Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
WO 2019/149461
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1
Description
Stud and pneumatic vehicle tyre with studs
The invention relates to a stud for anchoring in a stud hole of a tread of a
pneumatic vehicle
tire, having a stud body which is composed of a nonmetallic, elastic material,
in particular a
rubber material, and which comprises a base flange, and having a stud pin,
which stud pin
is composed of hard metal and is anchored in an insert which is situated
within the stud
body and which comprises a base part, and which stud pin projects with an end
portion
beyond the stud body, wherein the base part together with a enveloping layer
composed of
the material of the stud body forms the base flange of the stud body, and
wherein the base
flange has an outer contour which is designed symmetrically with respect to at
least one
plane of symmetry and which has two longitudinal sides and two narrow sides.
Studs are normally held in the stud holes of the tread of pneumatic vehicle
tires by a
combination of positive locking and clamping. Conventional studs are composed
of a stud
body which is composed of aluminum or steel and in which the stud pin, which
projects
beyond the tread surface and which is composed of hard metal, is held.
It has already been proposed to use studs with stud bodies composed of rubber
or of plastic.
For example, WO 2017/088995 Al has disclosed a stud of the type mentioned in
the
introduction, in the case of which the stud pin and the insert composed of
plastic or
aluminum are embedded into a rubber casing or into rubber material. The
particular
advantages of this embodiment lie in the fundamental material properties of
the rubber
body. Its low density of approximately 1 g/cm3 makes rubber particularly light
in
comparison with aluminum or steel. Replacing aluminum or steel with rubber as
body
material therefore leads to a reduction in the stud weight, which has a
positive effect inter
alia on road wear and the formation of fine dust. The elastic material
properties of the
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rubber however have yet further advantages. Firstly, the elastic body material
dampens
impacts, with the result that smaller forces act on stones in the road surface
or on particles
of gritting material. This effect also reduces the road wear and the formation
of fine dust.
Moreover, stud bodies composed of rubber are superior to those composed of
aluminum or
steel in terms of abrasion behavior, because they have completely different
wear behavior.
Since stones in the road surface and grit normally have a greater hardness
than aluminum or
even steel, a stud body composed of aluminum or steel is heavily abraded, as a
result of
which the stud body height and the diameter of the stud body decrease. This
has the effect
that the edge regions of the stud body at the stud holes are subjected to
cutting abrasion
which erodes the edge regions, whereby the gap between the stud and the
surrounding
rubber matrix increases in size. This promotes the ingress of sand and small
stones, which
further accelerate the abrasion of the stud body. Stud bodies composed of
rubber can have
similar abrasion behavior to the rubber material of the tread, as a result of
which gaps
between the stud body and the tread material at least substantially no longer
arise. The
.. elastic characteristics of rubber furthermore give rise to embedding of the
stud in the rubber
material of the tread, which has a favorable effect on the durability of the
stud.
The invention is based on the object of utilizing, more effectively than
before and in
particular optimally, the elastic properties, mentioned in the introduction,
of the material of
the stud body in order to optimize the embedding stiffness of the stud in the
rubber material
of the tread.
The stated object is achieved according to the invention in that the outer
contour of the base
part differs geometrically from that of the base flange, such that the
enveloping layer has, at
that side of the base part which is assigned to a longitudinal side and/or to
a narrow side, at
least one portion in which said enveloping layer is thicker than at the
opposite side of the
base part.
The invention permits an optimization of the ice performance of the stud
through targeted
influencing of the embedding stiffness by means of corresponding design and
configuration
of the base part and of the base flange in order to form regions with
different layer
thicknesses of the enveloping layer at mutually opposite sides of the base
flange. The forces
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exerted on the stud pin under braking, under traction and during cornering on
icy
underlying surfaces are transmitted into the base flange with particular
intensity owing to
the lever action. A thicker enveloping layer with greater elasticity and
better damping
behavior is therefore provided at that region of the base flange side where
softer embedding
is advantageous. A thinner and therefore less elastic enveloping layer gives
rise to stiffer
embedding of the studs under particular loads.
