FORM 2
THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See section 10, rule 13) 1. Title of the invention: FILLER CONSTRUCTION IN RADIAL TIRES
2. Applicant(s)
NAME NATIONALITY ADDRESS
CEAT LIMITED Indian RPG HOUSE, 463, Dr. Annie Besant
Road, Worli, Mumbai- Maharashtra 400 030, India
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

TECHNICAL FIELD
[0001] The subject matter described herein, in general, relates to radial tires, and in particular relates to bead structure in the radial tires.
BACKGROUND
[0002] These days radial tires have become an essential requirement in passenger cars, sports utility vehicles (SUVs), commercial vans, light trucks, trailers, commercial trucks and buses etc., to meet the modern transportation needs. Further, the radial tires are continuously being improvised for safe and efficient operation.
[0003] A radial tire is an assembly of numerous components such as sidewalls, plies, beads, inner liner, belt system, treads etc. The bead is made up of bands of high tensile-strength steel wires, which lies in bead core of the radial tire and connects the radial tire to the rim and holds the entire wheel together. The steel wires move perpendicular to the tread and radially from one bead core to another bead core. An area adjacent to the bead core is filled with rubber having hardness different from that of the bead core. Furthermore, a reinforcing layer of the steel wires surrounds the plies for providing better strength to the bead core.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and components.
[0005] FIG. 1 shows a radial cross-section view of a radial tire being symmetrical about a mid-circumferential plane, as per an implementation of the present subject matter;
[0006] FIG. 2 shows an enlarged schematic view of a bead portion of the radial tire consisting of an inverted L-shaped bead filler along a bead core, as per an implementation of the present subject matter; and

[0007] FIG. 3 illustrates an exemplary method for forming the inverted L-shaped filler and applying the inverted L-shaped filler into the bead portion of the radial tire, in accordance with yet another implementation of the present subject matter.
DETAILED DESCRIPTION
[0008] The present invention relates to the construction of bead portion of a radial tire (hereinafter referred as tire), to improve process for manufacturing of the tire, in accordance with the present subject matter. Further, the present invention describes changing a shape of bead filler in the tire in accordance with the implementation of the present subject matter. Furthermore, the present invention describes a method for applying a new filler into a space in a bead core, limiting separation of adhesion between steel wire members and rupture of the steel wire to prevent serious tire trouble.
[0009] Generally, a tire consists of a bead portion, wherein the bead portion closely contacts with bead seat of a rim when the tire is mounted on a rim and provides a tight air sealing effect. When a carcass ply is wrapped over the bead portion, a space, approximately of triangular cross-section is created, on a radially inner side of the bead core. It is essential for the stability of a pneumatic tire that this space is filled, and preferably reinforced, by the "bead filler" component. [0010] The design of the bead portion of the tire is important as the design of the bead portion of the tire conforms to the shape of a rim without displacing bead core or greatly reducing the seating pressures at the tire to rim interface. The design of the bead portion also has a direct effect on handling performance of a vehicle. Also, a lateral movement(s) of the vehicle is directly influenced by the lateral stiffness of the tire. The tire's lateral stiffness is greatly influenced by the bead portion design. Bending elasticity of the lower bead portion of the tire with respect to the rim is a major factor in the lateral stiffness of the tire. The radial stiffness of the tire also has a direct effect on the ride comfort of the vehicle. [0011] Building of a green tire by conventional techniques includes initially laying tire building components one at a time around a cylindrical tire building

