well as improving the road holding ofthe tubulartyre in use. If, on the other hand, this latter fabric has warp threads disposed circu mferential Iy, that is to say in the direction of the movement, they act as further bracing for the tread, improving the resistanceto puncturing and lowering the rolling resistance of the tubular tyre in use.

The present invention seeks to improve the already considerable safety characteristics of a tubulartyre and to make it possible to use such a tyre, even on a rim intended for conventional tyres with an inner tube and an outer cover, having in all cases high safety properties in that it is almost impossible for the tyre to come offthe rim even in the event of accidental rapid deflation when going downhill or in a curve.In the event of the accidental puncturing of a tubulartyre, this is subjectto a more or less rapid deflation which, if the tyre is not securely adhesively retained to the rim with suitable mastic or adhesive, it can come off from the rim, particularly ifthetol- erances and dimensions of the casing and associated basetapeareatthemaximum limit and those of the rim at the minimum limit.

A particularfeature of the present invention is that it can be used on a normal rim fortubulartyres, or one provided with a groove deeper by 2 or3 mm than those normally provided on tubulartyre rims, or on a conventional rim intended for cover-type conventional tyres.

According to the present invention, there is provided a tubular pneumatictyre comprising atoroidal casing constituting or incorporating an airimpermeable chamber having a protective basetape on the radially innermost portion of the tyre cross- section, facing the rim of a wheel when fitted thereto, and a tread on the radially outermost portion of the tyre cross-section in which there is at least one reinforcing ring constituted by a plurality offilaments of high mechanical strength, extending circumferentiallyaroundthetoroidal casing.

Afeature of the present invention is that it allows the use of an outer protection tape in which the characteristics of economy and protection from abrasion, as well as adhesiveness to the casing and/orto the rim can be emphasised, the requirements for circum- ferential reinforcement no longer being of primary importance.

Embodiments of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure lisa corss-section of a tubular tyre formed as a first embodiment of the invention, fitted to a tubulartyre rim; Figure2 is a cross-section of a tubular pneumatic tyre formed as a second embodiment of the inven- tionfittedtoa light cover rim; Figure 3 is a cross-section of a tubulartyreformed as a third embodiment of the invention with a single circumferential reinforcement ring;; Figure4is a cross-section of a tubulartyreformed as a further embodiment ofthe invention having two adjacently disposed circumferential reinforcement rings with an innertape interposed between them; and FigureS is a cross section of a tubulartyre with two reinforcement rings located radially outwardly ofthe stitching, mounted on a special grooved rim which is also the subject of the invention.

In the different figures of the drawings, which show different embodiments of the invention,the same reference numerals have been used to identify the same or corresponding components.

With particular reference now to Figure 1 ofthe drawings, the pneumatictyre indicated generally with the reference numeral 1 has a toroidal casing 2 which encases within its interior an air chamber or inner tube generally indicated 3, also oftoroidal form. Between the toroidal casing and the rim ofthe wheel, indicated 41, is a protective strip 5, whilst on the radially outermost part of the casing it is protected by a tread 6.

On the radially outermost part ofthe casing 2 there are three fabric layers, a first layer7 on the outside, under the tread 6, a second fabric layer7' again on the outside ofthe casing 2, but underthefirstfabric layer 7, the second layer 7' extending round the cas- ing to meet up with the inner protective strip 5, and a third fabric layer 7" on the inside of the casing 2, between this and the innertube 3 constituting the air chamber.

The edges of the casing 2 are folded overto form hems 11 and these hemmed edges are then sewn together with a stitching thread 12. An inner band of tape 13 is provided between the air chamber 3 and the joined edges ofthe casing 2. Within the hemmed edges 11 there are respective "soft" reinforcing rings 10 offilaments, preferably made of kevlar (R.T.M.) or otherfibres having a high resistance to tension. The term "soft" is intended to define a reinforcing ring the cross-sectional shape ofwhich is not defined in a hard and fast shape so that as the tubulartyre is flexed in use or as it is fitted to the rim the crosssectional shape ofthe reinforcing rings can change.

