Note: Descriptions are shown in the official language in which they were submitted.
The present invention relates to improvements in tires
and more particularly in the beads of -tires oI very large si~e
which are intended for use on heavy equipement, such as those
used for civil engineering work.
~ t the present time, tires of the type in question are in
most cases mo~mted wi-thout an inner -tube on rims faving frustoco-
nical bead sea-ts. ~hus the bead must ful~ill -two e~sential roles,
namely:
- assure -the seal be-tween -the -tire and tl~e rim, alld
- secure -the tire to the rim, wh~tever the value of the
tangetial driving force -to be transmit-ted.
'~he bead rings presen-t as the reinforcement of the beads
contribute preponderantly to the carrying out of these two func-
-tions, but a-t the price O:r an excessive amount of material (steel
wire or ribbon).
~ ur-thermore, -the ~atigue strcngtll of the elements forming
the bead seems -to be related -to the value o~ the radial cross-
section selec-ted ~or the bead r:ings.
Finally, the shape of the rad:ial cross-section of the or-
finary bead rings formed of steel wires or ribbons causes, on therim, a distribution of the pressures of -the bead which is un~avo-
rable, due to the coexistence of zones of excessively high local
pxessures and zones of excessively low local pressures. ~s a re-
sult, the beads become worn and/or slide circumferentially with
respect to the rim.
~ he bead rings used in -the beads of tires of the -type in
question therefore have an excessive radial cross-section as com-
pared with that required, for instance, for sta-tic resistance.
In order to lighten the weight of -the bead rings i-t has
already been pro~osed to use a hollow member, for example, of me-
tal, the cavi-ty o~ which is filled with a ring of plas-tic material,
or a hollow member of extruded plastic material. However9 such
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ho:llow beacl rings would not be suitable for tires of the type in
question, due in particular to the fact that their resistance to
rup-ture and crushing is insufficient.
The problem at which the inven-tion is directed is therc-
fore to create a hollow metallic bead ring the weight of which is
low for a relatively high o~erall radial cross-section, but which
is nevertheless resistant to rupture and crushing and the shape
of radial cross-section of which causes as uniform as possible a
distribution of the bead pressures on the rim.
~ccordingly, the tire in accordance with the present in-
vention, having a carcass reinforcement anchored to at least one -
bead ring, the bead ring consisting of a hollow metallic member, -~
is characteri~ed by thè fact that the bead ring, as seen in radial
cross-section, is essentially formed of four sid~s which converge
two by two and of an interior reinforccment connecting the two
regions where -two consecutive converging sides meet, and by the
fact that the bead ring is arranged in the bead in such a manner
that the interior reinforce~ent forms an angle of less than -~ 60 -
with the bisector of the angle formed by the bead seat on -the rim
with the -tangent to the rim flange adjacent to said bead seat, the
bisector being directed towards the inside of the tire, the latter
being mounted and inflated.
~ y interior reinforoement there is understood not only the
reinforcement itself or its axis of symmetry in the case of a li-
near reinforcement or of a reinforcement with linear axis of sym~
metry, bu-t also the chord connecting the two ends of the reinfor~
cement in the event that the reinforcement is curved.
~ hus, by means of the invention, the radial cross-section
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of the bead ring is, by triangulation, made nondeformable, parti-
cularly with respect to the forces coming from the rim and the
carcass reinforcement and -tending -to c~lsh the radial cross-section
of the bead ring.
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The radl~l cross-sec-tion of a bead ring in accordance with
the invention preferably is essentiallvv formed of two sides of lit-
tle or no curvature facing the rim and two other curved sides.
A-t the limit, the radial cross-scction of the bead ring
in accordance with the invention may be circular or approxima-tely
elliptical wi-th its minor axis sllbstantially parallel to -the in-
terior reinforce~ent or contained within the interior reinforcement,~
or else in the shape of a square or parallelogram with rounded
corners, -the small diagonal of the parallelo~ram being substantial-
ly parallel to the in-terior rein:Corcemen-t or con-tained within i-t.
It is advantageous to arrange the interior reinforcement
of the bead rin~ of the invention along the-bisector of the angle
formed by the converging sides facin~ the rim or by -the chords
subtendin~ the converging sides, or in such a manner that the in-
terior reinforcemen-t has such bisector as the axis of symmetry.
~he converging sides of -the radial cross-section of the
bead ring which face the rim or -the chords subtending said sides
can foxm c~n an~le s~lbs-tantially equal to thc an~le Iormed by the
bead seat on the rim with -the tangent to the rim flange adjacent
to said bead seat.
~he bead ring in accordance wi-th the invention can also -: -
be arranged in -the bead in such a manner that the interior rein-
forcement or its axis of symmetry is parallel -to the bisector of
the angle formed by -the bead seat on the rim with the tangent to
the rim flange adjacent to said bead seat, or -tha-t this interior ~-:
reinforcement contains such bisector or has such as the axis of .. - -.
symmetry .
Such bead rings are well-sui.ted for tires whose carcass .
reinforcement is essentially formed of radial metal ca`bles and
which are intended for heavy and very hea-vy vehic~es. ~
~y means of -the bead ring of the invention, -the pressure ~ ~ -
on the xim o~ the portion of -the bead in ~rhich the bead ring is
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placed is made u~if`orm. ~ur~he~nore, the radial cross-section
of the bead ring can be given a shape and area ~hich are suita-
ble for assuring sufficient fatigue strength for the elements
forming the bead al~d for assuring the bead ring itself suitable
resistance to stresses which tend to deform i-t.