In a preferred embodiment, the at least one portion in which the enveloping
layer has a
relatively great thickness forms an enveloping layer cushion. The embodiment
as a cushion
is associated with the advantage of a substantially continuous transition into
the adjacent
enveloping layer portions via layer thicknesses which become thinner.
Also particularly advantageous is an embodiment of the stud in which the base
flange has
outer surfaces which, in plan view, run in a straight manner along the
longitudinal sides of
said base flange and run in an outwardly curved manner along the narrow sides
of said base
flange. Here, the longitudinal sides may, in plan view, run in a straight
manner and in
particular parallel to one another, and the two narrow sides are in particular
of arcuately
outwardly rounded design, and may also be of corresponding design. The
longitudinal sides
may furthermore run such that the base flange has a greater width at one
narrow side than at
the other narrow side. The base flange therefore has, in particular, one of
the common and
uniform, in plan view substantially oval, shapes which permit good anchoring
of the stud in
conventional stud holes of treads in pneumatic vehicle tires.
Also particularly advantageous is an embodiment of the base part of the insert
with
longitudinal and narrow sides which are assigned to the longitudinal and
narrow sides of
the base flange and which have outwardly rounded delimiting surfaces at the
narrow sides
and with, along one longitudinal side, two delimiting surfaces which run at an
obtuse
internal angle with respect to one another, such that the enveloping layer
forms, to the outer
surface of the base flange, two enveloping layer cushions which are preferably
triangular in
plan view. The obtuse internal angle between the delimiting surfaces amounts
in particular
to 150 to 170 , and the greatest thickness of the enveloping layer cushions
amounts, in the
preferred embodiment, to 0.35 mm to 1.0 mm, in particular 0.7 mm to 1.0 mm.
Particularly
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advantageous embedding stiffness of a stud designed in this way is obtained if
the stud is
positioned in the tread and in the tread halves thereof such that the
longitudinal sides of the
base flange extend in a circumferential direction and the enveloping layer
cushions in the
base flange are situated in each case closer to the adjacent tread edge. In
the event of the
stud pin being loaded in an axial or predominantly axial direction with
respect to the non-
cushioned base flange edge, the stud can be well supported in said region, and
forces for
good lateral guidance can be optimally transmitted. In the event of loading in
the opposite
axial direction, for example owing to slipping movements during the flattening-
out of the
tire, then the relatively soft embedding of the stud in the region of the
enveloping layer
cushions takes effect, and the stud can deflect in a relatively pliant manner
in the desired
way.
In the case of an embodiment of the stud with at least one enveloping layer
cushion at a
longitudinal side of the base part or of the base flange, the enveloping layer
has, in those
regions where no enveloping layer cushion is formed, a thickness smaller than
the greatest
thickness of the enveloping layer cushion(s).
In the case of embodiments of the stud with at least one enveloping layer
cushion at one
longitudinal side of the base part or base flange, a particular design of the
stud pin or of its
end portion which projects beyond the stud body, and of the grip edges formed
there at the
top surface, is also particularly advantageous for optimum ice grip. The end
portion of the
stud pin is elongate transversely with respect to the longitudinal sides of
the base flange and
of the base part and has two grip edges which extend in the direction of the
longitudinal
sides and which are of unequal length, wherein the longer grip edge is that
which is closer
to the longitudinal side at which the enveloping layer cushion(s) is or are
formed.
In a further advantageous embodiment of the stud, the base part has
longitudinal and
narrow sides which are assigned to the longitudinal and narrow sides of the
base flange and
which have outwardly rounded delimiting surfaces at the narrow sides, wherein
at least one
of said delimiting surfaces is, in the region of its rounding center, equipped
with a flattened
portion which runs in particular in a straight manner in plan view, such that
the enveloping
layer forms an enveloping layer cushion to the outer surface of the base
flange.