drum to build-up the carcass and the bead portion of the tire, at a first stage of manufacturing of the green tire. The bead portion of the tire include a bead core and bead filler along with sidewalls. After laying and assembling the tire building components on the tire building drum, the green tire is removed from the cylindrical drum and expanded into a toroidal shape, completing the manufacturing of the green tire.
[0012] The result is that components that end up in the sidewall of the tire have been rotated approximately by 90° during transition, going from the cylindrical shape to the toroidal shape during the manufacturing process. The rotation of both the sidewall components and the bead portion components about the bead core is one of the conventional technique of making a tire. The bead core is generally of a high torsional rigidity and does not rotate during this process and due to the high torsional rigidity of the bead core, bending of the bead filler becomes critical, as the high torsional rigidity of the bead core does not allow a smooth bending of the bead filler. Since, a rubber compound used for the carcass ply layers is relatively soft and a rubber compound used for the bead portion is relatively hard, the interconnection between the carcass ply layers and the bead portion may not be strong enough. Thus, this area may suffer from frequent bead separation. [0013] Further, during the manufacturing, the problem of separation may occur, due to air, that may get trapped in the bead portion during the first stage of tire manufacturing. The air trapping leads to disintegration of filler component inside the bead core, at the bead portion of the tire, that generally separates the core and the carcass ply. If the separation is minor, it becomes difficult to observe the disintegration of the filler component in the cured tire through internal inspection, which may lead to a potential tire failure in service.
[0014] Therefore, described herein, a green tire consisting of a bead portion which can easily be rotated about bead core of the tire to overcome the above explained technical problems encountered in manufacturing of the tire and not only provides a cured tire which can be easily mounted on a wheel, to seat on a rim as discussed above, but also has radial and lateral stiffness properties for improved vehicle handling and ride comfort.

[0015] To this end, approaches for improved strength efficient bead filler construction of the radial tire is discussed, which substantially prevent the separation of the carcass ply layers and the bead portion and prevents air entrapment in the bead portion, which are fatal flaws in radial tires for light duty vehicles, such as light-duty trucks.
[0016] An implementation of the present subject matter describes a light truck radial pneumatic tire. The tire includes a tread portion, a pair of sidewall portions provided on either side of the tread portion, wherein each of the pair of sidewall portions further includes a bead portion located at a distal end of the respective sidewall portion, wherein the bead portion has a bead core therein. The bead portion is formed by bead filler which is disposed directly within the bead core, wherein the bead filler has an inverted L-shaped filler profile before vulcanization process. In another example, the bead filler is made of a rubber of an elastic modulus in a range of 125 j 200 kg/cm2.
[0017] With the above disclosed subject matter, the inverted L-shaped filler is applied before the vulcanization process, at bead portion of a light truck radial tire, which allows for doing away with a need of bending the bead filler when going from the cylindrical shape to the toroidal shape during the tire building process. With the implementation of the present subject matter, the bead portion efficiently eliminates the separation of the carcass ply layers and the bead portion and prevents air entrapment in the bead portion. Implementation of the present subject matter also eliminates the stresses and strains that are developed due to the shearing and straining at the turn up portion in the bead portion.
[0018] The above and other features, aspects, and advantages of the subject matter will be better explained with regard to the following description and accompanying figures. It should be noted that the description and figures merely illustrate the principles of the present subject matter along with examples described herein and, should not be construed as a limitation to the present subject matter. It is thus understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and

examples thereof, are intended to encompass equivalents thereof. Further, for the sake of simplicity, and without limitation, the same numbers are used throughout the drawings to reference like features and components.
[0019] FIG. 1 shows a radial cross-section view of a radial tire being symmetrical about a mid-circumferential plane, as per an implementation of the present subject matter.
[0020] The cross-sectional view of FIG. 1 is a radial cut of a radial tire 100 showing only half of the tire's 100 cross-section as per an implementation of the present subject matter. The tire 100 is symmetrical with respect to a mid-circumferential plane Y of the tire 100. The top portion of the tire 100 includes a tread portion 102 constituting a tread surface for contacting a ground surface to support a vehicle by transferring vehicular loads from the rim through the tire 100 to the ground surface. The tire 100 further comprises a shoulder zone (not illustrated) disposed laterally on each side of said mid-circumferential plane and comprising a sidewall 104 which serves to increase lateral stability of the vehicle. The tread is also supported by a plurality of reinforced belt plies forming belt packages 118-A, 118-B in a band around the tire 100 interior to the tread portion. The belt packages 118-A, 118-B extends laterally over the top of the tire 100 from shoulder to shoulder.
[0021] The tire 100 further comprises a bead core 110 for use in light duty vehicles, as per an implementation of the present subject matter. The bead core 110 is composed of steel wires in varying numbers to form a loop in a bead portion that seals against a rim and forms an anchor on which a body ply is wound. The bead portion is located at a distal end of a respective sidewall portion 104 of the tire 100. Turn up plies 116-A, 116B encapsulate the bead core 110 from an inner side to an outer side forming the body of the tire 100. In an implementation, the turn up plies 116A, 116B may be composed of steel cords that gives sufficient strength to hold the air pressure and provide impact resistance to the sidewall 104.
[0022] The sidewall 104 protects the turn up plies 116-A, 116-B from flex fatigue and abrasion. Further, the tire 100 includes an inner liner layer 108. The

