Resilient tires and wheels – Tires – resilient – Pneumatic tire or inner tube
Reexamination Certificate
2001-01-23
2003-07-15
Johnstone, Adrienne C. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Pneumatic tire or inner tube
C152S539000, C152S543000, C152S546000, C152S548000, C152S554000
Reexamination Certificate
active
06591883
ABSTRACT:
The present invention relates to a tire with radial carcass reinforcement, and more particularly to a “heavy-vehicle” tire, intended to be fitted on vehicles such as lorries, road tractors, buses, trailers and others, and in which a novel reinforcement structure for the beads is adapted in order to improve the life of said beads.
Generally, a tire of the type in question comprises a carcass reinforcement formed of at least one ply of metal cables which is anchored in each bead to at least one bead wire, forming an upturn. The carcass reinforcement is radially surmounted by a crown reinforcement, composed of at least two plies of metal cables which are crossed from one ply to the next, forming angles of between 10° and 45° with the circumferential direction. The carcass reinforcement upturns are generally reinforced by at least one ply of metal cables oriented at a small angle relative to the circumferential direction.
In the case of the presence of a single bead reinforcement ply, the latter may be located along the carcass reinforcement upturn with a radially upper end located above or below the radially upper end of the carcass reinforcement upturn. As for the radially lower end of such a ply, it is generally located either on a straight line parallel to the axis of rotation and passing approximately through the center of gravity of the meridian section of the anchoring bead wire of the carcass reinforcement, in the case of a tire having beads intended to be mounted on rim seats inclined at 15°±2°, or on a straight line parallel to the axis of rotation and passing through a point located between the center of gravity of the meridian section of the anchoring bead wire and the point of maximum axial width of the carcass reinforcement, in the case of a tire having beads intended to be mounted on rim seats inclined at 0° or at 5°±1°. In this second case, the reinforcement ply of the bead is then wound around the bead wire, so as to have an axially outer strand and an axially inner strand, the radially upper end of the axially inner strand being generally located beneath the radially upper end of the axially outer strand.
The known solution aims to avoid deradialization of the cables of the carcass reinforcement upturn and to minimize the radial and circumferential deformations to which the end of said upturn and the outer rubber layer covering the bead and providing the connection to the rim are subjected.
In other cases, the metallic reinforcement ply has been replaced by a plurality of plies, textile ones, for example, located axially either on the same side of the upturn or on either side of said upturn, or alternatively partially along the upturn and partially along the carcass reinforcement. Another variant consists in placing two reinforcing plies along the upturn, on either side of said upturn, and a third ply along the carcass reinforcement axially to the outside of said reinforcement.
The life of “heavy-vehicle” tires, owing to the progress achieved, and to the fact that certain types of travel are made less of a handicap as far as wear of the tread is concerned, has become such that it is also necessary to improve the life of the beads, and more particularly of tires subject to prolonged travel, this travel frequently inducing a high temperature of the beads owing to the temperatures reached by the mounting rims.
In order to improve the life of a tire required to bear heavy loads and having beads intended to be mounted on flat rim seats or rim seats inclined at 5°, FR 2 356 528 proposes arranging on the inside of the carcass reinforcement and its upturn a reinforcement armature of radial metal elements having a great elongation, said armature being wound around the bead wire to form two strands, the axially outer strand having one end radially above, on one hand, the upturn of the carcass reinforcement and, on the other hand, the upper end of a second reinforcement armature of elements which are oriented at a certain angle relative to the circumferential direction.
To the same end, French Application FR 2 776 238 proposes, contrary to the above teaching, a tire comprising at least one radial carcass reinforcement, formed of at least one ply of inextensible reinforcement elements and anchored in each bead to a bead wire to form an upturn, the end of which is located at a radial distance Hi~c from the base of the bead, each bead being reinforced by at least two additional reinforcement armatures, at least one first armature formed of radial metallic reinforcement elements and at least one second armature formed of elements forming an angle &agr; with the circumferential direction such that 0°≦&agr;≦45°, characterized in that, viewed in meridian section, the first reinforcement armature formed of radial metallic elements is wound around the anchoring bead wire of the carcass reinforcement on the outside of said carcass reinforcement to form two strands, such that the radially upper end of the axially outer strand is radially located at a distance HLE from the base of the bead of between 65% and 95% of the distance H
RNC
, the second armature not being wound around said anchoring bead wire.
The carcass reinforcement of the radial tire as described above, mounted on its operating rim and inflated to the recommended pressure, has in one sidewall a regularly convex meridian profile between approximately the zones of connection with the meridian profile of the crown reinforcement and with the bead. In particular, starting from the radius where the carcass reinforcement is subject to the influence of the bead reinforcement ply (plies) having reinforcement elements which are inclined relative to the radial direction, said reinforcement has in the bead a concave meridian profile, substantially curved in the opposite direction to the curvature in the sidewalls, that is to say, substantially parallel to the curvature of the rim flanges from a point of inflection located radially approximately at the level of the radially upper end of the bead reinforcement ply having inclined elements, which is placed axially to the outside along the carcass reinforcement upturn. Generally, the meridian profile of any bead reinforcement armature, located axially to the inside or to the outside of the non-upturned part of the carcass reinforcement, is substantially parallel to the meridian profile of said non-upturned part.
SUMMARY OF THE INVENTION
Studies and tests have resulted in improvements in the life of said tire, having beads intended to be mounted on flat rim seats or rim seats inclined at 5°, by using differently the bead reinforcement armature having radial elements. The tire of height H on rim, according to the invention, and comprising at least one radial carcass reinforcement, formed of at least one ply of inextensible reinforcement elements and anchored in each bead B to a bead wire to form an upturn, the end of which is located at a radial distance H
RNC
from the base D of the bead wire, each bead B being reinforced by at least two additional reinforcement armatures, at least one first armature formed of radial metallic reinforcement elements and at least one second armature formed of metallic elements which form with the circumferential direction an angle &agr; such that 0°≦&agr;≦45°, is characterized in that, viewed in meridian section, the first reinforcement armature is formed of at least one ply of inextensible elements which is wound around the anchoring bead wire of the carcass reinforcement on the inside of said carcass reinforcement to form two strands, such that the axially inner strand, between the radially lower end A of its radially upper edge adjacent to the carcass reinforcement and its point of tangency T to the anchoring bead wire, follows a rectilinear trace AT referred to as “shortest-path”, and that the radially upper end of said axially inner strand is radially located at a distance H
LI
from the base of the bead wire D of between 0.216 and 0.432 times the height H, the axially outer strand which is located axially to the inside of th
Baker & Botts L.L.P.
Johnstone Adrienne C.
LandOfFree
Reinforced bead for a radial tire does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Reinforced bead for a radial tire, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Reinforced bead for a radial tire will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3015403