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Here, an embodiment of the stud is particularly preferred in which the narrow
sides of the
base flange and of the base part are of unequal width, wherein the base part
is, at least at its
wider narrow side, in the region of the rounding center, equipped with a
flattened portion
5 which runs in particular in a straight manner in plan view and which
preferably has a length
of 2.0 mm to 3.0 mm. The greatest thickness of said enveloping layer cushion
amounts in
particular to 0.5 mm to 1.0 mm, preferably 0.7 mm to 1.0 mm. It is
particularly
advantageous here if such studs are positioned in the tread such that the
enveloping layer
cushion is assigned to, or faces toward, the circumferential direction of the
tire. This stud
arrangement is particularly favorable for the embedding stiffness in the case
of forces
which act under traction loading and braking loading on icy underlying
surfaces.
In a further preferred and advantageous embodiment of the stud, at each of the
outwardly
rounded delimiting surfaces, at the narrow sides, in the region of the
rounding center, there
is provided a flattened portion which runs in a straight manner in plan view,
wherein the
enveloping layer cushion at the narrow side with the greater width has a
greater thickness at
its thickest point than the enveloping layer cushion at the narrow side with
the smaller
width. In this way, the embedding stiffness under braking and traction loading
can be
influenced in a targeted manner.
In a further advantageous embodiment of said stud, provision is made whereby
the base
part has, at its longitudinal sides, delimiting surfaces which run in a
concavely inwardly
curved manner, wherein the enveloping layer is, at these delimiting surfaces,
preferably
formed so as to have outer surfaces which run in a straight manner in plan
view and a
correspondingly varying layer thickness of in particular 0.2 mm to 0.4 mm. The
layer
thickness is therefore smaller along these delimiting surfaces than in the
region of
enveloping layer cushions at the narrow sides. In the central region of these
delimiting
surfaces, the layer thickness is at its greatest owing to the concave design
of the delimiting
surfaces, and can therefore likewise influence the embedding stiffness of the
stud.
In the case of this stud embodiment, a particular embodiment of the stud pin
or of its grip
edges at its outer top surface is of particular advantage for good ice
performance. In the
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case of this embodiment, the end portion of the stud pin is, in plan view,
elongate
transversely with respect to the longitudinal sides of the base flange and of
the base part
and has grip edges of unequal length in relation to the narrow sides of the
base part,
wherein the shorter grip edge is that which is situated closer to the
enveloping layer cushion
at the narrow side or, if enveloping layer cushions are formed at both narrow
sides, to the
respectively thicker enveloping layer cushion.
The invention furthermore relates to a pneumatic vehicle tire having a tread
with studs
designed according to the invention, wherein the studs are positioned in the
tread such that
their relatively long extent is assigned to the circumferential direction, or
substantially the
circumferential direction. Here, an arrangement is also particularly
advantageous in which
the studs arc arranged in stud tracks running over the circumference, and, in
each stud
track, there are situated in each case studs with enveloping layer cushions
formed at the
narrow sides and studs with enveloping layer cushions formed at the
longitudinal sides.
Also particularly favorable is an arrangement of the studs in the tread such
that
predominantly or exclusively studs with enveloping layer cushions at the
narrow sides are
formed in the central region of the tread, and primarily or exclusively studs
in the case of
which the enveloping layer cushions are formed at the longitudinal sides are
formed in the
lateral regions of the tread.
According to one aspect, there is provided a stud for anchoring in a stud hole
of a tread of a
pneumatic vehicle tire. The stud having a stud body which is composed of a
nonmetallic,
elastic material, and which comprises a base flange, and having a stud pin,
which stud pin
is composed of hard metal and is anchored in an insert which is situated
within the stud
body and which comprises a base part, and which stud pin projects with an end
portion
beyond the stud body, wherein the base part together with an enveloping layer
composed of
the material of the stud body forms the base flange of the stud body, and
wherein the base
flange has an outer contour which is designed symmetrically with respect to at
least one
plane of symmetry and which has two longitudinal sides and two narrow sides,
characterized in that the outer contour of the base part differs geometrically
from that of the
base flange, such that the enveloping layer has, at that side of the base part
which is
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assigned to a longitudinal side and/or to a narrow side, at least one portion
in which said
enveloping layer is thicker than at the opposite side of the base part.
