Patent Application
20120085477
The present invention relates to a pneumatic tire, and more particularly, to a less costly and more quickly manufactured pneumatic tire.
Historically, the pneumatic tire has been fabricated as a laminate structure of generally toroidal shape having beads, a tread, belt reinforcement, and a carcass. The tire is made of rubber, fabric, and steel. The manufacturing technologies employed for the most part involved assembling the many tire components from flat strips or sheets of material. Each component is placed on a building drum and cut to length such that the ends of the component meet or overlap creating a splice.
In the first stage of assembly, the prior art carcass will normally include one or more plies, and a pair of sidewalls, a pair of apexes, an innerliner (for a tubeless tire), a pair of chafers and perhaps a pair of gum shoulder strips. Annular bead cores can be added during this first stage of tire building and the plies can be turned around the bead cores to form the ply turnups. Additional components may be used or even replace some of those mentioned above.
This intermediate article of manufacture would be cylindrically formed at this point in the first stage of assembly. The cylindrical carcass is then expanded into a toroidal shape after completion of the first stage of tire building. Reinforcing belts beneath the tread are added to this intermediate article during a second stage of tire manufacture, which can occur using the same building drum or work station. This form of manufacturing a tire from flat components that are then toroidally formed limits the ability of the tire to be produced in an optimally uniform fashion.
Conventionally, it has been proposed to lay carcass plies in hoops or arcs having the ends of the carcass plies extending in a circumferential direction. A tire made this way may be dispensed of any circular bead core in the beads and the carcass would not have any lateral parts turned up radially with edges delimited by cut cables. While initially this process was not commercially viable, further developments have occurred constructing a ply using hoops of circular arcs so that the individual ply cords are laid across a convex toroidal cross section in an early stage of manufacture, converse to being made in the flat construction. The cords may thus extend in linear paths across the carcass. Early versions have included wrapping the ply cords around bead cores to effect a change in cord direction. These ply cords have been placed in tension around a circular arcuate shape in the course of manufacture. Later versions have included turning these linearly extending cords in opposite directions and sandwiching them between radially extending bead layers.
A similar conventional process simultaneously produces multiple arches using multiple cords in the process of manufacturing the carcass ply in an effort to speed the rate of manufacture. This process provides each of the circumferential portions being made from a single fine cord and the distance between cords, or the pitch, being very narrow. Thus, an array of cords has increased the pitch between cords as the array is applied.
In these conventional methods of manufacturing ply cords on a toroidal surface, it has been determined that a tension in the cords is optimal and that the cords should be laid in a straight line on a convex surface from turnaround to turnaround. In other words, a cord angle may be arranged other than 90° . However, 90° is a preferred orientation for the cord path because 90° mitigates likelihood of slippage off angle because 90° is the shortest ply path. Conventionally, these angles could not be adjusted in any fashion other than to provide a linear path because the tension placed on the cord during manufacture is required as the cord is being applied on the round or convex surface. In each conventional step, a carcass ply uses a technique called “winding” wherein the turnarounds apply tension across the entire cord path. Such a tire winding step for applying ply cords can only work on a convex surface and does not allow “placement” on a concave toroidal shape, as occurs in the sidewall regions, near the beads of the tire.
Another conventional method manufactures ply cords that allow placement on concave and convex surfaces, similar to the shape of a finished tire. This method does not require tension from turnaround to turnaround as the cord path is being established, thereby permitting nonlinear cord paths. Further, the cord loop endings, or turnarounds, may occur at different diameters and placement of the ply cords may be such that toroidially shaped ply cords may include forming turnups and allowing anchoring the ply using the bead cores. Additionally, the pitch between the cords may uniformly increase as the diameter increases along the cord path. The cord pitch increases uniformly as the diameter increases along the ply path due to a coordinated differential motion between the application of the cord and the movement of the toroidal surface.
The structure of a conventional pneumatic tire typically includes a pair of axially separated inextensible beads. A circumferentially disposed bead filler apex extends radially outward from each respective bead. At least one carcass ply extends between the two beads. The carcass ply has axially opposite end portions, each of which is turned up around a respective bead and secured thereto. Tread rubber and sidewall rubber is located axially and radially outward, respectively, of the carcass ply.
