Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
1999-03-11
2001-04-10
Maki, Steven D. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S209160, C152S209180, C152S209270, C152S901000, C152SDIG003
Reexamination Certificate
active
06213181
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle tire. Specifically, the invention relates to a pneumatic vehicle tire having a groove wall lining that reduces the formation of anomalies causing subjective user dissatisfaction.
Tires, especially commercial vehicle tires, may be removed from service due to anomalies on the tread region. These anomalies are depressions in the tread rib or tread block. The anomalies can be caused by unequal normal stress distribution laterally across the rib or block.
The stress concentration occurs at the edges of the tread rib or block. The stress concentration at the edges of the tread rib or block is known as the edge effect. The central portion of the tread rib or block experiences a lower stress than the edges of the tread rib or block. The stress at the edge of the tread rib or block may be approximately twice as large as the stress at the central portion of the tread rib or block. The stress concentration at the edges of the tread rib or block typically causes anomalies to form at the edges of the tread rib or block.
Once an anomaly forms at the edge of the rib or block, the anomaly will propagate to the remainder of the rib or block; and often to adjacent ribs or blocks. The propagation of the anomaly occurs quickly as the tire continues to roll.
The decision to remove a tire is subjective and may depend on the location of the tire on the truck/trailer combination. Generally, a driver can feel an anomaly on a steering tire by the ride comfort and handling of the vehicle. In that case, the driver pulls the tire when uncomfortable with the ride and/or handling of the vehicle. However, if a tire having an anomaly is a drive tire or is located on the trailer, the driver may not sense any discomfort. The driver may, however, hear an increase in tire noise. If the driver does not sense discomfort or an increase in noise, the driver will pull the tire during a subsequent visual inspection of the vehicle.
The removal of a tire due to anomalies causing subjective user dissatisfaction is premature when considering the portions of the tire without the anomaly. The portions of the tire without the anomaly are capable of substantial additional service on the vehicle. Extending the time until the onset of an anomaly or decreasing the severity of the anomaly once found may extend the life of the tire. The extended life of the tire reduces the cost of purchase and installation of new tires. In the commercial trucking field, these potential cost savings are significant.
Thus, it is an object of the present invention to provide a tire with an improved tread portion which reduces the formation of anomalies causing subjective user dissatisfaction.
It is a further object of the present invention to provide a tread portion which eliminates the edge effect or exhibits a reduced edge effect, defined as the high normal stress value at the edges of a tread rib or block as compared to the center portion of a tread rib or block.
It is a further object of the present invention to provide a tread portion which more uniformly distributes normal stress laterally across a tread rib or block.
SUMMARY OF THE INVENTION
These and other objects of the present invention are accomplished in a first embodiment of the present invention by a tire having a pair of beads; a carcass ply having ends, each of the ends anchored to a respective one of the beads; at least one belt ply extending circumferentially around the tire and disposed radially outward of the carcass ply; and a tread layer disposed radially outward of the at least one belt ply and formed generally from a first tread compound. The tread portion has at least a pair of shoulder ribs and a plurality of tread ribs each having a defining circumferential groove on each side thereof with two walls and a base; and a groove lining defining the groove walls and base forming composite shoulder and tread ribs. The groove lining is made from a second tread compound different than the first tread compound.
The tread portion has a radial thickness and extends laterally beneath the base of each groove which is defined by the groove lining. The groove lining in the area of the groove base has a radial thickness which is between about 25 and 50 percent of the combined tread layer and groove lining thickness in this area.
The composite shoulder and tread ribs are formed with a lateral width of which the groove wall lining of each wall comprises between 15 and 30 percent.
The tread compound forming the groove lining has a modulus of elasticity which is 40 to 80 percent of the modulus of elasticity of the tread compound forming the tread portion.
The tread ribs may include sipes and the groove lining may include sipes.
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Abstracts for Japan 6-191221, Japan 2-249707, Japan 6-48115, Japan 4-15107, Japan 58-35504, Japan 60-166506, Japan 4-306104.
Farrell Martin
Maki Steven D.
Michelin Recherche ET Technique S.A.
Reed Robert R.
LandOfFree
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