PNEUMATIQUE POUR VEHICULE A CHENILLE UNIQUE

PNEUMATIC TYRE FOR SINGLE-TRACK VEHICLE

Abrégé anglais

ABSTRACT OF THE INVENTION
There is provided a pneumatic vehicle tyre for single-
track vehicles having a carcase comprised of two or more rubberised
cord fabric plies, which plies are anchored by being looped around
the bead cores in the tyre bead regions, the lateral externally
folded over edges of said plies being stepped. According
to the invention, the folded over edge of the ply which extends
widest in the direction of the tread surface, terminates in
the region of the adjacent tread surface edge.

Revendications

The embodiments of the invention in which an
exclusive property or privilege is claimed are defined as follows:
1. A pneumatic vehicle tyre having a body with tyre
beads and bead cores for forming a hollow interior of the tyre
used in particular with single-track vehicles, said tyre having
a carcase anchored in said tyre beads by being looped around
respective bead cores, a tread in a zenith region of the tyre
body, and tyre sidewalls having a middle and an entire height
therewith in which said carcase comprises, in combination, at
least two rubberized fabric cord layers, the looped back around
ends of which are located laterally outwardly of the hollow
interior of said tyre in said sidewalls, the respective ends in
a pertaining sidewall ending at different stepped locations in
said pertaining sidewall influenced thereby over entire height
thereof, that end which extends the furthest in a sidewall from
said bead toward said tread ending in the vicinity of the
pertaining edge of said tread so that greatest flexibility
results in the zenith region of the tyre body rather than in the
middle of the tyre sidewall.

2. A pneumatic vehicle tyre as recited in claim 1. wherein,
with three cord fabric plies, the free edge of one ply terminates
substantially at a third of the height of the side wall of the
tyre, and a further edge of another ply terminates substantially
at two thirds of the height of the side wall of the tyre.
3. A pneumatic vehicle tyre as recited in claim 1, wherein the
free edge of the ply of maximum length faces laterally outwards and
the edge of the ply of smallest length faces the tyre cavity.
4. A pneumatic vehicle tyre as recited in claim 1, wherein,
seen from the tyre bead towards the adjacent tread surface edge, the
number of carcase plies is reduced and, in the region of the
tread surface the number of carcase plies is constant.
5. A pneumatic vehicle tyre as recited in claim 1, wherein
said cord plies have tension resistant filaments or the like
which extend at the same angles relative to the circumferential
direction of the tyre and in known manner such that the filaments
of one ply intersect the adjacent ply.
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Description

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The present invention relates to a pneumatic tyre for single-
track vehicles having a carcase formed of two or more rubberised
cord fabric plies, which plies are anchored by being looped around the
bead cores in the tyre bead regions, the lateral externally folded
over edges of said plies being stepped.
In known pneumatic tyres for single-track or two-wheeled vehicles, i
the lateral folded over carcase edges are only of small width. This
width results from the requirement of ensuring that the tyre side
walls are as flexible as possible so as to obtain perfect deflection
of the tyre.
It has been found that tyres of this type, in the high speed
range, tend to suffer from vibratory movements, whereby the tyre
executes lateral movements which cannot be eliminated even with
careful maintenance of all tolerances during assembly of the tyre body.
It is an object of the present invention to produce in tyres -
of the kind described above lateral stability in the high speed range
and hence to eliminate vibratory movements.
According to the present invention there is provided a pneumatic
vehicle tyre for single-track vehicles, having a carcase comprised
of two or more rubberised cord fabric plies, which plies are anchored
by being looped around the bead cores in the tyre bead regions,
the lateral externally folded over edges of said plies being stepped,
in which the folded over edge of the ply which extends widest in the
direction of the tread surface, terminates in the region of the
adjacent tread surface edge.
Since the folded over edges are stepped in any case9 there is
hence produced, seen from the bead portion towards the tread surface,
a reducing number of carcase plies, thus in such a manner that the
number of carcase plies diminishes towards the adjacent tread strip
3 edge, whilst over the width of the tread surface the number of
carcase plies remains constant. Maximum flexibility is therefDre
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obtained in the zenith region of the tyre body and not, as customary,
halfway up the height of the side wall of the tyre.
Preferably, the tension resistant filaments or the like of all
the cord fabric plies extend at the same angles relative to the
circumferential direction of the tyre and in known manner such that
the filaments of one ply intersect the adjacent ply.
This bracing of the side walls leads to a stabilisation of the
tyre body and the desired elimination of unfavourable lateral movements
at high speeds.
Surprisingly, the bracing of the side wall does not lead to
an adverse deflection behaviour when the tyre is subjected to ;
radial impacts.
The present invention will be further illustrated, by
way of example, with reference to the accompanying drawing in which
the single Figure shows a radial part section through a pneumatic
tyre in accordance with the invention for heavy motorcycles.
The tyre body, substantially comprised of rubber or rubber-like ;
materials, has a carcase comprised of three rubberised cord fabric
plies 1, 2, 3, each of which extends from one bead 4 to the other,
each ply being anchored by being looped around the tension resistant
bead cores 5 and 6. ~he tension resistant cord filaments of the
three plies 1, 2, 3 extend in the zenith portion of the tyre forming
a conventional symmetrical cross bracing at an angle of from 25 to
35 with the circumferential direction of the tyre.
The enveloped, lateral externally folded over free edges of the
plies 1, 2 and 3 are denoted by 7, 8 and 9, respectively.
~he tread surface 10 of the tyre extends substantially over
the region a. It is divided into ribs and blocks of known design.
In the shoulder region 11 on both sides of the tread surface 10,
projections are provided which make contact with the road surface
only during extreme cornering and normally do not form part of the
tread surface.
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The free edges 7, 8, 9 are stepped, and thus in such a manner
that the edge 9 of the inside carcase ply 1 terminates below the edge . .
of the tread surface 10, whilst the edge 8 of the central ply 2
terminate~ substantially at two thirds of the height of the tyre side
wall 12 and edge 7 of the external ply 3 about at one third of the l;
tyre side wall 12. This provides the desired stepping and, seen
from the bead 4 -towards the tread surface 10, a gradual decrease of
the effective reinforcing plies is effected, so that such plies are
located in a three-ply arrangement in the tread surface region and in .
gradually reducing numbers in the side wall 12 of the tyre. :
The reinforcement o f the side wall 12 of the tyre leads to
a lateral stabilisation of the pneumatic tyre whilst still maintaining ~: :
sufficient softness in the region of the tread surface 10.
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