WO2006024561A1

WO2006024561A1 - Extended mobility tyre comprising an anchoring area having a high moment of inertia

Info

Publication number: WO2006024561A1
Application number: PCT/EP2005/053040
Authority: WO
Inventors: Russell Shepherd
Original assignee: Societe De Technologie Michelin; Michelin Recherche Et Technique S.A.
Priority date: 2004-08-31
Filing date: 2005-06-28
Publication date: 2006-03-09

Abstract

The invention relates to an extended mobility tyre comprising a reinforcing structure, sidewalls reinforced by an sidewall insert, wherein each bead comprises an anchoring area which maintains said reinforcing structure and comprises a rubber anchoring mixture and a plurality of circumferential wire windings. Said circumferential wire arrangements are divided at least into four piles, namely, two high piles, each of which comprises at least six coils and is arranged on each side of the reinforcing structure and is directly connected thereto, wherein said high piles contain at least 14 coils and at least two low piles separated from the reinforcing structure by at least one high pile, wherein the difference in the coil numbers between each low pile with respect to each high pile is equal or greater than two coils.

Description

PNEUMATIC MOBILITY EXTENDED WITH ANCHORING ZONE AT TIME

OF HIGH INERTIA

The present invention relates to a self-supporting sidewall type extended mobility tire, the wedging characteristics against the rim or hook of a corresponding rim are optimal, thereby contributing to an improvement of the running characteristics in degraded mode. .

[0002] In recent years, the tire manufacturers have made particularly significant efforts to develop original solutions to a problem dating back to the very beginning of the use of tires with inflated type tires, namely how to allow the vehicle to continue. its course despite a significant loss or total pressure of one or more tires. For decades, the spare wheel was considered the unique and universal solution. Then, more recently, the considerable benefits of its eventual removal have emerged. The concept of "extended mobility" is developing. The associated techniques make it possible to ride with the same tire, according to certain limits to be respected, after a puncture or a pressure drop. This allows for example to get to a breakdown point without having to stop, in often hazardous circumstances, to install the spare wheel.

[0003] Two major types of extended mobility technologies are emerging today in the automotive market. On the one hand, we find self-supporting type of tires, (often referred to by their name in the English language ZP for "zero pressure"). The self-supporting tires are likely to withstand a load at reduced pressure or without pressure, thanks to reinforced sidewalls, usually by means of rubber inserts provided in the sidewalls. On the other hand, there are wheels equipped with supports, capable of supporting the inside of the tread of a tire during a collapse of the sidewalls following a pressure drop. This solution is advantageously coupled to a tire having a low area which can minimize the risk of sliding of the tire out of the rim. This solution is advantageous since it makes it possible to keep substantially intact the rolling characteristics under normal conditions. On the other hand, it has the disadvantage of requiring an additional piece, the support, for each of the wheels of the vehicle.

In order to achieve self-supporting sidewall tires of high quality and reliability, it is desirable to be able to ensure running characteristics in degraded mode (that is to say at low pressure or zero) which are the more advantageous, particularly as regards the radius of action. One of the key points to increase the autonomy of this type of product lies in the control of loosening phenomena. In fact, when driving in degraded mode, the stresses experienced at the level of the rim / low zone interface of the tire are extreme, and the buckling of the sidewall causes a strong tendency of the low zone of the tire to want to pivot and slide against the rim. of rim.

Several solutions are known today to try to overcome this type of problem. For example, conventionally, in order to increase the lateral stiffness of a self-supporting type of tire, one conventionally uses a thicker sidewall insert and / or with a material whose modulus is higher than that of reference.

However, these different solutions do not always optimize the other properties of the product. However, for certain products, particularly high-end products, it is desirable to be able to obtain better compromises between the characteristics of the tire. In particular, it is desired to act in such a way as to reduce the susceptibility to loosening during running at low or zero pressure, while maintaining the best qualities of comfort.

[0008] Furthermore, a 225 / 50R17 PILOT tire is known.

PREMACY, designed by the Applicant, which comprises, in the lower zone, a circumferential wire arrangement, arranged in three stacks, in the following order: four rounds, eight rounds, nine rounds and zero rounds, starting from the stack most axially outer, towards the most axially inner stack. The reinforcement structure passes between these four stacks. Such an arrangement extends radially over a large height, but with a small width, thus resulting in a rather low moment of inertia.