inner liner layer 108 is used to retard or minimize the escape of air used to inflate the tire 100, thereby maintaining tire pressure. The inner liner layer 108 may be adhered to the inner surface of the tire 100 and preferably extends over the entire inner surface of tire 100. The inner liner layer 108 may be made of a material (e.g., butyl or a halo butyl rubber or natural rubber) which has low air permeability and high elongation and flex resistance over the tire temperature range likely to be encountered by a tire in service.
[0023] In an implementation of the present subject matter, the tire 100 also includes a chafer 114 positioned around the tire's 100 bead portion and intended for contacting a rigid rim of the vehicle wheel. The chafer 114 may be made up of a rubber composition, conventionally designed to contact the rigid wheel rim and, therefore, act as an interface between the tire 100 and the wheel rim. The chafer rubber composition is very abrasion resistant, tough, and have a relatively high modulus while also having acceptable flex and rubber fatigue properties as well as having good resistance to cut growth. The chafer 114 is adjacent to the bead portion of the tire 100, leaving the rubber portion of the chafer 114 to contact the rigid wheel rim when the tire 100 is mounted on such rim and inflated. The chafers 114, their intended interface between the tire bead portion and rigid wheel rim, as well as their rather demanding physical properties, are well known to those skilled in the art and have not been elaborated in the present description.
[0024] Further, the tire 100 may be provided with a rim-cushion 106 so that the tire 100 has the ability of absorbing shock or cushioning effects due to the bumpy vehicle running surface. A shoulder pad 120, in some applications, may be provided in the tire 100 to reduce inflation pressures and to further improve the off-road traction. The shoulder pad 120 also helps in controlling bulging in the shoulder areas, reducing in those areas of the tire 100, a risk of puncture.
[0025] In an embodiment, in the tire 100, a belt cover layer 122 is provided which may consist of a nylon material or the like with lower rigidity than the belt packages 118-A, 118-B as described above. The belt cover layer 122 may be disposed on the belt plies in a tire circumferential direction in order to improve high

speed durability of the tire (100). Since, the belt cover layer 122 does not directly affect the performance to which the present invention pertains and already known in the art, therefore further description on the belt cover layer 122 is skipped here for the sake of brevity.
[0026] Although the foregoing description has described belt plies primarily as utilizing steel or like metal cords or cables as the reinforcing elements, it will be understood that the principles of the invention are applicable to belts made up of cords of other high modulus materials, such as rayon, glass fiber, and the like, well known in the art.
[0027] Further, in another implementation of the present subject matter, the bead portion may be provided with bead filler 112 disposed radially inside the bead core 110 and between a first turn up ply 116-A and a second turned ply 116-B of the tire 110. The bead filler 112 generally have triangular cross-sectional shape, an axially outer side and an axially inner side. The bead filler 112 may be composed of a rubber with elastic modulus in a range of 125 - 200 kg/cm2. The construction of bead filler 112 and the bead filler's constituents has been explained later in the description through FIG. 2.
[0028] In one embodiment of the present subject matter, the tire 100 may have an aspect ratio in a range of 80 - 100. Furthermore, in another embodiment, the aspect ratio may vary, depending upon the types of tires used. Such as, in manufacturing of an agricultural tire, using the teaching of the present subject matter, for the drive axle of a vehicle may be designed to have an aspect ratio of greater than 95.
[0029] FIG. 2 shows an enlarged schematic view of the bead portion, as per an implementation of the present subject matter. As shown in FIG. 2, the bead filler 112 has a base portion 202 extending radially outside of the bead core 110. As stated earlier, the bead filler, which is introduced during a first stage of the tire manufacturing, is generally of a triangular cross-section shape, with a thick base portion and thin turn up 116-B or top portion. The axially inner portion of the bead filler 112 is continuously decreased in the thickness towards the radially outer end

