AU697815B2

AU697815B2 - Tire without bead wire

Info

Publication number: AU697815B2
Application number: AU14847/95A
Authority: AU
Inventors: Michel Ahouanto
Original assignee: Compagnie Generale des Etablissements Michelin SCA
Current assignee: Compagnie Generale des Etablissements Michelin SCA
Priority date: 1994-03-16
Filing date: 1995-03-15
Publication date: 1998-10-15
Anticipated expiration: 2015-03-15
Also published as: JP3562664B2; CA2144129A1; KR100354579B1; CA2144129C; KR950031556A; EP0672547A1; RU2138402C1; DE69506152D1; EP0672547B1; AU1484795A; ES2125503T3; BR9501108A; JPH07266812A; RU95103732A; CN1113467A; DE69506152T2; FR2717425A1; CN1058454C

Description

M*~UM/ I 28/5/91 Regulation 3.2(2)

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: **0e o *o S S SOS S So S.

4 *0O S i nvention Title: TIRE WITHOUT BEAD WIRE The following statement is a full description of this invention, including the best method of performing it known to us 2- BACKGROUND OF THE INVENTION This invention relates to tires and their production process.

Patent FR-A-I 169 474 describes a tire without bead wire, having, at that location which is in mounting contact with the wheel rim, small plies of cables or cords which are parallel between themselves within each ply and are significantly inclined on the parallel to the joint, the various plies being at cross orientations to one another. The aim of this patent is to facilitate the production of this tire thanks to the absence of bead wire that doesn't need to be produced. However the manufacture of such a tire does present problems as it is difficult to secure the satisfactory holding up of its elements along the stages of building up, of conformation and of vulcanization, and once completed the tire does not allow for a satisfactory rolling endurance.

SUMMARY OF THE INVENTION The aim of this invention is to propose a tire without bead wire, having a satisfactory rolling endurance.

Another aim of this invention is to propose a manufacturing S process for such a tire. The present process has the interest of being simple and economical, at the same time as it allows for 4• the precise positioning and holding up of the elements of the tire during the times of the different stages of its production.

The radial tire in conformity with this invention has a crown, two bead portions and at least one radial carcass ply stretching from one bead portion to the other, characterized inasmuch as each bead portion has the following points: •r a) it has no bead wire, and it includes an annular member with a resistance to rupture in traction in its longitudinal direction noticeably inferior to the one necessary for a bead wire in any known tire of the same dimension, the axcis of this annular member being the revolution axis of this tire;

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3b) at least two contiguous plies called reinforcing members are placed in contact with the annular member, or close to it; each of these reinforcing members contains reinforcement cords which are parallel between themselves, the cords in each reinforcing member being cross oriented with respect to the cords in another reinforcing member; in each reinforcing member the angle alpha a is the acute angle formed, in any point along the cord,' by the cord direction and the tangent to a circle having as an axis the revolution axis of the tire and crossing that point of the cord. The angle alpha a conforms to the relation 0 alpha a s 100 the measurement being taken in an area where the reinforcing members are substantially parallel between themselves; c) the at least two contiguous plies forming a group of reinforcing me nbers has a resistance to rupture in traction measured in the longitudinal direction at least equal to that necessary for a bead wire in a known tire of the same dimension; d) the carcass ply surrounds the annular member; e) the superior (or radially external) ends of the reinforcing members are placed at different heights within the bead portion.

