Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
2000-02-03
2002-04-09
Cain, Edward J. (Department: 1714)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S454000, C152S525000, C152S539000
Reexamination Certificate
active
06367526
ABSTRACT:
TECHNICAL FIELD
This invention relates to a radial ply pneumatic tire, more specifically to an improved cross section profile for such tires.
BACKGROUND ART
Subtle changes in the molded shape of a pneumatic radial tire, the materials used to make the tire, the design of the tread pattern or the belt package or the reinforcing members can improve or detract from the performance of the tire. The tire designer is under constant pressure to improve the overall performance of the tire. In his pursuit of improving the product, he often must reverse or abandon the previously conceived design approaches and start anew with previously considered unworkable designs or approaches which when creatively applied in a new way solve problems or achieve performance goals heretofore believed unachievable.
Pneumatic tires are one of the most complex laminated composite structures devised by man. They are inherently difficult to correctly model and are routinely simplified in analysis leading to clearly erroneous design theories and approaches.
The very nature of the tire makes it possible for many conflicting design approaches to survive and even flourish because the structure is so complex that multiple variables are constantly being adjusted to optimize a particular design theory.
One particularly important variable that influences a tires performance is its molded shape and its resultant cross sectional profile when the tire is mounted and inflated on its design rim.
Rhyne et al in U.S. Pat. No. 5,637,162 assigned to Michelin teaches a tire structure for Improved Tread Life that claims a particular carcass and belt profile when the tire is properly inflated. The profile has a smaller than normal outside diameter combined with a larger cross-sectional width which enables a tread to have a flatter wider tread arc width which reduced the contact pressure across the tread profile. The resultant profile enables the tread life to achieve about 100,000 miles of service. Its tread width as taught extends axially outwardly of the mounted bead width.
An earlier U.S. Pat. No. 4,669,519 issued Jun. 1, 1987 to Tagaski et al, teaches a Reduced Rolling Resistance Pneumatic Radial Tire which has a molded lower sidewall and bead area that is 20%-50% wider than its design rim width. The tires profile is such that the maximum section width is located radially in the upper sidewall region or greater than 50% of the tires section height as measured from the nominal rim diameter. The conventional radial tire has the maximum section width located at a radial height about 50% of the section height. This Bridgestone Patent teaches that the hysterectic shear stresses in the shoulder region of the sidewall generates the most losses in terms of rolling resistance and that by minimizing these losses a benefit in reduced rolling resistance can be achieved because the tread shoulders will run cooler.
Both of these diverging solutions are plausibly correct. That is the beauty of the tire art. The engineers can practice what appears to be contradicting approaches to get to a similar improved result. It is for that reason that so many patents are issued. The unexpected results abound. Those of ordinary skill in the tire art routinely teach away from particular ideas, which are latter, discovered to provide beneficial solutions.
The prior art Patent No. GB-A-2 224703 assigned to Sumitomo Rubber Ind., Ltd. is regarded as the most relevant prior art and it teaches the features found in the preamble of claim 1; wherein the maximum section width of the tire is greater than the rim flange width and the tread width is less than the rim flange width.
The subject matter of the present invention teaches a novel tire profile that appears to be contrary to both of the above prior art patents and another departure from the conventional wisdom of those of ordinary skill in the art.
An object of the present invention is to provide a tire profile that minimized the rolling resistance of tire while minimizing the effect of the tread compound selection. In other words desensitizing the tires rolling resistance performance as a function of tread compounding.
Another object of the invention is to provide a lightweight tire.
Another object of the invention is to improve treadwear service mileage.
These and other objectives have been demonstrated by the tire as described here below.
SUMMARY OF THE INVENTION
A radial ply pneumatic tire is disclosed. The tire
30
has a maximum section width SW, a maximum section height SH, the ratio of SH/SW defining the tire aspect ratio, the aspect ratio being 85% or less. The tire has a nominal rim diameter ND, a nominal rim flange width W, and a tread having a tread width, TW.
The tire
30
has the maximum section width SW being located within a radial distance X from the nominal rim diameter ND, the distance X being less than a 50% of the maximum section height SH and wherein the maximum section width SW is greater than the rim flange width W and the tread width TW is less than the rim flange width W.
Preferably the distance X is about 40% of the maximum section height SH. The maximum section width SW is preferably at least 10% greater than the nominal rim flange width W and the tread width is preferably a least 10% less than de nominal rim flange width W.
The tire
30
his a carcass structure
36
having one or more radial ply, the ply or plies extended to and at least one ply is wrapped about or otherwise attached to a pair of annular bead cores
35
. The radial plies are reinforced by parallel cords
20
. The tire
30
when mounted on its design rim
40
and inflated has the cords
20
placed in tension. At a location between the radial location of the maximum section width SW and the nominal rim diameter ND a line L
1
, drawn through a point Y, the point Y intersecting the bead at the location of the nominal rim diameter ND, and tangent to the sidewall
21
is inclined radially and axially inwardly at an angle &thgr; relative to the rim flange, &thgr; being less than 40° in each sidewall
21
.
The tire
30
has its sidewall
21
, at a radial location Z between the location of the maximum section width SW and the radially outmost section height location SH, inclined such that a line L
2
drawn through Z and tangent to the sidewall
21
radially inwardly and axially outwardly is inclined at an angle &bgr;, relative to a plane perpendicular to the tires aids, &thgr; being 90% of &bgr; or greater in each sidewall
21
. Preferably &thgr; is about equal to &bgr;, most preferably in the range of 90-120% of &bgr;.
The locations Y and Z he on an axis A passing through the centroid C of the sidewall, the axis A being perpendicular to the tire axis of rotation. The centroid C of each sidewall is defined by the area within the sidewall
21
and between a line
70
drawn through a tread edge
30
A or
30
B and a tangent to the axially inner portion of the bead area
33
at location
12
.
Definitions
“Aspect ratio” of the tire means the ratio of its section height (SH) to its section width (SW) multiplied by 100% for expression as a percentage.
“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 structure” or “Reinforcing Belts” means at least two annular layers or plies of parallel cords, woven or unwove, 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.
“Cord” means one of the reinforcement strands of which the plie
Cain Edward J.
King David L
Lee Katarzyna W.
The Goodyear Tire & Rubber Company
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