This is demonstrably the case if the reinforcing rings 10 are composed of a bundle offilaments all extending circumferentially since these can clearly change their relative positions when acted on byforces transverse their length.

These filaments are positioned so as to exert a "betting" action,that is a circumferential reinforcemenu which prevents the tyre from coming off the rim more certainly than has hithertofore been the case with known tubulartyres.

The embodiment of Figure 1, has two rings 10, one in each ofthe folded or hemmed edges 11 of the casing 2, in the region of the stitching 12 underthe inner band of tape 13. In this embodiment the reinforcing rings 10 are held by the sewn edges 11 ofthe casing 2 in a position close to the median plane ofthe rim 41 orthogonal to its axis.

With specific reference now to Figure 2 there is shown a second em bodiment for use on a rim 42 for conventional light pneumatictyre covers. In this embodimentthe reinforcing rings, again identified with the reference numeral 10 are provided within the hemmed edges 11 which are joined bythestitching thread 12 in such a way as to allowthe rings 10 to lie further apart in such a way as to press the radially inner parts ofthe tubulartyre underthe anchoring lips ofthe channel ofthe rim 42.

With particular reference to Figure 3, here there is provided a single reinforcing ring 10 which is posi tioned between the sewn edges 11 with the stitching thread 12 passing radially outwardly of it. The in ternal tape 13 has its longitudinal edges folded out wardlyon either side ofthe ring and joined with the hemmed edges 11 of the casing by the stitching thread 12. The tubulartyre thus has a securely loc ated single reinforcing ring 10 coincident with the median plane of the rim 42.

With reference to Figure 4, there are provided "soft" rings 10 for reinforcing a tubulartyre, posi tioned in the central portion within the hemming 11, but outwardly ofthe stitching 12 in the sense that the stitching threads or cords 12 lie between the reinforc ing rings 10 and the edges of the casing 2. As in the embodiment of Figure 3 the longitudinal edges of the inner tape 13 are interposed between the edges of the cover 2.

The reinforcing rings 10 are, in each of the above embodiments, suitably pre-tensioned or formed on a production drum with a diameter such asto permit them to befitted to the rim of the wheel with the tubulartyre deflated and flattened and the reinforc ing rings 10 stretched to the maximum acceptable limit of elongation under load. Once positioned in the channel oftherimthe rings 10can exerttheirreinforcing effectto retainthetyrefrom coming offthe rim.

The filaments of the reinforcing rings can be provided as projecting, raised beads and/or may be embedded in the structure ofthe outer protection strip.

With the described arrangement, the reinforcing and tyre retaining functions, now being performed by the rings 10, the outer protection base tape 5 can become a simple preformed flap ofthe most simple type, in plastomeric or elastomeric materials or rubberised fabric or other suitable material. Moreover, this outer base tape can be drawn, moulded or otherwise formed in any particular shape and can possibly be conceived as a ribbon of tear strip normally known in commerce with the Trade Mark Velcro. Possiblythe base tape 5 may be formed in non-woven fabric, expanded cellular material, possibly coupled to a semi-rigid support, non-woven or woven fabric and soon, and possibly may be preliminarily provided with adhesive to be wound for one or more turns in the channel of the rim, also providing protective functions against abrasion and puncture as well as for improving the adhesion of the tubulartyreto the rim in use, and therefore under dynamic and thermal stresses.

It is moreover, possible to provide a rim fortubular tyres with one or more grooves or circumferential slots for improving the housing and anchorage ofthe soft rings 10, particularly for wheels intended for professional competition on track or road. In Figure 5 there is illustrated a rim 43fortubulartyres, provided with three circumferential grooves 14 obtained, for example, by rolling whereby not to reduce the thickness ofthe bottom wall ofthe channel, on which there is mounted on a tubulartyre provided with two soft rings 10 and a shaped base tape 15 formed in a particular shape and having the function of ensuring a more secure connection between the rim and the tyre.