The bead area is one part of the tire that contributes a substantial amount to the rolling resistance of the tire, due to cyclical flexure which also leads to heat buildup. Under conditions of severe operation, as with runflat and high performance tires, the flexure and heating in the bead region can be especially problematic, leading to separation of mutually adjacent components that have disparate properties, such as the respective moduli of elasticity. In particular, the ply turnup ends may be prone to separation from adjacent structural elements of the tire.
A conventional ply may be reinforced with materials such as nylon, polyester, rayon, and/or metal, which have much greater stiffness (i.e., modulus of elasticity) than the adjacent rubber compounds of which the bulk of the tire is made. The difference in elastic modulus of mutually adjacent tire elements may lead to separation when the tire is stressed and deformed during use.
A variety of conventional design approaches have been used to control separation of tire elements in the bead regions of a tire. For example, one method has been to provide a “flipper” surrounding the bead and the bead filler. The flipper works as a spacer that keeps the ply from making direct contact with the inextensible beads, allowing some degree of relative motion between the ply, where it turns upward under the bead, and the respective beads. In this role as a spacer, a flipper may reduce disparities of strain on the ply and on the adjacent rubber components of the tire (e.g., the filler apex, the sidewall rubber, in the bead region, and the elastomeric portions of the ply itself).
The flipper may be made of a square woven cloth that is a textile in which each fiber, thread, or cord has a generally round cross-section. When a flipper is cured with a tire, the stiffness of the fibers/cords becomes essentially the same in any direction within the plane of the textile flipper.
In addition to the use of flippers as a means by which to reduce the tendency of a ply to separate, or as an alternative, another method that has been used involves the placement of “chippers.” A chipper is a circumferentially deployed metal or fabric layer that is disposed within the bead region in the portion of the tire where the bead fits onto the wheel rim. More specifically, the chipper lies inward of the wheel rim (i.e., toward the bead) and outward (i.e., radially outward, relative to the bead viewed in cross section) of the portion of the ply that turns upward around the bead. Chippers serve to stiffen, and increase the resistance to flexure of, the adjacent rubber material, which itself is typically adjacent to the turnup ply endings.
In accordance with the present invention, a pneumatic tire has an axis of rotation. The pneumatic tire includes a reinforced ply placed in a predetermined location on a toroidal surface, a tread disposed radially outward of the reinforced ply, and a belt structure disposed radially between the reinforced ply and the tread. The reinforced ply includes at least one layer of an open construction woven or knitted fabric having warp yarns extending in a circumferential direction and weft yarns extending in a radial direction.
In one aspect of the present invention, the woven fabric has a 5 EPI to 18 EPI warp pair construction and a 5 EPI to 35 EPI weft construction.
In another aspect of the present invention, the warp yarns are 1220/1 Dtex rayon and the weft yarns are 1840/2 Dtex rayon or 2200/2 Dtex polyester. Other examples of weft constructions may be: 1100/2, 1440/2, 1670/2, 2200/2 polyester or 1220/2, 1840/2, 1840/3, 2440/2 Dtex rayon.
In still another aspect of the present invention, the warp yarns have a density of 18 EPI and the weft yarns have a density of 12 EPI.
In still another aspect of the present invention, the fabric has a LENO 2T or knitted configuration with a 5 EPI to 18 EPI warp pair construction and a 5 EPI to 35 EPI weft construction.
In yet another aspect of the present invention, the warp yarns have a density of 14 EPI and the weft yarns have a density of 26 EPI.
In still another aspect of the present invention, the pneumatic tire is a high performance tire.
In yet another aspect of the present invention, the woven fabric further comprises an adhesion promoter disposed thereon.
In still another aspect of the present invention, the reinforcing structure of the carcass has one or more layers of woven fabric.
In yet another aspect of the present invention, the warp yarns comprise at least two fibers of different fiber materials.
In still another aspect of the present invention, the woven or knitted fabric of the reinforced ply is constructed by placing a series of strips adjacent to each other.
“Apex” means an elastomeric filler located radially above the bead core and between the plies and the turnup ply.
“Annular” means formed like a ring.
“Aspect ratio” means the ratio of its section height to its section width.
“Axial” and “axially” are used herein to refer to lines or directions that are parallel to the axis of rotation of the tire.
“Bead” means that part of the tire comprising an annular tensile member wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes, toe guards and chafers, to fit the design rim.
“Belt structure” means at least two annular layers or plies of parallel cords, woven or unwoven, underlying the tread, unanchored to the bead, and having cords inclined respect to the equatorial plane of the tire. The belt structure may also include plies of parallel cords inclined at relatively low angles, acting as restricting layers.
