Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
2000-01-06
2002-11-19
Maki, Steven D. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S454000
Reexamination Certificate
active
06481479
ABSTRACT:
TECHNICAL FIELD
This invention relates to agricultural or off-road tires. More particularly to high aspect ratio tires in that field.
BACKGROUND OF THE INVENTION
Pneumatic tires generally have a tread overlaying a casing. The casing includes a belt or breaker structure. The carcass has at least one cord reinforced ply anchored to two annular substantially inextensible beads.
In radial tires, the carcass has at least one radial ply. In bias tires the carcass has at least two plies of equal but opposite orientation. In both cases the belts of radial tires or the breakers of bias tires prevents or restrict the growth of the tire when inflated. In automobile and truck tires, the ratio of section height divided by section width is usually much less than 95%, typically, in the range of 35% to 85%.
Agricultural or off-road vehicles generally have similar aspect ratios below 95%. In order to increase the load carrying capacity of such tires designers generally have required increasing the width of the tire while maintaining the same nominal rim diameter or simply increasing the tires overall size generally. This is so because the load carrying capacity of these tires is related to the air chamber capacity at a given inflation pressure. Another way to increase load carrying capacity is to increase the tire inflation pressure. This solution is commonly practiced in aircraft and earthmover and heavy construction equipment tires where the inflation pressure is up to 300 psi.
In agricultural tires, it is desirable to operate the tires at low pressure. This enables the tire to reduce soil compaction while improving the drawbar traction. In such a case, it is necessary to increase the air chamber volume to increase load capacity. This has meant in the past, increasing the tires section width, but wide tires means reduced crop yields once the crop is planted. One solution has been the development of narrow row crop tires. Such a tire is shown in U.S. design patent. These tires are narrow in width and have an aspect ratio up to 95%.
The inventors of the present invention have discovered that the use of ultra high aspect ratio agricultural or off-road tires can provide increased load carrying capacity at reduced operating pressures while increasing the tractive efficiency of the vehicle.
One of the objectives of the invention is to provide a pneumatic tire that can simulate the traction performance of tracked vehicles.
Another objective is to provide a ire having a reduced spring rate and improved vibration damping characteristic resulting in a softer ride performance tire. The objects being satisfied by the inventive tire described below.
SUMMARY OF THE INVENTION
An agricultural or off-road tire
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for the drive axle or axles of a vehicle, is disclosed. The tire has an axis of rotation, a nominal rim diameter NRD of 20 inches or greater, and a carcass
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. The carcass
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has at least one cord reinforced ply
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and a pair of annular bead cores
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. A tread
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is disposed radially outward of the carcass
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.
The tire
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has an aspect ratio of greater than 95%, preferably 100% or greater most preferably greater that 100%.
The tire
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has a contact patch when the tire is inflated to less than 16 psi and loaded on a hard flat surface, the contact patch having an axial width X and circumferential length of Y, wherein the ratio of Y/X is at least greater than 1.0. Preferably the contact patch has a leading end and a trailing end; the distance between the leading and trailing end defines the circumferential length Y. The tire
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when inflated to less than 16 psi and normally loaded has a first radial line intersecting the leading end and a second radial line intersecting the trailing end.
The tire can have a carcass having one or more radial plies and a belt reinforcing structure between the ply or plies and the tread. Alternatively, the carcass can have two or more bias plies and a breaker structure between the tread and the bias plies.
The tread has a plurality of lugs spaced between a pair of lateral edges. Each lug has a radially outer contact surface area, the sum of the radially outer contact surface areas between the lateral edges as measured around the total circumference of the tire divided by the area between the lateral edges around the total tires circumference is less than 40%, preferably less than 30%.
DEFINITIONS
“Aspect ratio,” means the ratio of its inflated section height to its inflated section width.
“Axial” and “axially” means the lines or directions that are parallel to the axis of rotation of the tire.
“Bead” or “Bead Core” means generally that part of the tire comprising an annular tensile member, the radially inner beads are associated with holding the tire to the rim being wrapped by or anchored to ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes or fillers, toe guards and chafers, the bead or beads under the tread being encapsulated in tread rubber can be with or without other cord reinforced fabric elements.
“Belt Structure” or Reinforcing Belts” means at least two annular layers or 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° to 27° with respect to the equatorial plane of the tire.
“Bias Ply tire” means that 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 the equatorial plane of the tire, the ply cords running at opposite angles in alternate layers.
“Carcass” means a laminate of tire ply material and other tire components cut to length suitable for splicing, or already spliced, into a cylindrical or toroidal shape. Additional components may be added to the carcass prior to its being vulcanized to create the molded tire.
“Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction.
“Design Rim” means a rim having a specified configuration and width. For the purposes of this specification, the design rim and design rim width is 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 specified in the European Tyre and Rim Technical organization-Standards Manual and the term design rim means the same as the standard measurement rims. In Japan, the standard organization is The Japan Automobile Tire Manufacturer's Association.
“Design Rim Width” is the specific commercially available rim width assigned to each tire size and typically is between 75% and 90% of the specific tire's section width.
“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.
“Inner” means toward the inside of the tire and “outer” means toward its exterior.
“Lateral Edge” means the axially outermost edge of the tread as defined by a plane parallel to the equatorial plane and intersecting the outer ends of the axially outermost traction lugs at the radial height of the inner tread surface.
“Leading” refers to a portion of part of the tread that contacts the ground first, with respect to a series of such parts or portions, during rotation of the tire in the direction of travel.
“Net-to-gross Ratio” means the ratio of the tread contacting surface area of the normally loaded and inflated tire to the total area of the tread, including non-contacting portions such as grooves as measured around the entire circumference of the fire.
“Normal Inflation Pressure” means the specific design inflation pressure and load assigned by the appropriate standards organization for the service condition for the tire.
“Normal Load” means the specific design inflation pressure and load assigned by
Bishel Steven George
Shorter Andrew Caperton
Weed David Busse
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