Patent Application
20220185034
The invention relates in general to pneumatic tires, and more particularly to a bead construction for heavy duty vehicles such as aircraft or trucks.
Annular tensile members, commonly referred to as tire bead cores, are designed to securely hold the tire on the rim during use. The tire beads provide a radially inner portion between the bead core and the rim that is radially compressed, and as this portion is compressed, the bead core is placed in tension. Radial compression occurs as the tire is mounted on a tapered rim seat by the action of the internal pressure of the tire pushing the bead axially outwardly toward the vertical bead flange.
Recently, attempts have been made to provide a heavy duty bead construction that has a reduced weight. However, problems have occurred such as creep under load and fretting. In creep under load, the synthetic cables or cords will stretch under load and as the plastic flows, the restraining force actually will lower with time. A second problem is fretting, which is when brittle fractures occur if the cords are placed in compression. Thus, an improved bead design which is light weight without sacrificing strength is desired, and that further overcomes the disadvantages mentioned above.
The invention provides in a first aspect a pneumatic radial tire having a bead portion provided therein with a bead core, and a first layer of a plurality of sheath wires surrounding the bead core, and a second layer formed of a plurality of sheath wires surrounding the first layer, wherein the second layer of shear wires has a diameter less than the sheath wires of the first layer.
“About” means, unless otherwise specified, +/−10%.
“Aspect Ratio” means the ratio of a tire's section height to its section width.
“Axial” and “axially” mean the lines or directions that are parallel to the axis of rotation of the tire.
“Bead” or “Bead Core” mean generally that part of the tire comprising an annular tensile member, the radially inner beads are associated with holding the tire to the rim being wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes or fillers, toe guards and chafers.
“Belt Structure” or “Reinforcing Belts” means at least two annular layers or plies of parallel cords, woven or unwoven, underlying the tread.
“Carcass” means a laminate of tire ply material and other tire components cut to length suitable for splicing, or already spliced, into a cylindrical or toroidal shape. Additional components may be added to the carcass prior to its being vulcanized to create the molded tire.
“Circumferential” means lines or directions perpendicular to the axial direction within + or −5 degrees.
“Cord” means one of the reinforcement strands, including fibers, which are used to reinforce the plies.
“Extensible” means a cord having a relative elongation at break of greater than 0.2% at 10% of the breaking load, when measured from a cord extracted from a cured tire. The tensile measurements for elongation at break (total elongation in %) are performed in accordance with ISO 6892-1B(2019) at preload no more than 25 mpa tested on a cable or cord when taken from a cured tire.
“Flipper” means a reinforced fabric wrapped about the bead core.
“Radial” and “radially” mean directions radially toward or away from the axis of rotation of the tire.
“Radial Ply Structure” means the one or more carcass plies or which at least one ply has reinforcing cords oriented at an angle of between 65° and 90° with respect to the equatorial plane of the tire.
“Rib” means a circumferentially extending strip of rubber of the tread which is defined by at least one circumferential groove and either a second circumferential groove or a lateral edge, wherein the strip is not divided by full depth grooves.
The invention will be described by way of example and with reference to the accompanying drawings in which:
With reference to
The tire 100 is a radial ply tire having air imperious inner liner 22 which contains fluid or air under pressure. Radially outward of the inner liner 22 are one or more radial plies 20. Each ply 20 extends from an annular tensile member commonly referred to as a bead core 30. As shown the plies 20 are anchored about the bead core 30 either turning axially out and up forming a ply turnup or alternately turning axially in and under the bead core 30. Radially above the bead core 30 is an optional rubber apex 40.
Radially outward of the carcass plies 20 is a belt package 50 comprising a plurality of belt reinforcing layers, each layer is reinforced with parallel reinforcement cords. A top belt layer 53 is shown radially outward of the belt layers 50. Above the belt is a tread 18 as shown, the tread 18 has a plurality of optional circumferentially continuous grooves 17. The tire structure 100 as mentioned is an example of one type of tire structures that can utilize the bead core 30 of the present invention. Although the tire 100 as shown is an aircraft tire structure, the invention is usable in any highly loaded heavy-duty tire structure.
With reference to
As further illustrated, the central core 33 is wrapped by a first annular row of inner sheath wires 35. Preferably, there is at least two annular rows of inner sheath wires 35, wherein each inner sheath wire has a. diameter B. Preferably, the diameter of the wires of the inner sheath wires 35 are the same, and range in size from 1.5 mm to about 3 mm, and more preferably, in the range of 1.8 mm to about 2.5 mm. Preferably, there are three to four annular rows of inner sheath wires 35. The wires 35 of the sheath layers are steel that are helically or spirally wound about the central core 33.
The bead core 30 further includes one or more annular rows of outer sheath layers 37. The wires in the outer annular row have a smaller diameter C than the diameter B of the wires in the inner sheath layers. Preferably, the diameter C of the wires of the outer sheath layer 37 are the same, and range in size from 1.5 mm to about 2.5 mm, and more preferably, in the range of 1. mm to about 2. mm.
The entire bead is coated in an adhesive rubber layer and then a textile ply cord is helically wrapped around the bead cord.
Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.