“Bias tire” (cross ply) means a tire in which the reinforcing cords in the carcass ply extend diagonally across the tire from bead to bead at about a 25°-65° angle with respect to equatorial plane of the tire. If multiple plies are present, the ply cords run at opposite angles in alternating layers.
“Breakers” means at least two annular layers or plies of parallel reinforcement cords having the same angle with reference to the equatorial plane of the tire as the parallel reinforcing cords in carcass plies. Breakers are usually associated with bias tires.
“Cable” means a cord formed by twisting together two or more plied yarns.
“Carcass” means the tire structure apart from the belt structure, tread, undertread, and sidewall rubber over the plies, but including the beads.
“Casing” means the carcass, belt structure, beads, sidewalls and all other components of the tire excepting the tread and undertread, i.e., the whole tire.
“Chipper” refers to a narrow band of fabric or steel cords located in the bead area whose function is to reinforce the bead area and stabilize the radially inwardmost part of the sidewall.
“Circumferential” means lines or directions extending along the perimeter of the surface of the annular tire parallel to the Equatorial Plane (EP) and perpendicular to the axial direction; it can also refer to the direction of the sets of adjacent circular curves whose radii define the axial curvature of the tread, as viewed in cross section.
“Cord” means one of the reinforcement strands of which the reinforcement structures of the tire are comprised.
“Cord angle” means the acute angle, left or right in a plan view of the tire, formed by a cord with respect to the equatorial plane. The “cord angle” is measured in a cured but uninflated tire.
“Denier” means the weight in grams per 9000 meters (unit for expressing linear density). Dtex means the weight in grams per 10,000 meters.
“Elastomer” means a resilient material capable of recovering size and shape after deformation.
“Equatorial plane (EP)” means the plane perpendicular to the tire's axis of rotation and passing through the center of its tread; or the plane containing the circumferential centerline of the tread.
“Fabric” means a network of essentially unidirectionally extending cords, which may be twisted, and which in turn are composed of a plurality of a multiplicity of filaments (which may also be twisted) of a high modulus material.
“Fiber” is a unit of matter, either natural or man-made that forms the basic element of filaments. Characterized by having a length at least 100 times its diameter or width.
“Filament count” means the number of filaments that make up a yarn. Example: 1000 denier polyester has approximately 190 filaments.
“Flipper” refers to a reinforcing fabric around the bead wire for strength and to tie the bead wire in the tire body.
“Gauge” refers generally to a measurement, and specifically to a thickness measurement.
“High Tensile Steel (HT)” means a carbon steel with a tensile strength of at least 3400 MPa@0.20 mm filament diameter.
“Inner” means toward the inside of the tire and “outer” means toward its exterior.
“Innerliner” means the layer or layers of elastomer or other material that form the inside surface of a tubeless tire and that contain the inflating fluid within the tire.
“Knitted” means intertwining threads in a series of connected loops. For example, knitted may define a method by which thread or yarn is turned into a fabric of consecutive loops, called stitches. As each row of stitches progresses, a new loop may be pulled through an existing loop.
“LASE” is load at specified elongation.
“Lateral” means an axial direction.
“Lay length” means the distance at which a twisted filament or strand travels to make a 360 degree rotation about another filament or strand.
“Mega Tensile Steel (MT)” means a carbon steel with a tensile strength of at least 4500 MPa@0.20 mm filament diameter.
“Normal Load” means the specific design inflation pressure and load assigned by the appropriate standards organization for the service condition for the tire.
“Normal Tensile Steel (NT)” means a carbon steel with a tensile strength of at least 2800 MPa@0.20 mm filament diameter.
“Ply” means a cord-reinforced layer of rubber-coated radially deployed or otherwise parallel cords.
“Radial” and “radially” are used to 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.
“Radial Ply Tire” means a belted or circumferentially-restricted pneumatic tire in which at least one ply has cords which extend from bead to bead are laid at cord angles between 65° and 90° with respect to the equatorial plane of the tire.
“Section Height” means the radial distance from the nominal rim diameter to the outer diameter of the tire at its equatorial plane.
“Section Width” means the maximum linear distance parallel to the axis of the tire and between the exterior of its sidewalls when and after it has been inflated at normal pressure for 24 hours, but unloaded, excluding elevations of the sidewalls due to labeling, decoration or protective bands.
“Sidewall” means that portion of a tire between the tread and the bead.
