Resilient tires and wheels – Tires – resilient – Pneumatic tire or inner tube
Reexamination Certificate
1999-08-27
2001-10-09
Johnstone, Adrienne C. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Pneumatic tire or inner tube
C152S454000, C152S539000, C152S548000
Reexamination Certificate
active
06298893
ABSTRACT:
TECHNICAL FIELD
This invention relates to a radial ply pneumatic tire having a predetermined ply cord path.
BACKGROUND ART
Tire engineers have historically established the contours of tires by building a mold having a predetermined contour, placing green or unvulcanized tires with predetermined amounts of rubber on either side of the reinforcing plies into the mold, expanding the tire casing against the mold using an inflatable bladder and then applying heat and pressure to cure the tire.
The mold is built with annular bead forming rings that form the contour of the bead portion
200
of the tire
100
. These bead rings have a molding surface that generally approximates the contour of the rim upon which the tire
100
will fit.
The ply
210
is anchored to the bead cores
200
and conventionally in prior art tires
100
has a working ply path between the bead core
200
and the belt packages
140
. At the lower portion of the tire the bead core and the rim flange limits the amount of movement the ply cords
210
can take. At the upper portion of the tire circumferentially extending belt package limits the radial growth of the ply. At a location just under the belt lateral edges
150
the ply cords when tensioned take a contour that approximates a single radius of curvature R
UP
. This single radius of curvature R
UP
is commonly called the “neutral ply line.”
This single radius contour can only be held to a point as shown in FIG.
1
. If the contour defined by R
UP
is maintained further a very steep curve is achieved that is axially extending at a location well above the rim flange of a conventional truck tire rim.
Ideally, one would like to optimize the ply cord path. One recent disclosure entitled “Tire With Reduce Bead Mass,” is disclosed in U.S. Pat. No. 5,526,863. It is suggested that a reduced bead mass of as much as 15% can be achieved by using a small apex with an elongated constant thickness outer component and a large axially outer filler component. The U.S. Pat. No. 5,526,863 patent teaches adding a massive amount of rubber axially outward of the ply turnup. This in combination with the placement of the ply turnup axially inward adjacent the radially outer location of the rim flange effectively enables ply turnup to be moved toward the lower ply curvature above the rim flange such that the gap between the ply turnup and the ply path is a constant T from a distance F
1
to below a location F
2
. This prior art tire had a slight improvement or reduction in tire mass with a corresponding reduction in rolling resistance. The ride performance was either better or worse dependent on the overall physical embodiment tested. Radial and cornering stiffness degraded with the lower dynamic spring rate. High speed capability was also worsened. This inventor seemed to believe that the lighter weight benefits outweighed the durability or performance reductions.
One inherent problem in the above-mentioned tires of the prior art is that the uncured rubber flows during vulcanization making the control of the ply path rather unpredictable.
A second and equally important problem is that the lower ply path must be altered to effectively anchor itself to the bead core. This is particularly true of conventional flange type rims. Those skilled in the art conventionally build a spline fit between the upper sidewall neutral contour and the lower sidewall. The resultant spline occupies the region between the maximum section width and the location radially near the bead flange. The spline fit has a very large radius of curvature often approximating an almost linear segment. In this portion of the ply, the ply path deviates from the neutral ply path, shear stresses develop that can generate heat and degrade the rolling resistance and durability of the tire. The tire of the present invention has a consistent ply path in the lower sidewall that has very low stresses. This lower ply path contour is controlled by a unique precured contoured apex that can minimize or even eliminate the use of a spline fit.
DESCRIPTION OF THE INVENTION
SUMMARY OF THE INVENTION
A tire
10
for mounting on a rim of a vehicle is disclosed. The tire
10
has a tread portion
12
, a belt package
14
radially inward of the tread
12
, a pair of sidewall portions
16
each extending radially inward from a lateral edge
15
of the belt package
14
, a pair of beads
22
each having an annular bead core
20
and positioned radially inward of a respective sidewall portion
16
, at least one carcass ply
24
located radially inward of the belt package and extending from bead
22
to bead
22
. The at least one carcass ply
24
has radially extending parallel cords
24
A and a pair of turnup ends
26
, one turnup end is wrapped about each bead core
20
and extends radially outwardly to an end point positioned radially outwardly of a flange
52
of the rim
50
. The tire
10
has a pair of precured bead filler portions
40
, one precured bead filler portion
40
being adjacent to a radially outer surface of a bead core
20
. The tire
10
is characterized by each precured bead filler
40
having an axially inner curvature
42
. The axially inner curvature
42
is defined by a convex surface
42
A and a concave surface
42
B. The convex surface
42
A is radially outwardly extending from axially inwardly of the bead core
20
to an inflection location T, the location T being substantially at or radially inward of a radially outer surface of the rim flange
52
. The concave curvature
42
B extends from the inflection location T to a radially outer end
41
located at or below the radial location of a maximum section width of the tire
10
. The axially inner surface curvatures
42
A,
42
B establishes a ply cord path
24
A of the carcass ply
24
when the tire
10
is normally inflated and unloaded. The ply path
24
A extends from radially above the rim flange
52
to the lateral ends of the belt package. The ply path
24
A has a radius of curvature (R
UPL
) between the belt lateral ends to the radial location H of the maximum section width and a second radius of curvature R
LPL
in the range of equal to or greater than R
UPL
, preferably 100% to 200% R
UPL
between the location H and the location T. The inflection location T can be at a point or may include a short spline having a midpoint below the rim flange.
Definitions
“Aspect ratio” of the tire means the ratio of its section height (SH) to its section width (SW);
“Axial” and “axially” means 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, under tread, 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” means 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;
“Design rim” means a rim having a specified configuration and width. For the purposes of this specification, the design rim and design rim width are as specified by the industry standards in effect in the location in which the tire is made. For example, in the United States, the design rims are as specified by the Tire and Rim Association. In Europe, the rims are as specifie
Cappelli Matthew Ray
Goldstein Arthur Allen
Tubb Gary Edwin
Vannan Frederick Forbes
Johnstone Adrienne C.
King David L
The Goodyear Tire & Rubber Company
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