~ he protion of the description which follo~rs describes
embodiments- of the invention, this description being given with
reference to -the drawing, in wnich:
~ ig. 1 shows, in radial cross section, a bead ring in ac-
cordance witn the invention arranged in a bead of a radial -tire,
and
Fig. 2 -to 8 show o-ther radial cross-sections of bead rings
in accordance with -the inven-tion.
~ ig. 1 shows a bead 1 of a tire with a radial carcass
reinforcement 2. The preferably meta:L carcass reinforcement 2
surrounds the bead ring 3 and its tul~led-up portion 21 rises to
above the bead ring 3. The bead 1 is arranged on rim o:E which
the drawing shows only the portion ~o~ningr a bead seat ~ and a
rim flange 5 in-tended to come into contact with the bead 1. In
the example selected, this bead seat ~ is inclined ~ith respect
to the axis of rotation of the rim, indica-ted by the straight line
Y~. The bead seat 4 and the tangent tl -to the adjacent rim flange
5 form a angle a.
~ he bead ring 3 in accordance with the invention has a
radial cross-section which is essentially Iormed of t~o converging
sides 31 and 32 which form wi-th each other an angle which is subs-
tantially equal to the angle a, and of a circular axc 33 connecting
the non-common ends of the converging sides ~~L and 32. On its in-
- side~ the bead ring 3 has an interior reinforcement which is sym- -
metrical with respect to the bisector S of the angle formed by the
two con~erging sides 31 ancl 32~ This interior reinforcement is
formed o~ a rib 34 coming from the region surrounding the point
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oE convcrgencc of -the two sides 31 and ~2, and oi another rib 35,
wider -than -the rib 34, coming from the circular arc 33 and provi-
ded at its Lree end with a groove 36. ~'he free end of the rib 34
fi-ts within the groove 36 of -the rib 35. The interior reinforce-
ment 34, 35 opposes deformation, par-ticularly by crushing, of the
hollow member in accordance with the inven-tion by dividing the
radial cross-section of the bead ring into -two trlangles (shown
in dashed line) of which the interior reinforcement forms a common
slde.
~he axis of symmetry S and, therefore, the reinforcement
34, 35 itself form an angle ~ o: about 20 with respec-t to the bi-
sector C of the angle ~ formed by the bead seat ~ on the rim with
the tangent tl to the rim flange 5.
'~he two sides 31 and 32 are quasi-linear and therefore of
practically ~ero curvature and face the bead seat ~r rim glange 5
of the rim. The angle formed by these -two sides 31 and 32 is
substantially equal to the angle a ~medby the bead seat ~ with
the tang~nt tl to the rim fl~mge 5. q`he circular arc 33 forms the
other two sides of the radial cross-sec-tion, which are thus loca-
ted in the extension of each other.
~ ig. 2 sho~s a bead ring 40 wllose radial cross-section is
circular on the ourside. In accordance ~rith the invention, the
diametrical intèrior reinIorceme~t consisting of two parts ~1, 42
divides this radial cross-section into t~o triangles (shown-in das- -
hed line) of ~hich said interior reinforcement constitutes the com-
mon side. -
Fig. 3 shows a bead ring 50 whose radial cross-section has
an approximately oval or elliptical shape. In accordance with the
~ invention, the bipartite interlor reinforcement 51, 52 divides this
ellipse into two triangles (shown in dashed line). od which said
i~terior reinforcement cons-titutes the common side. ~he dimension
A of the radial cross-sec-tion of the bead ring 50, measured paral-
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lel to -the in-terior reinforcemen-t 51, 52, is - as furthermore in
-the case o~ ï~igs. 1, 5, 7 and 8 - larger than its dimension B,
measured perpendicular to said interior reinforcement. In this
case, this side which is common to the two triangles merges with
the minor axis of the elliptical cross-section of the bead ring.
~ig. ~ shows a bead ring 60 of square shape wi-th roundes
corners. ~he bipartite interior rein~orcemen-t 61, 62 forms one
of the diagonals of the square. This diagonal merges with the
side co~non to the two t~iangles (shown in dashed line) into which
-the contour of this bead ring can be subdivided.
Fig. 5 shows a bead ring 70 having an outer section in the
from of a parallelogram with rounded corners. ~he bipartite in-
terior reinforcement 71, 72 con-tains the smallest diagonal of -the
parallelogram. This diagonal represents the side common to the
two triangles (shown in dashed line), in-to which the contour o~
said bead ring can be subdivided.
'rhe interior reinforcement Sl of the bead ring ~0 of square
radial cross-sec-tion shown iIl FiG. 6 di~fers from the interior rein-
~orcemen~ described above by the fac-t -that it consis-ts of a single
part ~1 whose ro~t ~2 is located in the region where the two con-
verging sides ~3 and 84 come together, while the opposite end 8 is
located in the region where the two opposite converging sides 85,
86 come together.
~he bead ring 90 illus-trated in Fig. 7 is distinguished
~rom all the preceding bead rings by the fact that two of its
converging sides, in this case the sides 92, 92', are joined toge-
ther and no longer formed of a single piece~ ~ikewise, its inte-
rior reinforcement is composed of two joined sections 91, 91~ which
are the extensions of the sides 92, 92', respectively.
}0 ~'inally~ the bead ring 100 of Fig, 8 has an interior rein-
forcement composed of two sections 101, 101' which are connected
to each other at their common apex 102~ I-ts twp sides 103) 104 i~
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have a zero curvature, while the opposite sides 105, 106 are curved.
It goes wi-thou-t saylng that -the principle o~ -the invention
can be extended to hollow bead rings having a pl.urali-ty o~ juxta-
posed cavities o:~ triangular radial cross-section, ~lith a single
side in common from one cavi-ty -to the ne}~t~
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