Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02941200 2016-08-30
ROLLING ASSEMBLY
[0001] The invention relates to a rolling assembly.
[0002] The
rolling assembly of the invention is preferably used in the field of
tyres for light vehicles such as passenger cars and vans, but may also be used
for
heavy vehicles, civil engineering plant tyres and agricultural tyres.
[0003] A reminder of the definitions used in the present invention is
given below:
- "axial direction": direction parallel to the axis of rotation of
the tyre,
-
"radial direction-: direction intersecting the axis of rotation of the tyre
and
perpendicular thereto,
- "cireumferential direction": direction perpendicular to a radius and
comprised
in a plane perpendicular to the axis of rotation of the tyre,
- "radial section-: section in a plane containing the axis of
rotation of the tyre,
- -
equatorial plane-: plane perpendicular to the axis of rotation and which
passes through the middle of the tread,
- -mounted assembly": assembly comprising a tyre, a steel or aluminium rim,
and the adaptor according to the invention.
[0004] In
order to reduce carbon dioxide gas emissions of motor vehicles,
manufacturers are looking to reduce the mass of these vehicles and also the
rolling
resistance of the tyres fitted thereto. This rolling resistance can be reduced
by
increasing the outside diameter of the tyres and therefore that of the wheels.
[0005]
However, that leads to an increase in the mass of the wheel and therefore
that of the vehicle.
[0006] Hence,
one known solution is to use materials that are more lightweight
than steel to make the rim, such as aluminium alloys. However, such rims,
while they
are more lightweight and have a more open visual appearance thus making it
easier for
the heat of the brakes to be dissipated, are not sufficiently resistant to
knocks such as
potholes and/or knocks against kerbs.
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[0007] Specifically, the knocks experienced by such rolling elements
may cause
one or more of the components of the rolling element (the tyre and/or the rim)
to
break.
[0008] Document US 1 250 405A describes a tyre comprising three
vulcanized
zones to constitute a pneumatic casing in the form of a flattened arch, an
interior
support and an elastie core. That document provides no specifics regarding the
ratio
(rim width W)/(adaptor width L).
[0009] Document WO 2013/045618A1 describes a lightweight wheel
comprising
a carbon-reinforced plastic rim and a wheel centre made of light metal.
[0010] Document CA2 281 651 describes a tyre and a mounted assembly
comprising same. The tyre comprises a base for mounting on the rim and means
for
immobilizing the lyre on the rim.
[0011] Document GB 2 039 831 describes a mounted assembly comprising a
tyre
and a rim which comprises no removable part.
[0012] Thus there is still a need for a rolling assembly that is more
lightweight
than rolling assemblies with steel rims, and which exhibits better resistance
to knocks
because of better protection of the tyre, while at the saine time maintaining
the same
high level of tyre road holding performance, in particular its ability to
develop high
cornering or drift thrust.
[0013] The subject of the invention is therefore a rolling assembly
comprising a
tyre comprising two beads, a rim having a rim well positioned between two rim
seats,
each one having an axially outer end, the said rim having a total width W
between
each axially outer end of the said two rim seats, and an adaptor providing the
connect ion between each bead and each rim scat.
[0014] The rolling assembly is characterized in that the adaptor
comprises
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- two axially outer ends, each one comprising an adaptor seat and an adaptor
bearing face substantially comprised in a plane perpendicular to the axis of
rotation,
- a body connecting the said two outer axial ends so as to form a single
component
and comprising at least one main reinforcement, and
- a face intended to be in contact with the rim well, and positioned
radially on the
inside,
the said adaptor having a total axial width L comprised between each adaptor
seat that
is such that the ratio W/L is greater than or equal to 20% and less than or
equal to
60%, in that the body comprises an immobilizing element intended to wedge the
said
adaptor in the rim well, and in that the rim is made of a material selected
from alloys
of aluminium and/or of magnesium, composite materials based on carbon fibres,
glass
fibres, aramid fibres, plant fibres, the said fibres being comprised in a
matrix based on
thermosetting compounds or on thermoplastic compounds, or of a complex
composite
containing an elastomer and a complex based on resin and on fibres selected
from
carbon fibres, glass fibres, aramid fibres, plant fibres or combinations of
these
materials.
