CA1269311A

CA1269311A - Pneumatic tire

Info

Publication number: CA1269311A
Application number: CA000508652A
Authority: CA
Inventors: Joe A. Powell; Shamim Ahmad; Kenneth V. Kenreich
Original assignee: Uniroyal Goodrich Tire Co
Current assignee: Uniroyal Goodrich Tire Co
Priority date: 1985-05-08
Filing date: 1986-05-07
Publication date: 1990-05-22
Anticipated expiration: 2007-05-22
Also published as: NL8601104A; YU72586A; IN166759B; KR860008888A; JPS61261111A; PT82533A

Abstract

ABSTRACT OF THE DISCLOSURE

An improved radial tire is reinforced with at least two carcass plies of rubberized cords wherein a radial inner or first ply extends continuously from one bead portion to another bead portion through the sidewall areas and across the crown of the tire and a radial outer or second ply has two sections disposed such that the second ply is discontinuous or interrupted in the crown area. The second ply is also foreshortened in the bead portion of the tire rather than being wrapped around the bead.

Description

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PNEU~ATIC TIRE

BACKGROUND OF THE INVENTION_ This invention relates to pneumatic tires and particularly to radial type pneumatic tires~
Radial type pneumatic tires typically include a crown area with an annular belt, a pair of sidewall areas~ a pair of bead portions, and a carcass or body which includes one or more carcass plies of rubberized cords oriented substantially at a 90 angle (radially) to the circumferential center plane of the tire. The cords of these carcass plies can be made of such material as metal, glass, natural textile or synthetic textile such as rayon, nylon, polyester, aromatic polyamide or other similar materials.
The carcass of a radial tire provides structural stability to the tire, reduces susceptibility of the tire to bruising, and reduces the possibility of separation of tire components occurring within the tire. In the crown area of the tire, an annular belt also aids in reducing susceptibility of the tire to bruising.
The number of carcass plies incorporated into a radial tire carcass is usually dependent on the intended service or use of the tire. Radial tires having at least two continuous carcass plies include such tires serving as large passenger tires and light truck radial tires. In such tires, the plies generally extend continuously from one bead portion of the tire adjacent to the shoulder and crown areas to the other bead portion and in most tires each ply is wrapped around a wire bead in each bead portion.

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- 2 -It has been found in a radial tire carcass with two continuous inner (first) and outer (second) plies that the second ply provides limited structural stability in the crown ar~ea of the tire and the bead portions of the tire. The second ply also provides limited resistance to bruising in the crown area of the tire because the belt provides much of the resistance to bruising.
Tire manufacturers are continuously searchin~ for ways to reduce the overall weight of radial tires and the costs to manufacture them.
Relatively unsuccessful attempts have been made to design a single ply radial tire for service which traditionally requires two or more carcass plies.
Other attempts have focused on reducing the amount of carcass material in one of the plies of a multi ply tire, as illustrated in tires containing discontinuous radial outer or second plies as described, for example, in U.S. Patents 3,058,509;

3,481,386; 3,509,93~; 4,096,899; and 4,185~675. In '509, a tire is disclosed having an outer carcass ply which is discontinuous or interrupted in the crown area of the tire. The outer plies disclosed in '386;
'930 and '899 are also discontinuous in the crown area of tires as well as at locations adjacent to the bead wire. Often the cords and/or rubber in such a discontinuous outer ply are of special materials other than the materials that make up the continuous radial inner or first ply. In '675, for example, a second discontinuous ply is di~ferent from the first ply in that the rubber of the second ply has a shore A hardness after vulcanization of ~0 to 50.
Advantages of incorporating a discontinuous ply are often negated when the materials in the second 1~93~