thereof. The bead filler 112 with a substantially triangular cross-sectional shape is disposed in such a manner that one side of the triangle is brought into contact with the bead core 110 and one side is brought into contact with the tire's 110 ply turned-up portion 116-B, as shown in FIG. 1.
[0030] In the present implementation, the bead filler 112 is in an inverted L-shape profile and is introduced during the first stage of the tire manufacturing. The inverted L-shaped bead filler 112 is disposed at the bead portion, between the sidewall portions 104 and a carcass ply layer of the tire 100.
[0031] It is to be understood that tire manufacturing, normally has two stages, wherein in the first stage, different tire building components are assembled together to form a green tire and in the second stage, the green tire is further passed through the curing process. The first stage, where the green tire is prepared, may also be called as the green stage, un-vulcanized or uncured stage etc. Tire manufacturing may further comprise stages consisting detaching supports from clamping means after curing etc., which is already known in the art, hence, not discussed herein for the sake of brevity.
[0032] In an example implementation of the present subject matter, the thickness of the base portion 202 of the inverted L-shaped bead filler 112 is in a range of not less than 9 mm, but not more than 12 mm. Width of the inverted L-shaped bead filler 112 is in a range preferably not less than 35 mm, but not more than 65 mm. Further, axial height of a main layer of the inverted L-shaped bead filler 112 may be in a range of 35 mm to 65 mm from the bead base line and quantity of the inverted L-shaped bead filler 112 used per tire may be in a range of is 0.65 kg to 1.15 kg.
[0033] With the implementation of the present subject matter, the bending of the bead filler is avoided at the time of transition, going from a cylindrical shape to a toroidal shape during the manufacturing process of the green tire. As the inverted L-shaped filler 112 provides pre-bended profile to a filler component, the rotation of both, the sidewall portion 104 and the bead portion about the bead core 110, during inflation of the tire 100 becomes smoother and the bead filler components

do not get crushed due to a high torsional rigidity of the bead core 110. The present subject matter is to construct the bead portion by forming the inverted L-shaped filler 112 profile, that efficiently eliminates the separation of the carcass ply layers and the bead portion and prevents air entrapment in the bead portion as no hollow part is present in the bead core 110.
[0034] Further, introducing pre-bended inverted L-shaped filler 112 profile also ensures eliminating the stresses and strains that are developed due to the shearing and straining at the turn up portion in the bead portion during the movement of the vehicle. Furthermore, since the cross-sectional shape of the bead filler 112 is made inverted "L", occurrence of the strain is contained in the bead portion and this improves a fatigue resistance of a cord in the belt ply members or side reinforcing member of the tire 100 and improve a separation durability of the tire 100.
[0035] In accordance with the embodiment of the present invention, once the green tire is passed through the curing process, the inverted L-shaped bead filler and the rubber reinforcing layer therein attains, substantially the triangular cross-sectional shape in cured stage, according to the process requirement. In the cured radial tire 100, the bead portion is extending from a position near to the bead core 110 to a position near to below mid sidewall region along an inner surface of an innermost carcass ply. In forming the inverted L-shaped bead filler 112, according to the invention by extrusion, in one of the example embodiment extrusion dies of width ranges from 37 mm to 67 mm is used, which may be small in the value of length to diameter and has a sufficiently small inner diameter compared with the inner diameter of a screw section of the extruder.
[0036] The shape and size of the bead core 110 and the bead filler 112 can also be altered within the scope of this invention. A bead core is generally formed as a polygonal shape with a cross-sectional area defined by notional sides contacting the outer surfaces of the steel cords or synthetic cords that make the annular bead core. The bead core 110 of the embodiment illustrated in FIGS. 1 and 2 has an irregular polygonal shape. Other shapes and sizes of the bead core 110 are within the scope of this invention.

