Resilient tires and wheels – Tires – resilient – With cooling devices
Reexamination Certificate
2000-02-24
2003-07-15
Maki, Steven D. (Department: 1733)
Resilient tires and wheels
Tires, resilient
With cooling devices
C152S532000, C152S537000, C156S110100
Reexamination Certificate
active
06591879
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. § 119 of German Patent Application No. 199 08 122.0, filed on Feb. 25, 1999 and European Patent Application No. 99123387.5, filed on Nov. 24, 1999, the disclosures of which are expressly incorporated by reference herein in their entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle tire having at least one inner layer that is impermeable to air, a rubberized reinforcement-containing carcass, which carcass extends from the uppermost area of the vehicle tire over the sidewalls into the bead area and is anchored there by looping around bead cores that are resistant to extension, a rubber tread having tread grooves located radially outside, a belt reinforcement with at least one stabilizer belt located between the rubber tread and the carcass, which stabilizer belt contains rubberized reinforcement, and other common components of vehicle tires such as bands.
2. Discussion of Background Information
Rubber compositions for the tread of conventional vehicle tires are especially tailored to provide optimal handling characteristics, such as rolling resistance and wet skid resistance. In general, rubber compositions, which provide optimal handling characteristics, show evidence of poor thermal conductivity, i.e., during tire use, the thermal energy generated by centrifugal forces and flexing forces is very poorly distributed and dissipated into the environment. Consequently, a build-up of heat in the tires results, thus impairing tire durability. It is known to one skilled in the art that using mixed compositions containing silica and silane reduces heat build-up. However, rubber compositions containing silica and silane possess even worse thermal conductivity than conventional compositions containing carbon black as a filler.
The temperature increases in partial areas of the tire caused by the flexing forces and the centrifugal force are not only related to the magnitude of these forces, but are also related to the thickness of the tire area and the variability in rigidity of the adjacent areas. For example, strong flexing forces occur in the bead and sidewall areas in coordination with the rim, and these forces are in turn intensified by the different rigidities of the materials (carcass, wrapping, etc.) used in the bead and sidewall area. Due to poor heat dissipation at the belt reinforcement, especially at the edges of the belt, the increase in temperature is especially strong. The belt reinforcement is constructed of the actual stabilizer belts and, optionally, tire plies being arranged radially outwards therefrom. The stabilizer belts normally include at least two plies of rubberized, metallic reinforcement, the individual cords of different plies being crossed with respect to one another. In commercial vehicle tires, at least three plies are normally arranged crossing over one another. The metallic reinforcement itself has very high thermal conductivity, which is common for metals. However, it is also possible to employ belt packages of one or more stabilizer belts made of different fabric types, such as aramide fabric. Due to the different rigidities of steel wire or aramide cord and the rubber, particularly strong forces occur in the area of the belt reinforcement, particularly the belt edges. Even if rubber compositions with a high tensile values are used in the belt area, as is known in the prior art, the deformation path and the forces associated therewith are influenced thereby only to a minor extent. The great build-up of heat may cause loosening of the belt edges, thus reducing the capability for retreading, or may cause the separation of the belt edges, thereby completely destroying the tire. Frequently, this type of tire damage may be observed with commercial vehicles such as trucks, busses, wheel loaders, etc., due to their especially high mileage and the effect of the strong forces acting upon these tires. The effects described above may also occur with other vehicles. Various attempts to counteract the problem of the separation of belt edges and to improve the durability of tires by controlling the temperature in tires, especially in the belt edge area, have been made.
U.S. Pat. No. 3,865,169 teaches the possibility of dissipating thermal energy generated in tires with cooling fins placed in a rim having good thermal conductivity, which rim is exposed to the atmosphere. Thus it is necessary for highly thermoconductive wires, networks or bands, such as metal wires, that are in direct contact with the rim to be present throughout the entire tire in order to ensure the thermal conduction to the outside of the tire. This design is very expensive and the patent does not indicate what changes in tire properties result from the introduction of the wires. However, one skilled in the art is aware that wires in the sidewall area have a negative effect on many tire properties, such as suspension, which would adversely affect the comfort of the occupants of the vehicle.
Published German Patent Application No. 1755301 teaches that the temperature build-up in vehicle tires, particularly in treads, may be reduced where the vehicle tire contains graphite homogeneously incorporated in the tire rubber, particularly in the tire tread. Thus, formerly common bias ply tires having a tire tread, which is manufactured in its entirety with a rubber composition containing graphite, have improved thermal conductivity, thus making possible the decrease of temperature in the shoulder of the tread and diminishing the danger of tread separation. However, the result of adding graphite to rubber compositions which are used especially for treads is that the properties of the vulcanized compositions change and no longer satisfy the requirements for today's high-performance tires, i.e., radial ply tires, especially with respect to optimal handling characteristics and tire properties, such as wet skid resistance, dry skid resistance, rolling resistance and wear. Furthermore, adding graphite to the rubber compositions affects the tires, since the lubricating properties of the graphite cannot be suppressed fully even if it is homogeneously distributed.
Published German Patent Application No. 196 52 893 A1 teaches another way of reducing the heat build-up and thus the temperature in the area of the belt edges, without producing serious disadvantages in terms of the tire properties. Each belt edge profile is arranged between two stabilizer belts, the belt edge profile being composed of a rubber composition whose Shore hardness is 60 to 95% of the rubber composition used for the stabilizer belts and whose rebound elasticity (at 70° C.) is ≧60%. The lower heat build-up in the areas of the belt edges is attributed to the fact that the occurring forced deformations are displaced largely into the soft, highly elastic belt edge profile. The thermal energy being generated, however, is not dissipated, but rather its point of origin is only partially displaced.
SUMMARY OF THE INVENTION
The present invention concerns the production of a vehicle tire wherein the temperature of the rubber compositions in the areas near the belt may be effectively reduced using suitable measures, thereby improving the durability and service life of the tire without sacrificing desired handling characteristics.
The present invention also concerns a rubber composition being arranged substantially in the direct vicinity of the tread groove base and the neighboring parts of the groove flank of at least one tread groove, the rubber composition essentially filling up the space between the base of the tread groove and the radially outer ply of the belt reinforcement.
Furthermore, the present invention concerns a rubber composition, which in a new and unused vehicle tire, does not contact a road surface, and which has a thermal conductivity (heat conductivity) at least 5% higher than the thermal conductivity of the rubber composition of the tread in contact therewith.
The present invention
Becker Axel
Beckmann Otto
Kreuser Helmut
Topp Andreas
Continental Aktiengesellschaft
Greenblum & Bernstein P.L.C.
Maki Steven D.
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