[0015] The axially outer end of the adaptor axially delimits a
"housing intended
to accept the bead of the tyre". The bearing face of the axially outer end
serves to
support, in the axial direction, the bead of the tyre in the manner of a rim
flange.
[00161 Thus, the housing accommodates the bead of the tyre in exactly
the same
\Nay as the seat of a rim conventionally would. The tyre is therefore axially
immobilized by the inflation pressure and is pressed firmly against the
bearing face of
this axially outer end, in the manner of what happens conventionally in the
case of the
bead of a tyre against the rim flange of a rim.
10017] Thus, when the rolling assembly according to the invention is
in operation
and at the service loadings for which it is designed, the tyre is immobilized
axially
with respect to the rim, more specifically the beads of the tyre are
immobilized axially
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with respect to the rim in the same way as in a conventional rolling assembly
in which
the beads of the tyre are mounted directly on the seats of a rim, while the
beads of the
tyre are not radially immobilized with respect to the rim, more specifically
the beads
of the tyre are capable of moving radially to some extent with respect to the
rim. In
standard running, it may be said that there is practically no axial
deformation of the
adaptor, or else that such deformation is negligible with respect to the
radial
deformation.
100181 By contrast, in a knock, the axial deformation of the adaptor
may be great,
thus contributing to reducing the stress loadings on the mounted assembly.
[0019] The assembly according to the invention offers the advantage of
being of
simple construction while at the same time ensuring good performance in terms
of the
road holding of the tyre, and in particular an ability to develop high
cornering or drift
thrust, this being with a rim made up of an elastic part and of an inelastic
part.
[0020] Specifically, combining an elastic rim part with an inelastic
rim part
allows the rim flange to deform under the effect of a knock thereby
significantly
reducing the extent to which the wheel and the vehicle pass on loads.
[0021] For preference, the carbon-based composite materials contain
long or short
carbon fibres.
[0022] For preference, the fibre-based composite materials comprise
fibres of a
length greater than 5 mm.
100231 For preference, the matrix based on thermosetting compounds is
selected
from epoxy resins, vinyl ester, unsaturated polyesters, cyanate ester,
bismaleimide,
acrylic resins, phenolic resins, polyurethanes and combinations thereof.
[0024] For preference, the matrix based on thermoplastic compounds is
selected
from polypropylene (PP), polyethylene (PE), polyamides (PAs), semiaromatic
polyamides, polyester (PET), polybutylene terephthalate (PBT),
polyetheretherketone
(PEEK), polyetherketoneketone (PEKK), polyethersulphone (PSU), polyetherim ide
(PEI), polyimide (PI), polyamideimide (PAI), polyphenylenesulphide (PPS),
polyoxymethylene (POM), polyphenylene oxide (PPO).
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[0025] For preference, the ratio W/L is greater than or equal to 25%
and less than
or equal to 50%.
[0026] The total width W of the rim needs to be less than the total
width L of the
adaptor so as to guarantee this adaptor enough elasticity to correctly absorb
the
5 transfer of mechanical forces inherent to a knock. Such elasticity cannot
be obtained
when the width of the rim is too great.
[00271 The ratio W/L as defined in the adaptor thus makes it possible
to
guarantee in the mounted and inflated assembly, on the one hand, a permanent
and
sufficient mechanical connection between the tyre and the adaptor and, on the
other
hand, correct absorption of the mechanical forces inherent to a knock.
100281 For preference, each outer axial end comprises an outer
reinforcing
element selected from a metal (steel), a composite material, a thermoplastic
material, a
resin, nylon, aramid. lt may comprise a matrix of resin and/or reinforcing
fibres, such
as rayon, aramid, PET, nylon, glass fibre, carbon fibre, basait fibre,
poly(ethylene 2,6-
naphthalate) (PEN), polyvinyl alcohol (PVA).
100291 The immobilizing element may have a total axial length greater
than or
equal to 10% and less than or equal to 80%, and preferably greater than or
equal to
30% and less than or equal to 50% of the total width W of the rim.
[0030] This immobilizing element is preferably present in the middle
part of the
adaptor. The immobilizing element may be made up of one or more parts which
may
or may not be joined together.
[0031] The immobilizing element may also be present near one of the
axially
outer ends or anywhere on the body positioned between the middle position of
the
adaptor and one of the axially outer ends.