To overcome these various drawbacks, the invention provides a tire adapted for running with extended mobility, comprising at least one carcass-type reinforcement structure anchored on each side of said tire in a bead whose base is intended to be mounted on a rim seat, each said bead extending substantially radially outwardly in the form of flanks, the flanks joining radially outwardly a tread, the carcass-type reinforcing structure extending circumferentially from the bead towards said flank a crown reinforcement, each of said sidewalls being reinforced by a sidewall insert made of a rubber composition capable of supporting a load corresponding to a portion of the weight of the vehicle in a situation where the inflation pressure is substantially reduced or nil , each of the beads also comprising an anchoring zone allowing the maintaining the reinforcing structure and comprising on the one hand a rubber anchoring mixture and a series of circumferential wire windings disposed in said rubber mixture, on either side of the end portion of the reinforcing structure said circumferential wire arrangements being divided into at least four cells:

two tall stacks, each having at least 6 turns, one on each side of the reinforcement structure and immediately adjacent to it, immediately adjacent, means that there is no other pile or wire between the reinforcing structure and said high pile, the two high piles totaling at least 14 turns (for the set of high batteries) and at least two low batteries, separated from the reinforcing structure by at least one high battery, and

the difference in the number of revolutions between each of the lower stacks with respect to each of the high stacks, being greater than or equal to two revolutions, (eg 3, 4, 5, or 6 according to the illustrated examples).

This type of arrangement increases the moment of inertia. The low zone is then less sensitive to the risks of loosening when driving in conditions of reduced pressure or zero. Moreover, these advantages are obtained without affecting the intrinsic properties of the lower zone and / or the sidewalls, as is the case for example when using a thicker side insert.

According to an advantageous embodiment, the total number of turns of the low batteries is less than the number of turns of the high stack having the largest number of turns.

The total number of turns of the low batteries is advantageously less than the number of turns of any high battery.

According to an advantageous embodiment, the anchoring zone comprises a low pile on the axially inner side with respect to the reinforcing structure and a low pile on the axially outer side with respect to the reinforcing structure.

According to another embodiment, the low zone comprises two low batteries on the same side of the reinforcing structure.

The high batteries advantageously comprise the same number of turns. The low batteries advantageously have an unequal number of turns, with a preferred gap of one revolution.

The low batteries preferably each have four turns or less.

Said rubber mix of the anchoring zone is preferably composed of a rubber composition having a 10% secant MA10 extension module of deformation, measured at 23 ° C. according to ASTM D 412, greater than 10 MPa ₁ and preferably between 30 and 60.

The flank insert is advantageously disposed axially inwardly with respect to said reinforcing structure.

Advantageously, the rubber mix of the anchoring zone consists of a rubber composition having a MA10 secant extension module at 10% deformation, measured at 23 ° C. according to ASTM D 412, greater than 10 MPa, and preferably between 30 and 60.

Advantageously, said flank insert is axially disposed internally with respect to said reinforcing structure. The reinforcement structure is then arranged axially externally, thus optimizing its path in a tension zone. This is particularly favorable for the level of endurance.

According to an advantageous embodiment of the tire according to the invention, each of said sidewall inserts is preferably made of a rubber composition having a secant MA10 extension module at 10% deformation, measured at 23 ° C. according to ASTM D 412, ranging from 5 to 13 MPa.

Preferably, each of said sidewall inserts has a thickness ranging from 3 mm to 20 mm, and preferably from 5 mm to 14 mm. All the details of implementation are given in the description which follows, supplemented by the appended FIGS. 1 and 2, in which:

- Figure 1 illustrates a radial section essentially showing a bead, a sidewall, and half the top of a first embodiment of a tire according to the invention;

- Figure 2 illustrates a radial section essentially showing a bead, a sidewall, and half of the top of an embodiment of a second type of tire according to the invention.

The reinforcement or reinforcement of the tires is currently - and most often - constituted by stacking one or more tables conventionally referred to as "carcass plies", "summit plies", etc. This method of designating reinforcing reinforcements comes from the manufacturing process, consisting in producing a series of semi-finished products in the form of plies, provided with wire reinforcements, often longitudinal, which are subsequently assembled or stacked in order to make a rough draft. pneumatic. Tablecloths are made flat, with large dimensions, and are subsequently cut according to the dimensions of a given product. The assembly of the plies is also made, initially, substantially flat. The blank thus produced is then shaped to adopt the typical toroidal profile of the tires. The so-called "finished" semi-finished products are then applied to the blank to obtain a product ready for vulcanization.

Such a type of "conventional" process involves, in particular for the manufacturing phase of the tire blank, the use of an anchoring element (generally a rod), used to carry out the anchoring or the maintenance of the carcass reinforcement in the area of the beads of the tire. Thus, for this type of process, a portion of all the plies constituting the carcass reinforcement (or of a part only) is turned around around a bead wire arranged in the bead of the body. pneumatic. In this way, an anchoring of the carcass reinforcement in the bead is created.