The possible accentuation ofthe depth ofthe channel ofthe rim fortubulartyres over that con ventionally used allows both the tubulartyre ofthe invention, which stretches less upon deflation than known tyres due to the presence ofthe soft reinforcing rings 10, or a conventional tubulartyreto befitted thereon. Moreover, there has been described the possibilityofforming in a rim fortubulartyres, one or more circumferential grooves or slots lodging and improving the anchorage ofthe soft rings, without however, prejudicing the use of a conventional tubulartyre.

The presence of the soft rings also gives the possibility of using an extremely simple protective base tape, of which are demanded only the functions of protection, anti-abrasion, and adhesion between the tubulartyre and the rim. It is appropriate to emphasisethat, even although hereinabove explicit re ference has been made to tubulartyres for bicycles, the use of tyres described hereinabove is not to be limited to bicycles, but must be extended to any other tyreforanytypeofvehiclehaving one or more wheels. Moreover, the above explained concept, manifesting itself in the application of soft reinforcing rings, can also be extended to the field of pneu maticorhydraulicsealing packings in which, for example, bythe effect or in the presence of dynamic stresses, it may be necessary to provide a particularly effective anchorage to a frame.

Claims (11)

1. Atubularpneumatictyrecomprising atoroidal casing constituting or incorporating an airimpermeable chamber having a protective base tape on the radially innermost portion ofthetyrecrosssection, facing the rim of a wheel when fitted thereto, and a tread on the radially outermost portion ofthe tyre cross-section, in which there is at least one reinforcing ring constituted by a plurality of filaments of high mechanical strength, extending circumferentially around the toroidal casing.

2. A tubular pneumatictyre as claimed in Claim 1, in which there are provided two such filamentary reinforcing rings spaced from one another parallel to the axis ofthe tyre such as to be able to constitute retaining cores for fitting the tyre onto a rim for high pressure covers.

3. Atubular pneumatictyres as claimed in Claim 1 or Claim 2, in which the said protective basetape has warp threads or cords which offer a high resistance to longitudinal tension, the said threads or cords projecting from and/or being incorporated in the thickness of a woven or non-woven textile fabric having solelythefunction of protecting the casing from abrasion.

4. Atubular pneumatictyre as claimed in any of claims 1 to 3, in which the said protective base tape is constituted by a non-woven fabric or a moulded or otherwise formed plastomeric or elastomeric material.

5. Atubularpneumatictyre as claimed in anypreceding claim, in which the said protective base tape is constituted by a tear ribbon for the anti-friction and anti-separation coupling between the tubulartyre and the rim.

6. Atubularpneumatictyre as claimed in any preceding Claim, in which the casing is formed from at least one circular band the longitudinal edges of which are sewn together to form the band into a toroid.

7. Atubular pneumatictyre as claimed in Claim 6, in which the longitudinal edges ofthe casing band arefoldedovertoform a hem and thefilamentary reinforcing rings are positioned in or adjacent the longitudinal folds constituting the hems.

8. Atubularpneumatictyreasclaimed in Claim 7, in which the sewing thread joining the edges ofthe casing passes through the casing radially inwardly of the filamentary reinforcing rings.

9. Atubular pneumatictyre as claimed in Claim 7, in which the sewing thread joining the edges of the casing passes through the filamentary reinforcing rings, passing between the adjacent filaments thereof.

10. Atubular pneumatictyre substantially as her- einbefore described with reference to, and as shown in, any of Figures 1 to 5 of the accompanying drawings.

11. A rimfora tubular pneumatictyre as claimed in any preceding Claim, having at the bottom of its tyre-receiving channel, at least one groove engageable by the said filamentary reinforcing rings.