“Super Tensile Steel (ST)” means a carbon steel with a tensile strength of at least 3650 MPa@0.20 mm filament diameter.
“Tenacity” is stress expressed as force per unit linear density of the unstrained specimen (gmAex or gm/denier). Used in textiles.
“Tensile” is stress expressed in forces/cross-sectional area. Strength in psi=12,800 times specific gravity times tenacity in grams per denier.
“Toe guard” refers to the circumferentially deployed elastomeric rim-contacting portion of the tire axially inward of each bead.
“Tread” means a molded rubber component which, when bonded to a tire casing, includes that portion of the tire that comes into contact with the road when the tire is normally inflated and under normal load.
“Tread width” means the arc length of the tread surface in a plane including the axis of rotation of the tire.
“Turnup end” means the portion of a carcass ply that turns upward (i.e., radially outward) from the beads about which the ply is wrapped.
“Ultra Tensile Steel (UT)” means a carbon steel with a tensile strength of at least 4000 MPa@0.20 mm filament diameter.
“Woven” means interlacing lengthwise yarns (warp) with filling yarns (weft). The interlaced yarns may be two or more sets of yarns at right angles to each other.
“Yarn” is a generic term for a continuous strand of textile fibers or filaments. Yarn occurs in the following forms: 1) a number of fibers twisted together; 2) a number of filaments laid together without twist; 3) a number of filaments laid together with a degree of twist; 4) a single filament with or without twist (monofilament); 5) a narrow strip of material with or without twist.
The structure, operation, and advantages of the present invention will become more apparent upon contemplation of the following description as viewed in conjunction with the accompanying drawings, wherein:
With reference to
The robotic computer controlled system 110 has a computer 120 and preprogrammed software which dictates a ply path 10 to be used for a particular tire size. Each movement of the system 110 can be precisely articulated. The robot 150, which is mounted on a pedestal 151, has a robotic arm 152 which can be moved in six axes. The manipulated robotic arm 152 is attached to the ply mechanism 70 as shown.
Loop end forming mechanisms 60 are positioned on each side 56 of the toroidal mandrel 52. The robotic arm 152 feeds the ply cord 2 in predetermined paths 10 and the loop end forming mechanism 60 holds the ply cord 2 in place as a looped end 12 is formed. Each time a looped end 12 is formed, the toroidal mandrel 52 is rotated to index to a next pitch P and an adjacent ply path 10 around the toroidal mandrel 52.
The movement of the ply mechanism 70 permits convex curvatures to be coupled to concave curvatures near the bead areas, thus mimicking the final, as molded, shape of the pneumatic tire. A means 63 for rotating the mandrel 52 about an axle 64 may be mounted to a rigid frame 65 as shown.
With reference to
With reference to
To advance the ply cords 2 on the predetermined ply path 10, the ply mechanism 70, which contains two pairs of parallel pins or rollers 40, 42 with the second pair 42 placed 90° relative to the first pair 40 and in a physical space of about one inch above the first pair 40 and forms a center opening 30 between the two pairs of rollers, which enables the predetermined ply path 10 to be centered. As illustrated, the ply cords 2 are held in place by a combination of embedding the cord into the elastomeric surface 4 previously placed onto the toroidal surface 50 and the surface tackiness of the uncured surface. Once the ply cords 2 are properly applied around the entire circumference of the toroidal surface 50, a subsequent lamination of elastomeric topcoat compound (not shown) can be used to complete the construction of the carcass 20.
As illustrated in
As shown in
Preferably, the ply cord 2 is wrapped around a tension or ply mechanism 70 to adjust and maintain the required tension in the ply cord. If the tension is too high, the ply cord 2 will lift from the elastomeric layer 4 when the roller pins 40, 42 reverse direction. If the tension is too low, the ply cord 2 will not form a loop at a correct length around the loop pin mechanism 60. As an example, tension on the ply cord 2 is created as the ply cord passes between a series of rollers 72 capable of adjusting and maintaining tension, as needed for the process and the roller 40, 42. The amount of tension applied should be sufficiently small so that the ply cords 2 do not lift from the placed position on the toroidal surface 50. In other words, the ply cord 2 rests on the toroidal surface 50 positioned and stitched to an elastomeric layer 4 such that the tack between the ply cord and the elastomeric layer is larger than the tension applied by the ply mechanism 70. This permits the ply cords 2 to lay freely on the toroidal surface 50 without moving or separating during the ply construction step. This is significantly different from other conventional mechanisms, which require linear paths and a large amount of tension to maintain the paths 10 as the equipment is traversing over a convex surface to create a laminated ply.