According to another aspect, there is provided a pneumatic vehicle tire having
a tread with
studs as described above, characterized in that the studs are positioned in
the tread such
that, in each tread half, the enveloping layer cushions in the base flange are
situated in each
case closer to the adjacent tread edge.
According to another aspect, there is provided a pneumatic vehicle tire having
a tread with
.. studs as described above, characterized in that the studs are positioned in
the tread such that
the enveloping layer cushion(s) is or are assigned to, or face(s) toward, the
circumferential
direction of the tire.
Further features, advantages and details of the invention will now be
described in more
detail on the basis of the drawing, which illustrates exemplary embodiments.
In the
drawing:
figure 1 and figure 2 show side views of a first embodiment of a stud
according to the
invention,
figure 3 shows an oblique view of the stud as per figure 1 and figure 2,
figure 4 shows a plan view of the stud according to the first embodiment,
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figure 5 is a sectional illustration along the section plane denoted by the
line V-V in figure
4,
figure 6 is a sectional illustration along the section plane denoted by the
line VI-VI in figure
4,
figure 7 is a sectional illustration along the section plane denoted by the
line VII-VII in
figure 1,
figure 8 and figure 9 show side views of a second embodiment of a stud
according to the
invention,
figure 10 shows an oblique view of the stud as per figure 8 and figure 9,
figure 11 shows a plan view of the stud according to the second embodiment,
figure 12 is a sectional illustration along the section plane denoted by the
line XII-XII in
figure 11,
figure 13 is a sectional illustration along the section plane denoted by the
line XIII-XIII in
figure 11,
figure 14 is a sectional illustration along the section plane denoted by the
line XIV-XIV in
figure 1, and
figure 15 shows a plan view of a circumferential portion of a tread of a
pneumatic vehicle
tire with a design variant of the arrangement of the studs.
Figures 1 to 14 are simplified illustrations of studs 1, 1' according to the
invention.
Expressions such as vertical, above, below and the like used in the following
description
relate to the illustrations of the studs 1, 1' in the figures.
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The studs 1 (figure 1 to figure 7) and 1' (figure 8 to figure 14) shown in the
figures are
composed basically of a stud body 2 (figure 1 to figure 7) and 2' (figure 8 to
figure 14) and
of a stud pin 3 (figure 1 to figure 7) and 3' (figure 8 to figure 14). In the
stud body 2, 2',
there is contained an insert 4, 4' which has a base part 4a, 4'a and a pin
holder 4b, 4'b, in the
center of which in each case the stud pin 3, 3' is anchored, which projects
with an end
portion 3a, 3'a beyond the stud body 2, 2'. The studs 1, 1' have vertically
running central
vertical axes a (figures 5 and 6; figures 12 and 13) on which the center of
gravity (not
designated) of the studs 1, 1' is situated.
The insert 4, 4' is composed of plastic, in particular of a thermosetting
plastic or
thermoplastic material, or of metal, in particular of aluminum. The pin holder
4, 4', which
in the embodiments shown is of block-like form by way of example, extends into
the
central region of the stud body 2, 2'. The base part 4a, 4'a of the insert 4
is a component
which projects beyond the pin holder 4b, 4'b preferably at all sides and whose
greatest
thickness di (figure 5, figure 12) is of the order of magnitude of 1.0 mm to
1.4 mm.
The stud body 2, 2' has a base flange 6, 6' which is composed of the base part
4a, 4'a of the
insert 4, 4' and of an enveloping layer 5, 5' which surrounds the base part
4a, 4'a, such that
the base part 4a, 4'a is embedded into the material of the stud body 2, 2'.
Aside from the
base flange 6, 6', the stud body 2, 2' is a cylindrical component in the
simplified
embodiments illustrated. The stud body 2, 2' may however also have some other
external
form, for example may be of frustoconical or some other conical design.