discontinuous ply are different from the ma~erials in the first continuous ply.
Also, it has been found that significant forces can act between the rim of the wheel upon which the tire is mounted and the lower sidewall portions of the tire. In the sidewall portion, significant forces act on the tire in the region where the wheel rim flange physically contacts the sidewall of the tire. In this rim flange contact region, the sidewall flexes over the rim flange. The rim flange contact reyion of the tire must be made strong enough to endure such flexing and forces resulting therefrom.
Furthermore~ it has been found that a predetermined thickness in each bead portion between the radial inner part of the bead wire and the surface of the bead portion must be maintained to allow for suitable mounting of the tire on the rim.
Thus, when designing tires with discontinuous carcass plies, unsatisfactory tires can result by ignoring particular areas of the tire where special forces occur and specific requirements in the bead area are desired.
SUMMARY OF THE_INVENTION
It is an object of the invention to provide an improved pneumatic radial type tir~.
Another object of this invention is to provide a radial tire which performs comparably to a typical radial tire with two or more continuous carcass plies but which is characterized by reduced manufacturing costs and weight when compared with such a typical tire.
These and other objects, which will become evident Erom the following description, are attained in accordance with this invention by having a radial . ' ~

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type pneumatic tire which includes a circumferen~
-tial center plane, a pair of bead portions con-taining bead wire, a crown area or portion which includes a belt assembly, a pair of sidewall areas and a carcass comprising: a radial inner ply which contains rubberized cords oriented radially to the circumferential center plane of a tire/
which radial inner ply extends continuously from one beacl portion to the other bead portion; and a radial outer ply, which has two sections, such that such radial outer ply is discontinuous in the crown area of the tire and the bead portion of the tire. Each section of the radial outer ply extends from outward of the bead portion to axial inward of the edges of the belt assembly.
In a particular embodimen-t the radial inner ply is anchored in such bead portion by being wrapped around the bead wire.
sRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a cross-sectional view of a radial tire containing one embodiment of this invention.
Fig. 2 is a fragmentary view of a crown area of the tire of Fig. 1.
DETAILED DESCRIPTION
This invention can be described in further detail in terms of the presentl~ preferred embodi-ments and with reference to the two figures of the drawings wherein like reference characters refer to like fea-tures or components.
The invention is described embodied as a large passenger radial tire. Although this inven-tion is very well suited to passenger tires, it is also adaptable to other types and sizes of tires such as light truck, radial tires and other larger multiple ply radial tires.
In Figs. 1 and 2 a shaped and vulcanized radial pneumatic tire 6 is shown mounted on a rim 7 .

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of a wheel 8. The tire 6 includes a crown area or portion 9, a pair of sidewall areas 10 ana a pair of bead portions 11 shaped for engagement with the rim 7 on which the tire 6 is to be mounted. Include~ in S each bead portion 11 is a wire bead 22.
The crown portion 9 generally includes a layer of tread rubber 28 which has a suitable pattern 29 of alternate grooves and ribs to provide traction and resistance to skid. Ra~ally inward of the layer of tread rubber 28 is a belt assembly 12. The belt assembly 12 contains two belts 13 and 14 composed of rubberized cords of low extensible materials such as nylon, rayon, fiberglass, steel or aromatic polyamide. The cords in the belts 13 and 14 are disposed at an acute angle at between about 10 to about 30 relative to the circumferential center plane P of the tire 6. It is preferred that such cords are oriented at equal but opposite angles in adjacent belts 13 and 14.
Each of the pair of sidewall areas 10 are generally composed of a suitable thickness of sidewall rubber 26 which extends from the margins of the tread rubber 28 to each bead portion 11. Each sidewall area 10 presents a region 60 adjacent to t~e rim 7 where flexing of the sidewall area 10 against the rim 7 occurs. Such regions 60 in the sidewall area are referred to as a rim flange contact region.
The tire 6 has a carcass 15 having two plies of rubberized cords, a radial inner or first ply 17 and a radial outer or second ply 18. The second ply 18 has two sections 18a and 18b. The cords in the two carcass plies 17 and 18 may be of suitable material used as carcass reinforcing coras and are oriented such that the individual rubberized cords lie radially (i.e~ at substantially a 90 angle~
relative to the circumferential center plane P of ~.Z~