[0032] The rim well may also be arranged so that it is offset from the
middle of
the rim. The rim would therefore have two rim seats of different lengths.
10033] The well may then be positioned in any possible location on one
of the
two rim seats.
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[0034] The immobilizing element preferably has a reinforcer with an
extension
modulus greater than 4 GPa and preferably greater than 12 GPa. This reinforcer
may
be selected from metal (steel), nylon, polyethylene terephthalate (PET) and
aramid.
The immobilizing element may comprise a matrix of resin and/or reinforcing
fibres
such as rayon, aramid, PET, nylon, glass fibre, carbon fibre, basait fibre,
poly(ethylene 2,6 naphthalate) (PEN), polyvinyl alcohol (PVA), polyketones.
[0035] The immobilizing element may be positioned at a length "I"
situated
between a median axis YY' passing through the centre of the said immobilizing
element and one of the bearing faces of the said adaptor.
[0036] This length "1" is comprised between a minimum length and a maximum
length which are defined by the following mathematical formulae:
= 0.1 (W + W/2 + L) and
= L ¨ 0.1 (W + W/2 + L)
in the case of use on a passenger vehicle, the rim seat will have a length at
least
equal to 5 mm, with
= 5 + 0.1 OW/2 + 0.1 L and 'maxi = L ¨ (5 + 0.1 W/2 + 0.1 L)
[0037] The body of the adaptor may comprise at least one projection.
This
projection may be present as desired on one axially outer end or on both. The
projection is preferably made of an elastomer conventionally used in the field
of tyres.
100381 The body may comprise at least one projection. The projection may be
present, as desired, on one axially upper end or on both. The projection is
preferably
made of an elastomer conventionally used in the field of tyres. The projection
may be
made of metal, of composite material, of thermoplastic material, of resin.
[0039] The position of the projection on the adaptor according to the
invention
may advantageously conform to the parametric conditions defined by the ETRTO
(the
European Tyre and Rim Technical Organisation).
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[0040] Thus, the distance -d- comprised between the centre of the
projection and
the bearing face of the adaptor will be dependent on the total axial width L
of the
adaptor. Table 1 below provides a number of pairings between values of L and
"d".
Axial width L (inches) Minimum "d" (mm)
3 13
Between 3.5 and 4 16
>4.5 21
Table I
[0041] The rim seat width -A" is greater than or equal to 10% of the width
W of
the rim.
[0042] The width "B" between the bearing face of an axially outer end
of the
adaptor and the axial end of the closest rim seat is greater than or equal to
10% of the
total width L of the adaptor, and preferably greater than or equal to 15%
thereof. For
the wheel of a passenger vehicle, this width "B" is equal to 21 mm.
[0043] The body of the adaptor according to the invention is
preferably made up
of a main reinforcement formed of at least one ply of cords made of metal
(steel),
textile (rayon), aramid, PET, nylon, glass fibre, carbon fibre, basait fibre,
poly(ethylene 2,6-naphtalate) (PEN), polyvinyl alcohol (PVA), polyketones
which are
parallel to one another within the ply and radial. The ply is anchored in each
axially
outer end to each outer reinforcing element, such as a bead wire, to form a
turnup.
When the body comprises several plies, these are at an angle of between 90
and 35
with respect to the circumferential direction. When the body comprises just
one
reinforcing ply, this will be oriented between 60 and 90 , more preferably at
90 ,
70 with respect to the circumferential direction.
[0044] The main reinforcement of the said body may have an extension
modulus
greater than or equal to 4 GPa.
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[0045] The plies and the complex composite preferably contain
elastomeric
ingredients conventionally used in the field of tyres, such as rubbers that
can be
crosslinked, by vulcanization chemical reactions, by sulphur bridges, by
carbon-
carbon bonds created by the action of peroxides or of ionizing radiation or by
other
chains of specific atoms of the elastomer molecule, secondly thermoplastic
elastomers
(TPEs) in which the elastically deformable parts form a network between
somewhat
non-deformable "hard" regions, the cohesion of which is the product of
physical bonds
(crystallites or amorphous regions above their glass transition temperature)
and lastly
non-thermoplastic elastomers and finally thermosetting resins.
[0046] The body of the adaptor may comprise a hoop arranged on at least
part of
its radially external surface and/or at least a radially internai part of the
reinforcement.