The generalization in the industry of this type of conventional method, despite many variations in the manner of making webs and assemblies, led the skilled person to use a vocabulary modeled on the process; hence the generally accepted terminology, including in particular the terms "plies", "carcass", "rod", "conformation" to designate the passage from a flat profile to a toroidal profile, etc.

However, today there are tires that do not involve strictly bet not "tablecloths" or "rods" according to the above definitions. For example, EP 0 582 196 discloses tires manufactured without the aid of semi-finished products in the form of webs. For example, the threads of the various reinforcement structures are applied directly to the adjacent layers of rubber mixes, the whole being applied in successive layers to a toroidal core whose shape makes it possible to directly obtain a profile that is similar to the final profile of the tire. during manufacture. Thus, in this case, there is no longer "semi-finished", or "tablecloths" or "rod". Basic products such as rubber mixes and reinforcements in the form of threads or filaments are directly applied to the core. Since this core is of toroidal shape, it is no longer necessary to form the blank to pass from a flat profile to a profile in the form of a torus.

Moreover, most of the embodiments of tires described in this document do not have the "traditional" reversal carcass ply around a bead wire. In these examples, this type of anchorage is replaced by an arrangement in which adjacent circumferential filaments are disposed adjacent to said sidewall reinforcing structure, all of which is embedded in an anchoring or bonding rubber composition.

There are also toroidal core assembly methods using semi-finished products specially adapted for rapid installation, effective and simple on a central core. Finally, it is also possible to use a combination of both semi-finished products to achieve certain architectural aspects (such as tablecloths, rods, etc.), while others are made from direct application mixtures and / or reinforcements in the form of filaments or strips.

In this document, in order to take account of recent technological developments both in the field of manufacturing and for the design of products, the conventional terms such as "tablecloths", "rods", etc., are advantageously replaced by terms that are neutral or independent of the type of process used. Thus, the term "carcass-type reinforcement" or "sidewall reinforcement" is used to designate the reinforcing threads of a carcass ply in the conventional method, and the corresponding threads, generally applied at the flanks, of a pneumatic produced according to a process without semi-finished. The term "anchoring zone" for its part, can refer to both the "traditional" carcass ply rollover around a rod of a conventional method, that the assembly formed by the circumferential filaments, the rubber composition and adjacent portions of sidewall reinforcement of a low zone made with a method with application to a toroidal core.

In the present description, the term "wire" generally refers to both monofilaments and multifilaments or assemblies such as cables, twisted or any type of equivalent assembly, and this, whatever the material and the treatment of these threads. It may be for example surface treatments, coating or pre-sizing to promote adhesion to the rubber. The term "unitary wire" refers to a single-component wire, without assembly. The term "multifilament" means on the contrary an assembly of at least two unitary elements to form a cable, a twist, etc. By characteristics of the wire, one understands for example its dimensions, its composition, its characteristics and mechanical properties (in particular the module), its characteristics and chemical properties, etc.

In the present description, the term "contact" between a wire and a layer of bonding rubber means that at least a portion of the outer circumference of the wire is in intimate contact with the constituent rubber composition of the gum binding.

It is known that, in a traditional manner, the carcass ply or plies are turned around a bead wire. The rod then performs a function of anchoring the carcass. Thus, in particular, it supports the tension developing in the carcass son for example under the effect of the inflation pressure. The arrangement described herein provides a similar anchoring function. It is also known to use the traditional type of rod to ensure a function of tightening the bead on a rim. The arrangement described in this document also provides a similar role of clamping.

• _* • • * •

"Flanks" refers to the tire portions most often low flexural stiffness located between the top and the beads. So-called "sidewall mixtures" rubber mixtures located axially externally relative to the son of the carcass reinforcement structure and their gum binding. These mixtures usually have a low modulus of elasticity.

The portion of the tire adjacent radially internally to the sidewall is called "bead".

The term "MA10 extension module" of a rubber composition, an apparent secant extension module obtained at a deformation of uniaxial extension of the order of 10% measured at 23 ⁰ C according to the standard ASTM D 412. As a reminder, "radially upwards", or "radially upper" or "radially outward" means towards the largest radii.

A carcass-type reinforcement or reinforcement structure will be said to be radial when its wires are arranged at 90 °, but also, according to the terminology in use, at an angle close to 90 °.