With reference to
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As demonstrated by
Alternatively, or in conjunction with the longer cord paths 124, one or more shorter cord paths 126 may be formed. The shorter cord paths 126 may initiate opposite a first concave curvature 120 on one side of the mandrel 52 adjacent the bead attachment area 22. The shorter cord path 126 may therefrom extend through the sidewall curvature 122 and over the crown area 55, or terminate within the sidewall curvature 122. The shorter cord path 126, extended over the crown area 55, may have a looped end located at the upper sidewall of the opposite mandrel side. Such a shorter cord path 126, by ending at a higher location on the opposite sidewall of the mandrel 52, may reduce the concentration of cord paths in the bead area of the tire. The shorter cord paths 126 further conserve cord material in the finished tire and reduce manufacturing cost. Accordingly, cord paths forming a ply layer may be custom designed such that cord paths have differing path extensions and lengths. The shorter paths may terminate before crossing the equatorial plane of the mandrel (tire) or cross over the crown area to the sidewall on the opposite side. The longer paths may extend from bead attachment region 22 to bead attachment region 22 on the opposite side, crossing the crown region 26 of the tire. As a result, a cord layer may be constructed having fewer cord paths present (lower cord path density) at the bead attachment area 22 and a higher ply cord path density at the crown region 26 of the tire.
A tire may accordingly be constructed having cord ply cord paths of differing lengths. A like number of longer and shorter cord paths, or a different number of longer and shorter paths, may be employed depending on the tire performance characteristics desired. The longer cord paths may be constructed to extend over the crown region 26 of the toroidal surface 50 to the bead attachment areas 22. The shorter cord paths may be constructed to have loop ends that terminate either in the crown region 26, or the sidewall region 24. The cord paths may be advantageously constructed through placement and embedding one or more cords in continuous lengths onto the elastomeric layer 4 in predetermined relatively longer and shorter cord paths, the longer cord paths extending from a respective side of the toroidal surface 50 over the convex crown region 26 of the toroidal surface and one or more relatively shorter cord paths having opposite path ends located within a sidewall or crown region (
The carcass ply 214 and/or underlay 219 may be a conventional rubberized ply having a plurality of substantially parallel carcass reinforcing members made of such material as polyester, rayon, or similar suitable organic polymeric compounds. The carcass ply 214 may engage the axial outer surfaces of two flippers 232a, 232b and two chippers 234a, 234b.
If the example tire 210 is built utilizing the above described method and apparatus 100, the carcass ply 214 and underlay 219 will likely comprise Single End Dipped (SED) cords. For production efficiency, the SED cords will be large diameter cords. In accordance with the present invention, the use of square woven fabric made of filament yarns of different stress-strain characteristics for warp and weft will improve production cost and time. The fabric may be constructed with the Leno (standard or 2 T) weaving technique. The following materials may be utilized for warp and/or weft: PEN, PET, PK, PBO, PVA, Rayon, Nylon 6 and 6,6, aramid, carbon fiber, and glass fiber. The warp yarn may be of different modulus than the weft yarn. Further, warp yarns within the same fabric may also vary, such as aramid warp yarn combined with nylon weft yarn. Utilization of such a fabric for the entire carcass ply 214 and the entire underlay 219 may shorten the winding process compared to the use of the above described Single End Dipped cords for the carcass ply and underlay. The fabric may be dipped, tackified, and woven to the specified width (i.e., prefabricated). Advantageously, the fabric need not be calendered (no more need of extruder or gear pumps) and may be applied directly at a tire building machine, as described above.
In accordance with the present invention, the example carcass ply 214 and/or underlay 219 may be reinforced with a woven or knitted reinforcing structure 141. The woven reinforcing structure 141 may comprise parallel carcass reinforcing members (weft) 312, 512 of the carcass ply 214 and additional supporting members (warp) 311, 511 for supporting the cords during the tire building process. The woven or knitted fabric of the reinforced ply 214 and/or underlay 219 may be constructed by placing a series of strips adjacent to each other at the ply mechanism 70.