The hoop used according to the invention is selected from the materials
conventionally used in this function and in the field of tyres, and having an
extension
modulus greater than or equal to 4 GPa or even greater than or equal to 12
GPa.
[0047] This hoop may or may not be secured to the adaptor. If it is flot
secured to
the adaptor, it may be fitted after the adaptor has been mounted on the rim.
[0048] The hoop can be cold or hot bonded to the adaptor. The hoop may
alternatively be secured by any mechanical means, such as by clamping or
screwing.
[0049] In the event that the adaptor is fixed in position before being
applied to the
rim, the rim and the adaptor are then assembled by force. The adaptor is
therefore
rendered inseparable from the rim and cannot therefore be removed.
100501 The adaptor may be cold or hot bonded to the rim after a
preliminary
treatment of the metal of which the rim is made. When the adaptor is hot or
cold
bonded to the rim, the adaptor is irremovable.
[0051] The adaptor comprises at least one removable or otherwise conducting
strip positioned over ail or part of the circumferential periphery of the said
adaptor,
and over a complete path extending from the adaptor bearing face to the rim J.
The
presence of the conducting strip also makes it possible to ensure the
conduction of
electricity between the ground and the wheel, and therefore between the ground
and
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the vehicle notably when the conductivity of the elastomeric compositions is
insufficient, this being ail the more important as the tyre rests not directly
on the
wheel but against an adaptor.
[0052] For
preference, when the conducting strip is removable or irremovable, it
is positioned entirely at the radially external surface of the body.
[0053] For
preference, when the conducting strip is irremovable, it is partially
buried under the radially external surface of the body.
[0054] For
preference, the conducting strip has an electrical resistivity less than or
equal to 108 Ohm.cm, and preferably less than or equal to 10' Ohm.cm.
[0055] For preference,
the conducting strip is made up, as desired, from a metallic
leaf or from an elastomeric composition containing carbon black in a quantity
greater
than or equal to 15%.
[0056] For
preference, the carbon black in the elastomeric composition has a
speci fie. surface area greater than or equal to 500 m2/g.
[0057] For preference,
when the conducting strip is irremovable, it is bonded or
crosslinked to the elastomeric composition of the body.
[0058] In other instances, it may be considered to be removable.
[0059] The
invention will now be described with the support of the examples and
attached figures which are given solely by way of illustration and in which:
- Figure 1 is a schematic view in cross section of the assembly according to
the
invention,
- Figure
2 is a schematic view in cross section of a first embodiment of the adaptor
of the assembly according to the invention, and
- Figure
3 depicts a schematic view in cross section of a second embodiment of the
adaptor of the assembly according to the invention, and
- Figure
4 depicts a schematic view in cross section of a third embodiment of the
adaptor and of the rim of the assembly according to the invention,
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- Figure
5 depicts a schematic view in cross section of a fourth embodiment of the
adaptor and of the rim of the assembly according to the invention.
100601 As
Figure 1 shows, the mounted assembly of general reference 1,
comprises a tyre 2 with two beads 3, a rim 4 with a rim well 5. The rim is
made of
carbon/epoxy composite. The well 5 is positioned between two rim seats 6. The
rim
hos a length W equal to 50 mm for a tyre of size 7.5J17. This length W is
measured
between each axially outer end of each rim seat 6. This assembly 1 further
comprises
an adaptor 7.
100611 The adaptor 7
comprises two axially outer ends 8. Each of these ends 8
comprises an adaptor seat 9 on which the bead 3 of the tyre 2 rests, and an
adaptor
bearing face 10 substantially comprised in a plane perpendicular to the axis
of rotation
of the tyre.
[00621 The
adaptor 7 further comprises a body 11 which connects each end 8 and
forms a single component. This body 11 is made of a conventional reinforcement
lia
known in the field of tyres.
100631 When
mounted, the tyre rests on each adaptor seat 9 and bears against
each bearing face 10. Fora tyre of size 7.5J17, the total axial width L
between each
adaptor seat 9 is equal to 190.5 mm, and "1" is equal to 56 mm.
100641 The body 11
comprises in its middle part, on each side of the median axis
XX'. an immobilizing element 13 having a total axial length "1" equal to 25%
of the
width L. The immobilizing element 13 is made of rubber with an extension
modulus
equal to 50 GPa.