The manufacturing process of a tire without bead wire according to this invention is characterized as follows: r C *j a) one places on a tire building drum: C c C C one annular member with a longitudinal direction resistance to rupture in traction noticeably inferior to that necessary for a bead wire i,n any known tire of the sELme S' dimension, the axis of this element being the rotation axis of the building drum; at least two contiguous plies called "reinforcing members" Q) are placed in contact with the annular member, or close to it; each of these reinforcing members contains reinforcement cords which are parallel between themselves within the reinforcing member, these cords being cross layered from one reinforcing member to another reinforcing member; OZi rLU 4 at least one carcass ply with reinforcement cords placed substantially in the same general directional sense as the generatrices of the tire building drum; b) the tire is conformed in such a way that in each reinforcing member the angle alpha a conforms to the relation 0 alpha a 100, alpha a being the acute angle formed, at any point along a reinforcement cord, by the cord direction and the tangent to a circle having as an axis the revolution axis of the tire and crossing that point of the cord, the measurement being taken in an area where the reinforcing members are substantially parallel between themselves; c) the tire is vulcanized.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be clearly understood with the following examples, by referring to the figures, all schematic, with the following meaning: o o s*o 0 figure 1 shows the radial cross section of a tire conforming with the invention, having two bead portions; re*r S figure 2 shows, in more detail, the radial cross section of one of the tire bead portions shown in figure 1; *4oo S figure 3 shows the profile of part of the bead portion shown on figure 2; figure 4 shows the radial cross section, of a bead portion of another tire conforming to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Figure 1 shows a pneumatic tire 1 conforming to the invention.

Figure 1 is a radial cross section, that is to say, a cross section as seen through a plane passing through the rotation axis of the tire 1, this axis not shown on figure 1, being parallel to straight line D. This tire 1 comprises a crown 2, reinforced in a known way by two belt packages 21,22, two sidewalls 3, and two

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4 I bead portions 4. Each bead portion 4 comprises a reinforcing package 40 which will be described in more detail later.

A radial carcass ply 5 extends from one bead portion 4 to the other, crossing crown 2 and sidewalls 3.

Tire 1 is mounted on the wheel rim 6, the equatorial plane of the tire being schematically shown by line xx, this plane passing through the middle of crown 2 and being perpendic7 lar to the rotation axis of the tire. Figure 2 is a more detailed representation of bead portion 4 in tire 1. This bead portion 4 comprises an annular member 7 comprised of, as an example, an annular cord, the axis of the circle described by the annular cord being the revolution axis of the tire.

Two adjacent reinforcing members 8 and 9 have their respective inferior ends 8i, 9i in contact with the annular member 7 and these members extend above this annular member 7, that is to say, they are closer to crown 2 than member 7. Each member 8, 9 comprises a rubber composition 80, 90 in which are placed re,tnforcement cords 81, 91. A reinforcing member 10 surrounds member 7 and both members 8, 9, in thus forming two basic plies 10B which are applied against members 8, 9 which are themselves thus sandwiched between basic plies 10A, 10B, the S plies in contact 10A, 8, 9, 10B, referred to from now on as the "reinforcing members", being thus substantially parallel between themselves. Ply 10 comprises a rubber composition 100 in which S are placed reinforcement cords 101. The assembly comprising member 7 and reinforcing members 10A, 8, 9, O1B is referred to as 40, and the assembly of all these members, excluding member 7, is referred to as In any given reinforcing member 8, 9, 10A, 10B, the cords within it are parallel between themselves and determine an acute angle alpha a which is formed at any given point of the cord between the cord longitudinal direction and that of the tangent to a circle having as an axis the revolution axis of the tire and passing through this point. Figure 3 shows the profile view of a portion of the basic ply IOB according to a directiun parallel to the revolution axis of tire 1. A substantially rectilinear portion of the cord 101 can be seen on this figure, represented by the straight line segment lOla and part of a circle C passing fr j 6 through a point P of this portion of the cord, the circle C having as its axis the revolution axis of the tire 1, the tangent to this circle C at P being referred to as T. The angle alpha a is thus the acute angle determined by T and 101a, the measure being taken at the place where members 10A, 8, 9, 10B are substantially parallel between themselves.

For each member 10A, 8, 9, 10B the angle alpha a varies as a function of the position of point P, but it is in any case always superior to 0 degree and at most equal to 10 degrees.

The cords in a reinforcing member are at a cross orientation with the cords of the adjacent reinforcing member or members, that is to say, the cords of two contiguous reinforcing members are not parallel to each other. Thus, for instance, cords 81 of reinforcing member 8 are crossed with cords 101 of the contiguous member 10A and with cords 91 of contiguous member 9; cords 101 in member 10A being crossed with cords 101 of member O10B as members O10B are constituted by the turn-up of the same member about the member 7.

