Resilient tires and wheels – Tires – resilient – Pneumatic tire or inner tube
Reexamination Certificate
2000-05-12
2003-02-25
Ball, Michael W. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Pneumatic tire or inner tube
C152S539000, C152S543000, C152S547000, C152S549000
Reexamination Certificate
active
06523591
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a tire comprising at least one tread joined to two beads by means of two sidewalls and a carcass reinforcement, said tire being able to be used with or without an independent inner tube and being intended, after mounting on a standardized rim and after inflation, to be fitted on any vehicle capable of rolling.
The tires may be mounted on several types of standardized rim. Said rims may have frustoconical seats inclined relative to the axis of rotation, forming with said axis an angle which may be between 4° and 16°. Among the latter, there are integral rims which are then referred to as hollow rims, semi-hollow rims or even drop-center rims, or rims made of several sections which are referred to as interim or “advanced” rims. The rims in question may also have rim seats parallel to the axis of rotation and are generally referred to as flat-based.
The most frequently used rims, referred to as hollow or drop-center rims, comprise a mounting groove, the diameter of which is distinctly less than the nominal diameter of the rim. This rim groove diameter is considered by users to be too small, and it does not make it possible to select brake drums of dimensions suitable for effective braking of vehicles which are becoming ever more powerful.
It is furthermore highly desirable, whatever the reasons (reducing the pressures exerted by the tire on the ground, increasing the transverse stiffness of the tire, increasing the available internal space of the rim, lowering the center of gravity of certain types of machinery, to name but a few), to produce tires, the H/S form ratio of which is reduced, H being the height of the tire on its rim and S its maximum axial width.
The development of tires with reduced form ratios, more particularly intended to be fitted on heavy vehicle-type vehicles, such as lorries, buses, subway trains and tractor-trailer units, or of the very large heavy-vehicle type, such as loading, transport and earthmoving machinery used in construction, or aircraft machinery, is very delicate; in particular, the endurance of the beads becomes significantly less as the H/S ratio decreases, the inadequacies in endurance being found at the ends of upturns of the carcass reinforcement or the ends of reinforcement plies located in the beads of the tire, the structure of said beads being a conventional structure with, in each bead, a carcass reinforcement upturn and reinforcement plies, the meridian profiles of which are substantially parallel to the meridian profile of the carcass reinforcement in the zone of said beads. Furthermore, such form ratios, despite the possible reduction in the inflation pressures, involve a notable lack of comfort, which may be quite unbearable in the case of tires traveling long distances on relatively bumpy roads.
In order to overcome such disadvantages and to facilitate the production of tires, Application FR 94/14688 proposes a tire of form ratio of less than 0.8, intended to be mounted on a hollow rim or a drop-center rim, the seats of which are inclined relative to the axis of rotation by an angle which may be between 4° and 16°. Said tire has a carcass reinforcement, surmounted radially by a crown reinforcement, the carcass reinforcement being composed of at least one ply of cords or cables and being turned up in each bead about an anchoring bead wire, passing from the outside to the inside to form an upturn, said upturn being reinforced by at least one additional reinforcement ply of metal cables, oriented by an angle of between 0° and 20° relative to the circumferential direction, the value 0° being included in said range, and the meridian profile of said reinforced upturn, in the tire not mounted on its rim, being substantially parallel to the meridian profile of at least the portion of the seat located axially to the inside of the projection of the center of the circle circumscribed on the bead wire on said rim seat.
Although the production methods of a tire are currently very highly developed, the use of bead wires requires separate production and treatment of said bead wires (coating, for example), the transport and positioning of the same bead wires on a building drum or on a given support for manufacture of the bead, all operations which require time and multiple precautions, and which are therefore costly. Furthermore, since current tires are subjected to ever-increasing driving torques, the compromise between clamping on the rim which is necessary to avoid inopportune rotations and maximum clamping to permit mounting on the rim is difficult to control by the person skilled in the art in the current structures of tires with bead wires around which a carcass reinforcement is wound.
SUMMARY OF THE INVENTION
It has been discovered that the distribution of the contact pressures between the rim and the tire at the level of the respective rim and bead seats can be controlled and rendered as regular as possible in a very simple and reproducible manner while permitting an improvement in the resistance to unwinding of the carcass reinforcement in the event of a high degree of heating of the beads.
Thus, the tire according to the invention which is intended to be mounted on a standardized rim of axial width L, with rim flanges with rounded hooks, comprising a tread joined to two beads by two sidewalls and at least one carcass reinforcement formed of at least one ply of reinforcement elements, is characterized in that, viewed in meridian section, each bead is without a bead core or wire, said carcass reinforcement having in each bead a curved meridian profile which is formed axially and radially from the outside to the inside of at least one convex arc of a circle BC, possibly extended tangentially by a straight-line segment CD, to form a carcass reinforcement edge in the bead, located in an acute angle open axially and radially towards the inside, one of the edges of which is parallel to the axis of rotation, and of a value of at most 25°, said carcass reinforcement being reinforced in each bead at least radially to the outside and axially to the inside by a first continuous additional layer, of meridian profile substantially parallel to the meridian profile of said carcass reinforcement in the bead and comprising at least one section composed of at least one ply formed of inextensible reinforcement elements forming an angle of between −2.5° and +2.5° with the circumferential direction, the radially upper end of said one section of the additional ply being distant from the axis of rotation by an amount at least equal to 0.96 times the distance between said axis and the point of the corresponding flange of the mounting rim farthest from said axis of rotation, and the axially inner end being distant from the equatorial plane by an amount at most 0.43 times the width L of the mounting rim.
“Rim flange, viewed in meridian section” is to be understood to mean the assembly formed by the part substantially perpendicular to the axis of rotation extended, firstly, radially to the outside, by a circular part, forming what is sometimes referred to as the rim hook, and secondly, radially to the inside, by the arc of a circle connecting the axially outer end of the rim seat to said assembly. “Meridian profile of a carcass reinforcement in a bead” is to be understood to mean the meridian profile of the geometric center line of said reinforcement, viewed in meridian section, said profile being considered radially to the inside of a straight line parallel to the axis of rotation of the mounting rim and of the tire passing through the point of the rim hook, corresponding to the bead in question, the farthest from the axis of rotation.
“Inextensible reinforcement element” is to be understood to mean a cable or a monofilament having a relative elongation of at most 1.5% under a force of 20% of the breaking load. The additional layer will preferably be formed of metal cables or monofilaments, preferably of steel, in the case of tires of the “heavy vehicle” or “construction” type, but may advantageousl
Billieres Jean
Durif Pierre
Baker & Botts L.L.P.
Ball Michael W.
Compagnie Generale des Etablissements Michelin--Michelin & Cie
Fischer Justin
LandOfFree
Tire bead without bead cord does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tire bead without bead cord, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tire bead without bead cord will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3153306