[0065]
According to this embodiment, the adaptor comprises no hoop. When the
rolling assembly according to the invention comprises a hoop, the latter is
arranged
mainly in the middle part of the body 11 on each side of the axis XX', and is
made of
materials conventionally used in tyres, based on textiles or on metal.
[0066] Each
radially external end 8 each comprises an outer reinforcing element
14, also known as a bead wire, made of a glass/resin composite material.
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[0067] As Figure 2 shows, only the adaptor 7 is depicted. It comprises
a hoop 15
arranged on each side of the median axis XX'.
[0068] In the embodiment of Figure 3, the adaptor comprises, in
addition to the
aforementioned elements, two projections 16 each one arranged on the body 11,
at
least 21 mm away from the end of the bearing surface 10 in the case of a rim
of size
7.5J17.
[0069] These two projections 16 are made of elastomeric rubber,
possibly
reinforeed with cords arranged in the cireumferential direction.
[0070] This assembly is mounted in the conventional and known way by
forcibly
positioning the adaptor on the rim in such a way that the immobilizing element
13
becomes inserted into the well 5 of the rim 4. The beads 3 of the tyre 2 are
then each
positioned on a seat of the adaptor 9. The mounted assembly is then inflated
to its
nominal pressure.
[0071] In Figure 3, the immobilizing element 13 is positioned in the
middle part
of the adaptor 7.
[0072] As Figure 4 shows, the immobilizing element 13 is positioned
offset from
the median axis XX' of the adaptor but centrally with respect to the median
axis ZZ' of
the rim. It is arranged at a distance "1" that is greater than or equal to
(W/2 + 21).
[0073] The length "I" situated between the centre of the rim well and
the axially
outer end of the adaptor complies with the physical constraints A> 5 mm and
B > 21 mm, where A is the width of a rim seat and B is the distance between
the
bearing face 4 of an axially outer end of the adaptor and an axial end of a
rim seat.
[0074] As Figure 5 shows, the immobilizing element 8 is positioned offset
from
the median axis ZZ" of the rim and from the median axis XX' of the adaptor. In
this
figure, it is positioned at a distance -1" in mm away from the centre of the
axially
outer end on the inboard side of the vehicle, where
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1 = L ¨ W + 5 + W/200 ¨21
For a passenger vehiele wheel of reference 7.5 J 17, W is equal to 50 mm mm, L
to
190.5 mm and "I" to 56 mm.
[0075] The following examples show the results obtained with the
adaptor
according to the invention.
[0076] Example : Kerb knock tests
This test involves causing a mounted assembly to mount a kerb at an angle of
attack of
300. This choice of angle is based on the fact that it represents a loading
that is very
pcnalizing to a tyre. The test is performed with two different kerb heights
(90 mm and
110 mm).
The test proceeds as follows. Several passes are made with the wheel at
different
speeds until the tyre becomes punctured. The starting speed is 20 km/h and
then the
speed is incremented by 5 km/h on each new pass.
A conventional assembly without an adaptor and with a conventional steel rim
(control 1) is compared against an assembly according to document WO 00/78565
(control 2) and an assembly according to the invention with a carbon/epoxy
composite
rim (of the invention). These assemblies are ail of the size 205/55R16
comprising a
6.5116 rim. The results are collated in Table II below and are given in
percentages:
Control l Control 2 Invention
Percentage of the 100 > 150 > 150
puncturing speed
compared with control
¨ kerb height 90 mm
Vertical thrust load 100 50 40
level (Fz) recorded at
the punctu ring speed
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Condition of mounted -"Eyre punctured - re and wheel Tyre. adaptor and
assembly following intact wheel intact
-Wheel markeci
knocks
-Adapter plastically
deformed
Table II
Results greater than 100 show an improvement in behaviour when subjected to a
lateral knock.
The test performed on the kerb height of 90 mm leads to the control tyre
puncturing at
a speed of 30 km/h, whereas the assembly according to the invention suffers no
damage at this sanie speed, or even at a speed of 50 km/h.
The test performed on the kerb height of 110 mm leads to the control tyre
puncturing
at a speed of 20 km/h, whereas the assembly according to the invention suffers
no
damage at this same speed, or even at a speed of 50 km/h.
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