44*4 rrr The expression "cord" must be understood in a very general St meaning for member 7 and for cords 81, 91, 101 as such a cord can be made of a single monofilament or multifilament cord or by the S combination of such cords twisted together, forming in particular cables or plied yarns. The material used for these cords can 4* vary, it can be metallic for example, notably steel, it can be o organic polymer, for example, cellulose material, polyester or polyamide non aromatic or aromatic, notably aramid cords. It can also be mineral, for example, glass or carbon, each cord being S possibly composed of plurality of such materials.

The annular member 7 has a resistance to rupture in traction measured in the longitudinal direction substantially inferior to that necessary for a bead wire in a known tire of the same dimension, and the assembly of reinforcing members 40A has a resistance to rupture in traction measured in the longitudinal direction, at least equal to that necessary for a bead wire in a known tire of the same dimension. By "longitudinal direction", it is to be understood as that of a circle having as an axis, the revolution axis of the tire, and passing through the bead wire in the case of a known tire, or through the group of reinforcing II I 1 _bl ~d 7 members, in the case of the tire conforming with the invention.

The mechanical resistance of these reinforcing members is thus the essential contribution to the mechanical resistance of the reinforcing package 40 comprising member 7 and members 8, 9, which allows this package to replace the bead wire of a conventional tire.

The carcass ply 5 surrounds package 40 and thus also member 7.

This carcass ply 5 comprises, as is known, a rubber composition in which reinforcement cords 51 are placed, the name "cords" having the broad meaning above mentioned. For clarity's sake, only a portion of cord 51 is shown on figure 2. The modulus of the rubber composition 50 is preferably noticeably inferior to that of the rubber compositions 80, 90, 100. Between carcass ply and group 40A, two rubber compositions 11, 12 are placed, these being the so-called decoupling rubber compositions. The value of compositions 11, 12 is preferably comprised between the value of rubber composition 50 on one hand and the value of rubber composition 80, 90, 100 on the other hand.

In what follows, for a given rubber composition, M10 represents the tensile stress at an elongation of 10%, this stress being determined according to norm AFNOR-NF-T46-002 of September 1988, under normal temperature and normal hygrometric conditions as defined by norm AFNOR-NF-T40-101 of December 1979. The values of of rubber compositions 80, 90, 100 can be identical or different and the values of M1O of rubber compositions 11, 12 can also be identical or different.

On the layout of figure 2, the ends of members 8,9 opposed to member 7 are referred to as 8a, 9a. In the same way the ends of basic plies 10A, 10B, not in contact with member 7, are referred to respectively as 10a, lOb. All the ends 8a, 9a, 10a, lOb are called superior ends and are placed in bead portion 4.

Rubber composition 11 is placed outside package 40, against the superior part of member 10A and continues above package 40 in sidewall 3, and rubber composition 12 is applied between the ends and lo0b, and is in contact with the four members 10A, 8, 9, 7]l ii 8- All these superior ends are placed at different heights on the layout of figure 2: when one moves toward the crown in the direction of vertical arrow F parallel to the equatorial plane posed at vertical, one finds at increasing heights and in this order the ends o10b, 9a, 8a, 10a, that is to say, the thickness and thus the rigidity of assembly 40 diminishes as one gets closer to the crown, in the direction of arrow F. Increasing heights Hl0b, H9a, H8a, Hl0a, correspond respectively to ends 9a, 8a, 10a, and are delineated on a vertical line delta A extending from the horizontal line delta 6 passing through the inferior end 4i of the bead portion 4.