The stud body 2, 2' is composed of a non metallic, elastic material,
preferably a rubber
material, in particular a cut-resistant and abrasion-resistant rubber
material. Alternatively,
the stud body 2, 2' is composed of a thermoplastic vulcanizate with properties
similar to
rubber materials. Mixture compositions for producing suitable rubber
materials, and
suitable thermoplastic vulcanizates, are well known to a person skilled in the
art in the field
of tires. The material of the stud body 2, 2' furthermore encases the end
portion 3a, 3'a of
the stud pin 3, 3', possibly with or without covering the top surface 7, 7' of
the end portion
3a, 3'a.
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The stud pin 3, 3' is composed in particular of a hard metal and is a
component which is of
pin-like design and which tapers conically over its length and which is
fixedly anchored
with its tapered end portion in the pin holder 4b, 4'b. The cross-sectional
area of the stud
pin 3, 3' becomes continuously smaller along the longitudinal extent of the
stud pin 3, 3'
owing to the taper of the stud pin 3, 3', but remains geometrically similar in
the preferred
embodiment of the stud pin 3, 3'.
In the embodiment shown in figure 1 to figure 7, the base part 4a of the
insert 4 is an
elongate oval component with narrow sides which are of equal width in plan
view and with
two differently designed longitudinal sides. As shown in particular in figure
7, at the
narrow sides, there are situated arcuately outwardly rounded delimiting
surfaces 8a,
wherein the delimiting surfaces 8a are connected to one another at one
longitudinal side by
a straight-running delimiting surface 8b and at the other longitudinal side by
two delimiting
surfaces 8ci and 8c2 which run at an obtuse internal angle a with respect to
one another.
The obtuse angle a is of the order of magnitude of 150 to 170 . The two
delimiting
surfaces 8ci and 8c2 preferably have corresponding lengths, and the transition
region
thereof into one another is of rounded form in the exemplary embodiment shown.
The enveloping layer 5 surrounds the foot part 4a along the delimiting
surfaces 8a and 8b
with an in each case constant or virtually constant thickness of the order of
magnitude of
0.2 mm to 0.30 mm. Along the delimiting surfaces 8ci and 8c2, the enveloping
layer 5 has
an outer surface which runs parallel to the outer surface which runs along the
delimiting
surface 8b at the opposite region of the enveloping layer 5, such that, along
the delimiting
surfaces 8ci and 8c2, there are enveloping layer cushions 9 which, in plan
view (figure 7) or
in cross section, are triangular and thickened in relation to the rest of the
layer thickness of
the enveloping layer 5. The thickness d2 of said enveloping layer cushions 9
is, at its
thickest point, of the order of magnitude of 0.35 mm to 1.0 mm, in particular
at least 0.7
mm. In the region of the transition rounding between the delimiting surfaces
8ci and 8c2,
there is only a very thin rubber layer with a thickness of the order of
magnitude of 0.1 mm
to 0.15 mm.
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In the preferred embodiment, the width bi of the base flange 7 is of the order
of magnitude
of 6.5 mm to 7.0 mm, in particular 6.7 mm, and its greatest length 11 amounts
to 7.7 mm to
8.3 mm, in particular 8.0 mm. Owing to the embodiment of the base part 4a, the
stud 1 has
a single plane of symmetry which extends through the vertical axis a and which
runs at
5 right angles to the longitudinal sides of the base flange 7 and which is
represented in figure
4 by the line Si.