One example woven reinforcing structure 141 for the carcass ply 214 and/or underlay 219 may define a layer of LENO weave fabric. As illustrated in the example of
As illustrated alternatively in the example of
As seen in
As stated above, examples of suitable materials for the warp yarns 311, 511 include polyamide, aramids (including meta and para forms), polyester, polyvinyl acetate, nylon (including nylon 6, nylon 6,6, and nylon 4,6), polyethylene naphthalate (PEN), rayon, polyketone, carbon fiber, PBO, and glass fiber.
The weft yarns 312, 512 may be a multifilament yarn, and/or a monofilament yarn formed of a suitable material. Examples of suitable materials for the weft yarns 312, 512 include polyamide, aramids (including meta and para forms), polyester, polyvinyl acetate, nylon (including nylon 6, nylon 6,6, and nylon 4,6), polyethylene naphthalate (PEN), cotton, rayon, polyketone, carbon fiber, PBO, and glass fiber.
The warp and/or weft yarns 311, 312, 511, 512 may also be hybrid yarns. Hybrid yarns may be multiple yarns, made up of at least 2 fibers of different material (for example, aramid and nylon). These different fiber materials may produce hybrid yarns with various chemical and physical properties. Hybrid yarns may be able to change the physical properties of the final product in which they are used. Example hybrid yarns may be an aramid fiber with a nylon fiber, an aramid fiber with a rayon fiber, and an aramid fiber with a polyester fiber.
As used herein, mechanical resiliency of a yarn is the ability of the yarn to displace longitudinally without an elastic deformation of the material. Mechanical resiliency allows the LENO fabric 310, 510 to have a minor amount of resilient elongation for compatibility with the example tire 10, but use stronger yarns in the carcass ply 214 or underlay 219.
The woven reinforcing structure 141 is an open construction fabric which permits the strike through of rubber in a tire 10 for a better bonded construction. The openness of the fabric used for the woven reinforcing structure 141 may be determined by the spacing and character of the warp yarns 311 or 511. The weft yarns 312 are typically spaced as necessary to maintain the position of the warp yarns 311 or 511 provide suitable strength to the carcass ply 214 and/or underlay 219.
The woven reinforcing structure 141 may be treated with an adhesion promoter. Examples of adhesion promoters include resorcinol formaldehyde latex (RFL), isocyanate based material, epoxy based material, and materials based on melamine formaldehyde resin. The woven reinforcing structure 141 may also have a tackified finish, or green tack, applied for facilitating adhesion during the building process of a green tire. The selection of materials for the tackified finish may depend upon the materials selected for use in the tire 10. Tackified finishes may be achieved by various methods such as coating the fabric in an aqueous blend of rosin and rubber lattices, or with a solvent solution of an un-vulcanized rubber compound.
Further, the woven or knitted reinforcing structure 141 may comprises multiple layers, e.g. two, three, or even more layers, of the LENO fabric 310, 510 to provide extra strength for the carcass and/or underlay. When more than one layer of LENO tape 310, 510 is used for the carcass ply 214 and/or underlay 219, a layer of unvulcanized rubber may be placed between the layers of LENO tape to ensure an effective bond.
The formation of the woven reinforcing structure 141 may begin with the acquisition of the basic yarns for the fabric. Subsequently, the yarns may be twisted to provide additional mechanical resilience. After the twisting, warp yarns 311, 511 may be placed on a large beam for the formation of the woven reinforcing structure 141. The woven reinforcing structure 141 may be formed by LENO weaving with the appropriate spacing of the warp yarn pairs 311, 511. After the woven reinforcing structure 141 formation, the structure may be finished with adhesive promoter, such as an RFL treatment. If a tackified finish is desired, this is provided following the adhesive promoter finishing. The final layer may be slit into the specific widths.
The woven reinforcing structure 141 in accordance with the present invention may reduce cost and complexity of the tire building process without lessening rolling resistance, high speed capability, and handling characteristics. Additionally, the woven reinforcing structure 141 may reduce noise due to vibration damping (i.e., circumferential reinforcement provided by the warp yarns 311 or 511).
One example construction for the woven reinforcing structure 141 may comprise 1220/1 Dtex 14 EPI (ends per inch) rayon warp yarns and 2200/2 Dtex 26 EPI polyester weft yarns. In general, the warp pairs 311, 511 may have a density of 10 EPI to 18 EPI and the weft yarns 312, 512 may have a density of 5 EPI to 35 EPI.
The woven reinforcing structure 141 of square woven fabric made may be made of filament yarns of different stress-strain characteristics for warp and weft. The fabric 300, 500 may be produced with the Leno (standard or 2T) weaving technique or knitted. The warp yarns 311, 511 may be different modulus than the weft yarns 312, 512, or the same.