Tire 1 can be manufactured in the following way on a tire building drum. One places the carcass ply 5, then the decoupling rubber composition 11 followed by member 10. Then one places annular member 7 on top of member 10, for example, by winding in circles one or several turns of a rubber coated cord to form the member. One then applies on member 10, contiguous to member 7, the two members 8, 9 superimposed on each other, the ends of S" which 8a, 9a, are placed in the direction of the center of the tire building drum. One then accomplishes a turn up of carcass ply 5, and of member 10 around member 7 and members 8,9. One 0 finishes the manufacturing process of the tire by building, conformation, and vulcanization in the conventional way. The *'wraps of member 7 are well bonded together, and with the rest o, the tire, without any particular attachment means, thanks to the tackiness of the rubber composition that surrounds the cord constituting member 7.

SThe annular member 7 has a resistance to rupture in traction S measured in the longitudinal direction, preferably inferior to 500 daN, and even more preferably inferior to 300 daN, that is to say, this member has a mechanical resistance largely inferior to 0 that necessary for a bead wire, the tire 1 being thus without a conventional bead wire. However this resistance to rupture in traction is chosen so that it allows for the building up, the turn up, the conformation and vulcanization, above described, that is to say that the member 7 has a level of mechanical resistance largely inferior to that of a classical bead wire, as member 7 does not play the role of a bead wire, but rather of a member allowing the placement of reinforcing members 10A, 8, 9, in relation to each other.

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ii i I 9 The assembly 40A of reinforcing members has a resistance to rupture in traction measured in the longitudinal direction, superior to 800 daN and more preferably, superior to 1000 daN.

As an example tire 1 has the following characteristics: Dimension 175/70-13.

Crown plies 21,22: known plies comprising steel reinforcement cables at a 21 degree angle with the equatorial plane, and being crossed from ply to ply.

A carcass ply 5: classical ply having cords 51 in polyester; value of M10 of rubber composition 50: 0.3MPa.

An annular member 7: two wraps of a cord constituted of a plied yarn of aramid; resistance to rupture in traction: 100 daN, global resistance, in the longitudinal direction of member 7 being thus 200 daN.

Reinforcing members 10A, 8, 9, 10OB: identical members having aramid cords; .resistance to rupture in traction, measured in each member in the cord direction of the member: 5000 daN/dm of the width of the member, the resistance to rupture in traction measured in the longitudinal direction of assembly 40A being around 4500 daN; .value of MO1 of rubber tissues 80, 90, 100 (identical): 2.4 MPa, Decoupling rubber compositions 11, 12 (identical): .value of M10: 0.6 MPa.

.these rubber compositions 11, 12 have, for example, an hysteretical loss, measured at 60 degrees C, inferior to that of rubber compositions 80, 90, 100, Tire weight: 6.3 kg.

This tire is rolled at a speed of 215 Km/h until failure occurs.

When it does, one observes that it is due to the failure of crown 2, not due to the failure of assembly 10 Furthermore, one manufactures a known tire of the same dimension 175/70-13, and identical to the tire of the invention except that the reinforcing assembly 40 is replaced by a classical metal bead wire, the resistance to rupture in traction of which, measured in the longitudinal direction, is 2000 daN.

The weight of this witness tire is 6.8 Kg, that is to say that the i.<vention procures a weight loss superior to 7%.

This witness tire is rolled under the same condition as the one conforming to the invention and one observes that its performance characteristics are analogous to those of the tire of the invention.

Embodiments of the invention present the following advantages: the manufacture of the tire is simple and economical as the assembly 40 is formed directly on the tire building drum, no previous bead wire manufacture is needed; the presence of annular member 7 allows for a precise positioning of reinforcing members 10A, 8, 9, 10B, easily reproduced without any other holding element; furthermore, the presence of decoupling rubber compositions 11, 12 as well as the staging of the superior ends of the plies in the bead portions allows for shearing action to occur between the radial carcass ply and the a:sembly 40, rigid in its longitudinal direction, as well as a progressive transition between the rigidity of the bead portions 4 and the flexibility of sidewalls 3; when non metallic materials are used to manufacture the assembly 40 there is a considerable loss of weight in comparison to classical tires with metallic bead wires; the tire without bead wire allows for an endurance comparable to that of a classical tire with bead wire in spite of the simplicity of its manufacture.

Obviously, the invention applications are not limited to the previously described embodiments.