the tire. Preferably the first ana second ply are made of the same cord and rubber materialO The edges 27 of the first ply 17 arè wrapped around the wire beads 22 in bead portions 11.
In Figs. 1 and 2, each of the two sections 18a and 18b of the second ply 18 extend from radia~y inward of the belt 13 to a point between the rim flange contact region 60 and the bead portion 11.
Each section 18a and 18b extends axially inwardly to overlap each belt edge 63 by preferably at least about 12 percent of the width of the belt 13 to reduce possible occurrence of separations. In Figs~
1 and 2, the width of belt 13 is about 6 inches (21.24 cm) whereby each section 18a and 18b extend axially inwardly of each belt edge 63 by at least about three-fourths of one inch (1.86 cm).
To reduce possible separation of the first ply 17 and the second ply 18 in the sidewall area 10 of tire adjacent the bead portion 11, the second ply 18 extends radial inwardly of edge 73 of the first ply 17 by at least one~and one-half inches (3.72 cm). Also, to reduce possible occurrence of separations of the second ply 18 from the sidewall 26 in the rim flange contact region 60, the second ply 18 preferably extends about three-eights of an inch (0.93 cm) radially inward of the rim flange contact region 60 but terminates radially outwardly of beads 22.
The tire 6 includes an inner liner 25 which is composed of rubber material such as butyl rubber which is suitable to resist diffusion of air from the tire 6. As shown in Fig. 1, the inner liner 25 extends from one bead portion 11, through each sidewall area 10 and the crown area 9 to the other bead portion 11. In this embodiment; inner liner 25 serves to provide additional or "filler" material in .. :............. . .

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each bead portion ll to allow for suitable mounting of the tire 6 on the rim 7 of the wheel 8. The thickness oE the inner liner 25 is preferably about the same as the thickness of the second ply 18 to provide substantially the same material thickness between the bead wire 22 and the rim 7 as found in tires containing a second ply which is wrapped aroun~
the wire beads.
Each bead portion ll includes a "toe" 50 and a finishing strip l9 which ~enerally comprlses rubber-coated square woven fabric. As shown in Fig.
l, each finishing strip l9 extends from axial outward of the second ply 18 and the inner liner 25, to a position about 3/8 inch (0.92 cm) radial outwar~ of the toe 50. The finishing strip l9 generally extends radial outward of the edge of the second ply 18 by ahout 3/4 inch (1.86 cm). In this embodiment, finishing strip 19 serves to resist chafing between the bead portion 11 and the rim 7.
It is understood that certain departures from and modifications to the preferred embodiment described are possible within the scope of the invention which is to be measured by the following claims.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A radial type pneumatic tire having a circumferential center plane and adapted for mounting on a wheel with a pair of rim flanges such that portions of the tire interface with said rim flanges along rim contact regions, said tire comprising:
A. a pair of bead portions having annular wire beads embedded therein;
B. a crown portion having i) an annular layer of tread rubber and ii) an annular belt assembly of selected width disposed radially inwardly of said layer of tread rubber;
C. a pair of sidewall areas each comprising i) a selected thickness of sidewall rubber and ii) a rim flange contact region; and D. a carcass comprising i) a first radially inner ply of rubberized, mutually parallel cords a) extending continuously from one bead portion to the other radially along said pair of sidewall portions and axially across said crown portion, and b) oriented throughout their extent at substantially a 90 degree angle relative to the circumferential center plane, and ii) a second radially outer ply having two sections, each section having rubberized, mutually parallel cords a) extending from axially inwardly of an edge of said belt assembly radially along a portion of each sidewall area to locations adjacent a rim flange contact region, b) oriented throughout their extent at substantially a 90 degree angle relative to the circumferential center plane, and c) each section of said second ply extending axially inwardly of the edge of said belt assembly by at least 12 percent of said width of said belt assembly and with each section of said second ply extending to a location which is radially inwardly about 3/8 inch (0.9 cm) of a rim contact region and radially outwardly of a bead.

2. The tire of claim 1 wherein the rubber comprising said first and second plies is made of the same material and the cords comprising said first and second plies are made of the same material.