[0037] In the present embodiment, the bead portion along with the inverted L-shaped bead filler 112 bend so that the tire 100 conforms to the shape of the wheel rim without displacing the bead core 110 or greatly reducing the seating pressures at the tire to rim interface as shown in FIG. 1. The ability of the inverted L-shaped bead filler helps the tire 100 to conform to the wheel rim is enhanced without addition of another layer. As the bending of the bead portion is more critical during lateral maneuvers of the vehicle and related maneuvers of the vehicle, the same may be improved with the introduction of inverted L-shaped bead filler 112, without the addition of another layer in the filler. Thus, using the technique prescribed in the present subject matter, the tire manufacturing is made simple without incurring additional cost.
[0038] FIG. 3 describes a method 300 forming a filler and applying the filler into a bead portion of a tire 100 of a vehicle, in accordance with an example implementation of the present subject matter. The order in which the method 300 is described is not intended to be construed as a limitation, and any number of the described method blocks may be combined in any order to implement the method 300, or an alternative method.
[0039] At block 302, the bead portion is provided at a distal end of each sidewall portion of the tire. The sidewall portion is located on either side of a tread portion of the tire. The bead portion of the tire is comprising a bead core therein. In an example, a radial cross-section view of the tire which is symmetrical about a mid-circumferential plane of the tire is shown in FIG. 1. The cross-sectional view of FIG. 1 is showing only half of the tire's cross-section as per an implementation of the present subject matter. Thus, at block 302, the implementation may be done in any portion of the tire.
[0040] At block 304, a bead filler is applied in the bead core. The bead filler is applied directly to the bead core and the bead filler is of substantially inverted L-shape. As explained earlier, the inverted L-shaped bead filler profile is applied in the bead core of the bead portion during a first stage of the tire building process, i.e. before the vulcanization process of the tire.

[0041] At block 306, once the inverted L-shaped bead filler is applied to the correct position, during manufacturing of the green tire, the tire is put through further processing, such as curing of the tire in a curing mold. After the curing process is complete, the inverted L-shaped bead filler and the rubber reinforcing layer therein attains, substantially the triangular cross-sectional shape, according to the process requirement of a finished tire.
[0042] The embodiments of this invention can be used in combination or individually to form tires made by improved manufacturing processes and/or with improved performance features. The combinations depend on the intended use of the tire and includes conventional as well a run-flat tire uses. The overall design of the bead filler of the invention disclosed herein results in a combination being an improved process for making, namely but not exclusively, light duty vehicle tires for improving the mounting bead portion separation durability of the of the tire and improving driving performances of the vehicle, especially with light duty vehicle designed tires and may also be used for other types of tires as well.
[0043] Although implementations for bead portion durability improvement are described, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features are disclosed as implementations.

I/We Claim:
1. A tire (100) comprising:
a tread portion (102);
a pair of sidewall portions (104) provided on either side of the tread portion (102), each of the pair of sidewall portions (104) comprising:
a bead portion located at a distal end of a respective sidewall portion (104), the bead portion having a bead core (110) therein;
bead filler (112) disposed within the bead core (110), wherein
the bead filler (112) has an inverted L-shaped filler profile, and
the bead filler (112) is made of rubber having an elastic modulus in a range of 125 - 200 kg/cm2.
2. The tire (100) as claimed in claim 1, wherein the inverted L-shaped filler profile (112) is disposed between the sidewall portions (104) and a carcass ply layer of the tire (100) in a light truck radial tire.
3. The tire (100) as claimed in claim 2, wherein the light truck radial tire is in a green stage.
4. The tire (100) as claimed in claim 2, wherein the bead filler (112) is introduced during carcass preparation in a green stage.
5. The tire as claimed in claim 2, wherein the bead filler (112) attains substantially a triangular cross-sectional shape in a cured stage, the bead filler (112) extending from a position near to the bead core (110) to a position near to below mid sidewall region along an inner surface of an innermost carcass ply layer.
6. The method of forming a filler and applying the filler into a bead portion of a tire (100), the method comprising:

providing the bead portion at a distal end of each sidewall portions (104) of the tire (100), the sidewall portions (104) being located at either side of a tread portion (102) of the tire, the bead portion having a bead core (110) therein; and
applying bead filler (112) in the bead core (110), wherein the bead filler (112) is applied directly to the bead core (110), wherein the bead filler (112) has an inverted L-shaped filler profile before vulcanization process.
7. The method as claimed in claim 6, wherein, upon vulcanization, the bead filler (112) has a triangular profile.
8. The method as claimed in claim 6, wherein the tire (100) is a light truck radial tire.
9. The method as claimed in claim 6, further comprising bending of the filler (112) before applying the filler (112) into the core (110) of the bead portion.