Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1
Description
Spike for anchoring in a tread of a pneumatic tyre
The invention relates to a spike for anchoring in a spike hole of a tread of a
pneumatic
vehicle tyre, having a spike body composed of rubber, a base part, which is
situated at least
partially within the spike body and which is composed of a bottom flange and a
pin holder,
in which pin holder there is anchored a spike pin which projects with an end
portion beyond
the spike body and, when the spike is inserted in the tread, beyond the tread
surface,
wherein the end portion is surrounded by a rubber layer, and the bottom flange
is encased
with a rubber layer, wherein the bottom flange and the pin holder are each
parts with an
oval or approximately oval form in plan view, wherein the oval of the pin
holder is
rotationally offset through 900 in relation to the oval of the bottom flange,
and wherein, in
plan view, the bottom flange has a center width and the pin holder has a
length and a width.
The invention furthermore relates to a pneumatic vehicle tyre with spikes.
Spikes are generally held in the spike holes of the tread of pneumatic vehicle
tyres by a
combination of positive engagement and clamping. Conventional spikes generally
comprise
a spike body composed of aluminum or steel, in which is held the spike pin,
which projects
beyond the tread surface and is composed of hard metal.
It is customary to use gritting material on winter roads to increase traffic
safety. In recent
years, the use of sand has been reduced in favor of grit since sand tends to
be ground up by
tyres into dust or fine dust, which should be reduced or avoided to protect
the health of the
population. However, the use of grit leads to increased wear on the
conventional spikes
present in pneumatic vehicle tyres, especially if the spike body thereof is
composed of
aluminum.
There has therefore already been a proposal to use spikes with spike bodies
made of rubber.
Thus, WO 2017/088995 Al, for example, discloses spikes in which the spike pin
and/or the
bottom flange is or are integrated at least partially into a rubber jacket or
into rubber
material. WO 2017/088995 discloses variant embodiments of spikes which
correspond to a
Date Recue/Date Received 2021-06-29
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spike of the type stated at the outset. The particular advantages of these
embodiments
consist in the fundamental material properties of the rubber body. Its low
density of about 1
g/cm3 makes rubber particularly light in comparison with aluminum and steel.
Replacing
aluminum and steel with rubber as a body material leads to a reduction in the
spike weight,
which has a particularly positive effect on road wear and the formation of
fine dust. Road
wear is determined principally by the impact energy of the spike. The flexible
material
properties of rubber have even more advantages. On the one hand, the flexible
body
material damps impacts, with the result that smaller forces act on stones in
the road surface
or on particles of gritting material. Thus, road wear and the formation of
fine dust are also
.. reduced thereby. Moreover, spike bodies composed of rubber are superior to
those
composed of aluminum or steel in terms of abrasion behavior since they have
completely
different wear behavior. If the tyre rolls over stones in the road surface
and, in particular,
grit from gritting material in the vicinity of a conventional spike, the
profile in the tread is
deformed to a very great extent and "gives way" to the side. The fixed, rigid
spike cannot
.. follow this "movement of giving way". As a result, a gap is formed between
the spike and
the rubber, thus exposing the upper and the lateral surface of the spike body
to the abrasive
action of the stones. Since stones in the road surface and grit are generally
harder than
aluminum and even steel, the spike body is more severely abraded, resulting in
a reduction
in the spike body height and the diameter of the spike body. This leads to the
spike hole
edges being subject to abrasion with a cutting effect. They erode, as a result
of which the
gap between the spike and the surrounding rubber matrix is enlarged. This
favors the
penetration of sand and smaller stones, further accelerating spike body
abrosion. As a
consequence, the lateral retaining forces on the spike are reduced, leading to
a reduction in
the winter properties due to severe tilting and, in the worst case, to loss of
the spike.
The invention addresses the problem of improving a spike of the type mentioned
at the
beginning, in particular designing it in such a way that it is optimized with
regard to
flexible deformation and with regard to its suitability for absorbing impact.
.. According to the invention, the problem addressed is solved by virtue of
the fact that the
spike body is of circular-cylindrical design and has a diameter which
corresponds to the
center width of the bottom flange or which deviates from said width by up to
1.0 mm,
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wherein the base part has a height of 40% to 60% of the spike height, and
wherein the ratio
between the length and the width of the pin holder is 1.10 to 1.18.
The pin holder is therefore of almost circular-cylindrical design and is thus
encased to an
approximately equal thickness by rubber material of the circular-cylindrical
spike body. By
virtue of the adaptation of its diameter to the center width of the bottom
flange of the base
part, the spike body has a large rubber volume, wherein this measure, together
with the
measure that the height of the base part is no more than 60% of the spike
height, ensures
that the spike body encases both the pin and also the base part with a rubber
layer that is
ideal for flexible deformation and for damping shocks. Since gap formation is
avoided, the
body material made of rubber is abraded at substantially the same rate as that
of the
surrounding rubber matrix, and the spike hole edges are not subject to
abrasion with a
cutting effect. In the case of rubber spikes according to the invention, there
is no reduction
in the spike body diameter or increased length reduction, and therefore the
lateral retaining
forces are maintained at a high level. These effects lead to maintenance of
the winter
properties, especially "ice performance", of the spike at a high level.
In a preferred embodiment of the spike, the ratio between the length and the
width of the
pin holder of the base part is up to 1.16. As a result, the external form of
the pin holder
advantageously approaches that of a circular cylinder to an even greater
extent.
Also preferred is an embodiment in which the spike pin is of elongate design
in plan view
and is anchored in the pin holder in such a way that its longitudinal extent
extends along the
longitudinal extent of the pin holder. With the preferred orientation of the
bottom flange of
.. the spike in the installed state in the circumferential direction of the
tread, the spike pin is
oriented with its longer extent in the axial direction and is therefore
particularly effective on
an icy underlying surface.
In another preferred embodiment, the bottom flange has, in plan view, a length
of 7.0 mm
to 9.0 mm and a center width which is 1.0 mm to 2.0 mm less than the length of
said flange.
These dimensions of the bottom flange are particularly favorable for good
retaining forces
of the spike in the tread.
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Another preferred embodiment is one in which the length of the pin holder is
4.0 mm to 4.5
mm and the width of the pin holder is 0.4 mm to 0.6 mm less than the length of
said pin
holder.
As mentioned, the bottom flange can be of oval or approximately oval design.
In the case of
an approximately oval embodiment of the bottom flange, said flange has
straight and
mutually parallel side faces along the longer extent of said flange or
straight and mutually
tapered side faces along the longer extent of said flange, for example. Both
embodiments
are advantageous for good anchoring of the bottom flange in the rubber
material of the
tread.
The rubber layer on the upper end portion of the spike pin and on the bottom
flange
preferably has a thickness of 0.2 mm to 0.5 mm. A rubber layer of this
thickness is easy to
produce, especially when using an adhesion promoter.
In another preferred embodiment, the bottom flange has, on the underside
thereof, a recess
with a depth of 0.3 mm to 0.5 mm, which is filled with rubber material,
wherein the
underside of the bottom flange is at least largely flat. The rubber cushion
formed by the
recess acts as a damping element in the presence of vertical forces acting on
the spike as the
tyre rolls.
The total height of the spike is 6.0 mm to 20.0 mm, in particular 8.0 mm to
12.0 mm, and
the height of the base part is 40% to 60% of the spike height.
According to an aspect, a spike for anchoring in a spike hole of a tread of a
pneumatic
vehicle tyre is provided. The spike has a spike body composed of rubber, a
base part
situated at least partially within the spike body and which is composed of a
bottom flange
and a pin holder. A spike pin is anchored and projects from the pin holder,
with an end
portion of the spike pin projecting beyond the spike body and, when the spike
is inserted in
the tread, beyond a tread surface. The end portion is surrounded by a first
rubber layer, and
the bottom flange is encased with a second rubber layer, where the bottom
flange and the
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pin holder are each parts with an oval, or approximately oval, form in plan
view. The oval
of the pin holder is rotationally offset through 900 in relation to the oval
of the bottom
flange, and wherein the bottom flange, in plan view, has a center width and
the pin holder,
in plan view, has a length and a width, wherein the spike body is of circular-
cylindrical
design and has a diameter which corresponds to the center width of the bottom
flange or
which deviates from the center width by up to 1.0 mm, wherein the base part
has a height of
40% to 60% of a spike height, and wherein the ratio between the length and the
width of
the pin holder of the base part is between 1.10 and 1.18.
The invention furthermore relates to a pneumatic vehicle tyre having a tread
with spikes
that are embodied in accordance with the invention, wherein the spikes are
anchored in the
tread in such a way that the bottom flanges of said spikes extend in the
circumferential
direction.
Further features, advantages and details of the invention will now be
described in more
detail on the basis of the drawing, which illustrates an exemplary embodiment.
In the
drawing,
Figure 1 shows a plan view of a spike according to the invention,
Figure 2 shows a sectional illustration of the spike along the line II-II of
figure 1, and
Figure 3 shows a sectional illustration of the spike along the line of
figure 1.
The spike 1 shown in the figures comprises a base part 2, a spike pin 3 and a
spike body 4.
The base part 2, which, in particular, is composed of aluminum, has a bottom
flange 5 and a
pin holder 6 formed integrally therewith. The base part 2 and the spike body 4
are of
symmetrical design in relation to two mutually perpendicular planes of
symmetry Si and S2
which intersect along the central vertical axis of the spike 1. In plan view,
the bottom flange
5 has an oval or approximately oval shape with two side faces 5a oriented in
the longer
extent of the oval and parallel to plane of symmetry Si and two arc-shaped end
faces 5b
connecting these side faces 5a to one another. The bottom flange 5 therefore
has its greatest
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length 1F, which is 7.0 mm to 9.0 mm, along plane of symmetry Si, and its
greatest width bF
corresponds to the mutual spacing between the straight side faces 5a and is
1.0 mm to 2.0
mm, in particular up to 1.5 mm, less than its length IF. The spike 1 is
preferably positioned
in the tread of a pneumatic vehicle tyre in such a way that the side faces 5a
of the bottom
flange 5 run parallel to the circumferential direction of the tread. In the
case of an
alternative embodiment (not illustrated), the side faces are slightly tapered
relative to one
another, with the result that, at its one end, the bottom flange has a width
which is greater
by up to 1.0 mm than at its other end.
On its underside, the bottom flange 5 is provided with a shallow recess Sc,
which has its
maximum depth tF of 0.3 mm to 0.6 mm at the center of the bottom flange 5.
Situated
centrally on the bottom flange 5 is the pin holder 6, which in plan view is an
oval body, in
which the spike pin 3 is held centrally. In plan view, the pin holder 6 has
its greatest extent
along plane of symmetry S2, and therefore its maximum length 1p, which is
along plane of
symmetry S,, is preferably 4M mm to 4.5 mm, and its maximum width bp along
plane of
symmetry Si is, in particular, 0.4 mm to 0.6 mm less than its length 1p. The
ratio between
the length and the width of the pin holder 6 is 1.10 to 1.18, in particular up
to 1.16.
In particular, the spike pin 3 is composed of a hard metal and is likewise of
elongate design
in plan view and, according to a preferred embodiment, is of symmetrical
design with
respect to the two planes of symmetry Si and Sz. Like the pin holder 6, the
spike pin 3 has
its greatest extent along plane of symmetry S2. In plan view, the spike pin 3
can be of oval
or quadrilateral design or can be designed as some other polygon and one end
portion 3a
thereof projects beyond the spike body 4 in the direction of the vertical
axis. In the
embodiment shown, the cross-sectional area of the spike pin 3 becomes
continuously
smaller in the direction of its end portion anchored in the pin holder 6,
starting from its
outer surface on the end portion 3a. The pin holder 6 thus forms a socket for
the spike pin 3
with a wall thickness d which is in the range of 0.9 mm to 1.2 mm.
The spike body 4 is composed of rubber and surrounds the pin holder 6 of the
base part 2 as
well as that part of the spike pin 3 which projects beyond the pin holder 6 -
apart from the
end portion 3a - as a circular-cylindrical body in which these parts are
embedded. In the
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preferred and illustrated embodiment, the diameter D of the spike body 4
corresponds to the
width bF of the bottom flange 5 and, in the case of a bottom flange with
tapering side faces,
corresponds to the width in the center of the bottom flange, but it can
deviate by up to 1.0
mm from this, in particular being less than this. The end portion 3a of the
spike pin 3
projects beyond the spike body 4 by 1.3 mm 0.2 mm and is that portion of the
spike pin 3
which projects beyond the tread periphery when the spike 1 is positioned in
the tread of a
pneumatic vehicle tyre and which comes into contact with the underlying
surface or the
road as the tyre rolls. The end portion 3a of the spike pin 3 is surrounded on
the outside by
a thin rubber layer 7 of the rubber material of the spike body 4, wherein the
outer surface in
the tip region of the spike pin 3 preferably does not have a rubber layer.
The bottom flange 5 of the base part 2 is surrounded or encased by a thin
rubber layer 8 of
the rubber material of the spike body 4. In this case, the recess Sc on the
underside of the
bottom flange 5 is filled with rubber material, ensuring that the underside of
the spike 1
forms a substantially flat surface. The rubber cushion thereby formed in the
recess Sc acts
as a damping element in the presence of vertical forces acting on the spike 1
as the tyre
rolls.
The rubber layers 7, 8 mentioned, which encase the bottom flange 5 and extend
around the
end portion of the spike pin 3 on the outside, have a thickness of, in
particular, 0.2 mm to
0.5 mm. The spike 1 is therefore sheathed by rubber material over all its
outer surfaces
which come into contact with the rubber material of the tread within the
tread. By means of
a conventional adhesion promoter for rubber materials, the spike 1 can thus be
connected in
a particularly durable manner to the rubber material of the tread.
The large rubber volume of the spike body 4, said volume being optimized in
the case of
spikes according to the invention, prevents the penetration of particles, such
as sand or grit,
into the region between the spike body 4 and the tread in a particularly
effective manner.
These particles are often to be found on roads or on an underlying surface on
which tyres
provided with spikes are used. Spikes according to the invention therefore
retain their effect
over the life of the tyre. In the case of an alternative embodiment, which is
not shown
separately, the spike body which surrounds the pin holder and the spike pin
and which, in
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the embodiment shown, is circular-cylindrical can be provided with a waist, a
recess which
encircles it. The total height H of the spike 1 can vary from embodiment to
embodiment
and is 6 mm to 20 mm, in particular 8 mm to 12 mm, particularly preferably 9
mm to 10
mm. The total height hi of the base part 2 is 40% to 60% of the spike height
H, wherein the
bottom flange 5 has a height he of 1.1 mm to 1.4 mm.
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List of reference signs
1. ............ Spike
2. ............ Base part
3 ....... Spike pin
3a ............ End portion
4 ............. Spike body
5 ............. Bottom flange
5a ............ Side face
5b ...... End face
5c ............ Recess
6 ............. Pin holder
7, 8 .......... Rubber layer
bF ............ Width of the bottom flange
bp ...... Width of the pinholder
D ............. Diameter of the spike body
d ............. Wall thickness
H ............. Spike height
hi ............ Height of the base part
hF ...... Height of the bottom flange
IF ............ Length of the bottom flange
1p ............ Length of the pin holder
Si, S2 ........ Plane of symmetry
t ............. Depth
Date Recue/Date Received 2021-06-29