O OF l* *r 11 For example, it would be possible to have an assembly 40 with only two reinforcing members such as 8, 9, or members 10A, Also members 8, 9, could be placed in the proximity of member 7, for example, by being separated from this member by a rubber composition of slight thickness, for instance inferior to 5 mm, and members 8, 9, 10 could be different, with, for example, rubber compositions of different modulus and only one decoupling rubber composition could be used.

Members 8, 9, furthermore, could be manufactured by folding a single ply. One can anticipate cases in which the carcass ply is placed between reinforcing members, as seen on figure 4, where carcass ply 5-1 is directly wound around the annular member 7-1, two reinforcing members 8-1, and 9-1 are wound around carcass ply 5-1 and member 7-1. In this case, at the time of manufacture of the tire, one disposes on the tire building drum the stacking of the plies 9-1, 8-1, decoupling rubber composition 11-1, ply 5-1 0' and member 7-1, all in this order.

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Claims

1. Radial tire having a crown, two bead portions and at least a carcass ply extending from one bead portion to the other, characterized by the fact that each bead portion is as follows: a) it is without bead wire and has an annular member with a resistance to rupture in traction in its longitudinal direction considerably inferior to that necessary for a bead wire in a known tire of the same dimension, the axis of the annular member being the axis of the tire revolution; b) at least two contiguous reinforcing members are placed in contact with the annular meiber or close to o it; each of these reinforcing members comprises reinforcement cords parallel between themselves, crossed from ply to ply; in each reinforcing member, the angle alpha a is the acute angle formed at any point of the cord, by the cord direction and the tangent to a circle having as an axis the revolution axis of the tire and passing through this point on the cord, this angle alpha a conforming to the relation 0 alpha a s 100, the measurement being taken in the area where the reinforcing members are substantially parallel between themselves; c) the at least two contiguous reinforcing members forming a group of reinforcing members which have a resistance to rupture in traction, measured in its longitudinal direction, at least equal to that necessary for a bead wire in a known tire of the same dimension; d) the carcass ply winds around the annular member; e) the reinforcing members have their radially external ends placed in the bead portion at different heights.

2. A tire according to claim 1 characterized by said annular member having a resistance to rupture in traction, measured in the longitudinal direction inferior to 500 daN. 13

3. A tire according to claim 2 characterized by the annular member having a resistance to rupture in traction, measured in the longitudinal direction, inferior to 300 daN.

4.A tire according to claim 1 characterized by a resistance to rupture in traction, measured in the longitudinal direction, of the group of reinforcing members, superior to 800 daN. A tire according to claim 4 characterized by a resistance to rupture in traction, measured in the longitudinal direction of the group of reinforcing members, superior to 1000 daN.

6.A tire according to claim 1 characterized by a carcass ply wound ar6und the group of reinforcing members.

7.A tire according to claim 1 characterized by the fact that at least one reinforcing member is wound around the carcass ply and the annular member.

8. The manufacturing process of a tire without bead wire characterized by the following steps: a) disposing on a tire building drum: -an annular member with a resistance to rupture in traction in the longitudinal direction noticeably inferior to that necessary for a bead wire in a known tire of the same dimension, the axis of this member being the axis of the drum rotation; -at least two contiguous members, called "reinforcing members", in contact with the annular member or close to it; these reinforcing members each have reinforcing cords parallel between themselves in each member and crossed from member to member; at least one carcass ply comprising reinforcing corcJG placed substantially in the directional sense of the generatrices of the tire building drum; ABSTRACT OF THE DISCLOSURE The present invention provides a tire with bead portions which do not include a bead wire. Each bead portion is provided with an annular member with a resistance to rupture in traction notably lower than the resistance necessary for a bead wire and two reinforcing members at least are situated in contact with or close to this annular member. The group of reinforcing members has a resistance to rupture in traction at least equal to the °o resistance necessary. for a bead wire. The carcass ply surrounds the annular member. The superior ends of the reinforcing members are placed at different heights within the bead portion. 0 oe 9 *0 0 048,0.0* 1-11.1-1-- 1 I I I