In the illustrated and preferred embodiment, the stud pin 3 is likewise of
symmetrical
design only with respect to the plane of symmetry Si. Of importance for the
ice grip is the
10 design of the outer top surface 7 at the end portion 3a of the stud pin
3. The top surface 7
has its greatest extent length along the plane of symmetry Si, such that, in
plan view, the
stud pin 3 is elongate along the plane of symmetry Si. The length 12 (figure
4) of the top
surface 7 amounts to 2.7 mm to 3.2 mm, and the greatest width b2 thereof
amounts to 2.0
mm to 2.3 mm. The top surface 7 thus has, at its narrow sides situated in the
longitudinal
extent, in each case one grip edge 10ai, 10a2 running at right angles to the
plane of
symmetry Si, wherein the grip edge 10ai is longer than the grip edge 10a2. The
length of
the grip edge 10ai amounts to 1.6 mm to 2.2 mm, and the length of the grip
edge 10a2 is
smaller by 0.2 mm to 0.5 mm. The stud pin 3 is anchored in the pin holder 4b
such that the
longer grip edge 10ai is that which is situated closer to the delimiting
surfaces 8ci and 8c2
of the base part 4a of the insert 4.
In the embodiment shown, the two grip edges 10ai, 10a2 are connected to one
another in
each case by two grip edges 1 lai and 1 1a2 which are of identical design and
which run at
an obtuse internal angle (3 of the order of magnitude of preferably 160 to
170 with respect
to one another. Furthermore, in the embodiment shown, the grip edge llai
directly
adjoining the grip edge 10ai is shorter than the grip edges 11a2. In
alternative embodiments
which are not separately illustrated, the grip edges 10ai, 10a2 are connected
to one another
in each case by a single straight grip edge or by an arcuately outwardly
running grip edge.
The grip edges 10ai, 10a2, llai and 11a2 transition, along the stud pin 3,
into said
correspondingly delimiting side surfaces.
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The special embodiment of the base part 4a of the insert 4 makes it easier for
the insert 4
with the stud pin 3 to be inserted with the correct orientation into the mold
in order to be
encapsulated with the material of the stud body 2.
.. For the properties of the stud 1, the special embodiment of the base flange
6 with
enveloping layer cushions 9 is of importance, which enveloping layer cushions
make it
possible for the embedding stiffness of the stud 1 inserted in the tread to be
influenced and
optimized. As indicated for example in figure 4 by the arrow U, the stud 1 is
positioned in
the tread preferably with its longer extent of the base flange 6 parallel or
approximately
parallel - with a deviation of up to approximately 15 - to the
circumferential direction of
the tread, and, in the tread halves, furthermore such that the enveloping
layer cushions 9 in
the base flange 6 are situated in each case closer to the adjacent tread edge,
resulting in a
different embedding stiffness of the stud 1 in a manner dependent on the
predominantly
acting loading direction. In the event of loading of the stud pin 3 in an
axial or
predominantly axial direction, as indicated in figure 7 by the arrow Pi, then
the stud 1 is
supported in the region of the non-cushioned base flange edge. Forces for good
lateral
guidance can thus be optimally transmitted. In the event of loading from the
direction of the
arrow P2, for example owing to slipping movements during the flattening-out of
the tire,
then the relatively soft embedding of the stud 1 in the region of the
enveloping layer
cushions 9 takes effect, and the stud 1 can deflect in a relatively pliant
manner in the
desired way.
In the embodiment shown in figure 8 to figure 14, the base part 4'a of the
insert 4' is
likewise an elongate oval component, but with narrow sides which are of
unequal width in
plan view and with identically designed longitudinal sides (figure 14). The
stud 1' is of
symmetrical design with respect to a plane of symmetry S2 (figure 11) running
in the
longitudinal extent of the base flange 4'a through the vertical axis a. At the
narrow sides of
the base part 4'a, there are situated arcuately outwardly rounded delimiting
surfaces 8'ai and
8'a2. At the longitudinal sides, there are situated delimiting surfaces 8'b
which run in a
concavely inwardly curved manner. Straight lines which connect the ends of the
delimiting
surfaces 8'b run in each case at an acute angle 7, of the order of magnitude
of 50 to 200
,
with respect to the plane of symmetry S2, such that the spacing of said
straight lines to one
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another at their ends at the delimiting surface 8'ai is smaller than the
spacing of said straight
lines to one another at their ends at the delimiting surface 8'a2. The
delimiting surfaces 8'ai
and 8'a2 are, in each case in the region of their rounding centers, equipped
with a flattened
portion 12ai and 12a2 which runs in a straight manner in plan view. Said
portions 12ai and
12a2 run at right angles to the plane of symmetry S2. The portion 12ai is
shorter by 0.3 mm
to 0.8 mm than the portion 12a2, the length of which is of the order of
magnitude of 2.0 mm
to 3.0 mm. The enveloping layer 5' surrounds the delimiting surfaces 8'ai and
8'a2
unifoinily and in each case overall in an outwardly rounded manner and, at the
rounded
portions of the delimiting surfaces 8'ai and 8'a2, with a constant or
substantially constant
layer thickness d3, da. The layer thickness d3 of the enveloping layer 5'
along the rounded
portions of the relatively short delimiting surface 8'ai may however also be
smaller than
that along the rounded portions of the relatively long delimiting surface
8'a2. In any case, a
larger and thicker enveloping layer cushion 9' is formed along the flattened
portion 12a2 at
the relatively long delimiting surface 8'a2 than along the portion 12ai at the
delimiting
surface 8'ai. The thickness ds of said enveloping layer cushion 9' at the
flattened portion
12a2 amounts to 0.5 mm to 1.0 mm. Along the delimiting surfaces 8'b, which run
in a
concavely inwardly curved manner, of the base part 4'a, the enveloping layer
5' is formed
preferably with a planar outer surface and therefore with a correspondingly
varying layer
thickness d6 of 0.2 mm to 0.4 mm.
The stud pin 3', which is positioned in the center of the stud 1' along the
vertical axis a, has
a top surface 7' which approximately the form of an elongate rectangle with
beveled corners
and a length 13 of 2.8 mm to 3.2 mm and a width b3 of 1.8 mm to 2.0 mm,
wherein the stud
pin 3' is anchored in the insert 4' so as to extend at right angles to the
plane of symmetry S2
and thus so as to be symmetrical in relation thereto. The top surface 7'
therefore has two
relatively long grip edges 13ai and 13a2, which run at right angles to the
plane of symmetry
S2, and furthermore two relatively short grip edges 13b which run parallel to
the plane of
symmetry S, and which are of equal length. The grip edges 13b have in
particular an extent
length of 1.0 mm to 1.7 mm, the grip edge 13ai has a length of 2.3 mm to 3.2
mm, and the
grip edge 13a2 has a length which is shorter by up to 1.2 mm than the length
of the grip
edge 13ai. Corner edges 14a connect the grip edge 13ai to the grip edges 13b,
and corner
edges 14b connect the grip edge 13a2 to the grip edges 13b. Situated in an
adjoining manner
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13
along the extent of the stud pin 3' are side surfaces which proceed from the
grip edges 13at,
13a2, 13b and the corner edges 14a, 14b and which are designed correspondingly
and which
are not designated. Instead of corner edges and associated corner surfaces,
the stud pin 3'
may have transition roundings and rounded transition surfaces.
The stud 1' is a so-called traction and braking stud, which is preferably
provided in all stud
tracks of a tread, in particular in combination with studs 1. In the case of
treads of non-
directional design, approximately half of the studs 1' which are provided in
the tread are - in
a manner correspondingly distributed over the circumference - arranged with an
orientation
with respect to the circumferential direction (arrow U in figure 11) as
illustrated in the
figures, and the second half of the studs 1' which are provided are arranged
with an
opposite orientation. What is particularly advantageous, however, is the
arrangement of the
studs 1' in treads of tires with a predefined direction of rotation during
forward travel, that
is to say in tires with a tread which is of directional design. Here, the
studs 1' are arranged
such that, as the tire rolls during forward travel, the wider side of the base
flanges 6' points
in the rolling direction, as indicated by the arrow U in figure 11. Such an
arrangement of
the studs 1' is particularly advantageous for the embedding stiffness in the
case of forces
which act under traction loading and braking loading on icy underlying
surfaces.
Under traction, the stud pin 3' of the stud 1' easily engages with its
relatively short grip
edge 13a2 into the ice surface and commences the transmission of force; in the
process, it is
tilted and is supported in a stiff manner on the relatively narrow enveloping
layer cushion 9.
The front, relatively thick enveloping layer cushion 9' facilitates the
tilting of the stud,
because the elastic rubber material has a lower stiffness than the plastics or
aluminum
material of the base part 4'a. In this way, the stud 1' can easily "stand
upright" in order to
form a greater projecting length and in order to more quickly assume the
optimum cutting
angle.
During the transmission of braking force, the stud pin 3' also initially
engages with its
relatively short grip edge 13a2 into the ice, but is then "tipped over owing
to the relative
movement between tire and road surface, and then transmits the braking forces
by way of
its relatively long grip edge 13ai. During the "tipping over" of the stud, the
pin 3' is, in
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14
effect, automatically pressed into the ice. To maximize the braking forces, it
is particularly
important for the stud 1' to be embedded in a flexible manner in order that
stress peaks are
dissipated and thus premature ice breakage is prevented. The flexible
embedding is realized
by means of the relatively thick, elastic enveloping layer cushion 9' on the
base flange 6'.
Figure 15 schematically shows a circumferential portion of a tread for a
passenger motor
vehicle winter tire with a directional profile. The tread shown by way of
example has two
shoulder-side profile block rows 15 and, between these, in the central tread
region, further
profile blocks 16 which are formed by transverse channels 17 running in a V
shape over the
width of the tread and by a number of circumferential channels 18 and oblique
channels 19.
The direction of rotation during forward travel is denoted by an arrow P. B
denotes the
width of that part of the tread which makes contact with the ground. Within
this width B,
the studs 1, l' are arranged in so-called stud tracks Sp, the number of which
normally
amounts to between 4 and 25, in particular 12 and 20. Stud tracks Sp are lines
running in a
circular encircling manner parallel to the circumferential direction, and are
represented in
figure 15 by dashed lines. In the embodiment shown in figure 15, seven stud
tracks Sp are
provided in each tread half, the arrangement of which is symmetrical in
relation to the tire
equator A-A.
In the circumferential portion shown at least one stud 1 and at least one stud
1' are shown in
each stud track by way of example. Normally, 4 to 25, in particular 7 to 16,
studs 1, 1' are
positioned over the circumference of the tire in each stud track Sp. In an
alternative
embodiment, exclusively studs 1 are positioned in the stud tracks Sp in the
two lateral
circumferential regions, and exclusively studs 1' are positioned in the stud
tracks Sp in the
central circumferential region.
Date Recue/Date Received 2020-07-13
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List of reference designations
5 ......... 1,1' Stud
2, 2' ......... Stud body
2a ............ Stud body part
3,3' .......... Stud pin
4, 4' ......... Insert
10 ........ 4a, 4'a Base part
4b, 4'b ....... Pin holder
5, 5' ......... Enveloping layer
6, 6' ......... Base flange
7, 7' ......... Top surface
15 8a, 8b Delimiting surface
8'a2 .......... Delimiting surface
8'b ........... Delimiting surface
8ci, 8c2 ...... Delimiting surface
9, 9' ......... Enveloping layer cushion
........ 10al, 10a2 Grip edge
11a2 .......... Grip edge
12ai, 12a2 .... Portion
13a2 .......... Grip edge
13b ........... Grip edge
........ 14a, 14b Comer edge
15 ............ Profile block row
16 ............ Profile block
17 ............ Transverse channel
18 Circumferential channel
19 Oblique channel
ct, 0, y ...... Angles
AA ............ Tire equator
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a ............. Vertical axis
.............. Width
bi, b2, h3 .... Width
11,12,13 ...... Length
......... di, d2 Thickness
d3, da, d5, d6 .. Thickness
Pi, P2 ........ Arrow
Pv ............ Arrow
Si, S2 ........ Plane of symmetry
........ SP Stud track
Date Recue/Date Received 2020-07-13