Figures 1 and 2 illustrate the lower zone, in particular the bead 1 of a tire according to the invention. The bead 1 has an axially outer portion 2 provided and shaped so as to be placed against the edge of a rim. The upper or radially outer portion of the portion 2 forms a portion 5 adapted to the rim hook. This portion is often curved axially outwards, as shown in Figure 1. The portion 2 ends radially and axially inwardly by a bead seat 4, adapted to be disposed against a rim seat. The bead also comprises an axially inner portion 3, extending substantially radially from the seat 4 towards the sidewall 6.

The tire also comprises a reinforcing structure 10 or reinforcing carcass type provided with reinforcements advantageously configured in a substantially radial arrangement. This structure can be arranged continuously from one bead to the other, through the sides and the top of the tire, or it can comprise two or more parts, arranged for example along the sidewalls, without covering the entire summit.

In order to position the reinforcing son as accurately as possible, it is very advantageous to make the tire rigid support, for example a central core imposing the shape of its inner cavity. On this core, in the order required by the final architecture, are applied all the constituents of the tire, which are placed directly in their final place, without the profile of the tire having to be modified during manufacture. The anchoring function is in particular achieved by means of an arrangement of circumferential threads, as illustrated for example in FIG. 2. Circumferential threads 21, preferably arranged in the form of stacks 22, form an arrangement of threads. anchorage, provided in each of the beads. These son are preferably metal, and possibly brass. Various variants advantageously provide yarns of textile nature, such as aramid, nylon, PET, PEN, or hybrid, or other, such as for example fiberglass. In each stack, the son are advantageously substantially concentric and superimposed.

In order to ensure perfect anchoring of the reinforcing structure, a laminated composite bead is produced. Inside the bead 1, between the wire alignments of the reinforcing structure, there are 21 son oriented circumferentially. These are arranged in a stack 22 as in the figures, or in several adjacent piles, or in any judicious arrangement, depending on the type of tire and / or the desired characteristics.

The radially inner end portions of the reinforcing structure 10 cooperate with the wire windings. An anchoring of these portions is thus created in said beads. In order to promote this anchoring, the space between the circumferential threads and the reinforcing structure is occupied by a bonding or anchoring rubber composition 60. It is also possible to use several mixtures having different characteristics, delimiting several zones, the combinations of mixtures and the resulting arrangements being almost unlimited. By way of nonlimiting example, the extension module of such a mixture can reach or exceed 10 to 15 MPa, and even in some cases reach or exceed 40 MPa. In the example shown, the module is 55 MPa.

The son arrangements can be arranged and manufactured in many ways. For example, a battery may advantageously consist of a single wire wound (substantially zero degrees) spirally over several turns, preferably from the smallest diameter to the largest diameter. A The stack may also consist of several concentric threads placed one inside the other, so that rings of progressively increasing diameter are superimposed. It is not necessary to add a rubber mixture to ensure the impregnation of the reinforcing thread, or circumferential windings of thread.

In the embodiment of Figure 1, the circumferential windings are arranged in four cells, respectively having two turns, three turns, eight turns and eight turns, from the axially outer battery to the axially inner battery. The reinforcement structure travels between the two large stacks.

In the example of Figure 2, this arrangement corresponds to four turns, seven turns, seven turns and three turns, respectively, from the axially outer battery to the axially inner battery. The reinforcement structure travels between these four stacks, with two stacks on each side.

Many other distributions are possible, insofar as the criteria defined in the context of the present invention are respected. This gives developers a great deal of latitude, so that they can consider, in addition to the basic objective related to the invention, other technological considerations.

A bead seat area 80, consisting of a rubber mix secant extension module 10% deformation, measured at 23 ° C according to ASTM D 412, ranging from 5 to 15 MPa, and preferably between 6 and 9 MPa, and less than that of the mixture of the anchoring zone, is arranged radially internally to the anchoring zone, and makes it possible to separate said anchoring zone from the seat of the rim when the tire is mounted . In the example of Figure 2, this module is 7.5 MPa.

A flank insert 30, consisting of a substantially rigid rubber composition, extends substantially radially between the region of the base of the flank, up to the shoulder area of the tire. This insert has the main function of allowing the tire to withstand a certain load when used at low pressure, or even at zero pressure.

Although the figures illustrate an insert of significant size, a similar function could be filled by one or more inserts of significantly different size, especially smaller.

In a large proportion of the sidewall, the insert 30 occupies a width greater than 50% of the total thickness of the wall of the sidewall.

Axially internally relative to the insert 30, a layer of substantially sealed rubber composition 40 advantageously extends over substantially the entire inner portion of the tire. The sealing layer being the innermost, all other layers benefit from the barrier effect thus created. The mixture is advantageously based on butyl rubber. The expansion module of this mixture is relatively small.