The fabric 310, 510 may be used as carcass reinforcement and/or underlay reinforcement. The fabric 310, 510 may be dipped, tackified, and woven/knitted to a specified ply width. The fabric 300, 500 does not require calendering and may thus be applied directly at a tire building machine, as described above.
Further, there is now no requirement to calender the fabric 310, 510 or slit the material prior to application on a green tire. Rolls of fabric strips produced at specified width may be supplied to a tire plant and directly applied on a tire building machine.
The warp yarn may provide a circumferential reinforcement whereas a conventional carcass provides only a radial reinforcement. The woven or knitted reinforcing structure 141 provides additional circumferential stiffness to a carcass package, thus reducing rolling resistance.
As stated above, a carcass ply 214 or underlay 219 with a reinforcement structure 141 in accordance with the present invention produces an excellent and less costly and more efficiently manufactured pneumatic tire 10. This carcass ply 214 and/or underlay may thus enhance tire production, even though the complexities of the structure and behavior of the pneumatic tire are such that no complete and satisfactory theory has been propounded. Temple, Mechanics of Pneumatic Tires (2005). While the fundamentals of classical composite theory are easily seen in pneumatic tire mechanics, the additional complexity introduced by the many structural components of pneumatic tires readily complicates the problem of predicting tire performance. Mayni, Composite Effects on Tire Mechanics (2005). Additionally, because of the non-linear time, frequency, and temperature behaviors of polymers and rubber, analytical design of pneumatic tires is one of the most challenging and underappreciated engineering challenges in today's industry. Mayni.
A pneumatic tire has certain essential structural elements. United States Department of Transportation, Mechanics of Pneumatic Tires, pages 207-208 (1981). Important structural elements are the carcass ply and underlay, typically made up of many flexible, high modulus cords of natural textile, synthetic polymer, glass fiber, or fine hard drawn steel embedded in, and bonded to, a matrix of low modulus polymeric material, usually natural or synthetic rubber. Id. at 207 through 208.
The flexible, high modulus cords are usually disposed as a single layer. Id. at 208. Tire manufacturers throughout the industry cannot agree or predict the effect of different twists of carcass ply cords or underlay cords on noise characteristics, handling, durability, comfort, etc. in pneumatic tires. Mechanics of Pneumatic Tires, pages 80 through 85.
These complexities are demonstrated by the below table of the interrelationships between tire performance and tire components.
As seen in the table, carcass ply and underlay cord characteristics affect the other components of a pneumatic tire (i.e., carcass ply/underlay affects apex, belt, overlay, etc.), leading to a number of components interrelating and interacting in such a way as to affect a group of functional properties (noise, handling, durability, comfort, high speed, and mass), resulting in a completely unpredictable and complex composite. Thus, changing even one component can lead to directly improving or degrading as many as the above ten functional characteristics, as well as altering the interaction between that one component and as many as six other structural components. Each of those six interactions may thereby indirectly improve or degrade those ten functional characteristics. Whether each of these functional characteristics is improved, degraded, or unaffected, and by what amount, certainly would have been unpredictable without the experimentation and testing conducted by the inventors.
Thus, for example, when the structure (i.e., twist, cord construction, etc.) of the carcass ply or underlay cords of a pneumatic tire is modified with the intent to improve one functional property of the pneumatic tire, any number of other functional properties may be unacceptably degraded. Furthermore, the interaction between the carcass ply/underlay cords and the apex, belt, carcass, and tread may also unacceptably affect the functional properties of the pneumatic tire. A modification of the carcass ply or underlay cords may not even improve that one functional property because of these complex interrelationships.
Thus, as stated above, the complexity of the interrelationships of the multiple components makes the actual result of modification of a carcass ply or underlay, in accordance with the present invention, impossible to predict or foresee from the infinite possible results. Only through extensive experimentation have the carcass ply 214, underlay 219, and woven reinforcement structure 141 of the present invention been revealed as an excellent, unexpected, and unpredictable option for a tire carcass.
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.
While the present invention has been illustrated by a description of various illustrative embodiments and while these embodiments have been described in some detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The various features of the invention may be used alone or in numerous combinations depending on the needs and preferences of the user. This has been a description of the present invention, along with the preferred methods of practicing the present invention as currently known. However, the invention itself should only be defined by the appended claims, wherein what is claimed is:
