Resilient tires and wheels – Tires – resilient – Pneumatic tire or inner tube
Reexamination Certificate
1999-06-24
2002-07-23
Johnstone, Adrienne C. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Pneumatic tire or inner tube
C152S545000, C245S001500
Reexamination Certificate
active
06422280
ABSTRACT:
TECHNICAL FIELD
This invention relates to heavy duty pneumatic tires such as are commonly used on earthmoving equipment, aircraft, agriculture and specialty applications such as run-flat tires, and more particularly to pneumatic tires having a specified relationship between the lower bead area of the tire and a flange portion of an associated rim upon which the tire is designed to be mounted.
BACKGROUND ART
Pneumatic tires that experience high loads and deflections such as off-the-road earthmover and airplane pneumatic tires have historically been subjected to tremendous stresses and heat buildup problems in the bead area. Agricultural drive axle tires and specialty tires similarly experience extremely high levels of torque which requires the bead and rim fitmer to be precisely matched to avoid tire-to-rim slippage. These tires operate at very high internal pressures and are filled with large volumes of internal fluids, generally air or some other inert gas. Radial deflections of these tires generally occur under very high impacts while the tire is heavily loaded. In the past, these tires would deflect with the bead portion contacting the rim flange harshly. Repeated impacts in this area can cause a phenomena commonly referred as “bead erosion”. These severe deflections stress the internal components of the tire carcass such as ply endings and other component interfaces, and if severe enough can initiate ply ending separation or other associated problems which can injure the tire's casing.
A recent development in pneumatic tires is the run-flat passenger tire. These run-flat tires, unlike the abovementioned high pressure and high-torque tires of the aircraft and off-the-road industry, normally operate similarly to conventional passenger tires with one big exception, these tires generally have stiffened sidewalls that when the tire is operated with little or no air must support the weight of the vehicle. In such situations, high deflection and loads are transmitted to the bead area of the tire. Rapidly, these uninflated tires build up high heats which can limit the run-flat capability of the tire. In these circumstances, the run-flat passenger tire becomes overstressed and overloaded similar to the conditions seen in the high pressure, high load and high torque applications of the larger aircraft and off-the-road tires. Therefore, the run-flat tire design also must be equipped to accommodate these conditions.
In U.S. patent 5,368,082 a unique bead design was disclosed for run-flat tire applications. The bead was made of a single steel monofilament having a truncated triangular shape. This bead design had a very wide based that ensured that the tire remained seated on the rim when the tire was operated in an uninflated condition. The tire had a hard rubber apex flange. The bead core was radially extended a distance substantially below the radially outer surface of the rim flange.
Large pneumatic tires to be used on earthmoving equipment, commonly known as earthmover tires, are well known. Earthmover tires are required to perform in difficult environments. When used “off-the-road”, they are required to provide excellent traction for extremely heavy vehicles pushing, pulling and lifting extremely heavy loads. The environment is fraught with rocks and other sharp debris which can damage the tires. Due to the relatively high cost of these large tires, durability and long life is a primary design parameter. A second environment in which the tires might be expected to perform is on public highways. Sometime the earthmoving equipment must travel on such highways to move from construction site to construction site.
Previously, the required strength was built into such tires by incorporating certain curves into the molded shape of the exterior of the tire. These extra curves or bulges were believed to give extra support to those areas of the tire where durability was especially important, such as the lower sidewall, mid sidewall and tread center. In the bead flange area, the prior art off-the-road tires employed an interference fit whereby the tire bead portion was in contact with the radially outer surface of the rim flange. Off-the-road tire engineering conventionally added mass to structurally improve the durability of the tire.
In the aircraft tire art, tire engineers must look to reduce mass due to the unique weight limitations. Still the tires still must be durable.
In U.S. Pat. Nos. 4,790,364 and 4,813,467 an aircraft tire and rim combination is disclosed which shows a clearance between a rim flange and the surface of the bead portion of the tire. Although aircraft tires are much different in construction and design compared to earthmover tires or off-the-road tires, they still must survive these high deflections and overload conditions previously discussed.
In U.S. Pat. No. 5,429,168 a unique earthmover design was developed that had permitted a reduction in the thickness of the lower sidewall region and bead portions of the tire by providing a clearance between the rim flange and the bead portion. That invention was particularly adapted for a radial ply carcass construction. It achieved in an earthmover tire some of the beneficial attributes of the aircraft tire technology.
In the present invention a unique bead core design has been found to be very beneficial in both bias or radial ply heavy duty tire applications. As used herein heavy duty tire applications include off-the-road, earthmover, aircraft, agricultural tires and specialty industrial type tires as well as the new run-flat tire technology. The unique design of this bead core enables large reductions in rubber mass to be achieved while increasing the lateral stiffness of the bead portion of the tire.
The present invention also has as one of its objects improved durability in the heavy duty tires, but does so by providing a bead area design which has demonstrated a marked improvement over the prior art.
It is therefore, an object of the invention to provide a heavy duty tire having improved durability.
It is another object of the invention to provide a heavy duty tire having a bead portion which cooperates with the flange portion of an associated rim to improve the durability and rigidity of the bead portion of the tire.
It is a further object of the invention to provide a heavy duty tire bead core having a certain relationship between the flange area of the tire in the rim flange, such relationship creating a clearance between the tire and the radially outer surface of the rim flange. The nature of the clearance is discussed herein and meets certain requirements in order to provide the durability sought.
DISCLOSURE OF THE INVENTION
Summary
An improved heavy duty pneumatic tire
11
is disclosed. The improved heavy duty pneumatic tire
11
has a nominal rim diameter D, an axis of rotation and a carcass
14
having a pair of bead portions
25
. Each bead portion
25
has at least one annular inextensible bead core
15
. The carcass
14
for a radial ply tire further includes a cord reinforced radial ply
18
extending between and wrapped around the bead core
15
. The carcass
14
for a bias ply tire
110
includes pluralities of cord reinforced pairs of bias plies
180
. The bias plies
180
have turnup ends
280
that wrap about one or more bead cores
15
,
150
,
151
,
250
,
251
,
252
. The tire
11
,
110
has ply turnup ends
28
,
280
extending axially and radially outwardly from each bead core
15
,
150
,
151
,
250
,
251
,
252
and the plurality of reinforcing belt disposed radially outwardly of the ply or plies. A tread
12
is disposed radially outwardly of the carcass
14
. Each bead portion has a radially inner first surface
96
and a radially outwardly extending second surface
100
. The first and second surfaces
96
,
100
of the bead portion
25
are designed to engage a design rim as specified by the applicable standards organization. The design rim
60
has a pair of bead seat portions
92
and a pair of rim flange portions
98
respectively. Each bead portion has the first surface
96
contacting th
Johnstone Adrienne C.
King David L
The Goodyear Tire & Rubber Company
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