As illustrated in the various embodiments, the layer 40 is preferably anchored in the axially inner portion of the bead. This anchored portion 41 thus resulting provides effective protection against possible crack initiation, or detachment, etc.

A bonding mixture layer 50 is advantageously disposed between the sealing layer 40 and the insert 30. This layer consists of a substantially intermediate modulus of rubber composition relative to the two types of materials. which surround it: on the one hand the sealing layer 40, low extension module, and the insert 30, substantially high expansion module. This layer may extend substantially over the entire height of the insert 30, on each side, and is interrupted in the area of the summit. According to another embodiment, as illustrated in FIG. 2, the layer 50 extends from one bead to the other, including in the region of the crown. According to a variant not illustrated, this same layer has a greater thickness than in the other examples illustrated.

The carcass-type reinforcement structure 10 runs along the sidewall along a preferential path close to said insert 30. Thus, in FIG. 2, said structure 10 is laid axially externally with respect to the insert 30 and travels advantageously in direct contact with the insert over most of the sidewall path. At the base of the flank, in the area where the insert shrinks, the path of the structure 10 deviates from the insert. Advantageously, in the interface region between the anchoring zone and the sidewall, the reinforcing structure 10 follows a path as direct as possible. In the illustrated example, an inclination of the anchoring zone, in particular of the stacks 22, allows the whole of the anchoring zone and the structural portion 10 located in this zone to be substantially aligned with the axially outer edge of the insert 30, at the base thereof, in the portion outside the narrowing zone 31. This type of arrangement allows effective recovery of the forces of the carcass-type reinforcement structure by the anchor zone, without creation of stress concentration zone. If

The direct contact between the reinforcing structure and the insert optimizes the stiffness and strength characteristics of the sidewall.

The industrial manufacture of a tire according to the invention can be carried out according to several types of processes. Advantageously, a principle of laying on a central core is used allowing either the individual laying of the constituent elements such as rubber mixes and reinforcements (son) or the laying of semi-finished products such as rubber reinforced lamellae.

Claims

A tire adapted for traveling with extended mobility, comprising at least one carcass-type reinforcing structure anchored on each side of said tire in a bead whose base is intended to be mounted on a rim seat, each of said beads extending substantially radially outwardly in the form of flanks, the flanks joining radially outwardly a tread, the carcass-type reinforcing structure extending circumferentially from the bead towards said flank, a crown reinforcement, each of said flanks being reinforced by a sidewall insert consisting of a rubber composition capable of supporting a load corresponding to a portion of the weight of the vehicle during a situation in which the inflation pressure is substantially reduced or zero, each of the beads also comprising an anchoring zone allowing the maintenance of the reinforcing structure and comprising on the one hand a melan anchoring rubber geometry and a series of circumferential wire windings disposed in said rubber mixture, on either side of the end portion of the reinforcing structure, said circumferential wire arrangements being distributed in at least four cells:

two high piles, each having at least 6 turns, one on each side of the reinforcing structure and immediately adjacent thereto, the two high stacks totaling at least 14 turns and at least two stacks separated from the structure of reinforcement by at least one high stack, and

the difference in the number of revolutions between each of the lower stacks with respect to each of the high stacks being greater than or equal to two revolutions.

A tire according to claim 1, wherein the total number of revolutions of the lower stacks is less than the number of revolutions of the high stack having the greatest number of revolutions.

3. A tire according to one of claims 1 or 2, wherein the total number of turns of the low batteries is less than the number of turns of any high battery.

4. A tire according to one of claims 1 to 3, wherein the anchoring zone comprises a low pile on the axially inner side with respect to the reinforcing structure and a low pile on the axially outer side with respect to the reinforcing structure. .

5. A tire according to one of claims 1 to 3, wherein the low zone comprises two low batteries on the same side of the reinforcing structure.

6. Tire according to one of the preceding claims, wherein the high batteries have the same number of turns.

7. A tire according to one of the preceding claims, wherein the low batteries have an unequal number of turns, with a preferred gap of one revolution.

8. A tire according to one of the preceding claims, wherein the low batteries each comprise at most four turns.

9. A tire according to one of the preceding claims, wherein said rubber mixture of the anchoring zone consists of a rubber composition having a secant extension module MA10 at 10% deformation, measured at 23 ° C according to the standard ASTM D 412, greater than 10 MPa, and preferably between 30 and 60.

10. A tire according to one of the preceding claims, wherein said sidewall insert is axially disposed internally with respect to said reinforcing structure.