Resilient tires and wheels – Tires – resilient – Pneumatic tire or inner tube
Reexamination Certificate
2002-07-30
2004-11-16
Johnstone, Adrienne C. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Pneumatic tire or inner tube
C057S218000, C057S902000, C152S451000
Reexamination Certificate
active
06817395
ABSTRACT:
TECHNICAL FIELD
This invention relates to a belt reinforcing structure for heavy duty tires, more specifically for off-road tires commonly referred to as earthmover tires.
BACKGROUND OF THE INVENTION
The large off-road pneumatic tires used in heavy construction and earthmoving operations have operating loads and inflation pressures much higher than conventional trucks and lightweight vehicles.
The radial ply earthmover tires exhibit tremendous load-carrying capacity. The very thick rubber tread and the massive amount of rubber in the sidewalls contribute to high heat generated tire issues.
The use of a large steel cord in the carcass ply in combination with steel cords in the belt structure has been a common practice. Tire manufacturers employ a variety of constructions for optimizing the tires' durability.
A primary concern for the performance of the tire is insuring adequate rubber penetration into the cords is achieved during the manufacture of the belt layers and in subsequent tire vulcanization. Coupled to this better rubber flow is a desire for higher steel mass and improved wire cut resistance to improve the tires' overall durability.
The prior art belt constructions for such tires have employed steel cords having many filaments of fine or small diameters. A typical construction would have four or more working belt layers and a pair of high elongation wire reinforced layers for the outermost layers located between the tread and the working belts. These tires would have filaments having diameters between 0.15 and 0.265 mm.
One such tire, a 36.00 R51 earthmover tire, employed a wire construction of 7×7×0.25+1 mm featuring a wrap (“+1”) to stabilize the construction with an overall unwrapped cord diameter of 2.25 mm. Alternatively, a 5/8/14×0.265+1 super tensile steel wire construction was used with an overall unwrapped cord diameter of 1.6 mm. These very fine diameter filament constructions are very closely packed making it much more difficult for rubber to penetrate into the interior of the cords. As a result the filaments are more susceptible to cutting and frictional wear, particularly with such small diameter filaments.
The present invention uses multiple filament diameters in a 7×7 cord design to increase the filament spacings in the cord, which allows better rubber penetration for improved resistance to corrosion as well as superior cut resistance. The fracture fatigue common in such large filaments is compensated for by the unique construction of the cord that takes advantage of large internal spaces to allow for maximum rubber coating to protect and cushion the filaments against filament-to-filament frictional wear. In addition, the 7×7 cord of the present invention was designed to be stable without the use of a wrap wire. Thus, the wrapless 7×7 construction eliminated the significant wear mechanism between the wrap and the outer filaments of the construction.
SUMMARY OF THE INVENTION
A pneumatic radial ply tire has a tread, a carcass, and a belt reinforcing structure. The carcass has a steel cord reinforced radial ply extending from one annular bead to a second annular bead. The belt reinforcing structure lies radially between the tread and the carcass.
The belt reinforcing structure has at least two steel cord reinforced belt layers, two of the belt layers have steel cords having large filaments in the range of 0.3 mm to 0.6 mm in diameter twisted into a seven by seven cord construction. The cords are oriented parallel to each other within the belt layer. Each belt layer has cords directionally oppositely inclined relative to the adjacent belt layer.
The at least two steel cord reinforced belt layers have cords having an overall unwrapped diameter D of 3.0 mm to 4.0 mm.
In one embodiment of the invention at least one of the at least two steel cord reinforced belt layers has a cord construction 1×(0.40+6×0.365)+6×(0.365+6×35); preferably four belt layers employ this cord construction.
In another embodiment the belt reinforcing structure has two belt layers have a cord construction of 1×(0.40+6×0.365)+6×(0.365+6×0.35) and two belt layers with a cord construction of 7×(3+9+15×0.245)+1 HT.
In both these tire constructions it is optionally recommended that an overlay of two layers reinforced by high elongation (HE) wire be employed between the belt layers and the tread. A cord of 4×6×0.265 (HE) can be used for such an overlay as one example.
Definitions
“Aspect ratio” of the tire means the ratio of its section height (SH) to its section width (SW);
“Axial” and “axially” mean 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 reinforcing structure” means at least two layers of plies of parallel cords, woven or unwoven, underlying the tread, unanchored to the bead, and having both left and right cord angles in the range from 17 degrees to 27 degrees with respect to the equatorial plane of the tire;
“Carcass” means the tire structure apart from the belt structure, tread, undertread, and sidewall rubber over the plies, but including the beads;
“Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction;
“Chafers” refers to narrow strips of material placed around the outside of the bead to protect cord plies from the rim, distribute flexing above the rim, and to seal the tire;
“Chippers” mean a reinforcement structure located in the bead portion of the tire;
“Cord” means one of the reinforcement strands of which the plies in the tire are comprised;
“Equatorial plane (EP)” means the plane perpendicular to the tire's axis of rotation and passing through the center of its tread;
“Footprint” means the contact patch or area of contact of the tire tread with a flat surface at zero speed and under normal load and pressure;
“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;
“Net-to-gross ratio” means the ratio of the tire tread rubber that makes contact with the road surface while in the footprint, divided by the area of the tread in the footprint, including non-contacting portions such as grooves;
“Nominal rim diameter” means the average diameter of the rim flange at the location where the bead portion of the tire seats;
“Normal inflation pressure” refers to the specific design inflation pressure and load assigned by the appropriate standards organization for the service condition for the tire;
“Normal load” refers to the specific design inflation pressure and load assigned by the appropriate standards organization for the service condition for the tire;
“Ply” means a continuous layer of rubber-coated parallel cords;
“Radial” and “radially” means directions radially toward or away from the axis of rotation of the tire;
“Radial-ply tire” means a belted or circumferentially-restricted pneumatic tire in which the ply 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” (SH) means the radial distance from the nominal rim diameter to the outer diameter of the tire at its equatorial plane.
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patent: 3825052 (1974-07-01), Matsuyama et al.
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patent: 4158946 (1979-06-01), Bourgois
patent: 4506500 (1985-03-01), Miyauchi et al.
patent: 4586324 (1986-05-01), Mizuma
patent: 4715419 (1987-12-01), Kawasaki et al.
patent: 4781016 (1988-11-01), Sato et al.
patent: 4947638 (1990-08-01), Nagami
Hamiel Charles Elmer
Matrana Barry Allen
Sinopoli Italo Marziale
Johnstone Adrienne C.
King David L.
Rickey June E.
The Goodyear Tire & Rubber Company
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