GB1587711A

GB1587711A - Tyre cover

Info

Publication number: GB1587711A
Application number: GB2164678A
Authority: GB
Original assignee: Euteco SpA
Current assignee: Euteco SpA
Priority date: 1978-05-23
Filing date: 1978-05-23
Publication date: 1981-04-08

Description

(54) TYRE COVER (71) We, EUTECO S.p.A., an Italian Joint Stock Company, of ii, Via Galiani, Turin, Italy, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a tyre cover of the radial ply type, i.e. having a carcass body the cords of which lie on meridian planes passing through the axis of rotation of the tyre, or at least form small angles with the said planes.

As is known, such tyres are also provided with a circumferential reinforcement or breaker, or "cincture" interposed between the body and the tread, the said reinforcement having, inter alia, the purpose of checking the peripheral dilation of the body, which would otherwise assume a too pronounced curve.

The peripheral reinforcement has very high strength, and hence low deformation under tension and under compression so that the tread, firmly attached to it, spreads out on the road surface like a belt, with consequent reduction of skidding hence of wear.

The peripheral structure is usually composed of several layers of fabric, the width of which is substantially equal to that of the tread, the cords of which form a small angle with the plane of symmetry of the tyre.

The said cords may be of textile material, such as, for example, rayon or aliphatic polyamide, or may be metallic, for example, of steel.

Peripheral structures are known in which textile fabrics alternate with metallic materials.

In any case it is usual to employ at least two fabric layers for the peripheral structure, up to a maximum of five or more, for example, in tyres of large dimensions intended for heavy duties on lorries.

These peripheral structures efficiently fulfil the task of checking the dilation of the tyre body, but they have the disadvantage of rendering the tyre rather uncomfortable, especially when travelling on badly paved roads having patches, holes, expansion joints and the like.

This results from the fact that the peripheral structures, owing to the different layers of material of which they are composed, are not very flexible and hence not very suitable for riding over obstacles in the road.

The object of this invention, therefore, is a tyre for the wheels of any kind of vehicle, which will attain a high travel-comfort level which is decidedly better than that obtainable with tyres either of the cross-ply type, or of the radial-ply type, hitherto known.

More particularly, a tyre cover according to the present invention is of the radial-ply type, and is characterised in that it comprises, in combination: (a) a radial-ply body consisting of one single ply of cords lying in planes which pass through the axis of rotation of the tyre, or else which form small angles with the said planes; (b) a peripheral reinforcement, placed between the said body and the tread, having a width substantially equal to that of the tread, consisting of the spiral winding, in one single layer, of a cord with a uniform pitch of 1 to 4 times the diameter of the said cord; (c) an H/C ratio, wherein H is the height and C the greatest width of the cross-section of the tyre, with a value in the range of from 0.40/1 to 0.65/1; and (d) an L/C ratio in which L is the width of the wheel rim, with a value greater than 0.80/1 and not greater than 0.95/1.

Hence according to the present invention there is provided a peripheral structure in a single layer of textile or metal cords, the said cords being parallel to the equatorial plane, that is, perpendicular to the cords of the body, thus effecting an optimal degree of flexibility and an outstanding improvement in travelling comfort of the tyre on uneven roads.

There has also been noticed an unexpected improvement in steering facility, specifically a decided reduction in the force which has to be applied to the steering wheel of the vehicle in making a turn.

Furthermore, an optical evenness is also given to the tyre, with consequent lack of vibration during the vehicle's movement at any speed, an optical resistance to tread detachment at high speed, as well as reduced resistance to rolling.

It is known that the coupling described between the radial-ply body and the peripheral reinforcement does, however, decrease driving stability, lacking the stabilising action effected by all the peripheral tread reinforcements crossing over each other as in the prior art.

The present invention avoids this negative aspect, inasmuch it has been found that with tyres having the -H/C ratio kept at values within a range from 0.40/1 to 0.65/1, high rates of stability and drive are achieved.

The best results are produced with values of the said ratio of about 0.58/1.

It has also been found that, other conditions being equal, widening of the mounting rim further improves the transverse stability of the tyre.

Therefore, the L/C ratio is kept at values above 0.8/1 up to a maximum of 0 95/1 with optimal values of about 0.87/1.

It should be pointed out that in tyres in general use the L/C ratio usually varies from 0.60/1 to 0.80/1.

The radial body may consist of a single cord ply of rayon, of aliphatic polyamide (for example, nylon), or of aromatic polyamide (for example, that known by the commercial name of Kevlar), or metal (generally steel).

Moreover the peripheral reinforcement may consist of a single layer of cords of rayon, or of aromatic polyamide, or of metal, especially steel.

In each case the cords can be made from a twisted yarn consisting of various elements so as to give very good properties, especially relative to the breakage load.

The siad reinforcement, the width of which is substantially equal to that of the tread, is formed by spiral winding from a single cord, the turns being side by side either with a uniform of from 1 to 4 times the thickness (diameter) of the said cord. More over, after the spiral winding the two free ends of the cord will be on opposite sides of the peripheral reinforcement, and preferably in a diametrally opposite position.

Obviously, there can be applied to tyres of this invention, other devices known and used in this technology, designed to facilitate -stability, such, for example, as textile or metal reinforcements disposed in one or more layers (intercrossed with each other when their number is more than one) and arranged in the area extending into each side of the bead cores to the position of greatest width.

The said elements are generally called loops, strengthener edges, or something else.

Finally the tyre may comprise: two beads, in each of which there is situated an inextensible bead core, formed from metal wires, around which the carcass fabric is anchored, as well as a tread, having slots, positioned above the peripheral reinforcement and two walls of an elastomer mixture.

Other features of the invention are set out in the following description which shows some embodiments of the invention and is made with reference to the attached drawings in which Figure 1 is a cross section of a tyre according to the invention, Figure 2 is a perspective view of the peripheral reinforcement of the tyre according to Figure 1, Figure 3 is an enlarged cross section of the peripheral reinforcement according to Figure 2, In the tyre shown in Figure 1 the reference numeral 1 denotes the tread provided with notches 2, and 3 the tyre sidewall. This tyre is provided with a peripheral reinforcement 4 in a single layer, made with a spiral winding of cords of suitable tensile strength.

The carcass body is made of a single ply -5 which links with the folds 6 around the bead cores 7, and incorporates metal fabric reinforcements 8, two for each bead in the case illustrated in the Figure. 9 denotes the wheel rim on which the tyre is mounted.

H is the section height of the inflated tyre, and C is the greatest transverse dimension, known also as the "chord".

In the case shown the ratio H/C is equal to 0.58/1, the value of H being 85 mm and of C 145 mm.

Since the width of the circle L is 127 mm, the ratio L/C will be equal to 0.87/1.

As shown in Figure 2 the structure of the peripheral reinforcement is formed by one single layer of a spirally wound cord, in which the ends A and Al of the said cord are on the two opposite sides of the reinforcement, and diametrally opposite.

The peripheral reinforcement, with width 1, has the cord wound at a constant pitch p, equal to 1-5 times the thickness S of the said cord, over the whole width of the reinforcement.

WHAT WE CLAIM IS:- 1. A tyre cover of the raidal type characterised in that it comprises, in combination: (a) a radial-ply body consisting of one single ply of cords which lie in planes passing through the axis of rotation of the tyre, or else form small angles with the said planes; (b) a peripheral reinforcement, placed between the said body and the tread, of width substantially equal to that of the tread, and consisting of the spiral winding, in a

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. be applied to the steering wheel of the vehicle in making a turn. Furthermore, an optical evenness is also given to the tyre, with consequent lack of vibration during the vehicle's movement at any speed, an optical resistance to tread detachment at high speed, as well as reduced resistance to rolling. It is known that the coupling described between the radial-ply body and the peripheral reinforcement does, however, decrease driving stability, lacking the stabilising action effected by all the peripheral tread reinforcements crossing over each other as in the prior art. The present invention avoids this negative aspect, inasmuch it has been found that with tyres having the -H/C ratio kept at values within a range from 0.40/1 to 0.65/1, high rates of stability and drive are achieved. The best results are produced with values of the said ratio of about 0.58/1. It has also been found that, other conditions being equal, widening of the mounting rim further improves the transverse stability of the tyre. Therefore, the L/C ratio is kept at values above 0.8/1 up to a maximum of 0 95/1 with optimal values of about 0.87/1. It should be pointed out that in tyres in general use the L/C ratio usually varies from 0.60/1 to 0.80/1. The radial body may consist of a single cord ply of rayon, of aliphatic polyamide (for example, nylon), or of aromatic polyamide (for example, that known by the commercial name of Kevlar), or metal (generally steel). Moreover the peripheral reinforcement may consist of a single layer of cords of rayon, or of aromatic polyamide, or of metal, especially steel. In each case the cords can be made from a twisted yarn consisting of various elements so as to give very good properties, especially relative to the breakage load. The siad reinforcement, the width of which is substantially equal to that of the tread, is formed by spiral winding from a single cord, the turns being side by side either with a uniform of from 1 to 4 times the thickness (diameter) of the said cord. More over, after the spiral winding the two free ends of the cord will be on opposite sides of the peripheral reinforcement, and preferably in a diametrally opposite position. Obviously, there can be applied to tyres of this invention, other devices known and used in this technology, designed to facilitate -stability, such, for example, as textile or metal reinforcements disposed in one or more layers (intercrossed with each other when their number is more than one) and arranged in the area extending into each side of the bead cores to the position of greatest width. The said elements are generally called loops, strengthener edges, or something else. Finally the tyre may comprise: two beads, in each of which there is situated an inextensible bead core, formed from metal wires, around which the carcass fabric is anchored, as well as a tread, having slots, positioned above the peripheral reinforcement and two walls of an elastomer mixture. Other features of the invention are set out in the following description which shows some embodiments of the invention and is made with reference to the attached drawings in which Figure 1 is a cross section of a tyre according to the invention, Figure 2 is a perspective view of the peripheral reinforcement of the tyre according to Figure 1, Figure 3 is an enlarged cross section of the peripheral reinforcement according to Figure 2, In the tyre shown in Figure 1 the reference numeral 1 denotes the tread provided with notches 2, and 3 the tyre sidewall. This tyre is provided with a peripheral reinforcement 4 in a single layer, made with a spiral winding of cords of suitable tensile strength. The carcass body is made of a single ply -5 which links with the folds 6 around the bead cores 7, and incorporates metal fabric reinforcements 8, two for each bead in the case illustrated in the Figure. 9 denotes the wheel rim on which the tyre is mounted. H is the section height of the inflated tyre, and C is the greatest transverse dimension, known also as the "chord". In the case shown the ratio H/C is equal to 0.58/1, the value of H being 85 mm and of C 145 mm. Since the width of the circle L is 127 mm, the ratio L/C will be equal to 0.87/1. As shown in Figure 2 the structure of the peripheral reinforcement is formed by one single layer of a spirally wound cord, in which the ends A and Al of the said cord are on the two opposite sides of the reinforcement, and diametrally opposite. The peripheral reinforcement, with width 1, has the cord wound at a constant pitch p, equal to 1-5 times the thickness S of the said cord, over the whole width of the reinforcement. WHAT WE CLAIM IS:-

1. A tyre cover of the raidal type characterised in that it comprises, in combination: (a) a radial-ply body consisting of one single ply of cords which lie in planes passing through the axis of rotation of the tyre, or else form small angles with the said planes; (b) a peripheral reinforcement, placed between the said body and the tread, of width substantially equal to that of the tread, and consisting of the spiral winding, in a

single layer, of a cord with a uniform pitch of from 1 to 4 times the diameter of the said cord; (c) an H/C ratio, wherein H is the height and C the greatest width of the cross-section of the tyre assembled on a wheel rim and inflated, with a value in the range of from 040/1 to 0.65/1; and (d) an L/C ratio, in which L is the width of the wheel rim, with a value greater than 0.80/1 and not greater than 0.95/1.

2. A tyre cover according to claim 1 wherein said H/C ratio is about 0.58/1.

3. A tyre cover according to claim 1 or 2 wherein the L/C ratio is about 0.87/1.

4. A tyre cover according to any one of the preceding claims, in which the radial body consists of cords of rayon, aliphatic polyamide, aromatic polyamide, or metal.

5. A tyre according to any one of the preceding claims, in which the peripheral reinforcement consists of cords of rayon, or alternatively of aromatic polyamide, or alternatively of metal.

6. A tyre cover substantially as described, with reference to the accompanying drawings.